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/Modules/parsermodule.c

http://unladen-swallow.googlecode.com/
C | 3405 lines | 2521 code | 428 blank | 456 comment | 1103 complexity | b2835d6145228b011be75992b6438b0a MD5 | raw file
   1/*  parsermodule.c
   2 *
   3 *  Copyright 1995-1996 by Fred L. Drake, Jr. and Virginia Polytechnic
   4 *  Institute and State University, Blacksburg, Virginia, USA.
   5 *  Portions copyright 1991-1995 by Stichting Mathematisch Centrum,
   6 *  Amsterdam, The Netherlands.  Copying is permitted under the terms
   7 *  associated with the main Python distribution, with the additional
   8 *  restriction that this additional notice be included and maintained
   9 *  on all distributed copies.
  10 *
  11 *  This module serves to replace the original parser module written
  12 *  by Guido.  The functionality is not matched precisely, but the
  13 *  original may be implemented on top of this.  This is desirable
  14 *  since the source of the text to be parsed is now divorced from
  15 *  this interface.
  16 *
  17 *  Unlike the prior interface, the ability to give a parse tree
  18 *  produced by Python code as a tuple to the compiler is enabled by
  19 *  this module.  See the documentation for more details.
  20 *
  21 *  I've added some annotations that help with the lint code-checking
  22 *  program, but they're not complete by a long shot.  The real errors
  23 *  that lint detects are gone, but there are still warnings with
  24 *  Py_[X]DECREF() and Py_[X]INCREF() macros.  The lint annotations
  25 *  look like "NOTE(...)".
  26 */
  27
  28#include "Python.h"                     /* general Python API             */
  29#include "Python-ast.h"                 /* mod_ty */
  30#include "graminit.h"                   /* symbols defined in the grammar */
  31#include "node.h"                       /* internal parser structure      */
  32#include "errcode.h"                    /* error codes for PyNode_*()     */
  33#include "token.h"                      /* token definitions              */
  34#include "grammar.h"
  35#include "parsetok.h"
  36                                        /* ISTERMINAL() / ISNONTERMINAL() */
  37#include "compile.h"
  38#undef Yield
  39#include "ast.h"
  40#include "pyarena.h"
  41
  42extern grammar _PyParser_Grammar; /* From graminit.c */
  43
  44#ifdef lint
  45#include <note.h>
  46#else
  47#define NOTE(x)
  48#endif
  49
  50/*  String constants used to initialize module attributes.
  51 *
  52 */
  53static char parser_copyright_string[] =
  54"Copyright 1995-1996 by Virginia Polytechnic Institute & State\n\
  55University, Blacksburg, Virginia, USA, and Fred L. Drake, Jr., Reston,\n\
  56Virginia, USA.  Portions copyright 1991-1995 by Stichting Mathematisch\n\
  57Centrum, Amsterdam, The Netherlands.";
  58
  59
  60PyDoc_STRVAR(parser_doc_string,
  61"This is an interface to Python's internal parser.");
  62
  63static char parser_version_string[] = "0.5";
  64
  65
  66typedef PyObject* (*SeqMaker) (Py_ssize_t length);
  67typedef int (*SeqInserter) (PyObject* sequence,
  68                            Py_ssize_t index,
  69                            PyObject* element);
  70
  71/*  The function below is copyrighted by Stichting Mathematisch Centrum.  The
  72 *  original copyright statement is included below, and continues to apply
  73 *  in full to the function immediately following.  All other material is
  74 *  original, copyrighted by Fred L. Drake, Jr. and Virginia Polytechnic
  75 *  Institute and State University.  Changes were made to comply with the
  76 *  new naming conventions.  Added arguments to provide support for creating
  77 *  lists as well as tuples, and optionally including the line numbers.
  78 */
  79
  80
  81static PyObject*
  82node2tuple(node *n,                     /* node to convert               */
  83           SeqMaker mkseq,              /* create sequence               */
  84           SeqInserter addelem,         /* func. to add elem. in seq.    */
  85           int lineno,                  /* include line numbers?         */
  86           int col_offset)              /* include column offsets?       */
  87{
  88    if (n == NULL) {
  89        Py_INCREF(Py_None);
  90        return (Py_None);
  91    }
  92    if (ISNONTERMINAL(TYPE(n))) {
  93        int i;
  94        PyObject *v;
  95        PyObject *w;
  96
  97        v = mkseq(1 + NCH(n) + (TYPE(n) == encoding_decl));
  98        if (v == NULL)
  99            return (v);
 100        w = PyInt_FromLong(TYPE(n));
 101        if (w == NULL) {
 102            Py_DECREF(v);
 103            return ((PyObject*) NULL);
 104        }
 105        (void) addelem(v, 0, w);
 106        for (i = 0; i < NCH(n); i++) {
 107            w = node2tuple(CHILD(n, i), mkseq, addelem, lineno, col_offset);
 108            if (w == NULL) {
 109                Py_DECREF(v);
 110                return ((PyObject*) NULL);
 111            }
 112            (void) addelem(v, i+1, w);
 113        }
 114
 115        if (TYPE(n) == encoding_decl)
 116            (void) addelem(v, i+1, PyString_FromString(STR(n)));
 117        return (v);
 118    }
 119    else if (ISTERMINAL(TYPE(n))) {
 120        PyObject *result = mkseq(2 + lineno + col_offset);
 121        if (result != NULL) {
 122            (void) addelem(result, 0, PyInt_FromLong(TYPE(n)));
 123            (void) addelem(result, 1, PyString_FromString(STR(n)));
 124            if (lineno == 1)
 125                (void) addelem(result, 2, PyInt_FromLong(n->n_lineno));
 126            if (col_offset == 1)
 127                (void) addelem(result, 3, PyInt_FromLong(n->n_col_offset));
 128        }
 129        return (result);
 130    }
 131    else {
 132        PyErr_SetString(PyExc_SystemError,
 133                        "unrecognized parse tree node type");
 134        return ((PyObject*) NULL);
 135    }
 136}
 137/*
 138 *  End of material copyrighted by Stichting Mathematisch Centrum.
 139 */
 140
 141
 142
 143/*  There are two types of intermediate objects we're interested in:
 144 *  'eval' and 'exec' types.  These constants can be used in the st_type
 145 *  field of the object type to identify which any given object represents.
 146 *  These should probably go in an external header to allow other extensions
 147 *  to use them, but then, we really should be using C++ too.  ;-)
 148 */
 149
 150#define PyST_EXPR  1
 151#define PyST_SUITE 2
 152
 153
 154/*  These are the internal objects and definitions required to implement the
 155 *  ST type.  Most of the internal names are more reminiscent of the 'old'
 156 *  naming style, but the code uses the new naming convention.
 157 */
 158
 159static PyObject*
 160parser_error = 0;
 161
 162
 163typedef struct {
 164    PyObject_HEAD                       /* standard object header           */
 165    node* st_node;                      /* the node* returned by the parser */
 166    int   st_type;                      /* EXPR or SUITE ?                  */
 167    PyCompilerFlags st_flags;           /* Parser and compiler flags        */
 168} PyST_Object;
 169
 170
 171static void parser_free(PyST_Object *st);
 172static int parser_compare(PyST_Object *left, PyST_Object *right);
 173static PyObject *parser_getattr(PyObject *self, char *name);
 174
 175
 176static
 177PyTypeObject PyST_Type = {
 178    PyVarObject_HEAD_INIT(NULL, 0)
 179    "parser.st",                        /* tp_name              */
 180    (int) sizeof(PyST_Object),          /* tp_basicsize         */
 181    0,                                  /* tp_itemsize          */
 182    (destructor)parser_free,            /* tp_dealloc           */
 183    0,                                  /* tp_print             */
 184    parser_getattr,                     /* tp_getattr           */
 185    0,                                  /* tp_setattr           */
 186    (cmpfunc)parser_compare,            /* tp_compare           */
 187    0,                                  /* tp_repr              */
 188    0,                                  /* tp_as_number         */
 189    0,                                  /* tp_as_sequence       */
 190    0,                                  /* tp_as_mapping        */
 191    0,                                  /* tp_hash              */
 192    0,                                  /* tp_call              */
 193    0,                                  /* tp_str               */
 194    0,                                  /* tp_getattro          */
 195    0,                                  /* tp_setattro          */
 196
 197    /* Functions to access object as input/output buffer */
 198    0,                                  /* tp_as_buffer         */
 199
 200    Py_TPFLAGS_DEFAULT,                 /* tp_flags             */
 201
 202    /* __doc__ */
 203    "Intermediate representation of a Python parse tree."
 204};  /* PyST_Type */
 205
 206
 207static int
 208parser_compare_nodes(node *left, node *right)
 209{
 210    int j;
 211
 212    if (TYPE(left) < TYPE(right))
 213        return (-1);
 214
 215    if (TYPE(right) < TYPE(left))
 216        return (1);
 217
 218    if (ISTERMINAL(TYPE(left)))
 219        return (strcmp(STR(left), STR(right)));
 220
 221    if (NCH(left) < NCH(right))
 222        return (-1);
 223
 224    if (NCH(right) < NCH(left))
 225        return (1);
 226
 227    for (j = 0; j < NCH(left); ++j) {
 228        int v = parser_compare_nodes(CHILD(left, j), CHILD(right, j));
 229
 230        if (v != 0)
 231            return (v);
 232    }
 233    return (0);
 234}
 235
 236
 237/*  int parser_compare(PyST_Object* left, PyST_Object* right)
 238 *
 239 *  Comparison function used by the Python operators ==, !=, <, >, <=, >=
 240 *  This really just wraps a call to parser_compare_nodes() with some easy
 241 *  checks and protection code.
 242 *
 243 */
 244static int
 245parser_compare(PyST_Object *left, PyST_Object *right)
 246{
 247    if (left == right)
 248        return (0);
 249
 250    if ((left == 0) || (right == 0))
 251        return (-1);
 252
 253    return (parser_compare_nodes(left->st_node, right->st_node));
 254}
 255
 256
 257/*  parser_newstobject(node* st)
 258 *
 259 *  Allocates a new Python object representing an ST.  This is simply the
 260 *  'wrapper' object that holds a node* and allows it to be passed around in
 261 *  Python code.
 262 *
 263 */
 264static PyObject*
 265parser_newstobject(node *st, int type)
 266{
 267    PyST_Object* o = PyObject_New(PyST_Object, &PyST_Type);
 268
 269    if (o != 0) {
 270        o->st_node = st;
 271        o->st_type = type;
 272        o->st_flags.cf_flags = 0;
 273    }
 274    else {
 275        PyNode_Free(st);
 276    }
 277    return ((PyObject*)o);
 278}
 279
 280
 281/*  void parser_free(PyST_Object* st)
 282 *
 283 *  This is called by a del statement that reduces the reference count to 0.
 284 *
 285 */
 286static void
 287parser_free(PyST_Object *st)
 288{
 289    PyNode_Free(st->st_node);
 290    PyObject_Del(st);
 291}
 292
 293
 294/*  parser_st2tuple(PyObject* self, PyObject* args, PyObject* kw)
 295 *
 296 *  This provides conversion from a node* to a tuple object that can be
 297 *  returned to the Python-level caller.  The ST object is not modified.
 298 *
 299 */
 300static PyObject*
 301parser_st2tuple(PyST_Object *self, PyObject *args, PyObject *kw)
 302{
 303    PyObject *line_option = 0;
 304    PyObject *col_option = 0;
 305    PyObject *res = 0;
 306    int ok;
 307
 308    static char *keywords[] = {"ast", "line_info", "col_info", NULL};
 309
 310    if (self == NULL) {
 311        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!|OO:st2tuple", keywords,
 312                                         &PyST_Type, &self, &line_option,
 313                                         &col_option);
 314    }
 315    else
 316        ok = PyArg_ParseTupleAndKeywords(args, kw, "|OO:totuple", &keywords[1],
 317                                         &line_option, &col_option);
 318    if (ok != 0) {
 319        int lineno = 0;
 320        int col_offset = 0;
 321        if (line_option != NULL) {
 322            lineno = (PyObject_IsTrue(line_option) != 0) ? 1 : 0;
 323        }
 324        if (col_option != NULL) {
 325            col_offset = (PyObject_IsTrue(col_option) != 0) ? 1 : 0;
 326        }
 327        /*
 328         *  Convert ST into a tuple representation.  Use Guido's function,
 329         *  since it's known to work already.
 330         */
 331        res = node2tuple(((PyST_Object*)self)->st_node,
 332                         PyTuple_New, PyTuple_SetItem, lineno, col_offset);
 333    }
 334    return (res);
 335}
 336
 337static PyObject*
 338parser_ast2tuple(PyST_Object *self, PyObject *args, PyObject *kw)
 339{
 340    if (PyErr_WarnPy3k("ast2tuple is removed in 3.x; use st2tuple", 1) < 0)
 341        return NULL;
 342    return parser_st2tuple(self, args, kw);
 343}
 344
 345
 346/*  parser_st2list(PyObject* self, PyObject* args, PyObject* kw)
 347 *
 348 *  This provides conversion from a node* to a list object that can be
 349 *  returned to the Python-level caller.  The ST object is not modified.
 350 *
 351 */
 352static PyObject*
 353parser_st2list(PyST_Object *self, PyObject *args, PyObject *kw)
 354{
 355    PyObject *line_option = 0;
 356    PyObject *col_option = 0;
 357    PyObject *res = 0;
 358    int ok;
 359
 360    static char *keywords[] = {"ast", "line_info", "col_info", NULL};
 361
 362    if (self == NULL)
 363        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!|OO:st2list", keywords,
 364                                         &PyST_Type, &self, &line_option,
 365                                         &col_option);
 366    else
 367        ok = PyArg_ParseTupleAndKeywords(args, kw, "|OO:tolist", &keywords[1],
 368                                         &line_option, &col_option);
 369    if (ok) {
 370        int lineno = 0;
 371        int col_offset = 0;
 372        if (line_option != 0) {
 373            lineno = PyObject_IsTrue(line_option) ? 1 : 0;
 374        }
 375        if (col_option != NULL) {
 376            col_offset = (PyObject_IsTrue(col_option) != 0) ? 1 : 0;
 377        }
 378        /*
 379         *  Convert ST into a tuple representation.  Use Guido's function,
 380         *  since it's known to work already.
 381         */
 382        res = node2tuple(self->st_node,
 383                         PyList_New, PyList_SetItem, lineno, col_offset);
 384    }
 385    return (res);
 386}
 387
 388static PyObject*
 389parser_ast2list(PyST_Object *self, PyObject *args, PyObject *kw)
 390{
 391    if (PyErr_WarnPy3k("ast2list is removed in 3.x; use st2list", 1) < 0)
 392        return NULL;
 393    return parser_st2list(self, args, kw);
 394}
 395
 396
 397/*  parser_compilest(PyObject* self, PyObject* args)
 398 *
 399 *  This function creates code objects from the parse tree represented by
 400 *  the passed-in data object.  An optional file name is passed in as well.
 401 *
 402 */
 403static PyObject*
 404parser_compilest(PyST_Object *self, PyObject *args, PyObject *kw)
 405{
 406    PyObject*     res = 0;
 407    PyArena*      arena;
 408    mod_ty        mod;
 409    char*         str = "<syntax-tree>";
 410    int ok;
 411
 412    static char *keywords[] = {"ast", "filename", NULL};
 413
 414    if (self == NULL)
 415        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!|s:compilest", keywords,
 416                                         &PyST_Type, &self, &str);
 417    else
 418        ok = PyArg_ParseTupleAndKeywords(args, kw, "|s:compile", &keywords[1],
 419                                         &str);
 420
 421    if (ok) {
 422        arena = PyArena_New();
 423        if (arena) {
 424           mod = PyAST_FromNode(self->st_node, &(self->st_flags), str, arena);
 425           if (mod) {
 426               res = (PyObject *)PyAST_Compile(mod, str, &(self->st_flags), arena);
 427           }
 428           PyArena_Free(arena);
 429        }
 430    }
 431
 432    return (res);
 433}
 434
 435static PyObject*
 436parser_compileast(PyST_Object *self, PyObject *args, PyObject *kw)
 437{
 438    if (PyErr_WarnPy3k("compileast is removed in 3.x; use compilest", 1) < 0)
 439        return NULL;
 440    return parser_compilest(self, args, kw);
 441}
 442
 443
 444/*  PyObject* parser_isexpr(PyObject* self, PyObject* args)
 445 *  PyObject* parser_issuite(PyObject* self, PyObject* args)
 446 *
 447 *  Checks the passed-in ST object to determine if it is an expression or
 448 *  a statement suite, respectively.  The return is a Python truth value.
 449 *
 450 */
 451static PyObject*
 452parser_isexpr(PyST_Object *self, PyObject *args, PyObject *kw)
 453{
 454    PyObject* res = 0;
 455    int ok;
 456
 457    static char *keywords[] = {"ast", NULL};
 458
 459    if (self == NULL)
 460        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!:isexpr", keywords,
 461                                         &PyST_Type, &self);
 462    else
 463        ok = PyArg_ParseTupleAndKeywords(args, kw, ":isexpr", &keywords[1]);
 464
 465    if (ok) {
 466        /* Check to see if the ST represents an expression or not. */
 467        res = (self->st_type == PyST_EXPR) ? Py_True : Py_False;
 468        Py_INCREF(res);
 469    }
 470    return (res);
 471}
 472
 473
 474static PyObject*
 475parser_issuite(PyST_Object *self, PyObject *args, PyObject *kw)
 476{
 477    PyObject* res = 0;
 478    int ok;
 479
 480    static char *keywords[] = {"ast", NULL};
 481
 482    if (self == NULL)
 483        ok = PyArg_ParseTupleAndKeywords(args, kw, "O!:issuite", keywords,
 484                                         &PyST_Type, &self);
 485    else
 486        ok = PyArg_ParseTupleAndKeywords(args, kw, ":issuite", &keywords[1]);
 487
 488    if (ok) {
 489        /* Check to see if the ST represents an expression or not. */
 490        res = (self->st_type == PyST_EXPR) ? Py_False : Py_True;
 491        Py_INCREF(res);
 492    }
 493    return (res);
 494}
 495
 496
 497#define PUBLIC_METHOD_TYPE (METH_VARARGS|METH_KEYWORDS)
 498
 499static PyMethodDef
 500parser_methods[] = {
 501    {"compile",         (PyCFunction)parser_compilest,  PUBLIC_METHOD_TYPE,
 502        PyDoc_STR("Compile this ST object into a code object.")},
 503    {"isexpr",          (PyCFunction)parser_isexpr,     PUBLIC_METHOD_TYPE,
 504        PyDoc_STR("Determines if this ST object was created from an expression.")},
 505    {"issuite",         (PyCFunction)parser_issuite,    PUBLIC_METHOD_TYPE,
 506        PyDoc_STR("Determines if this ST object was created from a suite.")},
 507    {"tolist",          (PyCFunction)parser_st2list,    PUBLIC_METHOD_TYPE,
 508        PyDoc_STR("Creates a list-tree representation of this ST.")},
 509    {"totuple",         (PyCFunction)parser_st2tuple,   PUBLIC_METHOD_TYPE,
 510        PyDoc_STR("Creates a tuple-tree representation of this ST.")},
 511
 512    {NULL, NULL, 0, NULL}
 513};
 514
 515
 516static PyObject*
 517parser_getattr(PyObject *self, char *name)
 518{
 519    return (Py_FindMethod(parser_methods, self, name));
 520}
 521
 522
 523/*  err_string(char* message)
 524 *
 525 *  Sets the error string for an exception of type ParserError.
 526 *
 527 */
 528static void
 529err_string(char *message)
 530{
 531    PyErr_SetString(parser_error, message);
 532}
 533
 534
 535/*  PyObject* parser_do_parse(PyObject* args, int type)
 536 *
 537 *  Internal function to actually execute the parse and return the result if
 538 *  successful or set an exception if not.
 539 *
 540 */
 541static PyObject*
 542parser_do_parse(PyObject *args, PyObject *kw, char *argspec, int type)
 543{
 544    char*     string = 0;
 545    PyObject* res    = 0;
 546    int flags        = 0;
 547    perrdetail err;
 548
 549    static char *keywords[] = {"source", NULL};
 550
 551    if (PyArg_ParseTupleAndKeywords(args, kw, argspec, keywords, &string)) {
 552        node* n = PyParser_ParseStringFlagsFilenameEx(string, NULL,
 553                                                       &_PyParser_Grammar,
 554                                                      (type == PyST_EXPR)
 555                                                      ? eval_input : file_input,
 556                                                      &err, &flags);
 557
 558	if (n) {
 559	    res = parser_newstobject(n, type);
 560            if (res)
 561                ((PyST_Object *)res)->st_flags.cf_flags = flags & PyCF_MASK;
 562        }
 563        else
 564            PyParser_SetError(&err);
 565    }
 566    return (res);
 567}
 568
 569
 570/*  PyObject* parser_expr(PyObject* self, PyObject* args)
 571 *  PyObject* parser_suite(PyObject* self, PyObject* args)
 572 *
 573 *  External interfaces to the parser itself.  Which is called determines if
 574 *  the parser attempts to recognize an expression ('eval' form) or statement
 575 *  suite ('exec' form).  The real work is done by parser_do_parse() above.
 576 *
 577 */
 578static PyObject*
 579parser_expr(PyST_Object *self, PyObject *args, PyObject *kw)
 580{
 581    NOTE(ARGUNUSED(self))
 582    return (parser_do_parse(args, kw, "s:expr", PyST_EXPR));
 583}
 584
 585
 586static PyObject*
 587parser_suite(PyST_Object *self, PyObject *args, PyObject *kw)
 588{
 589    NOTE(ARGUNUSED(self))
 590    return (parser_do_parse(args, kw, "s:suite", PyST_SUITE));
 591}
 592
 593
 594
 595/*  This is the messy part of the code.  Conversion from a tuple to an ST
 596 *  object requires that the input tuple be valid without having to rely on
 597 *  catching an exception from the compiler.  This is done to allow the
 598 *  compiler itself to remain fast, since most of its input will come from
 599 *  the parser directly, and therefore be known to be syntactically correct.
 600 *  This validation is done to ensure that we don't core dump the compile
 601 *  phase, returning an exception instead.
 602 *
 603 *  Two aspects can be broken out in this code:  creating a node tree from
 604 *  the tuple passed in, and verifying that it is indeed valid.  It may be
 605 *  advantageous to expand the number of ST types to include funcdefs and
 606 *  lambdadefs to take advantage of the optimizer, recognizing those STs
 607 *  here.  They are not necessary, and not quite as useful in a raw form.
 608 *  For now, let's get expressions and suites working reliably.
 609 */
 610
 611
 612static node* build_node_tree(PyObject *tuple);
 613static int   validate_expr_tree(node *tree);
 614static int   validate_file_input(node *tree);
 615static int   validate_encoding_decl(node *tree);
 616
 617/*  PyObject* parser_tuple2st(PyObject* self, PyObject* args)
 618 *
 619 *  This is the public function, called from the Python code.  It receives a
 620 *  single tuple object from the caller, and creates an ST object if the
 621 *  tuple can be validated.  It does this by checking the first code of the
 622 *  tuple, and, if acceptable, builds the internal representation.  If this
 623 *  step succeeds, the internal representation is validated as fully as
 624 *  possible with the various validate_*() routines defined below.
 625 *
 626 *  This function must be changed if support is to be added for PyST_FRAGMENT
 627 *  ST objects.
 628 *
 629 */
 630static PyObject*
 631parser_tuple2st(PyST_Object *self, PyObject *args, PyObject *kw)
 632{
 633    NOTE(ARGUNUSED(self))
 634    PyObject *st = 0;
 635    PyObject *tuple;
 636    node *tree;
 637
 638    static char *keywords[] = {"sequence", NULL};
 639
 640    if (!PyArg_ParseTupleAndKeywords(args, kw, "O:sequence2st", keywords,
 641                                     &tuple))
 642        return (0);
 643    if (!PySequence_Check(tuple)) {
 644        PyErr_SetString(PyExc_ValueError,
 645                        "sequence2st() requires a single sequence argument");
 646        return (0);
 647    }
 648    /*
 649     *  Convert the tree to the internal form before checking it.
 650     */
 651    tree = build_node_tree(tuple);
 652    if (tree != 0) {
 653        int start_sym = TYPE(tree);
 654        if (start_sym == eval_input) {
 655            /*  Might be an eval form.  */
 656            if (validate_expr_tree(tree))
 657                st = parser_newstobject(tree, PyST_EXPR);
 658            else
 659                PyNode_Free(tree);
 660        }
 661        else if (start_sym == file_input) {
 662            /*  This looks like an exec form so far.  */
 663            if (validate_file_input(tree))
 664                st = parser_newstobject(tree, PyST_SUITE);
 665            else
 666                PyNode_Free(tree);
 667        }
 668        else if (start_sym == encoding_decl) {
 669            /* This looks like an encoding_decl so far. */
 670            if (validate_encoding_decl(tree))
 671                st = parser_newstobject(tree, PyST_SUITE);
 672            else
 673                PyNode_Free(tree);
 674        }
 675        else {
 676            /*  This is a fragment, at best. */
 677            PyNode_Free(tree);
 678            err_string("parse tree does not use a valid start symbol");
 679        }
 680    }
 681    /*  Make sure we throw an exception on all errors.  We should never
 682     *  get this, but we'd do well to be sure something is done.
 683     */
 684    if (st == NULL && !PyErr_Occurred())
 685        err_string("unspecified ST error occurred");
 686
 687    return st;
 688}
 689
 690static PyObject*
 691parser_tuple2ast(PyST_Object *self, PyObject *args, PyObject *kw)
 692{
 693    if (PyErr_WarnPy3k("tuple2ast is removed in 3.x; use tuple2st", 1) < 0)
 694        return NULL;
 695    return parser_tuple2st(self, args, kw);
 696}
 697
 698
 699/*  node* build_node_children()
 700 *
 701 *  Iterate across the children of the current non-terminal node and build
 702 *  their structures.  If successful, return the root of this portion of
 703 *  the tree, otherwise, 0.  Any required exception will be specified already,
 704 *  and no memory will have been deallocated.
 705 *
 706 */
 707static node*
 708build_node_children(PyObject *tuple, node *root, int *line_num)
 709{
 710    Py_ssize_t len = PyObject_Size(tuple);
 711    Py_ssize_t i;
 712    int  err;
 713
 714    for (i = 1; i < len; ++i) {
 715        /* elem must always be a sequence, however simple */
 716        PyObject* elem = PySequence_GetItem(tuple, i);
 717        int ok = elem != NULL;
 718        long  type = 0;
 719        char *strn = 0;
 720
 721        if (ok)
 722            ok = PySequence_Check(elem);
 723        if (ok) {
 724            PyObject *temp = PySequence_GetItem(elem, 0);
 725            if (temp == NULL)
 726                ok = 0;
 727            else {
 728                ok = PyInt_Check(temp);
 729                if (ok)
 730                    type = PyInt_AS_LONG(temp);
 731                Py_DECREF(temp);
 732            }
 733        }
 734        if (!ok) {
 735            PyObject *err = Py_BuildValue("os", elem,
 736                                          "Illegal node construct.");
 737            PyErr_SetObject(parser_error, err);
 738            Py_XDECREF(err);
 739            Py_XDECREF(elem);
 740            return (0);
 741        }
 742        if (ISTERMINAL(type)) {
 743            Py_ssize_t len = PyObject_Size(elem);
 744            PyObject *temp;
 745
 746            if ((len != 2) && (len != 3)) {
 747                err_string("terminal nodes must have 2 or 3 entries");
 748                return 0;
 749            }
 750            temp = PySequence_GetItem(elem, 1);
 751            if (temp == NULL)
 752                return 0;
 753            if (!PyString_Check(temp)) {
 754                PyErr_Format(parser_error,
 755                             "second item in terminal node must be a string,"
 756                             " found %s",
 757                             Py_TYPE(temp)->tp_name);
 758                Py_DECREF(temp);
 759                return 0;
 760            }
 761            if (len == 3) {
 762                PyObject *o = PySequence_GetItem(elem, 2);
 763                if (o != NULL) {
 764                    if (PyInt_Check(o))
 765                        *line_num = PyInt_AS_LONG(o);
 766                    else {
 767                        PyErr_Format(parser_error,
 768                                     "third item in terminal node must be an"
 769                                     " integer, found %s",
 770				     Py_TYPE(temp)->tp_name);
 771                        Py_DECREF(o);
 772                        Py_DECREF(temp);
 773                        return 0;
 774                    }
 775                    Py_DECREF(o);
 776                }
 777            }
 778            len = PyString_GET_SIZE(temp) + 1;
 779            strn = (char *)PyObject_MALLOC(len);
 780            if (strn != NULL)
 781                (void) memcpy(strn, PyString_AS_STRING(temp), len);
 782            Py_DECREF(temp);
 783        }
 784        else if (!ISNONTERMINAL(type)) {
 785            /*
 786             *  It has to be one or the other; this is an error.
 787             *  Throw an exception.
 788             */
 789            PyObject *err = Py_BuildValue("os", elem, "unknown node type.");
 790            PyErr_SetObject(parser_error, err);
 791            Py_XDECREF(err);
 792            Py_XDECREF(elem);
 793            return (0);
 794        }
 795        err = PyNode_AddChild(root, type, strn, *line_num, 0);
 796        if (err == E_NOMEM) {
 797            PyObject_FREE(strn);
 798            return (node *) PyErr_NoMemory();
 799        }
 800        if (err == E_OVERFLOW) {
 801            PyObject_FREE(strn);
 802            PyErr_SetString(PyExc_ValueError,
 803                            "unsupported number of child nodes");
 804            return NULL;
 805        }
 806
 807        if (ISNONTERMINAL(type)) {
 808            node* new_child = CHILD(root, i - 1);
 809
 810            if (new_child != build_node_children(elem, new_child, line_num)) {
 811                Py_XDECREF(elem);
 812                return (0);
 813            }
 814        }
 815        else if (type == NEWLINE) {     /* It's true:  we increment the     */
 816            ++(*line_num);              /* line number *after* the newline! */
 817        }
 818        Py_XDECREF(elem);
 819    }
 820    return root;
 821}
 822
 823
 824static node*
 825build_node_tree(PyObject *tuple)
 826{
 827    node* res = 0;
 828    PyObject *temp = PySequence_GetItem(tuple, 0);
 829    long num = -1;
 830
 831    if (temp != NULL)
 832        num = PyInt_AsLong(temp);
 833    Py_XDECREF(temp);
 834    if (ISTERMINAL(num)) {
 835        /*
 836         *  The tuple is simple, but it doesn't start with a start symbol.
 837         *  Throw an exception now and be done with it.
 838         */
 839        tuple = Py_BuildValue("os", tuple,
 840                    "Illegal syntax-tree; cannot start with terminal symbol.");
 841        PyErr_SetObject(parser_error, tuple);
 842        Py_XDECREF(tuple);
 843    }
 844    else if (ISNONTERMINAL(num)) {
 845        /*
 846         *  Not efficient, but that can be handled later.
 847         */
 848        int line_num = 0;
 849        PyObject *encoding = NULL;
 850
 851        if (num == encoding_decl) {
 852            encoding = PySequence_GetItem(tuple, 2);
 853            /* tuple isn't borrowed anymore here, need to DECREF */
 854            tuple = PySequence_GetSlice(tuple, 0, 2);
 855        }
 856        res = PyNode_New(num);
 857        if (res != NULL) {
 858            if (res != build_node_children(tuple, res, &line_num)) {
 859                PyNode_Free(res);
 860                res = NULL;
 861            }
 862            if (res && encoding) {
 863                Py_ssize_t len;
 864                len = PyString_GET_SIZE(encoding) + 1;
 865                res->n_str = (char *)PyObject_MALLOC(len);
 866                if (res->n_str != NULL)
 867                    (void) memcpy(res->n_str, PyString_AS_STRING(encoding), len);
 868                Py_DECREF(encoding);
 869                Py_DECREF(tuple);
 870            }
 871        }
 872    }
 873    else {
 874        /*  The tuple is illegal -- if the number is neither TERMINAL nor
 875         *  NONTERMINAL, we can't use it.  Not sure the implementation
 876         *  allows this condition, but the API doesn't preclude it.
 877         */
 878        PyObject *err = Py_BuildValue("os", tuple,
 879                                      "Illegal component tuple.");
 880        PyErr_SetObject(parser_error, err);
 881        Py_XDECREF(err);
 882    }
 883
 884    return (res);
 885}
 886
 887
 888/*
 889 *  Validation routines used within the validation section:
 890 */
 891static int validate_terminal(node *terminal, int type, char *string);
 892
 893#define validate_ampersand(ch)  validate_terminal(ch,      AMPER, "&")
 894#define validate_circumflex(ch) validate_terminal(ch, CIRCUMFLEX, "^")
 895#define validate_colon(ch)      validate_terminal(ch,      COLON, ":")
 896#define validate_comma(ch)      validate_terminal(ch,      COMMA, ",")
 897#define validate_dedent(ch)     validate_terminal(ch,     DEDENT, "")
 898#define validate_equal(ch)      validate_terminal(ch,      EQUAL, "=")
 899#define validate_indent(ch)     validate_terminal(ch,     INDENT, (char*)NULL)
 900#define validate_lparen(ch)     validate_terminal(ch,       LPAR, "(")
 901#define validate_newline(ch)    validate_terminal(ch,    NEWLINE, (char*)NULL)
 902#define validate_rparen(ch)     validate_terminal(ch,       RPAR, ")")
 903#define validate_semi(ch)       validate_terminal(ch,       SEMI, ";")
 904#define validate_star(ch)       validate_terminal(ch,       STAR, "*")
 905#define validate_vbar(ch)       validate_terminal(ch,       VBAR, "|")
 906#define validate_doublestar(ch) validate_terminal(ch, DOUBLESTAR, "**")
 907#define validate_dot(ch)        validate_terminal(ch,        DOT, ".")
 908#define validate_at(ch)         validate_terminal(ch,         AT, "@")
 909#define validate_name(ch, str)  validate_terminal(ch,       NAME, str)
 910
 911#define VALIDATER(n)    static int validate_##n(node *tree)
 912
 913VALIDATER(node);                VALIDATER(small_stmt);
 914VALIDATER(class);               VALIDATER(node);
 915VALIDATER(parameters);          VALIDATER(suite);
 916VALIDATER(testlist);            VALIDATER(varargslist);
 917VALIDATER(fpdef);               VALIDATER(fplist);
 918VALIDATER(stmt);                VALIDATER(simple_stmt);
 919VALIDATER(expr_stmt);           VALIDATER(power);
 920VALIDATER(print_stmt);          VALIDATER(del_stmt);
 921VALIDATER(return_stmt);         VALIDATER(list_iter);
 922VALIDATER(raise_stmt);          VALIDATER(import_stmt);
 923VALIDATER(import_name);         VALIDATER(import_from);
 924VALIDATER(global_stmt);         VALIDATER(list_if);
 925VALIDATER(assert_stmt);         VALIDATER(list_for);
 926VALIDATER(exec_stmt);           VALIDATER(compound_stmt);
 927VALIDATER(while);               VALIDATER(for);
 928VALIDATER(try);                 VALIDATER(except_clause);
 929VALIDATER(test);                VALIDATER(and_test);
 930VALIDATER(not_test);            VALIDATER(comparison);
 931VALIDATER(comp_op);             VALIDATER(expr);
 932VALIDATER(xor_expr);            VALIDATER(and_expr);
 933VALIDATER(shift_expr);          VALIDATER(arith_expr);
 934VALIDATER(term);                VALIDATER(factor);
 935VALIDATER(atom);                VALIDATER(lambdef);
 936VALIDATER(trailer);             VALIDATER(subscript);
 937VALIDATER(subscriptlist);       VALIDATER(sliceop);
 938VALIDATER(exprlist);            VALIDATER(dictmaker);
 939VALIDATER(arglist);             VALIDATER(argument);
 940VALIDATER(listmaker);           VALIDATER(yield_stmt);
 941VALIDATER(testlist1);           VALIDATER(gen_for);
 942VALIDATER(gen_iter);            VALIDATER(gen_if);
 943VALIDATER(testlist_gexp);	VALIDATER(yield_expr);
 944VALIDATER(yield_or_testlist);	VALIDATER(or_test);
 945VALIDATER(old_test); 		VALIDATER(old_lambdef);
 946
 947#undef VALIDATER
 948
 949#define is_even(n)      (((n) & 1) == 0)
 950#define is_odd(n)       (((n) & 1) == 1)
 951
 952
 953static int
 954validate_ntype(node *n, int t)
 955{
 956    if (TYPE(n) != t) {
 957        PyErr_Format(parser_error, "Expected node type %d, got %d.",
 958                     t, TYPE(n));
 959        return 0;
 960    }
 961    return 1;
 962}
 963
 964
 965/*  Verifies that the number of child nodes is exactly 'num', raising
 966 *  an exception if it isn't.  The exception message does not indicate
 967 *  the exact number of nodes, allowing this to be used to raise the
 968 *  "right" exception when the wrong number of nodes is present in a
 969 *  specific variant of a statement's syntax.  This is commonly used
 970 *  in that fashion.
 971 */
 972static int
 973validate_numnodes(node *n, int num, const char *const name)
 974{
 975    if (NCH(n) != num) {
 976        PyErr_Format(parser_error,
 977                     "Illegal number of children for %s node.", name);
 978        return 0;
 979    }
 980    return 1;
 981}
 982
 983
 984static int
 985validate_terminal(node *terminal, int type, char *string)
 986{
 987    int res = (validate_ntype(terminal, type)
 988               && ((string == 0) || (strcmp(string, STR(terminal)) == 0)));
 989
 990    if (!res && !PyErr_Occurred()) {
 991        PyErr_Format(parser_error,
 992                     "Illegal terminal: expected \"%s\"", string);
 993    }
 994    return (res);
 995}
 996
 997
 998/*  X (',' X) [',']
 999 */
1000static int
1001validate_repeating_list(node *tree, int ntype, int (*vfunc)(node *),
1002                        const char *const name)
1003{
1004    int nch = NCH(tree);
1005    int res = (nch && validate_ntype(tree, ntype)
1006               && vfunc(CHILD(tree, 0)));
1007
1008    if (!res && !PyErr_Occurred())
1009        (void) validate_numnodes(tree, 1, name);
1010    else {
1011        if (is_even(nch))
1012            res = validate_comma(CHILD(tree, --nch));
1013        if (res && nch > 1) {
1014            int pos = 1;
1015            for ( ; res && pos < nch; pos += 2)
1016                res = (validate_comma(CHILD(tree, pos))
1017                       && vfunc(CHILD(tree, pos + 1)));
1018        }
1019    }
1020    return (res);
1021}
1022
1023
1024/*  validate_class()
1025 *
1026 *  classdef:
1027 *      'class' NAME ['(' testlist ')'] ':' suite
1028 */
1029static int
1030validate_class(node *tree)
1031{
1032    int nch = NCH(tree);
1033    int res = (validate_ntype(tree, classdef) &&
1034	       	((nch == 4) || (nch == 6) || (nch == 7)));
1035
1036    if (res) {
1037        res = (validate_name(CHILD(tree, 0), "class")
1038               && validate_ntype(CHILD(tree, 1), NAME)
1039               && validate_colon(CHILD(tree, nch - 2))
1040               && validate_suite(CHILD(tree, nch - 1)));
1041    }
1042    else {
1043        (void) validate_numnodes(tree, 4, "class");
1044    }
1045	
1046    if (res) {
1047	if (nch == 7) {
1048		res = ((validate_lparen(CHILD(tree, 2)) &&
1049			validate_testlist(CHILD(tree, 3)) &&
1050			validate_rparen(CHILD(tree, 4))));
1051	}
1052	else if (nch == 6) {
1053		res = (validate_lparen(CHILD(tree,2)) &&
1054			validate_rparen(CHILD(tree,3)));
1055	}
1056    }
1057    return (res);
1058}
1059
1060
1061/*  if_stmt:
1062 *      'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
1063 */
1064static int
1065validate_if(node *tree)
1066{
1067    int nch = NCH(tree);
1068    int res = (validate_ntype(tree, if_stmt)
1069               && (nch >= 4)
1070               && validate_name(CHILD(tree, 0), "if")
1071               && validate_test(CHILD(tree, 1))
1072               && validate_colon(CHILD(tree, 2))
1073               && validate_suite(CHILD(tree, 3)));
1074
1075    if (res && ((nch % 4) == 3)) {
1076        /*  ... 'else' ':' suite  */
1077        res = (validate_name(CHILD(tree, nch - 3), "else")
1078               && validate_colon(CHILD(tree, nch - 2))
1079               && validate_suite(CHILD(tree, nch - 1)));
1080        nch -= 3;
1081    }
1082    else if (!res && !PyErr_Occurred())
1083        (void) validate_numnodes(tree, 4, "if");
1084    if ((nch % 4) != 0)
1085        /* Will catch the case for nch < 4 */
1086        res = validate_numnodes(tree, 0, "if");
1087    else if (res && (nch > 4)) {
1088        /*  ... ('elif' test ':' suite)+ ...  */
1089        int j = 4;
1090        while ((j < nch) && res) {
1091            res = (validate_name(CHILD(tree, j), "elif")
1092                   && validate_colon(CHILD(tree, j + 2))
1093                   && validate_test(CHILD(tree, j + 1))
1094                   && validate_suite(CHILD(tree, j + 3)));
1095            j += 4;
1096        }
1097    }
1098    return (res);
1099}
1100
1101
1102/*  parameters:
1103 *      '(' [varargslist] ')'
1104 *
1105 */
1106static int
1107validate_parameters(node *tree)
1108{
1109    int nch = NCH(tree);
1110    int res = validate_ntype(tree, parameters) && ((nch == 2) || (nch == 3));
1111
1112    if (res) {
1113        res = (validate_lparen(CHILD(tree, 0))
1114               && validate_rparen(CHILD(tree, nch - 1)));
1115        if (res && (nch == 3))
1116            res = validate_varargslist(CHILD(tree, 1));
1117    }
1118    else {
1119        (void) validate_numnodes(tree, 2, "parameters");
1120    }
1121    return (res);
1122}
1123
1124
1125/*  validate_suite()
1126 *
1127 *  suite:
1128 *      simple_stmt
1129 *    | NEWLINE INDENT stmt+ DEDENT
1130 */
1131static int
1132validate_suite(node *tree)
1133{
1134    int nch = NCH(tree);
1135    int res = (validate_ntype(tree, suite) && ((nch == 1) || (nch >= 4)));
1136
1137    if (res && (nch == 1))
1138        res = validate_simple_stmt(CHILD(tree, 0));
1139    else if (res) {
1140        /*  NEWLINE INDENT stmt+ DEDENT  */
1141        res = (validate_newline(CHILD(tree, 0))
1142               && validate_indent(CHILD(tree, 1))
1143               && validate_stmt(CHILD(tree, 2))
1144               && validate_dedent(CHILD(tree, nch - 1)));
1145
1146        if (res && (nch > 4)) {
1147            int i = 3;
1148            --nch;                      /* forget the DEDENT     */
1149            for ( ; res && (i < nch); ++i)
1150                res = validate_stmt(CHILD(tree, i));
1151        }
1152        else if (nch < 4)
1153            res = validate_numnodes(tree, 4, "suite");
1154    }
1155    return (res);
1156}
1157
1158
1159static int
1160validate_testlist(node *tree)
1161{
1162    return (validate_repeating_list(tree, testlist,
1163                                    validate_test, "testlist"));
1164}
1165
1166
1167static int
1168validate_testlist1(node *tree)
1169{
1170    return (validate_repeating_list(tree, testlist1,
1171                                    validate_test, "testlist1"));
1172}
1173
1174
1175static int
1176validate_testlist_safe(node *tree)
1177{
1178    return (validate_repeating_list(tree, testlist_safe,
1179                                    validate_old_test, "testlist_safe"));
1180}
1181
1182
1183/* '*' NAME [',' '**' NAME] | '**' NAME
1184 */
1185static int
1186validate_varargslist_trailer(node *tree, int start)
1187{
1188    int nch = NCH(tree);
1189    int res = 0;
1190    int sym;
1191
1192    if (nch <= start) {
1193        err_string("expected variable argument trailer for varargslist");
1194        return 0;
1195    }
1196    sym = TYPE(CHILD(tree, start));
1197    if (sym == STAR) {
1198        /*
1199         *  ('*' NAME [',' '**' NAME]
1200         */
1201        if (nch-start == 2)
1202            res = validate_name(CHILD(tree, start+1), NULL);
1203        else if (nch-start == 5)
1204            res = (validate_name(CHILD(tree, start+1), NULL)
1205                   && validate_comma(CHILD(tree, start+2))
1206                   && validate_doublestar(CHILD(tree, start+3))
1207                   && validate_name(CHILD(tree, start+4), NULL));
1208    }
1209    else if (sym == DOUBLESTAR) {
1210        /*
1211         *  '**' NAME
1212         */
1213        if (nch-start == 2)
1214            res = validate_name(CHILD(tree, start+1), NULL);
1215    }
1216    if (!res)
1217        err_string("illegal variable argument trailer for varargslist");
1218    return res;
1219}
1220
1221
1222/*  validate_varargslist()
1223 *
1224 *  varargslist:
1225 *      (fpdef ['=' test] ',')*
1226 *           ('*' NAME [',' '**' NAME]
1227 *         | '**' NAME)
1228 *    | fpdef ['=' test] (',' fpdef ['=' test])* [',']
1229 *
1230 */
1231static int
1232validate_varargslist(node *tree)
1233{
1234    int nch = NCH(tree);
1235    int res = validate_ntype(tree, varargslist) && (nch != 0);
1236    int sym;
1237
1238    if (!res)
1239        return 0;
1240    if (nch < 1) {
1241        err_string("varargslist missing child nodes");
1242        return 0;
1243    }
1244    sym = TYPE(CHILD(tree, 0));
1245    if (sym == STAR || sym == DOUBLESTAR)
1246        /* whole thing matches:
1247         *      '*' NAME [',' '**' NAME] | '**' NAME
1248         */
1249        res = validate_varargslist_trailer(tree, 0);
1250    else if (sym == fpdef) {
1251        int i = 0;
1252
1253        sym = TYPE(CHILD(tree, nch-1));
1254        if (sym == NAME) {
1255            /*
1256             *   (fpdef ['=' test] ',')+
1257             *       ('*' NAME [',' '**' NAME]
1258             *     | '**' NAME)
1259             */
1260            /* skip over (fpdef ['=' test] ',')+ */
1261            while (res && (i+2 <= nch)) {
1262                res = validate_fpdef(CHILD(tree, i));
1263                ++i;
1264                if (res && TYPE(CHILD(tree, i)) == EQUAL && (i+2 <= nch)) {
1265                    res = (validate_equal(CHILD(tree, i))
1266                           && validate_test(CHILD(tree, i+1)));
1267                    if (res)
1268                        i += 2;
1269                }
1270                if (res && i < nch) {
1271                    res = validate_comma(CHILD(tree, i));
1272                    ++i;
1273                    if (res && i < nch
1274                        && (TYPE(CHILD(tree, i)) == DOUBLESTAR
1275                            || TYPE(CHILD(tree, i)) == STAR))
1276                        break;
1277                }
1278            }
1279            /* ... '*' NAME [',' '**' NAME] | '**' NAME
1280             * i --^^^
1281             */
1282            if (res)
1283                res = validate_varargslist_trailer(tree, i);
1284        }
1285        else {
1286            /*
1287             *  fpdef ['=' test] (',' fpdef ['=' test])* [',']
1288             */
1289            /* strip trailing comma node */
1290            if (sym == COMMA) {
1291                res = validate_comma(CHILD(tree, nch-1));
1292                if (!res)
1293                    return 0;
1294                --nch;
1295            }
1296            /*
1297             *  fpdef ['=' test] (',' fpdef ['=' test])*
1298             */
1299            res = validate_fpdef(CHILD(tree, 0));
1300            ++i;
1301            if (res && (i+2 <= nch) && TYPE(CHILD(tree, i)) == EQUAL) {
1302                res = (validate_equal(CHILD(tree, i))
1303                       && validate_test(CHILD(tree, i+1)));
1304                i += 2;
1305            }
1306            /*
1307             *  ... (',' fpdef ['=' test])*
1308             *  i ---^^^
1309             */
1310            while (res && (nch - i) >= 2) {
1311                res = (validate_comma(CHILD(tree, i))
1312                       && validate_fpdef(CHILD(tree, i+1)));
1313                i += 2;
1314                if (res && (nch - i) >= 2 && TYPE(CHILD(tree, i)) == EQUAL) {
1315                    res = (validate_equal(CHILD(tree, i))
1316                           && validate_test(CHILD(tree, i+1)));
1317                    i += 2;
1318                }
1319            }
1320            if (res && nch - i != 0) {
1321                res = 0;
1322                err_string("illegal formation for varargslist");
1323            }
1324        }
1325    }
1326    return res;
1327}
1328
1329
1330/*  list_iter:  list_for | list_if
1331 */
1332static int
1333validate_list_iter(node *tree)
1334{
1335    int res = (validate_ntype(tree, list_iter)
1336               && validate_numnodes(tree, 1, "list_iter"));
1337    if (res && TYPE(CHILD(tree, 0)) == list_for)
1338        res = validate_list_for(CHILD(tree, 0));
1339    else
1340        res = validate_list_if(CHILD(tree, 0));
1341
1342    return res;
1343}
1344
1345/*  gen_iter:  gen_for | gen_if
1346 */
1347static int
1348validate_gen_iter(node *tree)
1349{
1350    int res = (validate_ntype(tree, gen_iter)
1351               && validate_numnodes(tree, 1, "gen_iter"));
1352    if (res && TYPE(CHILD(tree, 0)) == gen_for)
1353        res = validate_gen_for(CHILD(tree, 0));
1354    else
1355        res = validate_gen_if(CHILD(tree, 0));
1356
1357    return res;
1358}
1359
1360/*  list_for:  'for' exprlist 'in' testlist [list_iter]
1361 */
1362static int
1363validate_list_for(node *tree)
1364{
1365    int nch = NCH(tree);
1366    int res;
1367
1368    if (nch == 5)
1369        res = validate_list_iter(CHILD(tree, 4));
1370    else
1371        res = validate_numnodes(tree, 4, "list_for");
1372
1373    if (res)
1374        res = (validate_name(CHILD(tree, 0), "for")
1375               && validate_exprlist(CHILD(tree, 1))
1376               && validate_name(CHILD(tree, 2), "in")
1377               && validate_testlist_safe(CHILD(tree, 3)));
1378
1379    return res;
1380}
1381
1382/*  gen_for:  'for' exprlist 'in' test [gen_iter]
1383 */
1384static int
1385validate_gen_for(node *tree)
1386{
1387    int nch = NCH(tree);
1388    int res;
1389
1390    if (nch == 5)
1391        res = validate_gen_iter(CHILD(tree, 4));
1392    else
1393        res = validate_numnodes(tree, 4, "gen_for");
1394
1395    if (res)
1396        res = (validate_name(CHILD(tree, 0), "for")
1397               && validate_exprlist(CHILD(tree, 1))
1398               && validate_name(CHILD(tree, 2), "in")
1399               && validate_or_test(CHILD(tree, 3)));
1400
1401    return res;
1402}
1403
1404/*  list_if:  'if' old_test [list_iter]
1405 */
1406static int
1407validate_list_if(node *tree)
1408{
1409    int nch = NCH(tree);
1410    int res;
1411
1412    if (nch == 3)
1413        res = validate_list_iter(CHILD(tree, 2));
1414    else
1415        res = validate_numnodes(tree, 2, "list_if");
1416
1417    if (res)
1418        res = (validate_name(CHILD(tree, 0), "if")
1419               && validate_old_test(CHILD(tree, 1)));
1420
1421    return res;
1422}
1423
1424/*  gen_if:  'if' old_test [gen_iter]
1425 */
1426static int
1427validate_gen_if(node *tree)
1428{
1429    int nch = NCH(tree);
1430    int res;
1431
1432    if (nch == 3)
1433        res = validate_gen_iter(CHILD(tree, 2));
1434    else
1435        res = validate_numnodes(tree, 2, "gen_if");
1436    
1437    if (res)
1438        res = (validate_name(CHILD(tree, 0), "if")
1439               && validate_old_test(CHILD(tree, 1)));
1440
1441    return res;
1442}
1443
1444/*  validate_fpdef()
1445 *
1446 *  fpdef:
1447 *      NAME
1448 *    | '(' fplist ')'
1449 */
1450static int
1451validate_fpdef(node *tree)
1452{
1453    int nch = NCH(tree);
1454    int res = validate_ntype(tree, fpdef);
1455
1456    if (res) {
1457        if (nch == 1)
1458            res = validate_ntype(CHILD(tree, 0), NAME);
1459        else if (nch == 3)
1460            res = (validate_lparen(CHILD(tree, 0))
1461                   && validate_fplist(CHILD(tree, 1))
1462                   && validate_rparen(CHILD(tree, 2)));
1463        else
1464            res = validate_numnodes(tree, 1, "fpdef");
1465    }
1466    return (res);
1467}
1468
1469
1470static int
1471validate_fplist(node *tree)
1472{
1473    return (validate_repeating_list(tree, fplist,
1474                                    validate_fpdef, "fplist"));
1475}
1476
1477
1478/*  simple_stmt | compound_stmt
1479 *
1480 */
1481static int
1482validate_stmt(node *tree)
1483{
1484    int res = (validate_ntype(tree, stmt)
1485               && validate_numnodes(tree, 1, "stmt"));
1486
1487    if (res) {
1488        tree = CHILD(tree, 0);
1489
1490        if (TYPE(tree) == simple_stmt)
1491            res = validate_simple_stmt(tree);
1492        else
1493            res = validate_compound_stmt(tree);
1494    }
1495    return (res);
1496}
1497
1498
1499/*  small_stmt (';' small_stmt)* [';'] NEWLINE
1500 *
1501 */
1502static int
1503validate_simple_stmt(node *tree)
1504{
1505    int nch = NCH(tree);
1506    int res = (validate_ntype(tree, simple_stmt)
1507               && (nch >= 2)
1508               && validate_small_stmt(CHILD(tree, 0))
1509               && validate_newline(CHILD(tree, nch - 1)));
1510
1511    if (nch < 2)
1512        res = validate_numnodes(tree, 2, "simple_stmt");
1513    --nch;                              /* forget the NEWLINE    */
1514    if (res && is_even(nch))
1515        res = validate_semi(CHILD(tree, --nch));
1516    if (res && (nch > 2)) {
1517        int i;
1518
1519        for (i = 1; res && (i < nch); i += 2)
1520            res = (validate_semi(CHILD(tree, i))
1521                   && validate_small_stmt(CHILD(tree, i + 1)));
1522    }
1523    return (res);
1524}
1525
1526
1527static int
1528validate_small_stmt(node *tree)
1529{
1530    int nch = NCH(tree);
1531    int res = validate_numnodes(tree, 1, "small_stmt");
1532
1533    if (res) {
1534        int ntype = TYPE(CHILD(tree, 0));
1535
1536        if (  (ntype == expr_stmt)
1537              || (ntype == print_stmt)
1538              || (ntype == del_stmt)
1539              || (ntype == pass_stmt)
1540              || (ntype == flow_stmt)
1541              || (ntype == import_stmt)
1542              || (ntype == global_stmt)
1543              || (ntype == assert_stmt)
1544              || (ntype == exec_stmt))
1545            res = validate_node(CHILD(tree, 0));
1546        else {
1547            res = 0;
1548            err_string("illegal small_stmt child type");
1549        }
1550    }
1551    else if (nch == 1) {
1552        res = 0;
1553        PyErr_Format(parser_error,
1554                     "Unrecognized child node of small_stmt: %d.",
1555                     TYPE(CHILD(tree, 0)));
1556    }
1557    return (res);
1558}
1559
1560
1561/*  compound_stmt:
1562 *      if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated
1563 */
1564static int
1565validate_compound_stmt(node *tree)
1566{
1567    int res = (validate_ntype(tree, compound_stmt)
1568               && validate_numnodes(tree, 1, "compound_stmt"));
1569    int ntype;
1570
1571    if (!res)
1572        return (0);
1573
1574    tree = CHILD(tree, 0);
1575    ntype = TYPE(tree);
1576    if (  (ntype == if_stmt)
1577          || (ntype == while_stmt)
1578          || (ntype == for_stmt)
1579          || (ntype == try_stmt)
1580          || (ntype == with_stmt)
1581          || (ntype == funcdef)
1582          || (ntype == classdef)
1583          || (ntype == decorated))
1584        res = validate_node(tree);
1585    else {
1586        res = 0;
1587        PyErr_Format(parser_error,
1588                     "Illegal compound statement type: %d.", TYPE(tree));
1589    }
1590    return (res);
1591}
1592
1593static int
1594validate_yield_or_testlist(node *tree)
1595{
1596	if (TYPE(tree) == yield_expr) 
1597		return validate_yield_expr(tree);
1598	else
1599		return validate_testlist(tree);
1600}
1601
1602static int
1603validate_expr_stmt(node *tree)
1604{
1605    int j;
1606    int nch = NCH(tree);
1607    int res = (validate_ntype(tree, expr_stmt)
1608               && is_odd(nch)
1609               && validate_testlist(CHILD(tree, 0)));
1610
1611    if (res && nch == 3
1612        && TYPE(CHILD(tree, 1)) == augassign) {
1613        res = validate_numnodes(CHILD(tree, 1), 1, "augassign")
1614		&& validate_yield_or_testlist(CHILD(tree, 2));
1615
1616        if (res) {
1617            char *s = STR(CHILD(CHILD(tree, 1), 0));
1618
1619            res = (strcmp(s, "+=") == 0
1620                   || strcmp(s, "-=") == 0
1621                   || strcmp(s, "*=") == 0
1622                   || strcmp(s, "/=") == 0
1623                   || strcmp(s, "//=") == 0
1624                   || strcmp(s, "%=") == 0
1625                   || strcmp(s, "&=") == 0
1626                   || strcmp(s, "|=") == 0
1627                   || strcmp(s, "^=") == 0
1628                   || strcmp(s, "<<=") == 0
1629                   || strcmp(s, ">>=") == 0
1630                   || strcmp(s, "**=") == 0);
1631            if (!res)
1632                err_string("illegal augmmented assignment operator");
1633        }
1634    }
1635    else {
1636        for (j = 1; res && (j < nch); j += 2)
1637            res = validate_equal(CHILD(tree, j))
1638                   && validate_yield_or_testlist(CHILD(tree, j + 1));
1639    }
1640    return (res);
1641}
1642
1643
1644/*  print_stmt:
1645 *
1646 *      'print' ( [ test (',' test)* [','] ]
1647 *              | '>>' test [ (',' test)+ [','] ] )
1648 */
1649static int
1650validate_print_stmt(node *tree)
1651{
1652    int nch = NCH(tree);
1653    int res = (validate_ntype(tree, print_stmt)
1654               && (nch > 0)
1655               && validate_name(CHILD(tree, 0), "print"));
1656
1657    if (res && nch > 1) {
1658        int sym = TYPE(CHILD(tree, 1));
1659        int i = 1;
1660        int allow_trailing_comma = 1;
1661
1662        if (sym == test)
1663            res = validate_test(CHILD(tree, i++));
1664        else {
1665            if (nch < 3)
1666                res = validate_numnodes(tree, 3, "print_stmt");
1667            else {
1668                res = (validate_ntype(CHILD(tree, i), RIGHTSHIFT)
1669                       && validate_test(CHILD(tree, i+1)));
1670                i += 2;
1671                allow_trailing_comma = 0;
1672            }
1673        }
1674        if (res) {
1675            /*  ... (',' test)* [',']  */
1676            while (res && i+2 <= nch) {
1677                res = (validate_comma(CHILD(tree, i))
1678                       && validate_test(CHILD(tree, i+1)));
1679                allow_trailing_comma = 1;
1680                i += 2;
1681            }
1682            if (res && !allow_trailing_comma)
1683                res = validate_numnodes(tree, i, "print_stmt");
1684            else if (res && i < nch)
1685                res = validate_comma(CHILD(tree, i));
1686        }
1687    }
1688    return (res);
1689}
1690
1691
1692static int
1693validate_del_stmt(node *tree)
1694{
1695    return (validate_numnodes(tree, 2, "del_stmt")
1696            && validate_name(CHILD(tree, 0), "del")
1697            && validate_exprlist(CHILD(tree, 1)));
1698}
1699
1700
1701static int
1702validate_return_stmt(node *tree)
1703{
1704    int nch = NCH(tree);
1705    int res = (validate_ntype(tree, return_stmt)
1706               && ((nch == 1) || (nch == 2))
1707               && validate_name(CHILD(tree, 0), "return"));
1708
1709    if (res && (nch == 2))
1710        res = validate_testlist(CHILD(tree, 1));
1711
1712    return (res);
1713}
1714
1715
1716static int
1717validate_raise_stmt(node *tree)
1718{
1719    int nch = NCH(tree);
1720    int res = (validate_ntype(tree, raise_stmt)
1721               && ((nch == 1) || (nch == 2) || (nch == 4) || (nch == 6)));
1722
1723    if (res) {
1724        res = validate_name(CHILD(tree, 0), "raise");
1725        if (res && (nch >= 2))
1726            res = validate_test(CHILD(tree, 1));
1727        if (res && nch > 2) {
1728            res = (validate_comma(CHILD(tree, 2))
1729                   && validate_test(CHILD(tree, 3)));
1730            if (res && (nch > 4))
1731                res = (validate_comma(CHILD(tree, 4))
1732                       && validate_test(CHILD(tree, 5)));
1733        }
1734    }
1735    else
1736        (void) validate_numnodes(tree, 2, "raise");
1737    if (res && (nch == 4))
1738        res = (validate_comma(CHILD(tree, 2))
1739               && validate_test(CHILD(tree, 3)));
1740
1741    return (res);
1742}
1743
1744
1745/* yield_expr: 'yield' [testlist]
1746 */
1747static int
1748validate_yield_expr(node *tree)
1749{
1750    int nch = NCH(tree);
1751    int res = (validate_ntype(tree, yield_expr)
1752               && ((nch == 1) || (nch == 2))
1753               && validate_name(CHILD(tree, 0), "yield"));
1754
1755    if (res && (nch == 2))
1756        res = validate_testlist(CHILD(tree, 1));
1757
1758    return (res);
1759}
1760
1761
1762/* yield_stmt: yield_expr
1763 */
1764static int
1765validate_yield_stmt(node *tree)
1766{
1767    return (validate_ntype(tree, yield_stmt)
1768            && validate_numnodes(tree, 1, "yield_stmt")
1769            && validate_yield_expr(CHILD(tree, 0)));
1770}
1771
1772
1773static int
1774validate_import_as_name(node *tree)
1775{
1776    int nch = NCH(tree);
1777    int ok = validate_ntype(tree, import_as_name);
1778
1779    if (ok) {
1780        if (nch == 1)
1781            ok = validate_name(CHILD(tree, 0), NULL);
1782        else if (nch == 3)
1783            ok = (validate_name(CHILD(tree, 0), NULL)
1784                  && validate_name(CHILD(tree, 1), "as")
1785                  && validate_name(CHILD(tree, 2), NULL));
1786        else
1787            ok = validate_numnodes(tree, 3, "import_as_name");
1788    }
1789    return ok;
1790}
1791
1792
1793/* dotted_name:  NAME ("." NAME)*
1794 */
1795static int
1796validate_dotted_name(node *tree)
1797{
1798    int nch = NCH(tree);
1799    int res = (validate_ntype(tree, dotted_name)
1800               && is_odd(nch)
1801               && validate_name(CHILD(tree, 0), NULL));
1802    int i;
1803
1804    for (i = 1; res && (i < nch); i += 2) {
1805        res = (validate_dot(CHILD(tree, i))
1806               && validate_name(CHILD(tree, i+1), NULL));
1807    }
1808    return res;
1809}
1810
1811
1812/* dotted_as_name:  dotted_name [NAME NAME]
1813 */
1814static int
1815validate_dotted_as_name(node *tree)
1816{
1817    int nch = NCH(tree);
1818    int res = validate_ntype(tree, dotted_as_name);
1819
1820    if (res) {
1821        if (nch == 1)
1822            res = validate_dotted_name(CHILD(tree, 0));
1823        else if (nch == 3)
1824            res = (validate_dotted_name(CHILD(tree, 0))
1825                   && validate_name(CHILD(tree, 1), "as")
1826                   && validate_name(CHILD(tree, 2), NULL));
1827        else {
1828            res = 0;
1829            err_string("illegal number of children for dotted_as_name");
1830        }
1831    }
1832    return res;
1833}
1834
1835
1836/* dotted_as_name (',' dotted_as_name)* */
1837static int
1838validate_dotted_as_names(node *tree)
1839{
1840	int nch = NCH(tree);
1841	int res = is_odd(nch) && validate_dotted_as_name(CHILD(tree, 0));
1842	int i;
1843
1844	for (i = 1; res && (i < nch); i += 2)
1845	    res = (validate_comma(CHILD(tree, i))
1846		   && validate_dotted_as_name(CHILD(tree, i + 1)));
1847	return (res);
1848}
1849
1850
1851/* import_as_name (',' import_as_name)* [','] */
1852static int
1853validate_import_as_names(node *tree)
1854{
1855    int nch = NCH(tree);
1856    int res = validate_import_as_name(CHILD(tree, 0));
1857    int i;
1858
1859    for (i = 1; res && (i + 1 < nch); i += 2)
1860	res = (validate_comma(CHILD(tree, i))
1861	       && validate_import_as_name(CHILD(tree, i + 1)));
1862    return (res);
1863}
1864
1865
1866/* 'import' dotted_as_names */
1867static int
1868validate_import_name(node *tree)
1869{
1870	return (validate_ntype(tree, import_name)
1871		&& validate_numnodes(tree, 2, "import_name")
1872		&& validate_name(CHILD(tree, 0), "import")
1873		&& validate_dotted_as_names(CHILD(tree, 1)));
1874}
1875
1876/* Helper function to count the number of leading dots in 
1877 * 'from ...module import name'
1878 */
1879static int
1880count_from_dots(node *tree)
1881{
1882        int i;
1883        for (i = 1; i < NCH(tree); i++)
1884		if (TYPE(CHILD(tree, i)) != DOT)
1885			break;
1886        return i-1;
1887}
1888
1889/* 'from' ('.'* dotted_name | '.') 'import' ('*' | '(' import_as_names ')' |
1890 *     import_as_names
1891 */
1892static int
1893validate_import_from(node *tree)
1894{
1895	int nch = NCH(tree);
1896	int ndots = count_from_dots(tree);
1897	int havename = (TYPE(CHILD(tree, ndots + 1)) == dotted_name);
1898	int offset = ndots + havename;
1899	int res = validate_ntype(tree, import_from)
1900		&& (nch >= 4 + ndots)
1901		&& validate_name(CHILD(tree, 0), "from")
1902		&& (!havename || validate_dotted_name(CHILD(tree, ndots + 1)))
1903		&& validate_name(CHILD(tree, offset + 1), "import");
1904
1905	if (res && TYPE(CHILD(tree, offset + 2)) == LPAR)
1906	    res = ((nch == offset + 5)
1907		   && validate_lparen(CHILD(tree, offset + 2))
1908		   && validate_import_as_names(CHILD(tree, offset + 3))
1909		   && validate_rparen(CHILD(tree, offset + 4)));
1910	else if (res && TYPE(CHILD(tree, offset + 2)) != STAR)
1911	    res = validate_import_as_names(CHILD(tree, offset + 2));
1912	return (res);
1913}
1914
1915
1916/* import_stmt: import_name | import_from */
1917static int
1918validate_import_stmt(node *tree)
1919{
1920    int nch = NCH(tree);
1921    int res = validate_numnodes(tree, 1, "import_stmt");
1922
1923    if (res) {
1924	int ntype = TYPE(CHILD(tree, 0));
1925
1926	if (ntype == import_name || ntype == import_from)
1927            res = validate_node(CHILD(tree, 0));
1928        else {
1929            res = 0;
1930            err_string("illegal import_stmt child type");
1931        }
1932    }
1933    else if (nch == 1) {
1934        res = 0;
1935        PyErr_Format(parser_error,
1936                     "Unrecognized child node of import_stmt: %d.",
1937                     TYPE(CHILD(tree, 0)));
1938    }
1939    return (res);
1940}
1941
1942
1943
1944
1945static int
1946validate_global_stmt(node *tree)
1947{
1948    int j;
1949    int nch = NCH(tree);
1950    int res = (validate_ntype(tree, global_stmt)
1951               && is_even(nch) && (nch >= 2));
1952
1953    if (!res && !PyErr_Occurred())
1954        err_string("illegal global statement");
1955
1956    if (res)
1957        res = (validate_name(CHILD(tree, 0), "global")
1958               && validate_ntype(CHILD(tree, 1), NAME));
1959    for (j = 2; res && (j < nch); j += 2)
1960        res = (validate_comma(CHILD(tree, j))
1961               && validate_ntype(CHILD(tree, j + 1), NAME));
1962
1963    return (res);
1964}
1965
1966
1967/*  exec_stmt:
1968 *
1969 *  'exec' expr ['in' test [',' test]]
1970 */
1971static int
1972validate_exec_stmt(node *tree)
1973{
1974    int nch = NCH(tree);
1975    int res = (validate_ntype(tree, exec_stmt)
1976               && ((nch == 2) || (nch == 4) || (nch == 6))
1977               && validate_name(CHILD(tree, 0), "exec")
1978               && validate_expr(CHILD(tree, 1)));
1979
1980    if (!res && !PyErr_Occurred())
1981        err_string("illegal exec statement");
1982    if (res && (nch > 2))
1983        res = (validate_name(CHILD(tree, 2), "in")
1984               && validate_test(CHILD(tree, 3)));
1985    if (res && (nch == 6))
1986        res = (validate_comma(CHILD(tree, 4))
1987               && validate_test(CHILD(tree, 5)));
1988
1989    return (res);
1990}
1991
1992
1993/*  assert_stmt:
1994 *
1995 *  'assert' test [',' test]
1996 */
1997static int
1998validate_assert_stmt(node *tree)
1999{
2000    int nch = NCH(tree);
2001    int res = (validate_ntype(tree, assert_stmt)
2002               && ((nch == 2) || (nch == 4))
2003               && (validate_name(CHILD(tree, 0), "assert"))
2004               && validate_test(CHILD(tree, 1)));
2005
2006    if (!res && !PyErr_Occurred())
2007        err_string("illegal assert statement");
2008    if (res && (nch > 2))
2009        res = (validate_comma(CHILD(tree, 2))
2010               && validate_test(CHILD(tree, 3)));
2011
2012    return (res);
2013}
2014
2015
2016static int
2017validate_while(node *tree)
2018{
2019    int nch = NCH(tree);
2020    int res = (validate_ntype(tree, while_stmt)
2021               && ((nch == 4) || (nch == 7))
2022               && validate_name(CHILD(tree, 0), "while")
2023               && validate_test(CHILD(tree, 1))
2024               && validate_colon(CHILD(tree, 2))
2025               && validate_suite(CHILD(tree, 3)));
2026
2027    if (res && (nch == 7))
2028        res = (validate_name(CHILD(tree, 4), "else")
2029               && validate_colon(CHILD(tree, 5))
2030               && validate_suite(CHILD(tree, 6)));
2031
2032    return (res);
2033}
2034
2035
2036static int
2037validate_for(node *tree)
2038{
2039    int nch = NCH(tree);
2040    int res = (validate_ntype(tree, for_stmt)
2041               && ((nch == 6) || (nch == 9))
2042               && validate_name(CHILD(tree, 0), "for")
2043               && validate_exprlist(CHILD(tree, 1))
2044               && validate_name(CHILD(tree, 2), "in")
2045               && validate_testlist(CHILD(tree, 3))
2046               && validate_colon(CHILD(tree, 4))
2047               && validate_suite(CHILD(tree, 5)));
2048
2049    if (res && (nch == 9))
2050        res = (validate_name(CHILD(tree, 6), "else")
2051               && validate_colon(CHILD(tree, 7))
2052               && validate_suite(CHILD(tree, 8)));
2053
2054    return (res);
2055}
2056
2057
2058/*  try_stmt:
2059 *      'try' ':' suite (except_clause ':' suite)+ ['else' ':' suite]
2060                                                   ['finally' ':' suite]
2061 *    | 'try' ':' suite 'finally' ':' suite
2062 *
2063 */
2064static int
2065validate_try(node *tree)
2066{
2067    int nch = NCH(tree);
2068    int pos = 3;
2069    int res = (validate_ntype(tree, try_stmt)
2070               && (nch >= 6) && ((nch % 3) == 0));
2071
2072    if (res)
2073        res = (validate_name(CHILD(tree, 0), "try")
2074               && validate_colon(CHILD(tree, 1))
2075               && validate_suite(CHILD(tree, 2))
2076               && validate_colon(CHILD(tree, nch - 2))
2077               && validate_suite(CHILD(tree, nch - 1)));
2078    else if (!PyErr_Occurred()) {
2079        const char* name = "except";
2080        if (TYPE(CHILD(tree, nch - 3)) != except_clause)
2081            name = STR(CHILD(tree, nch - 3));
2082
2083        PyErr_Format(parser_error,
2084                     "Illegal number of children for try/%s node.", name);
2085    }
2086    /* Handle try/finally statement */
2087    if (res && (TYPE(CHILD(tree, pos)) == NAME) &&
2088        (strcmp(STR(CHILD(tree, pos)), "finally") == 0)) {
2089        res = (validate_numnodes(tree, 6, "try/finally")
2090               && validate_colon(CHILD(tree, 4))
2091               && validate_suite(CHILD(tree, 5)));
2092        return (res);
2093    }
2094    /* try/except statement: skip past except_clause sections */
2095    while (res && (TYPE(CHILD(tree, pos)) == except_clause)) {
2096        res = (validate_except_clause(CHILD(tree, pos))
2097               && validate_colon(CHILD(tree, pos + 1))
2098               && validate_suite(CHILD(tree, pos + 2)));
2099        pos += 3;
2100    }
2101    /* skip else clause */
2102    if (res && (TYPE(CHILD(tree, pos)) == NAME) &&
2103        (strcmp(STR(CHILD(tree, pos)), "else") == 0)) {
2104        res = (validate_colon(CHILD(tree, pos + 1))
2105               && validate_suite(CHILD(tree, pos + 2)));
2106        pos += 3;
2107    }
2108    if (res && pos < nch) {
2109        /* last clause must be a finally */
2110        res = (validate_name(CHILD(tree, pos), "finally")
2111               && validate_numnodes(tree, pos + 3, "try/except/finally")
2112               && validate_colon(CHILD(tree, pos + 1))
2113               && validate_suite(CHILD(tree, pos + 2)));
2114    }
2115    return (res);
2116}
2117
2118
2119static int
2120validate_except_clause(node *tree)
2121{
2122    int nch = NCH(tree);
2123    int res = (validate_ntype(tree, except_clause)
2124               && ((nch == 1) || (nch == 2) || (nch == 4))
2125               && validate_name(CHILD(tree, 0), "except"));
2126
2127    if (res && (nch > 1))
2128        res = validate_test(CHILD(tree, 1));
2129    if (res && (nch == 4))
2130        res = (validate_comma(CHILD(tree, 2))
2131               && validate_test(CHILD(tree, 3)));
2132
2133    return (res);
2134}
2135
2136
2137static int
2138validate_test(node *tree)
2139{
2140    int nch = NCH(tree);
2141    int res = validate_ntype(tree, test) && is_odd(nch);
2142
2143    if (res && (TYPE(CHILD(tree, 0)) == lambdef))
2144        res = ((nch == 1)
2145               && validate_lambdef(CHILD(tree, 0)));
2146    else if (res) {
2147        res = validate_or_test(CHILD(tree, 0));
2148        res = (res && (nch == 1 || (nch == 5 &&
2149            validate_name(CHILD(tree, 1), "if") &&
2150            validate_or_test(CHILD(tree, 2)) &&
2151            validate_name(CHILD(tree, 3), "else") &&
2152            validate_test(CHILD(tree, 4)))));
2153    }
2154    return (res);
2155}
2156
2157static int
2158validate_old_test(node *tree)
2159{
2160    int nch = NCH(tree);
2161    int res = validate_ntype(tree, old_test) && (nch == 1);
2162
2163    if (res && (TYPE(CHILD(tree, 0)) == old_lambdef))
2164        res = (validate_old_lambdef(CHILD(tree, 0)));
2165    else if (res) {
2166        res = (validate_or_test(CHILD(tree, 0)));
2167    }
2168    return (res);
2169}
2170
2171static int
2172validate_or_test(node *tree)
2173{
2174    int nch = NCH(tree);
2175    int res = validate_ntype(tree, or_test) && is_odd(nch);
2176
2177    if (res) {
2178        int pos;
2179        res = validate_and_test(CHILD(tree, 0));
2180        for (pos = 1; res && (pos < nch); pos += 2)
2181            res = (validate_name(CHILD(tree, pos), "or")
2182                   && validate_and_test(CHILD(tree, pos + 1)));
2183    }
2184    return (res);
2185}
2186
2187
2188static int
2189validate_and_test(node *tree)
2190{
2191    int pos;
2192    int nch = NCH(tree);
2193    int res = (validate_ntype(tree, and_test)
2194               && is_odd(nch)
2195               && validate_not_test(CHILD(tree, 0)));
2196
2197    for (pos = 1; res && (pos < nch); pos += 2)
2198        res = (validate_name(CHILD(tree, pos), "and")
2199               && validate_not_test(CHILD(tree, 0)));
2200
2201    return (res);
2202}
2203
2204
2205static int
2206validate_not_test(node *tree)
2207{
2208    int nch = NCH(tree);
2209    int res = validate_ntype(tree, not_test) && ((nch == 1) || (nch == 2));
2210
2211    if (res) {
2212        if (nch == 2)
2213            res = (validate_name(CHILD(tree, 0), "not")
2214                   && validate_not_test(CHILD(tree, 1)));
2215        else if (nch == 1)
2216            res = validate_comparison(CHILD(tree, 0));
2217    }
2218    return (res);
2219}
2220
2221
2222static int
2223validate_comparison(node *tree)
2224{
2225    int pos;
2226    int nch = NCH(tree);
2227    int res = (validate_ntype(tree, comparison)
2228               && is_odd(nch)
2229               && validate_expr(CHILD(tree, 0)));
2230
2231    for (pos = 1; res && (pos < nch); pos += 2)
2232        res = (validate_comp_op(CHILD(tree, pos))
2233               && validate_expr(CHILD(tree, pos + 1)));
2234
2235    return (res);
2236}
2237
2238
2239static int
2240validate_comp_op(node *tree)
2241{
2242    int res = 0;
2243    int nch = NCH(tree);
2244
2245    if (!validate_ntype(tree, comp_op))
2246        return (0);
2247    if (nch == 1) {
2248        /*
2249         *  Only child will be a terminal with a well-defined symbolic name
2250         *  or a NAME with a string of either 'is' or 'in'
2251         */
2252        tree = CHILD(tree, 0);
2253        switch (TYPE(tree)) {
2254            case LESS:
2255            case GREATER:
2256            case EQEQUAL:
2257            case EQUAL:
2258            case LESSEQUAL:
2259            case GREATEREQUAL:
2260            case NOTEQUAL:
2261              res = 1;
2262              break;
2263            case NAME:
2264              res = ((strcmp(STR(tree), "in") == 0)
2265                     || (strcmp(STR(tree), "is") == 0));
2266              if (!res) {
2267                  PyErr_Format(parser_error,
2268                               "illegal operator '%s'", STR(tree));
2269              }
2270              break;
2271          default:
2272              err_string("illegal comparison operator type");
2273              break;
2274        }
2275    }
2276    else if ((res = validate_numnodes(tree, 2, "comp_op")) != 0) {
2277        res = (validate_ntype(CHILD(tree, 0), NAME)
2278               && validate_ntype(CHILD(tree, 1), NAME)
2279               && (((strcmp(STR(CHILD(tree, 0)), "is") == 0)
2280                    && (strcmp(STR(CHILD(tree, 1)), "not") == 0))
2281                   || ((strcmp(STR(CHILD(tree, 0)), "not") == 0)
2282                       && (strcmp(STR(CHILD(tree, 1)), "in") == 0))));
2283        if (!res && !PyErr_Occurred())
2284            err_string("unknown comparison operator");
2285    }
2286    return (res);
2287}
2288
2289
2290static int
2291validate_expr(node *tree)
2292{
2293    int j;
2294    int nch = NCH(tree);
2295    int res = (validate_ntype(tree, expr)
2296               && is_odd(nch)
2297               && validate_xor_expr(CHILD(tree, 0)));
2298
2299    for (j = 2; res && (j < nch); j += 2)
2300        res = (validate_xor_expr(CHILD(tree, j))
2301               && validate_vbar(CHILD(tree, j - 1)));
2302
2303    return (res);
2304}
2305
2306
2307static int
2308validate_xor_expr(node *tree)
2309{
2310    int j;
2311    int nch = NCH(tree);
2312    int res = (validate_ntype(tree, xor_expr)
2313               && is_odd(nch)
2314               && validate_and_expr(CHILD(tree, 0)));
2315
2316    for (j = 2; res && (j < nch); j += 2)
2317        res = (validate_circumflex(CHILD(tree, j - 1))
2318               && validate_and_expr(CHILD(tree, j)));
2319
2320    return (res);
2321}
2322
2323
2324static int
2325validate_and_expr(node *tree)
2326{
2327    int pos;
2328    int nch = NCH(tree);
2329    int res = (validate_ntype(tree, and_expr)
2330               && is_odd(nch)
2331               && validate_shift_expr(CHILD(tree, 0)));
2332
2333    for (pos = 1; res && (pos < nch); pos += 2)
2334        res = (validate_ampersand(CHILD(tree, pos))
2335               && validate_shift_expr(CHILD(tree, pos + 1)));
2336
2337    return (res);
2338}
2339
2340
2341static int
2342validate_chain_two_ops(node *tree, int (*termvalid)(node *), int op1, int op2)
2343 {
2344    int pos = 1;
2345    int nch = NCH(tree);
2346    int res = (is_odd(nch)
2347               && (*termvalid)(CHILD(tree, 0)));
2348
2349    for ( ; res && (pos < nch); pos += 2) {
2350        if (TYPE(CHILD(tree, pos)) != op1)
2351            res = validate_ntype(CHILD(tree, pos), op2);
2352        if (res)
2353            res = (*termvalid)(CHILD(tree, pos + 1));
2354    }
2355    return (res);
2356}
2357
2358
2359static int
2360validate_shift_expr(node *tree)
2361{
2362    return (validate_ntype(tree, shift_expr)
2363            && validate_chain_two_ops(tree, validate_arith_expr,
2364                                      LEFTSHIFT, RIGHTSHIFT));
2365}
2366
2367
2368static int
2369validate_arith_expr(node *tree)
2370{
2371    return (validate_ntype(tree, arith_expr)
2372            && validate_chain_two_ops(tree, validate_term, PLUS, MINUS));
2373}
2374
2375
2376static int
2377validate_term(node *tree)
2378{
2379    int pos = 1;
2380    int nch = NCH(tree);
2381    int res = (validate_ntype(tree, term)
2382               && is_odd(nch)
2383               && validate_factor(CHILD(tree, 0)));
2384
2385    for ( ; res && (pos < nch); pos += 2)
2386        res = (((TYPE(CHILD(tree, pos)) == STAR)
2387               || (TYPE(CHILD(tree, pos)) == SLASH)
2388               || (TYPE(CHILD(tree, pos)) == DOUBLESLASH)
2389               || (TYPE(CHILD(tree, pos)) == PERCENT))
2390               && validate_factor(CHILD(tree, pos + 1)));
2391
2392    return (res);
2393}
2394
2395
2396/*  factor:
2397 *
2398 *  factor: ('+'|'-'|'~') factor | power
2399 */
2400static int
2401validate_factor(node *tree)
2402{
2403    int nch = NCH(tree);
2404    int res = (validate_ntype(tree, factor)
2405               && (((nch == 2)
2406                    && ((TYPE(CHILD(tree, 0)) == PLUS)
2407                        || (TYPE(CHILD(tree, 0)) == MINUS)
2408                        || (TYPE(CHILD(tree, 0)) == TILDE))
2409                    && validate_factor(CHILD(tree, 1)))
2410                   || ((nch == 1)
2411                       && validate_power(CHILD(tree, 0)))));
2412    return (res);
2413}
2414
2415
2416/*  power:
2417 *
2418 *  power: atom trailer* ('**' factor)*
2419 */
2420static int
2421validate_power(node *tree)
2422{
2423    int pos = 1;
2424    int nch = NCH(tree);
2425    int res = (validate_ntype(tree, power) && (nch >= 1)
2426               && validate_atom(CHILD(tree, 0)));
2427
2428    while (res && (pos < nch) && (TYPE(CHILD(tree, pos)) == trailer))
2429        res = validate_trailer(CHILD(tree, pos++));
2430    if (res && (pos < nch)) {
2431        if (!is_even(nch - pos)) {
2432            err_string("illegal number of nodes for 'power'");
2433            return (0);
2434        }
2435        for ( ; res && (pos < (nch - 1)); pos += 2)
2436            res = (validate_doublestar(CHILD(tree, pos))
2437                   && validate_factor(CHILD(tree, pos + 1)));
2438    }
2439    return (res);
2440}
2441
2442
2443static int
2444validate_atom(node *tree)
2445{
2446    int pos;
2447    int nch = NCH(tree);
2448    int res = validate_ntype(tree, atom);
2449
2450    if (res && nch < 1)
2451        res = validate_numnodes(tree, nch+1, "atom");
2452    if (res) {
2453        switch (TYPE(CHILD(tree, 0))) {
2454          case LPAR:
2455            res = ((nch <= 3)
2456                   && (validate_rparen(CHILD(tree, nch - 1))));
2457
2458            if (res && (nch == 3)) {
2459		if (TYPE(CHILD(tree, 1))==yield_expr)
2460			res = validate_yield_expr(CHILD(tree, 1));
2461		else
2462                	res = validate_testlist_gexp(CHILD(tree, 1));
2463	    }
2464            break;
2465          case LSQB:
2466            if (nch == 2)
2467                res = validate_ntype(CHILD(tree, 1), RSQB);
2468            else if (nch == 3)
2469                res = (validate_listmaker(CHILD(tree, 1))
2470                       && validate_ntype(CHILD(tree, 2), RSQB));
2471            else {
2472                res = 0;
2473                err_string("illegal list display atom");
2474            }
2475            break;
2476          case LBRACE:
2477            res = ((nch <= 3)
2478                   && validate_ntype(CHILD(tree, nch - 1), RBRACE));
2479
2480            if (res && (nch == 3))
2481                res = validate_dictmaker(CHILD(tree, 1));
2482            break;
2483          case BACKQUOTE:
2484            res = ((nch == 3)
2485                   && validate_testlist1(CHILD(tree, 1))
2486                   && validate_ntype(CHILD(tree, 2), BACKQUOTE));
2487            break;
2488          case NAME:
2489          case NUMBER:
2490            res = (nch == 1);
2491            break;
2492          case STRING:
2493            for (pos = 1; res && (pos < nch); ++pos)
2494                res = validate_ntype(CHILD(tree, pos), STRING);
2495            break;
2496          default:
2497            res = 0;
2498            break;
2499        }
2500    }
2501    return (res);
2502}
2503
2504
2505/*  listmaker:
2506 *    test ( list_for | (',' test)* [','] )
2507 */
2508static int
2509validate_listmaker(node *tree)
2510{
2511    int nch = NCH(tree);
2512    int ok = nch;
2513
2514    if (nch == 0)
2515        err_string("missing child nodes of listmaker");
2516    else
2517        ok = validate_test(CHILD(tree, 0));
2518
2519    /*
2520     *  list_for | (',' test)* [',']
2521     */
2522    if (nch == 2 && TYPE(CHILD(tree, 1)) == list_for)
2523        ok = validate_list_for(CHILD(tree, 1));
2524    else {
2525        /*  (',' test)* [',']  */
2526        int i = 1;
2527        while (ok && nch - i >= 2) {
2528            ok = (validate_comma(CHILD(tree, i))
2529                  && validate_test(CHILD(tree, i+1)));
2530            i += 2;
2531        }
2532        if (ok && i == nch-1)
2533            ok = validate_comma(CHILD(tree, i));
2534        else if (i != nch) {
2535            ok = 0;
2536            err_string("illegal trailing nodes for listmaker");
2537        }
2538    }
2539    return ok;
2540}
2541
2542/*  testlist_gexp:
2543 *    test ( gen_for | (',' test)* [','] )
2544 */
2545static int
2546validate_testlist_gexp(node *tree)
2547{
2548    int nch = NCH(tree);
2549    int ok = nch;
2550
2551    if (nch == 0)
2552        err_string("missing child nodes of testlist_gexp");
2553    else {
2554        ok = validate_test(CHILD(tree, 0));
2555    }
2556
2557    /*
2558     *  gen_for | (',' test)* [',']
2559     */
2560    if (nch == 2 && TYPE(CHILD(tree, 1)) == gen_for)
2561        ok = validate_gen_for(CHILD(tree, 1));
2562    else {
2563        /*  (',' test)* [',']  */
2564        int i = 1;
2565        while (ok && nch - i >= 2) {
2566            ok = (validate_comma(CHILD(tree, i))
2567                  && validate_test(CHILD(tree, i+1)));
2568            i += 2;
2569        }
2570        if (ok && i == nch-1)
2571            ok = validate_comma(CHILD(tree, i));
2572        else if (i != nch) {
2573            ok = 0;
2574            err_string("illegal trailing nodes for testlist_gexp");
2575        }
2576    }
2577    return ok;
2578}
2579
2580/*  decorator:
2581 *    '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
2582 */
2583static int
2584validate_decorator(node *tree)
2585{
2586    int ok;
2587    int nch = NCH(tree);
2588    ok = (validate_ntype(tree, decorator) &&
2589	  (nch == 3 || nch == 5 || nch == 6) &&
2590	  validate_at(CHILD(tree, 0)) &&
2591	  validate_dotted_name(CHILD(tree, 1)) &&
2592	  validate_newline(RCHILD(tree, -1)));
2593
2594    if (ok && nch != 3) {
2595	ok = (validate_lparen(CHILD(tree, 2)) &&
2596	      validate_rparen(RCHILD(tree, -2)));
2597
2598	if (ok && nch == 6)
2599	    ok = validate_arglist(CHILD(tree, 3));
2600    }
2601
2602    return ok;
2603}
2604
2605/*  decorators:
2606 *    decorator+
2607 */
2608static int
2609validate_decorators(node *tree)
2610{
2611    int i, nch, ok; 
2612    nch = NCH(tree);
2613    ok = validate_ntype(tree, decorators) && nch >= 1;
2614
2615    for (i = 0; ok && i < nch; ++i)
2616	ok = validate_decorator(CHILD(tree, i));
2617
2618    return ok;
2619}
2620
2621/*  with_var
2622with_var: 'as' expr
2623 */
2624static int
2625validate_with_var(node *tree)
2626{
2627    int nch = NCH(tree);
2628    int ok = (validate_ntype(tree, with_var)
2629        && (nch == 2)
2630        && validate_name(CHILD(tree, 0), "as")
2631        && validate_expr(CHILD(tree, 1)));
2632   return ok;
2633}
2634
2635/*  with_stmt
2636 *           0      1       2       -2   -1
2637with_stmt: 'with' test [ with_var ] ':' suite
2638 */
2639static int
2640validate_with_stmt(node *tree)
2641{
2642    int nch = NCH(tree);
2643    int ok = (validate_ntype(tree, with_stmt)
2644        && ((nch == 4) || (nch == 5))
2645        && validate_name(CHILD(tree, 0), "with")
2646        && validate_test(CHILD(tree, 1))
2647        && (nch == 4 || validate_with_var(CHILD(tree, 2))) 
2648        && validate_colon(RCHILD(tree, -2))
2649        && validate_suite(RCHILD(tree, -1)));
2650   return ok;
2651}
2652
2653/*  funcdef:
2654 *      
2655 *     -5   -4         -3  -2    -1
2656 *  'def' NAME parameters ':' suite
2657 */
2658static int
2659validate_funcdef(node *tree)
2660{
2661    int nch = NCH(tree);
2662    int ok = (validate_ntype(tree, funcdef)
2663	       && (nch == 5)
2664	       && validate_name(RCHILD(tree, -5), "def")
2665	       && validate_ntype(RCHILD(tree, -4), NAME)
2666	       && validate_colon(RCHILD(tree, -2))
2667	       && validate_parameters(RCHILD(tree, -3))
2668	       && validate_suite(RCHILD(tree, -1)));
2669    return ok;
2670}
2671
2672
2673/* decorated
2674 *   decorators (classdef | funcdef)
2675 */
2676static int
2677validate_decorated(node *tree)
2678{
2679  int nch = NCH(tree);
2680  int ok = (validate_ntype(tree, decorated)
2681	    && (nch == 2)
2682	    && validate_decorators(RCHILD(tree, -2))
2683	    && (validate_funcdef(RCHILD(tree, -1))
2684		|| validate_class(RCHILD(tree, -1)))
2685	    );
2686  return ok;
2687}
2688
2689static int
2690validate_lambdef(node *tree)
2691{
2692    int nch = NCH(tree);
2693    int res = (validate_ntype(tree, lambdef)
2694               && ((nch == 3) || (nch == 4))
2695               && validate_name(CHILD(tree, 0), "lambda")
2696               && validate_colon(CHILD(tree, nch - 2))
2697               && validate_test(CHILD(tree, nch - 1)));
2698
2699    if (res && (nch == 4))
2700        res = validate_varargslist(CHILD(tree, 1));
2701    else if (!res && !PyErr_Occurred())
2702        (void) validate_numnodes(tree, 3, "lambdef");
2703
2704    return (res);
2705}
2706
2707
2708static int
2709validate_old_lambdef(node *tree)
2710{
2711    int nch = NCH(tree);
2712    int res = (validate_ntype(tree, old_lambdef)
2713               && ((nch == 3) || (nch == 4))
2714               && validate_name(CHILD(tree, 0), "lambda")
2715               && validate_colon(CHILD(tree, nch - 2))
2716               && validate_test(CHILD(tree, nch - 1)));
2717
2718    if (res && (nch == 4))
2719        res = validate_varargslist(CHILD(tree, 1));
2720    else if (!res && !PyErr_Occurred())
2721        (void) validate_numnodes(tree, 3, "old_lambdef");
2722
2723    return (res);
2724}
2725
2726
2727/*  arglist:
2728 *
2729 *  (argument ',')* (argument [','] | '*' test [',' '**' test] | '**' test)
2730 */
2731static int
2732validate_arglist(node *tree)
2733{
2734    int nch = NCH(tree);
2735    int i = 0;
2736    int ok = 1;
2737
2738    if (nch <= 0)
2739        /* raise the right error from having an invalid number of children */
2740        return validate_numnodes(tree, nch + 1, "arglist");
2741
2742    if (nch > 1) {
2743        for (i=0; i<nch; i++) {
2744            if (TYPE(CHILD(tree, i)) == argument) {
2745                node *ch = CHILD(tree, i);
2746                if (NCH(ch) == 2 && TYPE(CHILD(ch, 1)) == gen_for) {
2747                    err_string("need '(', ')' for generator expression");
2748                    return 0;
2749                }
2750            }
2751        }
2752    }
2753
2754    while (ok && nch-i >= 2) {
2755        /* skip leading (argument ',') */
2756        ok = (validate_argument(CHILD(tree, i))
2757              && validate_comma(CHILD(tree, i+1)));
2758        if (ok)
2759            i += 2;
2760        else
2761            PyErr_Clear();
2762    }
2763    ok = 1;
2764    if (nch-i > 0) {
2765        /*
2766         * argument | '*' test [',' '**' test] | '**' test
2767         */
2768        int sym = TYPE(CHILD(tree, i));
2769
2770        if (sym == argument) {
2771            ok = validate_argument(CHILD(tree, i));
2772            if (ok && i+1 != nch) {
2773                err_string("illegal arglist specification"
2774                           " (extra stuff on end)");
2775                ok = 0;
2776            }
2777        }
2778        else if (sym == STAR) {
2779            ok = validate_star(CHILD(tree, i));
2780            if (ok && (nch-i == 2))
2781                ok = validate_test(CHILD(tree, i+1));
2782            else if (ok && (nch-i == 5))
2783                ok = (validate_test(CHILD(tree, i+1))
2784                      && validate_comma(CHILD(tree, i+2))
2785                      && validate_doublestar(CHILD(tree, i+3))
2786                      && validate_test(CHILD(tree, i+4)));
2787            else {
2788                err_string("illegal use of '*' in arglist");
2789                ok = 0;
2790            }
2791        }
2792        else if (sym == DOUBLESTAR) {
2793            if (nch-i == 2)
2794                ok = (validate_doublestar(CHILD(tree, i))
2795                      && validate_test(CHILD(tree, i+1)));
2796            else {
2797                err_string("illegal use of '**' in arglist");
2798                ok = 0;
2799            }
2800        }
2801        else {
2802            err_string("illegal arglist specification");
2803            ok = 0;
2804        }
2805    }
2806    return (ok);
2807}
2808
2809
2810
2811/*  argument:
2812 *
2813 *  [test '='] test [gen_for]
2814 */
2815static int
2816validate_argument(node *tree)
2817{
2818    int nch = NCH(tree);
2819    int res = (validate_ntype(tree, argument)
2820               && ((nch == 1) || (nch == 2) || (nch == 3))
2821               && validate_test(CHILD(tree, 0)));
2822
2823    if (res && (nch == 2))
2824        res = validate_gen_for(CHILD(tree, 1));
2825    else if (res && (nch == 3))
2826        res = (validate_equal(CHILD(tree, 1))
2827               && validate_test(CHILD(tree, 2)));
2828
2829    return (res);
2830}
2831
2832
2833
2834/*  trailer:
2835 *
2836 *  '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
2837 */
2838static int
2839validate_trailer(node *tree)
2840{
2841    int nch = NCH(tree);
2842    int res = validate_ntype(tree, trailer) && ((nch == 2) || (nch == 3));
2843
2844    if (res) {
2845        switch (TYPE(CHILD(tree, 0))) {
2846          case LPAR:
2847            res = validate_rparen(CHILD(tree, nch - 1));
2848            if (res && (nch == 3))
2849                res = validate_arglist(CHILD(tree, 1));
2850            break;
2851          case LSQB:
2852            res = (validate_numnodes(tree, 3, "trailer")
2853                   && validate_subscriptlist(CHILD(tree, 1))
2854                   && validate_ntype(CHILD(tree, 2), RSQB));
2855            break;
2856          case DOT:
2857            res = (validate_numnodes(tree, 2, "trailer")
2858                   && validate_ntype(CHILD(tree, 1), NAME));
2859            break;
2860          default:
2861            res = 0;
2862            break;
2863        }
2864    }
2865    else {
2866        (void) validate_numnodes(tree, 2, "trailer");
2867    }
2868    return (res);
2869}
2870
2871
2872/*  subscriptlist:
2873 *
2874 *  subscript (',' subscript)* [',']
2875 */
2876static int
2877validate_subscriptlist(node *tree)
2878{
2879    return (validate_repeating_list(tree, subscriptlist,
2880                                    validate_subscript, "subscriptlist"));
2881}
2882
2883
2884/*  subscript:
2885 *
2886 *  '.' '.' '.' | test | [test] ':' [test] [sliceop]
2887 */
2888static int
2889validate_subscript(node *tree)
2890{
2891    int offset = 0;
2892    int nch = NCH(tree);
2893    int res = validate_ntype(tree, subscript) && (nch >= 1) && (nch <= 4);
2894
2895    if (!res) {
2896        if (!PyErr_Occurred())
2897            err_string("invalid number of arguments for subscript node");
2898        return (0);
2899    }
2900    if (TYPE(CHILD(tree, 0)) == DOT)
2901        /* take care of ('.' '.' '.') possibility */
2902        return (validate_numnodes(tree, 3, "subscript")
2903                && validate_dot(CHILD(tree, 0))
2904                && validate_dot(CHILD(tree, 1))
2905                && validate_dot(CHILD(tree, 2)));
2906    if (nch == 1) {
2907        if (TYPE(CHILD(tree, 0)) == test)
2908            res = validate_test(CHILD(tree, 0));
2909        else
2910            res = validate_colon(CHILD(tree, 0));
2911        return (res);
2912    }
2913    /*  Must be [test] ':' [test] [sliceop],
2914     *  but at least one of the optional components will
2915     *  be present, but we don't know which yet.
2916     */
2917    if ((TYPE(CHILD(tree, 0)) != COLON) || (nch == 4)) {
2918        res = validate_test(CHILD(tree, 0));
2919        offset = 1;
2920    }
2921    if (res)
2922        res = validate_colon(CHILD(tree, offset));
2923    if (res) {
2924        int rem = nch - ++offset;
2925        if (rem) {
2926            if (TYPE(CHILD(tree, offset)) == test) {
2927                res = validate_test(CHILD(tree, offset));
2928                ++offset;
2929                --rem;
2930            }
2931            if (res && rem)
2932                res = validate_sliceop(CHILD(tree, offset));
2933        }
2934    }
2935    return (res);
2936}
2937
2938
2939static int
2940validate_sliceop(node *tree)
2941{
2942    int nch = NCH(tree);
2943    int res = ((nch == 1) || validate_numnodes(tree, 2, "sliceop"))
2944              && validate_ntype(tree, sliceop);
2945    if (!res && !PyErr_Occurred()) {
2946        res = validate_numnodes(tree, 1, "sliceop");
2947    }
2948    if (res)
2949        res = validate_colon(CHILD(tree, 0));
2950    if (res && (nch == 2))
2951        res = validate_test(CHILD(tree, 1));
2952
2953    return (res);
2954}
2955
2956
2957static int
2958validate_exprlist(node *tree)
2959{
2960    return (validate_repeating_list(tree, exprlist,
2961                                    validate_expr, "exprlist"));
2962}
2963
2964
2965static int
2966validate_dictmaker(node *tree)
2967{
2968    int nch = NCH(tree);
2969    int res = (validate_ntype(tree, dictmaker)
2970               && (nch >= 3)
2971               && validate_test(CHILD(tree, 0))
2972               && validate_colon(CHILD(tree, 1))
2973               && validate_test(CHILD(tree, 2)));
2974
2975    if (res && ((nch % 4) == 0))
2976        res = validate_comma(CHILD(tree, --nch));
2977    else if (res)
2978        res = ((nch % 4) == 3);
2979
2980    if (res && (nch > 3)) {
2981        int pos = 3;
2982        /*  ( ',' test ':' test )*  */
2983        while (res && (pos < nch)) {
2984            res = (validate_comma(CHILD(tree, pos))
2985                   && validate_test(CHILD(tree, pos + 1))
2986                   && validate_colon(CHILD(tree, pos + 2))
2987                   && validate_test(CHILD(tree, pos + 3)));
2988            pos += 4;
2989        }
2990    }
2991    return (res);
2992}
2993
2994
2995static int
2996validate_eval_input(node *tree)
2997{
2998    int pos;
2999    int nch = NCH(tree);
3000    int res = (validate_ntype(tree, eval_input)
3001               && (nch >= 2)
3002               && validate_testlist(CHILD(tree, 0))
3003               && validate_ntype(CHILD(tree, nch - 1), ENDMARKER));
3004
3005    for (pos = 1; res && (pos < (nch - 1)); ++pos)
3006        res = validate_ntype(CHILD(tree, pos), NEWLINE);
3007
3008    return (res);
3009}
3010
3011
3012static int
3013validate_node(node *tree)
3014{
3015    int   nch  = 0;                     /* num. children on current node  */
3016    int   res  = 1;                     /* result value                   */
3017    node* next = 0;                     /* node to process after this one */
3018
3019    while (res && (tree != 0)) {
3020        nch  = NCH(tree);
3021        next = 0;
3022        switch (TYPE(tree)) {
3023            /*
3024             *  Definition nodes.
3025             */
3026          case funcdef:
3027            res = validate_funcdef(tree);
3028            break;
3029          case with_stmt:
3030            res = validate_with_stmt(tree);
3031            break;
3032          case classdef:
3033            res = validate_class(tree);
3034            break;
3035	  case decorated:
3036	    res = validate_decorated(tree);
3037	    break;
3038            /*
3039             *  "Trivial" parse tree nodes.
3040             *  (Why did I call these trivial?)
3041             */
3042          case stmt:
3043            res = validate_stmt(tree);
3044            break;
3045          case small_stmt:
3046            /*
3047             *  expr_stmt | print_stmt | del_stmt | pass_stmt | flow_stmt
3048             *  | import_stmt | global_stmt | exec_stmt | assert_stmt
3049             */
3050            res = validate_small_stmt(tree);
3051            break;
3052          case flow_stmt:
3053            res  = (validate_numnodes(tree, 1, "flow_stmt")
3054                    && ((TYPE(CHILD(tree, 0)) == break_stmt)
3055                        || (TYPE(CHILD(tree, 0)) == continue_stmt)
3056                        || (TYPE(CHILD(tree, 0)) == yield_stmt)
3057                        || (TYPE(CHILD(tree, 0)) == return_stmt)
3058                        || (TYPE(CHILD(tree, 0)) == raise_stmt)));
3059            if (res)
3060                next = CHILD(tree, 0);
3061            else if (nch == 1)
3062                err_string("illegal flow_stmt type");
3063            break;
3064          case yield_stmt:
3065            res = validate_yield_stmt(tree);
3066            break;
3067            /*
3068             *  Compound statements.
3069             */
3070          case simple_stmt:
3071            res = validate_simple_stmt(tree);
3072            break;
3073          case compound_stmt:
3074            res = validate_compound_stmt(tree);
3075            break;
3076            /*
3077             *  Fundamental statements.
3078             */
3079          case expr_stmt:
3080            res = validate_expr_stmt(tree);
3081            break;
3082          case print_stmt:
3083            res = validate_print_stmt(tree);
3084            break;
3085          case del_stmt:
3086            res = validate_del_stmt(tree);
3087            break;
3088          case pass_stmt:
3089            res = (validate_numnodes(tree, 1, "pass")
3090                   && validate_name(CHILD(tree, 0), "pass"));
3091            break;
3092          case break_stmt:
3093            res = (validate_numnodes(tree, 1, "break")
3094                   && validate_name(CHILD(tree, 0), "break"));
3095            break;
3096          case continue_stmt:
3097            res = (validate_numnodes(tree, 1, "continue")
3098                   && validate_name(CHILD(tree, 0), "continue"));
3099            break;
3100          case return_stmt:
3101            res = validate_return_stmt(tree);
3102            break;
3103          case raise_stmt:
3104            res = validate_raise_stmt(tree);
3105            break;
3106          case import_stmt:
3107            res = validate_import_stmt(tree);
3108            break;
3109	  case import_name:
3110	    res = validate_import_name(tree);
3111	    break;
3112	  case import_from:
3113	    res = validate_import_from(tree);
3114	    break;
3115          case global_stmt:
3116            res = validate_global_stmt(tree);
3117            break;
3118          case exec_stmt:
3119            res = validate_exec_stmt(tree);
3120            break;
3121          case assert_stmt:
3122            res = validate_assert_stmt(tree);
3123            break;
3124          case if_stmt:
3125            res = validate_if(tree);
3126            break;
3127          case while_stmt:
3128            res = validate_while(tree);
3129            break;
3130          case for_stmt:
3131            res = validate_for(tree);
3132            break;
3133          case try_stmt:
3134            res = validate_try(tree);
3135            break;
3136          case suite:
3137            res = validate_suite(tree);
3138            break;
3139            /*
3140             *  Expression nodes.
3141             */
3142          case testlist:
3143            res = validate_testlist(tree);
3144            break;
3145          case yield_expr:
3146            res = validate_yield_expr(tree);
3147            break;
3148          case testlist1:
3149            res = validate_testlist1(tree);
3150            break;
3151          case test:
3152            res = validate_test(tree);
3153            break;
3154          case and_test:
3155            res = validate_and_test(tree);
3156            break;
3157          case not_test:
3158            res = validate_not_test(tree);
3159            break;
3160          case comparison:
3161            res = validate_comparison(tree);
3162            break;
3163          case exprlist:
3164            res = validate_exprlist(tree);
3165            break;
3166          case comp_op:
3167            res = validate_comp_op(tree);
3168            break;
3169          case expr:
3170            res = validate_expr(tree);
3171            break;
3172          case xor_expr:
3173            res = validate_xor_expr(tree);
3174            break;
3175          case and_expr:
3176            res = validate_and_expr(tree);
3177            break;
3178          case shift_expr:
3179            res = validate_shift_expr(tree);
3180            break;
3181          case arith_expr:
3182            res = validate_arith_expr(tree);
3183            break;
3184          case term:
3185            res = validate_term(tree);
3186            break;
3187          case factor:
3188            res = validate_factor(tree);
3189            break;
3190          case power:
3191            res = validate_power(tree);
3192            break;
3193          case atom:
3194            res = validate_atom(tree);
3195            break;
3196
3197          default:
3198            /* Hopefully never reached! */
3199            err_string("unrecognized node type");
3200            res = 0;
3201            break;
3202        }
3203        tree = next;
3204    }
3205    return (res);
3206}
3207
3208
3209static int
3210validate_expr_tree(node *tree)
3211{
3212    int res = validate_eval_input(tree);
3213
3214    if (!res && !PyErr_Occurred())
3215        err_string("could not validate expression tuple");
3216
3217    return (res);
3218}
3219
3220
3221/*  file_input:
3222 *      (NEWLINE | stmt)* ENDMARKER
3223 */
3224static int
3225validate_file_input(node *tree)
3226{
3227    int j;
3228    int nch = NCH(tree) - 1;
3229    int res = ((nch >= 0)
3230               && validate_ntype(CHILD(tree, nch), ENDMARKER));
3231
3232    for (j = 0; res && (j < nch); ++j) {
3233        if (TYPE(CHILD(tree, j)) == stmt)
3234            res = validate_stmt(CHILD(tree, j));
3235        else
3236            res = validate_newline(CHILD(tree, j));
3237    }
3238    /*  This stays in to prevent any internal failures from getting to the
3239     *  user.  Hopefully, this won't be needed.  If a user reports getting
3240     *  this, we have some debugging to do.
3241     */
3242    if (!res && !PyErr_Occurred())
3243        err_string("VALIDATION FAILURE: report this to the maintainer!");
3244
3245    return (res);
3246}
3247
3248static int
3249validate_encoding_decl(node *tree)
3250{
3251    int nch = NCH(tree);
3252    int res = ((nch == 1)
3253        && validate_file_input(CHILD(tree, 0)));
3254
3255    if (!res && !PyErr_Occurred())
3256        err_string("Error Parsing encoding_decl");
3257
3258    return res;
3259}
3260
3261static PyObject*
3262pickle_constructor = NULL;
3263
3264
3265static PyObject*
3266parser__pickler(PyObject *self, PyObject *args)
3267{
3268    NOTE(ARGUNUSED(self))
3269    PyObject *result = NULL;
3270    PyObject *st = NULL;
3271    PyObject *empty_dict = NULL;
3272
3273    if (PyArg_ParseTuple(args, "O!:_pickler", &PyST_Type, &st)) {
3274        PyObject *newargs;
3275        PyObject *tuple;
3276
3277        if ((empty_dict = PyDict_New()) == NULL)
3278            goto finally;
3279        if ((newargs = Py_BuildValue("Oi", st, 1)) == NULL)
3280            goto finally;
3281        tuple = parser_st2tuple((PyST_Object*)NULL, newargs, empty_dict);
3282        if (tuple != NULL) {
3283            result = Py_BuildValue("O(O)", pickle_constructor, tuple);
3284            Py_DECREF(tuple);
3285        }
3286        Py_DECREF(empty_dict);
3287        Py_DECREF(newargs);
3288    }
3289  finally:
3290    Py_XDECREF(empty_dict);
3291
3292    return (result);
3293}
3294
3295
3296/*  Functions exported by this module.  Most of this should probably
3297 *  be converted into an ST object with methods, but that is better
3298 *  done directly in Python, allowing subclasses to be created directly.
3299 *  We'd really have to write a wrapper around it all anyway to allow
3300 *  inheritance.
3301 */
3302static PyMethodDef parser_functions[] =  {
3303    {"ast2tuple",       (PyCFunction)parser_ast2tuple, PUBLIC_METHOD_TYPE,
3304        PyDoc_STR("Creates a tuple-tree representation of an ST.")},
3305    {"ast2list",        (PyCFunction)parser_ast2list,  PUBLIC_METHOD_TYPE,
3306        PyDoc_STR("Creates a list-tree representation of an ST.")},
3307    {"compileast",      (PyCFunction)parser_compileast,PUBLIC_METHOD_TYPE,
3308        PyDoc_STR("Compiles an ST object into a code object.")},
3309    {"compilest",      (PyCFunction)parser_compilest,  PUBLIC_METHOD_TYPE,
3310        PyDoc_STR("Compiles an ST object into a code object.")},
3311    {"expr",            (PyCFunction)parser_expr,      PUBLIC_METHOD_TYPE,
3312        PyDoc_STR("Creates an ST object from an expression.")},
3313    {"isexpr",          (PyCFunction)parser_isexpr,    PUBLIC_METHOD_TYPE,
3314        PyDoc_STR("Determines if an ST object was created from an expression.")},
3315    {"issuite",         (PyCFunction)parser_issuite,   PUBLIC_METHOD_TYPE,
3316        PyDoc_STR("Determines if an ST object was created from a suite.")},
3317    {"suite",           (PyCFunction)parser_suite,     PUBLIC_METHOD_TYPE,
3318        PyDoc_STR("Creates an ST object from a suite.")},
3319    {"sequence2ast",    (PyCFunction)parser_tuple2ast, PUBLIC_METHOD_TYPE,
3320        PyDoc_STR("Creates an ST object from a tree representation.")},
3321    {"sequence2st",     (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3322        PyDoc_STR("Creates an ST object from a tree representation.")},
3323    {"st2tuple",        (PyCFunction)parser_st2tuple,  PUBLIC_METHOD_TYPE,
3324        PyDoc_STR("Creates a tuple-tree representation of an ST.")},
3325    {"st2list",         (PyCFunction)parser_st2list,   PUBLIC_METHOD_TYPE,
3326        PyDoc_STR("Creates a list-tree representation of an ST.")},
3327    {"tuple2ast",       (PyCFunction)parser_tuple2ast, PUBLIC_METHOD_TYPE,
3328        PyDoc_STR("Creates an ST object from a tree representation.")},
3329    {"tuple2st",        (PyCFunction)parser_tuple2st,  PUBLIC_METHOD_TYPE,
3330        PyDoc_STR("Creates an ST object from a tree representation.")},
3331
3332    /* private stuff: support pickle module */
3333    {"_pickler",        (PyCFunction)parser__pickler,  METH_VARARGS,
3334        PyDoc_STR("Returns the pickle magic to allow ST objects to be pickled.")},
3335
3336    {NULL, NULL, 0, NULL}
3337    };
3338
3339
3340PyMODINIT_FUNC initparser(void);  /* supply a prototype */
3341
3342PyMODINIT_FUNC
3343initparser(void)
3344{
3345    PyObject *module, *copyreg;
3346
3347    Py_TYPE(&PyST_Type) = &PyType_Type;
3348    module = Py_InitModule("parser", parser_functions);
3349    if (module == NULL)
3350    	return;
3351
3352    if (parser_error == 0)
3353        parser_error = PyErr_NewException("parser.ParserError", NULL, NULL);
3354
3355    if (parser_error == 0)
3356        /* caller will check PyErr_Occurred() */
3357        return;
3358    /* CAUTION:  The code next used to skip bumping the refcount on
3359     * parser_error.  That's a disaster if initparser() gets called more
3360     * than once.  By incref'ing, we ensure that each module dict that
3361     * gets created owns its reference to the shared parser_error object,
3362     * and the file static parser_error vrbl owns a reference too.
3363     */
3364    Py_INCREF(parser_error);
3365    if (PyModule_AddObject(module, "ParserError", parser_error) != 0)
3366        return;
3367
3368    Py_INCREF(&PyST_Type);
3369    PyModule_AddObject(module, "ASTType", (PyObject*)&PyST_Type);
3370    Py_INCREF(&PyST_Type);
3371    PyModule_AddObject(module, "STType", (PyObject*)&PyST_Type);
3372
3373    PyModule_AddStringConstant(module, "__copyright__",
3374                               parser_copyright_string);
3375    PyModule_AddStringConstant(module, "__doc__",
3376                               parser_doc_string);
3377    PyModule_AddStringConstant(module, "__version__",
3378                               parser_version_string);
3379
3380    /* Register to support pickling.
3381     * If this fails, the import of this module will fail because an
3382     * exception will be raised here; should we clear the exception?
3383     */
3384    copyreg = PyImport_ImportModuleNoBlock("copy_reg");
3385    if (copyreg != NULL) {
3386        PyObject *func, *pickler;
3387
3388        func = PyObject_GetAttrString(copyreg, "pickle");
3389        pickle_constructor = PyObject_GetAttrString(module, "sequence2st");
3390        pickler = PyObject_GetAttrString(module, "_pickler");
3391        Py_XINCREF(pickle_constructor);
3392        if ((func != NULL) && (pickle_constructor != NULL)
3393            && (pickler != NULL)) {
3394            PyObject *res;
3395
3396            res = PyObject_CallFunctionObjArgs(func, &PyST_Type, pickler,
3397                                               pickle_constructor, NULL);
3398            Py_XDECREF(res);
3399        }
3400        Py_XDECREF(func);
3401        Py_XDECREF(pickle_constructor);
3402        Py_XDECREF(pickler);
3403        Py_DECREF(copyreg);
3404    }
3405}