/pydbgr/lib/stack.py

# -*- coding: utf-8 -*-
#   Copyright (C) 2008, 2009, 2010 Rocky Bernstein <rocky@gnu.org>
#
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
""" Functions for working with Python frames"""
import re, types

from import_relative import import_relative
Mbytecode = import_relative('bytecode', top_name='pydbgr')
Mprint    = import_relative('print', top_name='pydbgr')

def count_frames(frame, count_start=0):
    "Return a count of the number of frames"
    count = -count_start
    while frame: 
        count += 1
        frame = frame.f_back
    return count

import repr as Mrepr
import inspect

_re_pseudo_file = re.compile(r'^<.+>')

def format_stack_entry(dbg_obj, frame_lineno, lprefix=': ',
                       include_location=True):
    """Format and return a stack entry gdb-style.
    Note: lprefix is not used. It is kept for compatibility.
    """
    frame, lineno = frame_lineno
    filename = frame2file(dbg_obj.core, frame)

    s = ''
    if frame.f_code.co_name:
        s = frame.f_code.co_name
    else:
        s = "<lambda>"
        pass

    args, varargs, varkw, local_vars = inspect.getargvalues(frame)
    if '<module>' == s and ([], None, None,) == (args, varargs, varkw,):
        is_module = True
        if is_exec_stmt(frame): 
            s += ' exec()'
        else:
            fn_name = get_call_function_name(frame)
            if fn_name: s += ' %s()' % fn_name
            pass
    else:
        is_module = False
        parms=inspect.formatargvalues(args, varargs, varkw, local_vars)
        maxargstrsize = dbg_obj.settings['maxargstrsize']
        if len(parms) >= maxargstrsize:
            parms = "%s...)" % parms[0:maxargstrsize]
            pass
        s += parms
        pass

    # Note: ddd can't handle wrapped stack entries (yet).
    # The 35 is hoaky though. FIXME.
    if len(s) >= 35: s += "\n    "

    if '__return__' in frame.f_locals:
        rv = frame.f_locals['__return__']
        s += '->'
        s += Mrepr.repr(rv)
        pass

    if include_location:
        is_pseudo_file = _re_pseudo_file.match(filename)
        add_quotes_around_file = not is_pseudo_file
        if is_module:
            if not is_exec_stmt(frame) and not is_pseudo_file:
                s += ' file'
        elif s == '?()':
            if is_exec_stmt(frame):
                s = 'in exec'
                # exec_str = get_exec_string(frame.f_back)
                # if exec_str != None:
                #     filename = exec_str
                #     add_quotes_around_file = False
                #     pass
                # pass
            elif not is_pseudo_file:
                s = 'in file'
                pass
            pass
        elif not is_pseudo_file:
            s += ' called from file'
            pass

        if add_quotes_around_file: filename = "'%s'" % filename
        s += " %s at line %r" % (filename, lineno)
    return s

def frame2file(core_obj, frame):
    return core_obj.filename(core_obj.canonic_filename(frame))

def is_exec_stmt(frame):
    """Return True if we are looking at an exec statement"""
    return hasattr(frame, 'f_back') and frame.f_back is not None and \
        Mbytecode.op_at_frame(frame.f_back)=='EXEC_STMT'

import dis
def get_call_function_name(frame):
    """If f_back is looking at a call function, return 
    the name for it. Otherwise return None"""
    f_back = frame.f_back
    if not f_back: return None
    if 'CALL_FUNCTION' != Mbytecode.op_at_frame(f_back): return None

    co         = f_back.f_code
    code       = co.co_code
    # labels     = dis.findlabels(code)
    linestarts = dict(dis.findlinestarts(co))
    inst       = f_back.f_lasti
    while inst >= 0:
        # c = code[inst]
        # op = ord(c)
        if inst in linestarts:
            inst += 1
            oparg = ord(code[inst]) + (ord(code[inst+1]) << 8)
            return co.co_names[oparg]
        inst -= 1
        pass
    return None

def print_stack_entry(proc_obj, i_stack):
    frame_lineno = proc_obj.stack[len(proc_obj.stack)-i_stack-1]
    frame, lineno = frame_lineno
    if frame is proc_obj.curframe:
        proc_obj.intf[-1].msg_nocr('->')
    else:
        proc_obj.intf[-1].msg_nocr('##')
    proc_obj.intf[-1].msg("%d %s" %
             (i_stack, format_stack_entry(proc_obj.debugger, frame_lineno)))

def print_stack_trace(proc_obj, count=None):
    "Print count entries of the stack trace"
    if count is None:
        n=len(proc_obj.stack)
    else:
        n=min(len(proc_obj.stack), count)
    try:
        for i in range(n):
            print_stack_entry(proc_obj, i)
    except KeyboardInterrupt:
        pass
    return

def print_dict(s, obj, title):
    if hasattr(obj, "__dict__"):
        d=obj.__dict__
        if type(d) == types.DictType or type(d) == types.DictProxyType:
            keys = d.keys()
            if len(keys) == 0:
                s += "\n  No %s" % title
            else:
                s += "\n  %s:\n" % title
            keys.sort()
            for key in keys:
                s+="    '%s':\t%s\n" % (key, d[key])
                pass
            pass
        pass
    return s

def eval_print_obj(arg, frame, format=None, short=False):
    """Return a string representation of an object """
    try:
        if not frame:
            # ?? Should we have set up a dummy globals
            # to have persistence? 
            val = eval(arg, None, None)
        else:
            val = eval(arg, frame.f_globals, frame.f_locals)
            pass
    except:
        return 'No symbol "' + arg + '" in current context.'

    return print_obj(arg, val, format, short)

def print_obj(arg, val, format=None, short=False):
    """Return a string representation of an object """
    what = arg
    if format:
        what = format + ' ' + arg
        val = Mprint.printf(val, format)
        pass
    s = '%s = %s' % (what, val)
    if not short:
        s += '\n  type = %s' % type(val)
        # Try to list the members of a class.
        # Not sure if this is correct or the
        # best way to do.
        s = print_dict(s, val, "object variables")
        if hasattr(val, "__class__"):
            s = print_dict(s, val.__class__, "class variables")
            pass
        pass
    return s

# Demo stuff above
if __name__=='__main__':
    class MockDebuggerCore():
        def canonic_filename(self, frame):
            return frame.f_code.co_filename
        def filename(self, name):
            return name
        pass
    class MockDebugger():
        def __init__(self):
            self.core = MockDebuggerCore()
            self.settings = {
                'maxargstrsize': 80
                }
            pass
        pass
        
    frame = inspect.currentframe()
    m = MockDebugger()
    print format_stack_entry(m, (frame, 10,))
    print "frame count: ", count_frames(frame)
    print "frame count: ", count_frames(frame.f_back)
    print "frame count: ", count_frames(frame, 1)
    print "def statement: x=5?: ", Mbytecode.is_def_stmt('x=5', frame)
    # Not a "def" statement because frame is wrong spot
    print Mbytecode.is_def_stmt('def foo():', frame)
    def sqr(x): x * x 
    def fn(x):
        frame = inspect.currentframe()
        print get_call_function_name(frame)
        return
    print '=' * 30
    eval('fn(5)')
    print '=' * 30
    print print_obj('fn', fn)
    print '=' * 30
    print print_obj('len', len)
    print '=' * 30
    print print_obj('MockDebugger', MockDebugger)
    pass