/third_party/gotools/go/types/api.go
Go | 365 lines | 131 code | 41 blank | 193 comment | 27 complexity | afc46522d2ec767948aae03eaae1a91d MD5 | raw file
Possible License(s): BSD-3-Clause, MIT
- // Copyright 2012 The Go Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style
- // license that can be found in the LICENSE file.
- // Package types declares the data types and implements
- // the algorithms for type-checking of Go packages.
- // Use Check and Config.Check to invoke the type-checker.
- //
- // Type-checking consists of several interdependent phases:
- //
- // Name resolution maps each identifier (ast.Ident) in the program to the
- // language object (Object) it denotes.
- // Use Info.{Defs,Uses,Implicits} for the results of name resolution.
- //
- // Constant folding computes the exact constant value (exact.Value) for
- // every expression (ast.Expr) that is a compile-time constant.
- // Use Info.Types[expr].Value for the results of constant folding.
- //
- // Type inference computes the type (Type) of every expression (ast.Expr)
- // and checks for compliance with the language specification.
- // Use Info.Types[expr].Type for the results of type inference.
- //
- package types // import "llvm.org/llgo/third_party/gotools/go/types"
- import (
- "bytes"
- "fmt"
- "go/ast"
- "go/token"
- "llvm.org/llgo/third_party/gotools/go/exact"
- )
- // Check type-checks a package and returns the resulting complete package
- // object, or a nil package and the first error. The package is specified
- // by a list of *ast.Files and corresponding file set, and the import path
- // the package is identified with. The clean path must not be empty or dot (".").
- //
- // For more control over type-checking and results, use Config.Check.
- func Check(path string, fset *token.FileSet, files []*ast.File) (*Package, error) {
- var conf Config
- pkg, err := conf.Check(path, fset, files, nil)
- if err != nil {
- return nil, err
- }
- return pkg, nil
- }
- // An Error describes a type-checking error; it implements the error interface.
- // A "soft" error is an error that still permits a valid interpretation of a
- // package (such as "unused variable"); "hard" errors may lead to unpredictable
- // behavior if ignored.
- type Error struct {
- Fset *token.FileSet // file set for interpretation of Pos
- Pos token.Pos // error position
- Msg string // error message
- Soft bool // if set, error is "soft"
- }
- // Error returns an error string formatted as follows:
- // filename:line:column: message
- func (err Error) Error() string {
- return fmt.Sprintf("%s: %s", err.Fset.Position(err.Pos), err.Msg)
- }
- // An importer resolves import paths to Packages.
- // The imports map records packages already known,
- // indexed by package path. The type-checker
- // will invoke Import with Config.Packages.
- // An importer must determine the canonical package path and
- // check imports to see if it is already present in the map.
- // If so, the Importer can return the map entry. Otherwise,
- // the importer must load the package data for the given path
- // into a new *Package, record it in imports map, and return
- // the package.
- // TODO(gri) Need to be clearer about requirements of completeness.
- type Importer func(map[string]*Package, string) (*Package, error)
- // A Config specifies the configuration for type checking.
- // The zero value for Config is a ready-to-use default configuration.
- type Config struct {
- // If IgnoreFuncBodies is set, function bodies are not
- // type-checked.
- IgnoreFuncBodies bool
- // If FakeImportC is set, `import "C"` (for packages requiring Cgo)
- // declares an empty "C" package and errors are omitted for qualified
- // identifiers referring to package C (which won't find an object).
- // This feature is intended for the standard library cmd/api tool.
- //
- // Caution: Effects may be unpredictable due to follow-up errors.
- // Do not use casually!
- FakeImportC bool
- // Packages is used to look up (and thus canonicalize) packages by
- // package path. If Packages is nil, it is set to a new empty map.
- // During type-checking, imported packages are added to the map.
- Packages map[string]*Package
- // If Error != nil, it is called with each error found
- // during type checking; err has dynamic type Error.
- // Secondary errors (for instance, to enumerate all types
- // involved in an invalid recursive type declaration) have
- // error strings that start with a '\t' character.
- // If Error == nil, type-checking stops with the first
- // error found.
- Error func(err error)
- // If Import != nil, it is called for each imported package.
- // Otherwise, DefaultImport is called.
- Import Importer
- // If Sizes != nil, it provides the sizing functions for package unsafe.
- // Otherwise &StdSizes{WordSize: 8, MaxAlign: 8} is used instead.
- Sizes Sizes
- // If DisableUnusedImportCheck is set, packages are not checked
- // for unused imports.
- DisableUnusedImportCheck bool
- }
- // DefaultImport is the default importer invoked if Config.Import == nil.
- // The declaration:
- //
- // import _ "llvm.org/llgo/third_party/gotools/go/gcimporter"
- //
- // in a client of go/types will initialize DefaultImport to gcimporter.Import.
- var DefaultImport Importer
- // Info holds result type information for a type-checked package.
- // Only the information for which a map is provided is collected.
- // If the package has type errors, the collected information may
- // be incomplete.
- type Info struct {
- // Types maps expressions to their types, and for constant
- // expressions, their values. Invalid expressions are omitted.
- //
- // For (possibly parenthesized) identifiers denoting built-in
- // functions, the recorded signatures are call-site specific:
- // if the call result is not a constant, the recorded type is
- // an argument-specific signature. Otherwise, the recorded type
- // is invalid.
- //
- // Identifiers on the lhs of declarations (i.e., the identifiers
- // which are being declared) are collected in the Defs map.
- // Identifiers denoting packages are collected in the Uses maps.
- Types map[ast.Expr]TypeAndValue
- // Defs maps identifiers to the objects they define (including
- // package names, dots "." of dot-imports, and blank "_" identifiers).
- // For identifiers that do not denote objects (e.g., the package name
- // in package clauses, or symbolic variables t in t := x.(type) of
- // type switch headers), the corresponding objects are nil.
- //
- // For an anonymous field, Defs returns the field *Var it defines.
- //
- // Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
- Defs map[*ast.Ident]Object
- // Uses maps identifiers to the objects they denote.
- //
- // For an anonymous field, Uses returns the *TypeName it denotes.
- //
- // Invariant: Uses[id].Pos() != id.Pos()
- Uses map[*ast.Ident]Object
- // Implicits maps nodes to their implicitly declared objects, if any.
- // The following node and object types may appear:
- //
- // node declared object
- //
- // *ast.ImportSpec *PkgName for dot-imports and imports without renames
- // *ast.CaseClause type-specific *Var for each type switch case clause (incl. default)
- // *ast.Field anonymous struct field or parameter *Var
- //
- Implicits map[ast.Node]Object
- // Selections maps selector expressions (excluding qualified identifiers)
- // to their corresponding selections.
- Selections map[*ast.SelectorExpr]*Selection
- // Scopes maps ast.Nodes to the scopes they define. Package scopes are not
- // associated with a specific node but with all files belonging to a package.
- // Thus, the package scope can be found in the type-checked Package object.
- // Scopes nest, with the Universe scope being the outermost scope, enclosing
- // the package scope, which contains (one or more) files scopes, which enclose
- // function scopes which in turn enclose statement and function literal scopes.
- // Note that even though package-level functions are declared in the package
- // scope, the function scopes are embedded in the file scope of the file
- // containing the function declaration.
- //
- // The following node types may appear in Scopes:
- //
- // *ast.File
- // *ast.FuncType
- // *ast.BlockStmt
- // *ast.IfStmt
- // *ast.SwitchStmt
- // *ast.TypeSwitchStmt
- // *ast.CaseClause
- // *ast.CommClause
- // *ast.ForStmt
- // *ast.RangeStmt
- //
- Scopes map[ast.Node]*Scope
- // InitOrder is the list of package-level initializers in the order in which
- // they must be executed. Initializers referring to variables related by an
- // initialization dependency appear in topological order, the others appear
- // in source order. Variables without an initialization expression do not
- // appear in this list.
- InitOrder []*Initializer
- }
- // TypeOf returns the type of expression e, or nil if not found.
- // Precondition: the Types, Uses and Defs maps are populated.
- //
- func (info *Info) TypeOf(e ast.Expr) Type {
- if t, ok := info.Types[e]; ok {
- return t.Type
- }
- if id, _ := e.(*ast.Ident); id != nil {
- if obj := info.ObjectOf(id); obj != nil {
- return obj.Type()
- }
- }
- return nil
- }
- // ObjectOf returns the object denoted by the specified id,
- // or nil if not found.
- //
- // If id is an anonymous struct field, ObjectOf returns the field (*Var)
- // it uses, not the type (*TypeName) it defines.
- //
- // Precondition: the Uses and Defs maps are populated.
- //
- func (info *Info) ObjectOf(id *ast.Ident) Object {
- if obj, _ := info.Defs[id]; obj != nil {
- return obj
- }
- return info.Uses[id]
- }
- // TypeAndValue reports the type and value (for constants)
- // of the corresponding expression.
- type TypeAndValue struct {
- mode operandMode
- Type Type
- Value exact.Value
- }
- // TODO(gri) Consider eliminating the IsVoid predicate. Instead, report
- // "void" values as regular values but with the empty tuple type.
- // IsVoid reports whether the corresponding expression
- // is a function call without results.
- func (tv TypeAndValue) IsVoid() bool {
- return tv.mode == novalue
- }
- // IsType reports whether the corresponding expression specifies a type.
- func (tv TypeAndValue) IsType() bool {
- return tv.mode == typexpr
- }
- // IsBuiltin reports whether the corresponding expression denotes
- // a (possibly parenthesized) built-in function.
- func (tv TypeAndValue) IsBuiltin() bool {
- return tv.mode == builtin
- }
- // IsValue reports whether the corresponding expression is a value.
- // Builtins are not considered values. Constant values have a non-
- // nil Value.
- func (tv TypeAndValue) IsValue() bool {
- switch tv.mode {
- case constant, variable, mapindex, value, commaok:
- return true
- }
- return false
- }
- // IsNil reports whether the corresponding expression denotes the
- // predeclared value nil.
- func (tv TypeAndValue) IsNil() bool {
- return tv.mode == value && tv.Type == Typ[UntypedNil]
- }
- // Addressable reports whether the corresponding expression
- // is addressable (http://golang.org/ref/spec#Address_operators).
- func (tv TypeAndValue) Addressable() bool {
- return tv.mode == variable
- }
- // Assignable reports whether the corresponding expression
- // is assignable to (provided a value of the right type).
- func (tv TypeAndValue) Assignable() bool {
- return tv.mode == variable || tv.mode == mapindex
- }
- // HasOk reports whether the corresponding expression may be
- // used on the lhs of a comma-ok assignment.
- func (tv TypeAndValue) HasOk() bool {
- return tv.mode == commaok || tv.mode == mapindex
- }
- // An Initializer describes a package-level variable, or a list of variables in case
- // of a multi-valued initialization expression, and the corresponding initialization
- // expression.
- type Initializer struct {
- Lhs []*Var // var Lhs = Rhs
- Rhs ast.Expr
- }
- func (init *Initializer) String() string {
- var buf bytes.Buffer
- for i, lhs := range init.Lhs {
- if i > 0 {
- buf.WriteString(", ")
- }
- buf.WriteString(lhs.Name())
- }
- buf.WriteString(" = ")
- WriteExpr(&buf, init.Rhs)
- return buf.String()
- }
- // Check type-checks a package and returns the resulting package object,
- // the first error if any, and if info != nil, additional type information.
- // The package is marked as complete if no errors occurred, otherwise it is
- // incomplete. See Config.Error for controlling behavior in the presence of
- // errors.
- //
- // The package is specified by a list of *ast.Files and corresponding
- // file set, and the package path the package is identified with.
- // The clean path must not be empty or dot (".").
- func (conf *Config) Check(path string, fset *token.FileSet, files []*ast.File, info *Info) (*Package, error) {
- pkg := NewPackage(path, "")
- return pkg, NewChecker(conf, fset, pkg, info).Files(files)
- }
- // AssertableTo reports whether a value of type V can be asserted to have type T.
- func AssertableTo(V *Interface, T Type) bool {
- m, _ := assertableTo(V, T)
- return m == nil
- }
- // AssignableTo reports whether a value of type V is assignable to a variable of type T.
- func AssignableTo(V, T Type) bool {
- x := operand{mode: value, typ: V}
- return x.assignableTo(nil, T) // config not needed for non-constant x
- }
- // ConvertibleTo reports whether a value of type V is convertible to a value of type T.
- func ConvertibleTo(V, T Type) bool {
- x := operand{mode: value, typ: V}
- return x.convertibleTo(nil, T) // config not needed for non-constant x
- }
- // Implements reports whether type V implements interface T.
- func Implements(V Type, T *Interface) bool {
- f, _ := MissingMethod(V, T, true)
- return f == nil
- }