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Package types

Overview

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 (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 (constant.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.

For a tutorial, see https://golang.org/s/types-tutorial.

Index

Examples

Info
MethodSet
Scope

Package files

api.go assignments.go builtins.go call.go check.go conversions.go decl.go errors.go eval.go expr.go exprstring.go initorder.go labels.go lookup.go methodset.go object.go objset.go operand.go ordering.go package.go predicates.go resolver.go return.go scope.go selection.go sizes.go stmt.go type.go typestring.go typexpr.go universe.go

Variables

var (
        Universe *Scope
        Unsafe   *Package
)
var Typ = []*Basic{
        Invalid: {Invalid, 0, "invalid type"},

        Bool:          {Bool, IsBoolean, "bool"},
        Int:           {Int, IsInteger, "int"},
        Int8:          {Int8, IsInteger, "int8"},
        Int16:         {Int16, IsInteger, "int16"},
        Int32:         {Int32, IsInteger, "int32"},
        Int64:         {Int64, IsInteger, "int64"},
        Uint:          {Uint, IsInteger | IsUnsigned, "uint"},
        Uint8:         {Uint8, IsInteger | IsUnsigned, "uint8"},
        Uint16:        {Uint16, IsInteger | IsUnsigned, "uint16"},
        Uint32:        {Uint32, IsInteger | IsUnsigned, "uint32"},
        Uint64:        {Uint64, IsInteger | IsUnsigned, "uint64"},
        Uintptr:       {Uintptr, IsInteger | IsUnsigned, "uintptr"},
        Float32:       {Float32, IsFloat, "float32"},
        Float64:       {Float64, IsFloat, "float64"},
        Complex64:     {Complex64, IsComplex, "complex64"},
        Complex128:    {Complex128, IsComplex, "complex128"},
        String:        {String, IsString, "string"},
        UnsafePointer: {UnsafePointer, 0, "Pointer"},

        UntypedBool:    {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
        UntypedInt:     {UntypedInt, IsInteger | IsUntyped, "untyped int"},
        UntypedRune:    {UntypedRune, IsInteger | IsUntyped, "untyped rune"},
        UntypedFloat:   {UntypedFloat, IsFloat | IsUntyped, "untyped float"},
        UntypedComplex: {UntypedComplex, IsComplex | IsUntyped, "untyped complex"},
        UntypedString:  {UntypedString, IsString | IsUntyped, "untyped string"},
        UntypedNil:     {UntypedNil, IsUntyped, "untyped nil"},
}

func AssertableToSource

func AssertableTo(V *Interface, T Type) bool

AssertableTo reports whether a value of type V can be asserted to have type T.

func AssignableToSource

func AssignableTo(V, T Type) bool

AssignableTo reports whether a value of type V is assignable to a variable of type T.

func ComparableSource

func Comparable(T Type) bool

Comparable reports whether values of type T are comparable.

func ConvertibleToSource

func ConvertibleTo(V, T Type) bool

ConvertibleTo reports whether a value of type V is convertible to a value of type T.

func DefPredeclaredTestFuncsSource

func DefPredeclaredTestFuncs()

DefPredeclaredTestFuncs defines the assert and trace built-ins. These built-ins are intended for debugging and testing of this package only.

func ExprStringSource

func ExprString(x ast.Expr) string

ExprString returns the (possibly simplified) string representation for x.

func IdSource

func Id(pkg *Package, name string) string

Id returns name if it is exported, otherwise it returns the name qualified with the package path.

func IdenticalSource

func Identical(x, y Type) bool

Identical reports whether x and y are identical.

func IdenticalIgnoreTagsSource

func IdenticalIgnoreTags(x, y Type) bool

IdenticalIgnoreTags reports whether x and y are identical if tags are ignored.

func ImplementsSource

func Implements(V Type, T *Interface) bool

Implements reports whether type V implements interface T.

func IsInterfaceSource

func IsInterface(typ Type) bool

IsInterface reports whether typ is an interface type.

func ObjectStringSource

func ObjectString(obj Object, qf Qualifier) string

ObjectString returns the string form of obj. The Qualifier controls the printing of package-level objects, and may be nil.

func SelectionStringSource

func SelectionString(s *Selection, qf Qualifier) string

SelectionString returns the string form of s. The Qualifier controls the printing of package-level objects, and may be nil.

Examples:

"field (T) f int"
"method (T) f(X) Y"
"method expr (T) f(X) Y"

func TypeStringSource

func TypeString(typ Type, qf Qualifier) string

TypeString returns the string representation of typ. The Qualifier controls the printing of package-level objects, and may be nil.

func WriteExprSource

func WriteExpr(buf *bytes.Buffer, x ast.Expr)

WriteExpr writes the (possibly simplified) string representation for x to buf.

func WriteSignatureSource

func WriteSignature(buf *bytes.Buffer, sig *Signature, qf Qualifier)

WriteSignature writes the representation of the signature sig to buf, without a leading "func" keyword. The Qualifier controls the printing of package-level objects, and may be nil.

func WriteTypeSource

func WriteType(buf *bytes.Buffer, typ Type, qf Qualifier)

WriteType writes the string representation of typ to buf. The Qualifier controls the printing of package-level objects, and may be nil.

type ArraySource

An Array represents an array type.

type Array struct {
        // contains filtered or unexported fields
}

func NewArraySource

func NewArray(elem Type, len int64) *Array

NewArray returns a new array type for the given element type and length.

func (*Array) ElemSource

func (a *Array) Elem() Type

Elem returns element type of array a.

func (*Array) LenSource

func (a *Array) Len() int64

Len returns the length of array a.

func (*Array) StringSource

func (t *Array) String() string

func (*Array) UnderlyingSource

func (t *Array) Underlying() Type

type BasicSource

A Basic represents a basic type.

type Basic struct {
        // contains filtered or unexported fields
}

func (*Basic) InfoSource

func (b *Basic) Info() BasicInfo

Info returns information about properties of basic type b.

func (*Basic) KindSource

func (b *Basic) Kind() BasicKind

Kind returns the kind of basic type b.

func (*Basic) NameSource

func (b *Basic) Name() string

Name returns the name of basic type b.

func (*Basic) StringSource

func (t *Basic) String() string

func (*Basic) UnderlyingSource

func (t *Basic) Underlying() Type

type BasicInfoSource

BasicInfo is a set of flags describing properties of a basic type.

type BasicInfo int

Properties of basic types.

const (
        IsBoolean BasicInfo = 1 << iota
        IsInteger
        IsUnsigned
        IsFloat
        IsComplex
        IsString
        IsUntyped

        IsOrdered   = IsInteger | IsFloat | IsString
        IsNumeric   = IsInteger | IsFloat | IsComplex
        IsConstType = IsBoolean | IsNumeric | IsString
)

type BasicKindSource

BasicKind describes the kind of basic type.

type BasicKind int
const (
        Invalid BasicKind = iota // type is invalid

        // predeclared types
        Bool
        Int
        Int8
        Int16
        Int32
        Int64
        Uint
        Uint8
        Uint16
        Uint32
        Uint64
        Uintptr
        Float32
        Float64
        Complex64
        Complex128
        String
        UnsafePointer

        // types for untyped values
        UntypedBool
        UntypedInt
        UntypedRune
        UntypedFloat
        UntypedComplex
        UntypedString
        UntypedNil

        // aliases
        Byte = Uint8
        Rune = Int32
)

type BuiltinSource

A Builtin represents a built-in function. Builtins don't have a valid type.

type Builtin struct {
        // contains filtered or unexported fields
}

func (*Builtin) ExportedSource

func (obj *Builtin) Exported() bool

func (*Builtin) IdSource

func (obj *Builtin) Id() string

func (*Builtin) NameSource

func (obj *Builtin) Name() string

func (*Builtin) ParentSource

func (obj *Builtin) Parent() *Scope

func (*Builtin) PkgSource

func (obj *Builtin) Pkg() *Package

func (*Builtin) PosSource

func (obj *Builtin) Pos() token.Pos

func (*Builtin) StringSource

func (obj *Builtin) String() string

func (*Builtin) TypeSource

func (obj *Builtin) Type() Type

type ChanSource

A Chan represents a channel type.

type Chan struct {
        // contains filtered or unexported fields
}

func NewChanSource

func NewChan(dir ChanDir, elem Type) *Chan

NewChan returns a new channel type for the given direction and element type.

func (*Chan) DirSource

func (c *Chan) Dir() ChanDir

Dir returns the direction of channel c.

func (*Chan) ElemSource

func (c *Chan) Elem() Type

Elem returns the element type of channel c.

func (*Chan) StringSource

func (t *Chan) String() string

func (*Chan) UnderlyingSource

func (t *Chan) Underlying() Type

type ChanDirSource

A ChanDir value indicates a channel direction.

type ChanDir int

The direction of a channel is indicated by one of these constants.

const (
        SendRecv ChanDir = iota
        SendOnly
        RecvOnly
)

type CheckerSource

A Checker maintains the state of the type checker. It must be created with NewChecker.

type Checker struct {
        *Info
        // contains filtered or unexported fields
}

func NewCheckerSource

func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker

NewChecker returns a new Checker instance for a given package. Package files may be added incrementally via checker.Files.

func (*Checker) FilesSource

func (check *Checker) Files(files []*ast.File) error

Files checks the provided files as part of the checker's package.

type ConfigSource

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

        // 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 &StdSizes{WordSize: 8, MaxAlign: 8} is used instead.
        Sizes Sizes

        // If DisableUnusedImportCheck is set, packages are not checked
        // for unused imports.
        DisableUnusedImportCheck bool
}

func (*Config) CheckSource

func (conf *Config) Check(path string, fset *token.FileSet, files []*ast.File, info *Info) (*Package, error)

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 *ast.Files and corresponding file set, and the package path the package is identified with. The clean path must not be empty or dot (".").

type ConstSource

A Const represents a declared constant.

type Const struct {
        // contains filtered or unexported fields
}

func NewConstSource

func NewConst(pos token.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const

func (*Const) ExportedSource

func (obj *Const) Exported() bool

func (*Const) IdSource

func (obj *Const) Id() string

func (*Const) NameSource

func (obj *Const) Name() string

func (*Const) ParentSource

func (obj *Const) Parent() *Scope

func (*Const) PkgSource

func (obj *Const) Pkg() *Package

func (*Const) PosSource

func (obj *Const) Pos() token.Pos

func (*Const) StringSource

func (obj *Const) String() string

func (*Const) TypeSource

func (obj *Const) Type() Type

func (*Const) ValSource

func (obj *Const) Val() constant.Value

type ErrorSource

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"
}

func (Error) ErrorSource

func (err Error) Error() string

Error returns an error string formatted as follows: filename:line:column: message

type FuncSource

A Func represents a declared function, concrete method, or abstract (interface) method. Its Type() is always a *Signature. An abstract method may belong to many interfaces due to embedding.

type Func struct {
        // contains filtered or unexported fields
}

func MissingMethodSource

func MissingMethod(V Type, T *Interface, static bool) (method *Func, wrongType bool)

MissingMethod returns (nil, false) if V implements T, otherwise it returns a missing method required by T and whether it is missing or just has the wrong type.

For non-interface types V, or if static is set, V implements T if all methods of T are present in V. Otherwise (V is an interface and static is not set), MissingMethod only checks that methods of T which are also present in V have matching types (e.g., for a type assertion x.(T) where x is of interface type V).

func NewFuncSource

func NewFunc(pos token.Pos, pkg *Package, name string, sig *Signature) *Func

func (*Func) ExportedSource

func (obj *Func) Exported() bool

func (*Func) FullNameSource

func (obj *Func) FullName() string

FullName returns the package- or receiver-type-qualified name of function or method obj.

func (*Func) IdSource

func (obj *Func) Id() string

func (*Func) NameSource

func (obj *Func) Name() string

func (*Func) ParentSource

func (obj *Func) Parent() *Scope

func (*Func) PkgSource

func (obj *Func) Pkg() *Package

func (*Func) PosSource

func (obj *Func) Pos() token.Pos

func (*Func) ScopeSource

func (obj *Func) Scope() *Scope

func (*Func) StringSource

func (obj *Func) String() string

func (*Func) TypeSource

func (obj *Func) Type() Type

type ImportModeSource

ImportMode is reserved for future use.

type ImportMode int

type ImporterSource

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, or an error if the package couldn't be imported.
        // Two calls to Import with the same path return the same
        // package.
        Import(path string) (*Package, error)
}

type ImporterFromSource

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 the package in srcDir, or an error
        // if the package couldn't be imported. The mode value must
        // be 0; it is reserved for future use.
        // Two calls to ImportFrom with the same path and srcDir return
        // the same package.
        ImportFrom(path, srcDir string, mode ImportMode) (*Package, error)
}

type InfoSource

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[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 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
}

Example

ExampleInfo prints various facts recorded by the type checker in a types.Info struct: definitions of and references to each named object, and the type, value, and mode of every expression in the package.

Code:

// Parse a single source file.
const input = `
package fib

type S string

var a, b, c = len(b), S(c), "hello"

func fib(x int) int {
        if x < 2 {
                return x
        }
        return fib(x-1) - fib(x-2)
}`
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "fib.go", input, 0)
if err != nil {
        log.Fatal(err)
}

// Type-check the package.
// We create an empty map for each kind of input
// we're interested in, and Check populates them.
info := types.Info{
        Types: make(map[ast.Expr]types.TypeAndValue),
        Defs:  make(map[*ast.Ident]types.Object),
        Uses:  make(map[*ast.Ident]types.Object),
}
var conf types.Config
pkg, err := conf.Check("fib", fset, []*ast.File{f}, &info)
if err != nil {
        log.Fatal(err)
}

// Print package-level variables in initialization order.
fmt.Printf("InitOrder: %v\n\n", info.InitOrder)

// For each named object, print the line and
// column of its definition and each of its uses.
fmt.Println("Defs and Uses of each named object:")
usesByObj := make(map[types.Object][]string)
for id, obj := range info.Uses {
        posn := fset.Position(id.Pos())
        lineCol := fmt.Sprintf("%d:%d", posn.Line, posn.Column)
        usesByObj[obj] = append(usesByObj[obj], lineCol)
}
var items []string
for obj, uses := range usesByObj {
        sort.Strings(uses)
        item := fmt.Sprintf("%s:\n  defined at %s\n  used at %s",
                types.ObjectString(obj, types.RelativeTo(pkg)),
                fset.Position(obj.Pos()),
                strings.Join(uses, ", "))
        items = append(items, item)
}
sort.Strings(items) // sort by line:col, in effect
fmt.Println(strings.Join(items, "\n"))
fmt.Println()

fmt.Println("Types and Values of each expression:")
items = nil
for expr, tv := range info.Types {
        var buf bytes.Buffer
        posn := fset.Position(expr.Pos())
        tvstr := tv.Type.String()
        if tv.Value != nil {
                tvstr += " = " + tv.Value.String()
        }
        // line:col | expr | mode : type = value
        fmt.Fprintf(&buf, "%2d:%2d | %-19s | %-7s : %s",
                posn.Line, posn.Column, exprString(fset, expr),
                mode(tv), tvstr)
        items = append(items, buf.String())
}
sort.Strings(items)
fmt.Println(strings.Join(items, "\n"))

Output:

InitOrder: [c = "hello" b = S(c) a = len(b)]

Defs and Uses of each named object:
builtin len:
  defined at -
  used at 6:15
func fib(x int) int:
  defined at fib.go:8:6
  used at 12:20, 12:9
type S string:
  defined at fib.go:4:6
  used at 6:23
type int int:
  defined at -
  used at 8:12, 8:17
type string string:
  defined at -
  used at 4:8
var b S:
  defined at fib.go:6:8
  used at 6:19
var c string:
  defined at fib.go:6:11
  used at 6:25
var x int:
  defined at fib.go:8:10
  used at 10:10, 12:13, 12:24, 9:5

Types and Values of each expression:
 4: 8 | string              | type    : string
 6:15 | len                 | builtin : func(string) int
 6:15 | len(b)              | value   : int
 6:19 | b                   | var     : fib.S
 6:23 | S                   | type    : fib.S
 6:23 | S(c)                | value   : fib.S
 6:25 | c                   | var     : string
 6:29 | "hello"             | value   : string = "hello"
 8:12 | int                 | type    : int
 8:17 | int                 | type    : int
 9: 5 | x                   | var     : int
 9: 5 | x < 2               | value   : untyped bool
 9: 9 | 2                   | value   : int = 2
10:10 | x                   | var     : int
12: 9 | fib                 | value   : func(x int) int
12: 9 | fib(x - 1)          | value   : int
12: 9 | fib(x-1) - fib(x-2) | value   : int
12:13 | x                   | var     : int
12:13 | x - 1               | value   : int
12:15 | 1                   | value   : int = 1
12:20 | fib                 | value   : func(x int) int
12:20 | fib(x - 2)          | value   : int
12:24 | x                   | var     : int
12:24 | x - 2               | value   : int
12:26 | 2                   | value   : int = 2

func (*Info) ObjectOfSource

func (info *Info) ObjectOf(id *ast.Ident) Object

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) TypeOfSource

func (info *Info) TypeOf(e ast.Expr) Type

TypeOf returns the type of expression e, or nil if not found. Precondition: the Types, Uses and Defs maps are populated.

type InitializerSource

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 (*Initializer) StringSource

func (init *Initializer) String() string

type InterfaceSource

An Interface represents an interface type.

type Interface struct {
        // contains filtered or unexported fields
}

func NewInterfaceSource

func NewInterface(methods []*Func, embeddeds []*Named) *Interface

NewInterface returns a new interface for the given methods and embedded types.

func (*Interface) CompleteSource

func (t *Interface) Complete() *Interface

Complete computes the interface's method set. It must be called by users of NewInterface after the interface's embedded types are fully defined and before using the interface type in any way other than to form other types. Complete returns the receiver.

func (*Interface) EmbeddedSource

func (t *Interface) Embedded(i int) *Named

Embedded returns the i'th embedded type of interface t for 0 <= i < t.NumEmbeddeds(). The types are ordered by the corresponding TypeName's unique Id.

func (*Interface) EmptySource

func (t *Interface) Empty() bool

Empty returns true if t is the empty interface.

func (*Interface) ExplicitMethodSource

func (t *Interface) ExplicitMethod(i int) *Func

ExplicitMethod returns the i'th explicitly declared method of interface t for 0 <= i < t.NumExplicitMethods(). The methods are ordered by their unique Id.

func (*Interface) MethodSource

func (t *Interface) Method(i int) *Func

Method returns the i'th method of interface t for 0 <= i < t.NumMethods(). The methods are ordered by their unique Id.

func (*Interface) NumEmbeddedsSource

func (t *Interface) NumEmbeddeds() int

NumEmbeddeds returns the number of embedded types in interface t.

func (*Interface) NumExplicitMethodsSource

func (t *Interface) NumExplicitMethods() int

NumExplicitMethods returns the number of explicitly declared methods of interface t.

func (*Interface) NumMethodsSource

func (t *Interface) NumMethods() int

NumMethods returns the total number of methods of interface t.

func (*Interface) StringSource

func (t *Interface) String() string

func (*Interface) UnderlyingSource

func (t *Interface) Underlying() Type

type LabelSource

A Label represents a declared label.

type Label struct {
        // contains filtered or unexported fields
}

func NewLabelSource

func NewLabel(pos token.Pos, pkg *Package, name string) *Label

func (*Label) ExportedSource

func (obj *Label) Exported() bool

func (*Label) IdSource

func (obj *Label) Id() string

func (*Label) NameSource

func (obj *Label) Name() string

func (*Label) ParentSource

func (obj *Label) Parent() *Scope

func (*Label) PkgSource

func (obj *Label) Pkg() *Package

func (*Label) PosSource

func (obj *Label) Pos() token.Pos

func (*Label) StringSource

func (obj *Label) String() string

func (*Label) TypeSource

func (obj *Label) Type() Type

type MapSource

A Map represents a map type.

type Map struct {
        // contains filtered or unexported fields
}

func NewMapSource

func NewMap(key, elem Type) *Map

NewMap returns a new map for the given key and element types.

func (*Map) ElemSource

func (m *Map) Elem() Type

Elem returns the element type of map m.

func (*Map) KeySource

func (m *Map) Key() Type

Key returns the key type of map m.

func (*Map) StringSource

func (t *Map) String() string

func (*Map) UnderlyingSource

func (t *Map) Underlying() Type

type MethodSetSource

A MethodSet is an ordered set of concrete or abstract (interface) methods; a method is a MethodVal selection, and they are ordered by ascending m.Obj().Id(). The zero value for a MethodSet is a ready-to-use empty method set.

type MethodSet struct {
        // contains filtered or unexported fields
}

Example

ExampleMethodSet prints the method sets of various types.

package main

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"log"
)

func main() {
	// Parse a single source file.
	const input = `
package temperature
import "fmt"
type Celsius float64
func (c Celsius) String() string  { return fmt.Sprintf("%g°C", c) }
func (c *Celsius) SetF(f float64) { *c = Celsius(f - 32 / 9 * 5) }
`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "celsius.go", input, 0)
	if err != nil {
		log.Fatal(err)
	}

	// Type-check a package consisting of this file.
	// Type information for the imported packages
	// comes from $GOROOT/pkg/$GOOS_$GOOARCH/fmt.a.
	conf := types.Config{Importer: importer.Default()}
	pkg, err := conf.Check("temperature", fset, []*ast.File{f}, nil)
	if err != nil {
		log.Fatal(err)
	}

	// Print the method sets of Celsius and *Celsius.
	celsius := pkg.Scope().Lookup("Celsius").Type()
	for _, t := range []types.Type{celsius, types.NewPointer(celsius)} {
		fmt.Printf("Method set of %s:\n", t)
		mset := types.NewMethodSet(t)
		for i := 0; i < mset.Len(); i++ {
			fmt.Println(mset.At(i))
		}
		fmt.Println()
	}

}

func NewMethodSetSource

func NewMethodSet(T Type) *MethodSet

NewMethodSet returns the method set for the given type T. It always returns a non-nil method set, even if it is empty.

func (*MethodSet) AtSource

func (s *MethodSet) At(i int) *Selection

At returns the i'th method in s for 0 <= i < s.Len().

func (*MethodSet) LenSource

func (s *MethodSet) Len() int

Len returns the number of methods in s.

func (*MethodSet) LookupSource

func (s *MethodSet) Lookup(pkg *Package, name string) *Selection

Lookup returns the method with matching package and name, or nil if not found.

func (*MethodSet) StringSource

func (s *MethodSet) String() string

type NamedSource

A Named represents a named type.

type Named struct {
        // contains filtered or unexported fields
}

func NewNamedSource

func NewNamed(obj *TypeName, underlying Type, methods []*Func) *Named

NewNamed returns a new named type for the given type name, underlying type, and associated methods. The underlying type must not be a *Named.

func (*Named) AddMethodSource

func (t *Named) AddMethod(m *Func)

AddMethod adds method m unless it is already in the method list. TODO(gri) find a better solution instead of providing this function

func (*Named) MethodSource

func (t *Named) Method(i int) *Func

Method returns the i'th method of named type t for 0 <= i < t.NumMethods().

func (*Named) NumMethodsSource

func (t *Named) NumMethods() int

NumMethods returns the number of explicit methods whose receiver is named type t.

func (*Named) ObjSource

func (t *Named) Obj() *TypeName

TypeName returns the type name for the named type t.

func (*Named) SetUnderlyingSource

func (t *Named) SetUnderlying(underlying Type)

SetUnderlying sets the underlying type and marks t as complete. TODO(gri) determine if there's a better solution rather than providing this function

func (*Named) StringSource

func (t *Named) String() string

func (*Named) UnderlyingSource

func (t *Named) Underlying() Type

type NilSource

Nil represents the predeclared value nil.

type Nil struct {
        // contains filtered or unexported fields
}

func (*Nil) ExportedSource

func (obj *Nil) Exported() bool

func (*Nil) IdSource

func (obj *Nil) Id() string

func (*Nil) NameSource

func (obj *Nil) Name() string

func (*Nil) ParentSource

func (obj *Nil) Parent() *Scope

func (*Nil) PkgSource

func (obj *Nil) Pkg() *Package

func (*Nil) PosSource

func (obj *Nil) Pos() token.Pos

func (*Nil) StringSource

func (obj *Nil) String() string

func (*Nil) TypeSource

func (obj *Nil) Type() Type

type ObjectSource

An Object describes a named language entity such as a package, constant, type, variable, function (incl. methods), or label. All objects implement the Object interface.

type Object interface {
        Parent() *Scope // scope in which this object is declared; nil for methods and struct fields
        Pos() token.Pos // position of object identifier in declaration
        Pkg() *Package  // nil for objects in the Universe scope and labels
        Name() string   // package local object name
        Type() Type     // object type
        Exported() bool // reports whether the name starts with a capital letter
        Id() string     // object id (see Id below)

        // String returns a human-readable string of the object.
        String() string
        // contains filtered or unexported methods
}

func LookupFieldOrMethodSource

func LookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool)

LookupFieldOrMethod looks up a field or method with given package and name in T and returns the corresponding *Var or *Func, an index sequence, and a bool indicating if there were any pointer indirections on the path to the field or method. If addressable is set, T is the type of an addressable variable (only matters for method lookups).

The last index entry is the field or method index in the (possibly embedded) type where the entry was found, either:

1) the list of declared methods of a named type; or
2) the list of all methods (method set) of an interface type; or
3) the list of fields of a struct type.

The earlier index entries are the indices of the anonymous struct fields traversed to get to the found entry, starting at depth 0.

If no entry is found, a nil object is returned. In this case, the returned index and indirect values have the following meaning:

	- If index != nil, the index sequence points to an ambiguous entry
	(the same name appeared more than once at the same embedding level).

	- If indirect is set, a method with a pointer receiver type was found
     but there was no pointer on the path from the actual receiver type to
	the method's formal receiver base type, nor was the receiver addressable.

type PackageSource

A Package describes a Go package.

type Package struct {
        // contains filtered or unexported fields
}

func NewPackageSource

func NewPackage(path, name string) *Package

NewPackage returns a new Package for the given package path and name; the name must not be the blank identifier. The package is not complete and contains no explicit imports.

func (*Package) CompleteSource

func (pkg *Package) Complete() bool

A package is complete if its scope contains (at least) all exported objects; otherwise it is incomplete.

func (*Package) ImportsSource

func (pkg *Package) Imports() []*Package

Imports returns the list of packages directly imported by pkg; the list is in source order. Package unsafe is excluded.

If pkg was loaded from export data, Imports includes packages that provide package-level objects referenced by pkg. This may be more or less than the set of packages directly imported by pkg's source code.

func (*Package) MarkCompleteSource

func (pkg *Package) MarkComplete()

MarkComplete marks a package as complete.

func (*Package) NameSource

func (pkg *Package) Name() string

Name returns the package name.

func (*Package) PathSource

func (pkg *Package) Path() string

Path returns the package path.

func (*Package) ScopeSource

func (pkg *Package) Scope() *Scope

Scope returns the (complete or incomplete) package scope holding the objects declared at package level (TypeNames, Consts, Vars, and Funcs).

func (*Package) SetImportsSource

func (pkg *Package) SetImports(list []*Package)

SetImports sets the list of explicitly imported packages to list. It is the caller's responsibility to make sure list elements are unique.

func (*Package) SetNameSource

func (pkg *Package) SetName(name string)

SetName sets the package name.

func (*Package) StringSource

func (pkg *Package) String() string

type PkgNameSource

A PkgName represents an imported Go package.

type PkgName struct {
        // contains filtered or unexported fields
}

func NewPkgNameSource

func NewPkgName(pos token.Pos, pkg *Package, name string, imported *Package) *PkgName

func (*PkgName) ExportedSource

func (obj *PkgName) Exported() bool

func (*PkgName) IdSource

func (obj *PkgName) Id() string

func (*PkgName) ImportedSource

func (obj *PkgName) Imported() *Package

Imported returns the package that was imported. It is distinct from Pkg(), which is the package containing the import statement.

func (*PkgName) NameSource

func (obj *PkgName) Name() string

func (*PkgName) ParentSource

func (obj *PkgName) Parent() *Scope

func (*PkgName) PkgSource

func (obj *PkgName) Pkg() *Package

func (*PkgName) PosSource

func (obj *PkgName) Pos() token.Pos

func (*PkgName) StringSource

func (obj *PkgName) String() string

func (*PkgName) TypeSource

func (obj *PkgName) Type() Type

type PointerSource

A Pointer represents a pointer type.

type Pointer struct {
        // contains filtered or unexported fields
}

func NewPointerSource

func NewPointer(elem Type) *Pointer

NewPointer returns a new pointer type for the given element (base) type.

func (*Pointer) ElemSource

func (p *Pointer) Elem() Type

Elem returns the element type for the given pointer p.

func (*Pointer) StringSource

func (t *Pointer) String() string

func (*Pointer) UnderlyingSource

func (t *Pointer) Underlying() Type

type QualifierSource

A Qualifier controls how named package-level objects are printed in calls to TypeString, ObjectString, and SelectionString.

These three formatting routines call the Qualifier for each package-level object O, and if the Qualifier returns a non-empty string p, the object is printed in the form p.O. If it returns an empty string, only the object name O is printed.

Using a nil Qualifier is equivalent to using (*Package).Path: the object is qualified by the import path, e.g., "encoding/json.Marshal".

type Qualifier func(*Package) string

func RelativeToSource

func RelativeTo(pkg *Package) Qualifier

RelativeTo(pkg) returns a Qualifier that fully qualifies members of all packages other than pkg.

type ScopeSource

A Scope maintains a set of objects and links to its containing (parent) and contained (children) scopes. Objects may be inserted and looked up by name. The zero value for Scope is a ready-to-use empty scope.

type Scope struct {
        // contains filtered or unexported fields
}

Example

ExampleScope prints the tree of Scopes of a package created from a set of parsed files.

package main

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"log"
	"regexp"
)

func main() {
	// Parse the source files for a package.
	fset := token.NewFileSet()
	var files []*ast.File
	for _, file := range []struct{ name, input string }{
		{"main.go", `
package main
import "fmt"
func main() {
	freezing := FToC(-18)
	fmt.Println(freezing, Boiling) }
`},
		{"celsius.go", `
package main
import "fmt"
type Celsius float64
func (c Celsius) String() string { return fmt.Sprintf("%g°C", c) }
func FToC(f float64) Celsius { return Celsius(f - 32 / 9 * 5) }
const Boiling Celsius = 100
`},
	} {
		f, err := parser.ParseFile(fset, file.name, file.input, 0)
		if err != nil {
			log.Fatal(err)
		}
		files = append(files, f)
	}

	// Type-check a package consisting of these files.
	// Type information for the imported "fmt" package
	// comes from $GOROOT/pkg/$GOOS_$GOOARCH/fmt.a.
	conf := types.Config{Importer: importer.Default()}
	pkg, err := conf.Check("temperature", fset, files, nil)
	if err != nil {
		log.Fatal(err)
	}

	// Print the tree of scopes.
	// For determinism, we redact addresses.
	var buf bytes.Buffer
	pkg.Scope().WriteTo(&buf, 0, true)
	rx := regexp.MustCompile(` 0x[a-fA-F0-9]*`)
	fmt.Println(rx.ReplaceAllString(buf.String(), ""))

}

func NewScopeSource

func NewScope(parent *Scope, pos, end token.Pos, comment string) *Scope

NewScope returns a new, empty scope contained in the given parent scope, if any. The comment is for debugging only.

func (*Scope) ChildSource

func (s *Scope) Child(i int) *Scope

Child returns the i'th child scope for 0 <= i < NumChildren().

func (*Scope) ContainsSource

func (s *Scope) Contains(pos token.Pos) bool

Contains returns true if pos is within the scope's extent. The result is guaranteed to be valid only if the type-checked AST has complete position information.

func (*Scope) EndSource

func (s *Scope) End() token.Pos

func (*Scope) InnermostSource

func (s *Scope) Innermost(pos token.Pos) *Scope

Innermost returns the innermost (child) scope containing pos. If pos is not within any scope, the result is nil. The result is also nil for the Universe scope. The result is guaranteed to be valid only if the type-checked AST has complete position information.

func (*Scope) InsertSource

func (s *Scope) Insert(obj Object) Object

Insert attempts to insert an object obj into scope s. If s already contains an alternative object alt with the same name, Insert leaves s unchanged and returns alt. Otherwise it inserts obj, sets the object's parent scope if not already set, and returns nil.

func (*Scope) LenSource

func (s *Scope) Len() int

Len() returns the number of scope elements.

func (*Scope) LookupSource

func (s *Scope) Lookup(name string) Object

Lookup returns the object in scope s with the given name if such an object exists; otherwise the result is nil.

func (*Scope) LookupParentSource

func (s *Scope) LookupParent(name string, pos token.Pos) (*Scope, Object)

LookupParent follows the parent chain of scopes starting with s until it finds a scope where Lookup(name) returns a non-nil object, and then returns that scope and object. If a valid position pos is provided, only objects that were declared at or before pos are considered. If no such scope and object exists, the result is (nil, nil).

Note that obj.Parent() may be different from the returned scope if the object was inserted into the scope and already had a parent at that time (see Insert, below). This can only happen for dot-imported objects whose scope is the scope of the package that exported them.

func (*Scope) NamesSource

func (s *Scope) Names() []string

Names returns the scope's element names in sorted order.

func (*Scope) NumChildrenSource

func (s *Scope) NumChildren() int

NumChildren() returns the number of scopes nested in s.

func (*Scope) ParentSource

func (s *Scope) Parent() *Scope

Parent returns the scope's containing (parent) scope.

func (*Scope) PosSource

func (s *Scope) Pos() token.Pos

Pos and End describe the scope's source code extent [pos, end). The results are guaranteed to be valid only if the type-checked AST has complete position information. The extent is undefined for Universe and package scopes.

func (*Scope) StringSource

func (s *Scope) String() string

String returns a string representation of the scope, for debugging.

func (*Scope) WriteToSource

func (s *Scope) WriteTo(w io.Writer, n int, recurse bool)

WriteTo writes a string representation of the scope to w, with the scope elements sorted by name. The level of indentation is controlled by n >= 0, with n == 0 for no indentation. If recurse is set, it also writes nested (children) scopes.

type SelectionSource

A Selection describes a selector expression x.f. For the declarations:

type T struct{ x int; E }
type E struct{}
func (e E) m() {}
var p *T

the following relations exist:

Selector    Kind          Recv    Obj    Type               Index     Indirect

p.x         FieldVal      T       x      int                {0}       true
p.m         MethodVal     *T      m      func (e *T) m()    {1, 0}    true
T.m         MethodExpr    T       m      func m(_ T)        {1, 0}    false
type Selection struct {
        // contains filtered or unexported fields
}

func (*Selection) IndexSource

func (s *Selection) Index() []int

Index describes the path from x to f in x.f. The last index entry is the field or method index of the type declaring f; either:

1) the list of declared methods of a named type; or
2) the list of methods of an interface type; or
3) the list of fields of a struct type.

The earlier index entries are the indices of the embedded fields implicitly traversed to get from (the type of) x to f, starting at embedding depth 0.

func (*Selection) IndirectSource

func (s *Selection) Indirect() bool

Indirect reports whether any pointer indirection was required to get from x to f in x.f.

func (*Selection) KindSource

func (s *Selection) Kind() SelectionKind

Kind returns the selection kind.

func (*Selection) ObjSource

func (s *Selection) Obj() Object

Obj returns the object denoted by x.f; a *Var for a field selection, and a *Func in all other cases.

func (*Selection) RecvSource

func (s *Selection) Recv() Type

Recv returns the type of x in x.f.

func (*Selection) StringSource

func (s *Selection) String() string

func (*Selection) TypeSource

func (s *Selection) Type() Type

Type returns the type of x.f, which may be different from the type of f. See Selection for more information.

type SelectionKindSource

SelectionKind describes the kind of a selector expression x.f (excluding qualified identifiers).

type SelectionKind int
const (
        FieldVal   SelectionKind = iota // x.f is a struct field selector
        MethodVal                       // x.f is a method selector
        MethodExpr                      // x.f is a method expression
)

type SignatureSource

A Signature represents a (non-builtin) function or method type.

type Signature struct {
        // contains filtered or unexported fields
}

func NewSignatureSource

func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature

NewSignature returns a new function type for the given receiver, parameters, and results, either of which may be nil. If variadic is set, the function is variadic, it must have at least one parameter, and the last parameter must be of unnamed slice type.

func (*Signature) ParamsSource

func (s *Signature) Params() *Tuple

Params returns the parameters of signature s, or nil.

func (*Signature) RecvSource

func (s *Signature) Recv() *Var

Recv returns the receiver of signature s (if a method), or nil if a function.

For an abstract method, Recv returns the enclosing interface either as a *Named or an *Interface. Due to embedding, an interface may contain methods whose receiver type is a different interface.

func (*Signature) ResultsSource

func (s *Signature) Results() *Tuple

Results returns the results of signature s, or nil.

func (*Signature) StringSource

func (t *Signature) String() string

func (*Signature) UnderlyingSource

func (t *Signature) Underlying() Type

func (*Signature) VariadicSource

func (s *Signature) Variadic() bool

Variadic reports whether the signature s is variadic.

type SizesSource

Sizes defines the sizing functions for package unsafe.

type Sizes interface {
        // Alignof returns the alignment of a variable of type T.
        // Alignof must implement the alignment guarantees required by the spec.
        Alignof(T Type) int64

        // Offsetsof returns the offsets of the given struct fields, in bytes.
        // Offsetsof must implement the offset guarantees required by the spec.
        Offsetsof(fields []*Var) []int64

        // Sizeof returns the size of a variable of type T.
        // Sizeof must implement the size guarantees required by the spec.
        Sizeof(T Type) int64
}

type SliceSource

A Slice represents a slice type.

type Slice struct {
        // contains filtered or unexported fields
}

func NewSliceSource

func NewSlice(elem Type) *Slice

NewSlice returns a new slice type for the given element type.

func (*Slice) ElemSource

func (s *Slice) Elem() Type

Elem returns the element type of slice s.

func (*Slice) StringSource

func (t *Slice) String() string

func (*Slice) UnderlyingSource

func (t *Slice) Underlying() Type

type StdSizesSource

StdSizes is a convenience type for creating commonly used Sizes. It makes the following simplifying assumptions:

	- The size of explicitly sized basic types (int16, etc.) is the
	  specified size.
	- The size of strings and interfaces is 2*WordSize.
	- The size of slices is 3*WordSize.
	- The size of an array of n elements corresponds to the size of
	  a struct of n consecutive fields of the array's element type.
     - The size of a struct is the offset of the last field plus that
	  field's size. As with all element types, if the struct is used
	  in an array its size must first be aligned to a multiple of the
	  struct's alignment.
	- All other types have size WordSize.
	- Arrays and structs are aligned per spec definition; all other
	  types are naturally aligned with a maximum alignment MaxAlign.

*StdSizes implements Sizes.

type StdSizes struct {
        WordSize int64 // word size in bytes - must be >= 4 (32bits)
        MaxAlign int64 // maximum alignment in bytes - must be >= 1
}

func (*StdSizes) AlignofSource

func (s *StdSizes) Alignof(T Type) int64

func (*StdSizes) OffsetsofSource

func (s *StdSizes) Offsetsof(fields []*Var) []int64

func (*StdSizes) SizeofSource

func (s *StdSizes) Sizeof(T Type) int64

type StructSource

A Struct represents a struct type.

type Struct struct {
        // contains filtered or unexported fields
}

func NewStructSource

func NewStruct(fields []*Var, tags []string) *Struct

NewStruct returns a new struct with the given fields and corresponding field tags. If a field with index i has a tag, tags[i] must be that tag, but len(tags) may be only as long as required to hold the tag with the largest index i. Consequently, if no field has a tag, tags may be nil.

func (*Struct) FieldSource

func (s *Struct) Field(i int) *Var

Field returns the i'th field for 0 <= i < NumFields().

func (*Struct) NumFieldsSource

func (s *Struct) NumFields() int

NumFields returns the number of fields in the struct (including blank and anonymous fields).

func (*Struct) StringSource

func (t *Struct) String() string

func (*Struct) TagSource

func (s *Struct) Tag(i int) string

Tag returns the i'th field tag for 0 <= i < NumFields().

func (*Struct) UnderlyingSource

func (t *Struct) Underlying() Type

type TupleSource

A Tuple represents an ordered list of variables; a nil *Tuple is a valid (empty) tuple. Tuples are used as components of signatures and to represent the type of multiple assignments; they are not first class types of Go.

type Tuple struct {
        // contains filtered or unexported fields
}

func NewTupleSource

func NewTuple(x ...*Var) *Tuple

NewTuple returns a new tuple for the given variables.

func (*Tuple) AtSource

func (t *Tuple) At(i int) *Var

At returns the i'th variable of tuple t.

func (*Tuple) LenSource

func (t *Tuple) Len() int

Len returns the number variables of tuple t.

func (*Tuple) StringSource

func (t *Tuple) String() string

func (*Tuple) UnderlyingSource

func (t *Tuple) Underlying() Type

type TypeSource

A Type represents a type of Go. All types implement the Type interface.

type Type interface {
        // Underlying returns the underlying type of a type.
        Underlying() Type

        // String returns a string representation of a type.
        String() string
}

func DefaultSource

func Default(typ Type) Type

Default returns the default "typed" type for an "untyped" type; it returns the incoming type for all other types. The default type for untyped nil is untyped nil.

type TypeAndValueSource

TypeAndValue reports the type and value (for constants) of the corresponding expression.

type TypeAndValue struct {
        Type  Type
        Value constant.Value
        // contains filtered or unexported fields
}

func EvalSource

func Eval(fset *token.FileSet, pkg *Package, pos token.Pos, expr string) (TypeAndValue, error)

Eval returns the type and, if constant, the value for the expression expr, evaluated at position pos of package pkg, which must have been derived from type-checking an AST with complete position information relative to the provided file set.

If the expression contains function literals, their bodies are ignored (i.e., the bodies are not type-checked).

If pkg == nil, the Universe scope is used and the provided position pos is ignored. If pkg != nil, and pos is invalid, the package scope is used. Otherwise, pos must belong to the package.

An error is returned if pos is not within the package or if the node cannot be evaluated.

Note: Eval should not be used instead of running Check to compute types and values, but in addition to Check. Eval will re-evaluate its argument each time, and it also does not know about the context in which an expression is used (e.g., an assignment). Thus, top- level untyped constants will return an untyped type rather then the respective context-specific type.

func (TypeAndValue) AddressableSource

func (tv TypeAndValue) Addressable() bool

Addressable reports whether the corresponding expression is addressable (https://golang.org/ref/spec#Address_operators).

func (TypeAndValue) AssignableSource

func (tv TypeAndValue) Assignable() bool

Assignable reports whether the corresponding expression is assignable to (provided a value of the right type).

func (TypeAndValue) HasOkSource

func (tv TypeAndValue) HasOk() bool

HasOk reports whether the corresponding expression may be used on the lhs of a comma-ok assignment.

func (TypeAndValue) IsBuiltinSource

func (tv TypeAndValue) IsBuiltin() bool

IsBuiltin reports whether the corresponding expression denotes a (possibly parenthesized) built-in function.

func (TypeAndValue) IsNilSource

func (tv TypeAndValue) IsNil() bool

IsNil reports whether the corresponding expression denotes the predeclared value nil.

func (TypeAndValue) IsTypeSource

func (tv TypeAndValue) IsType() bool

IsType reports whether the corresponding expression specifies a type.

func (TypeAndValue) IsValueSource

func (tv TypeAndValue) IsValue() bool

IsValue reports whether the corresponding expression is a value. Builtins are not considered values. Constant values have a non- nil Value.

func (TypeAndValue) IsVoidSource

func (tv TypeAndValue) IsVoid() bool

IsVoid reports whether the corresponding expression is a function call without results.

type TypeNameSource

A TypeName represents a declared type.

type TypeName struct {
        // contains filtered or unexported fields
}

func NewTypeNameSource

func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName

func (*TypeName) ExportedSource

func (obj *TypeName) Exported() bool

func (*TypeName) IdSource

func (obj *TypeName) Id() string

func (*TypeName) NameSource

func (obj *TypeName) Name() string

func (*TypeName) ParentSource

func (obj *TypeName) Parent() *Scope

func (*TypeName) PkgSource

func (obj *TypeName) Pkg() *Package

func (*TypeName) PosSource

func (obj *TypeName) Pos() token.Pos

func (*TypeName) StringSource

func (obj *TypeName) String() string

func (*TypeName) TypeSource

func (obj *TypeName) Type() Type

type VarSource

A Variable represents a declared variable (including function parameters and results, and struct fields).

type Var struct {
        // contains filtered or unexported fields
}

func NewFieldSource

func NewField(pos token.Pos, pkg *Package, name string, typ Type, anonymous bool) *Var

func NewParamSource

func NewParam(pos token.Pos, pkg *Package, name string, typ Type) *Var

func NewVarSource

func NewVar(pos token.Pos, pkg *Package, name string, typ Type) *Var

func (*Var) AnonymousSource

func (obj *Var) Anonymous() bool

func (*Var) ExportedSource

func (obj *Var) Exported() bool

func (*Var) IdSource

func (obj *Var) Id() string

func (*Var) IsFieldSource

func (obj *Var) IsField() bool

func (*Var) NameSource

func (obj *Var) Name() string

func (*Var) ParentSource

func (obj *Var) Parent() *Scope

func (*Var) PkgSource

func (obj *Var) Pkg() *Package

func (*Var) PosSource

func (obj *Var) Pos() token.Pos

func (*Var) StringSource

func (obj *Var) String() string

func (*Var) TypeSource

func (obj *Var) Type() Type

© Google, Inc.
Licensed under the Creative Commons Attribution License 3.0.
https://golang.org/pkg/go/types/