golang api 代码
文件路径：/src/cmd/compile/internal/types2/api.go
/ 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
/ Config.Check to invoke the type checker for a package.
/ Alternatively, create a new type checker with NewChecker
/ and invoke it incrementally by calling Checker.Files.
/
/ Type-checking consists of several interdependent phases:
/
/ Name resolution maps each identifier (syntax.Name) 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 (constant.Value)
/ for every expression (syntax.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 (syntax.Expr)
/ and checks for compliance with the language specification.
/ Use Info.Types[expr].Type for the results of type inference.
package types2
import (
"bytes"
"cmd/compile/internal/syntax"
"fmt"
"go/constant"
)
/ 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 {
Pos syntax.Pos / error position
Msg string / default error message, user-friendly
Full string / full error message, for debugging (may contain internal details)
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.Pos, err.Msg)
}
/ FullError returns an error string like Error, buy it may contain
/ type-checker internal details such as subscript indices for type
/ parameters and more. Useful for debugging.
func (err Error) FullError() string {
return fmt.Sprintf("%s: %s", err.Pos, err.Full)
}
/ An ArgumentError holds an error associated with an argument index.
type ArgumentError struct {
Index int
Err error
}
func (e *ArgumentError) Error() string { return e.Err.Error() }
func (e *ArgumentError) Unwrap() error { return e.Err }
/ An Importer resolves import paths to Packages.
/
/ CAUTION: This interface does not support the import of locally
/ vendored packages. See https://golang.org/s/go15vendor.
/ If possible, external implementations should implement ImporterFrom.
type Importer interface {
/ Import returns the imported package for the given import path.
/ The semantics is like for ImporterFrom.ImportFrom except that
/ dir and mode are ignored (since they are not present).
Import(path string) (*Package, error)
}
/ ImportMode is reserved for future use.
type ImportMode int
/ An ImporterFrom resolves import paths to packages; it
/ supports vendoring per https://golang.org/s/go15vendor.
/ Use go/importer to obtain an ImporterFrom implementation.
type ImporterFrom interface {
/ Importer is present for backward-compatibility. Calling
/ Import(path) is the same as calling ImportFrom(path, "", 0);
/ i.e., locally vendored packages may not be found.
/ The types package does not call Import if an ImporterFrom
/ is present.
Importer
/ ImportFrom returns the imported package for the given import
/ path when imported by a package file located in dir.
/ If the import failed, besides returning an error, ImportFrom
/ is encouraged to cache and return a package anyway, if one
/ was created. This will reduce package inconsistencies and
/ follow-on type checker errors due to the missing package.
/ The mode value must be 0; it is reserved for future use.
/ Two calls to ImportFrom with the same path and dir must
/ return the same package.
ImportFrom(path, dir string, mode ImportMode) (*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 {
/ Context is the context used for resolving global identifiers. If nil, the
/ type checker will initialize this field with a newly created context.
Context *Context
/ GoVersion describes the accepted Go language version. The string
/ must follow the format "go%d.%d" (e.g. "go1.12") or ist must be
/ empty; an empty string indicates the latest language version.
/ If the format is invalid, invoking the type checker will cause a
/ panic.
GoVersion string
/ 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-on errors.
/ Do not use casually!
FakeImportC bool
/ If IgnoreBranchErrors is set, branch/label errors are ignored.
IgnoreBranchErrors bool
/ If CompilerErrorMessages is set, errors are reported using
/ cmd/compile error strings to match $GOROOT/test errors.
/ TODO(gri) Consolidate error messages and remove this flag.
CompilerErrorMessages bool
/ If go115UsesCgo is set, the type checker expects the
/ _cgo_gotypes.go file generated by running cmd/cgo to be
/ provided as a package source file. Qualified identifiers
/ referring to package C will be resolved to cgo-provided
/ declarations within _cgo_gotypes.go.
/
/ It is an error to set both FakeImportC and go115UsesCgo.
go115UsesCgo bool
/ If Trace is set, a debug trace is printed to stdout.
Trace bool
/ 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)
/ An importer is used to import packages referred to from
/ import declarations.
/ If the installed importer implements ImporterFrom, the type
/ checker calls ImportFrom instead of Import.
/ The type checker reports an error if an importer is needed
/ but none was installed.
Importer Importer
/ If Sizes != nil, it provides the sizing functions for package unsafe.
/ Otherwise SizesFor("gc", "amd64") is used instead.
Sizes Sizes
/ If DisableUnusedImportCheck is set, packages are not checked
/ for unused imports.
DisableUnusedImportCheck bool
}
func srcimporter_setUsesCgo(conf *Config) {
conf.go115UsesCgo = true
}
/ 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, also 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.
/
/ The Types map does not record the type of every identifier,
/ only those that appear where an arbitrary expression is
/ permitted. For instance, the identifier f in a selector
/ expression x.f is found only in the Selections map, the
/ identifier z in a variable declaration 'var z int' is found
/ only in the Defs map, and identifiers denoting packages in
/ qualified identifiers are collected in the Uses map.
Types map[syntax.Expr]TypeAndValue
/ Instances maps identifiers denoting generic types or functions to their
/ type arguments and instantiated type.
/
/ For example, Instances will map the identifier for 'T' in the type
/ instantiation T[int, string] to the type arguments [int, string] and
/ resulting instantiated *Named type. Given a generic function
/ func F[A any](A), Instances will map the identifier for 'F' in the call
/ expression F(int(1)) to the inferred type arguments [int], and resulting
/ instantiated *Signature.
/
/ Invariant: Instantiating Uses[id].Type() with Instances[id].TypeArgs
/ results in an equivalent of Instances[id].Type.
Instances map[*syntax.Name]Instance
/ 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 embedded field, Defs returns the field *Var it defines.
/
/ Invariant: Defs[id] == nil || Defs[id].Pos() == id.Pos()
Defs map[*syntax.Name]Object
/ Uses maps identifiers to the objects they denote.
/
/ For an embedded field, Uses returns the *TypeName it denotes.
/
/ Invariant: Uses[id].Pos() != id.Pos()
Uses map[*syntax.Name]Object
/ Implicits maps nodes to their implicitly declared objects, if any.
/ The following node and object types may appear:
/
/ node declared object
/
/ *syntax.ImportDecl *PkgName for imports without renames
/ *syntax.CaseClause type-specific *Var for each type switch case clause (incl. default)
/ *syntax.Field anonymous parameter *Var (incl. unnamed results)
/
Implicits map[syntax.Node]Object
/ Selections maps selector expressions (excluding qualified identifiers)
/ to their corresponding selections.
Selections map[*syntax.SelectorExpr]*Selection
/ Scopes maps syntax.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:
/
/ *syntax.File
/ *syntax.FuncType
/ *syntax.TypeDecl
/ *syntax.BlockStmt
/ *syntax.IfStmt
/ *syntax.SwitchStmt
/ *syntax.CaseClause
/ *syntax.CommClause
/ *syntax.ForStmt
/
Scopes map[syntax.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 syntax.Expr) Type {
if t, ok := info.Types[e]; ok {
return t.Type
}
if id, _ := e.(*syntax.Name); 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 embedded struct field, ObjectOf returns the field (*Var)
/ it defines, not the type (*TypeName) it uses.
/
/ Precondition: the Uses and Defs maps are populated.
func (info *Info) ObjectOf(id *syntax.Name) 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 constant.Value
}
/ 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, nilvalue, commaok, commaerr:
return true
}
return false
}
/ IsNil reports whether the corresponding expression denotes the
/ predeclared value nil. Depending on context, it may have been
/ given a type different from UntypedNil.
func (tv TypeAndValue) IsNil() bool {
return tv.mode == nilvalue
}
/ Addressable reports whether the corresponding expression
/ is addressable (https://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 rhs of a comma-ok assignment.
func (tv TypeAndValue) HasOk() bool {
return tv.mode == commaok || tv.mode == mapindex
}
/ Instance reports the type arguments and instantiated type for type and
/ function instantiations. For type instantiations, Type will be of dynamic
/ type *Named. For function instantiations, Type will be of dynamic type
/ *Signature.
type Instance struct {
TypeArgs *TypeList
Type Type
}
/ 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 syntax.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(" = ")
syntax.Fprint(&buf, init.Rhs, syntax.ShortForm)
return buf.String()
}
/ Check type-checks a package and returns the resulting package object and
/ the first error if any. Additionally, if info != nil, Check populates each
/ of the non-nil maps in the Info struct.
/
/ 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 *syntax.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, files []*syntax.File, info *Info) (*Package, error) {
pkg := NewPackage(path, "")
return pkg, NewChecker(conf, pkg, info).Files(files)
}
/ AssertableTo reports whether a value of type V can be asserted to have type T.
/
/ The behavior of AssertableTo is unspecified in three cases:
/ - if T is Typ[Invalid]
/ - if V is a generalized interface; i.e., an interface that may only be used
/ as a type constraint in Go code
/ - if T is an uninstantiated generic type
func AssertableTo(V *Interface, T Type) bool {
/ Checker.newAssertableTo suppresses errors for invalid types, so we need special
/ handling here.
if T.Underlying() == Typ[Invalid] {
return false
}
return (*Checker)(nil).newAssertableTo(V, T) == nil
}
/ AssignableTo reports whether a value of type V is assignable to a variable
/ of type T.
/
/ The behavior of AssignableTo is unspecified if V or T is Typ[Invalid] or an
/ uninstantiated generic type.
func AssignableTo(V, T Type) bool {
x := operand{mode: value, typ: V}
ok, _ := x.assignableTo(nil, T, nil) / check not needed for non-constant x
return ok
}
/ ConvertibleTo reports whether a value of type V is convertible to a value of
/ type T.
/
/ The behavior of ConvertibleTo is unspecified if V or T is Typ[Invalid] or an
/ uninstantiated generic type.
func ConvertibleTo(V, T Type) bool {
x := operand{mode: value, typ: V}
return x.convertibleTo(nil, T, nil) / check not needed for non-constant x
}
/ Implements reports whether type V implements interface T.
/
/ The behavior of Implements is unspecified if V is Typ[Invalid] or an uninstantiated
/ generic type.
func Implements(V Type, T *Interface) bool {
if T.Empty() {
/ All types (even Typ[Invalid]) implement the empty interface.
return true
}
/ Checker.implements suppresses errors for invalid types, so we need special
/ handling here.
if V.Underlying() == Typ[Invalid] {
return false
}
return (*Checker)(nil).implements(V, T) == nil
}
/ Identical reports whether x and y are identical types.
/ Receivers of Signature types are ignored.
func Identical(x, y Type) bool {
return identical(x, y, true, nil)
}
/ IdenticalIgnoreTags reports whether x and y are identical types if tags are ignored.
/ Receivers of Signature types are ignored.
func IdenticalIgnoreTags(x, y Type) bool {
return identical(x, y, false, nil)
}