go.tools: code.google.com/p/go.tools/go/types Index | Files | Directories

package types

import "code.google.com/p/go.tools/go/types"

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.

Index

Package Files

api.go assignments.go builtins.go call.go check.go conversions.go decl.go errors.go eval.go expr.go exprstring.go go12.go labels.go lookup.go methodset.go methodsetcache.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

    UniverseByte *Basic // uint8 alias, but has name "byte"
    UniverseRune *Basic // int32 alias, but has name "rune"
)
var GcCompatibilityMode bool

If GcCompatibilityMode is set, printing of types is modified to match the representation of some types in the gc compiler:

- byte and rune lose their alias name and simply stand for
  uint8 and int32 respectively
- embedded interfaces get flattened (the embedding info is lost,
  and certain recursive interface types cannot be printed anymore)

This makes it easier to compare packages computed with the type- checker vs packages imported from gc export data.

Caution: This flag affects all uses of WriteType, globally. It is only provided for testing in conjunction with gc-generated data. It may be removed at any time.

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 AssertableTo

func AssertableTo(V *Interface, T Type) bool

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

func AssignableTo

func AssignableTo(V, T Type) bool

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

func Comparable

func Comparable(T Type) bool

Comparable reports whether values of type T are comparable.

func ConvertibleTo

func ConvertibleTo(V, T Type) bool

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

func DefPredeclaredTestFuncs

func DefPredeclaredTestFuncs()

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

func ExprString

func ExprString(x ast.Expr) string

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

func Id

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 Identical

func Identical(x, y Type) bool

Identical reports whether x and y are identical.

func Implements

func Implements(V Type, T *Interface) bool

Implements reports whether type V implements interface T.

func NewChecker

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 incrementally added via checker.Files.

func ObjectString

func ObjectString(this *Package, obj Object) string

ObjectString returns the string form of obj. Object and type names are printed package-qualified only if they do not belong to this package.

func SelectionString

func SelectionString(this *Package, s *Selection) string

SelectionString returns the string form of s. Type names are printed package-qualified only if they do not belong to this package.

func TypeString

func TypeString(this *Package, typ Type) string

TypeString returns the string representation of typ. Named types are printed package-qualified if they do not belong to this package.

func WriteExpr

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

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

func WriteSignature

func WriteSignature(buf *bytes.Buffer, this *Package, sig *Signature)

WriteSignature writes the representation of the signature sig to buf, without a leading "func" keyword. Named types are printed package-qualified if they do not belong to this package.

func WriteType

func WriteType(buf *bytes.Buffer, this *Package, typ Type)

WriteType writes the string representation of typ to buf. Named types are printed package-qualified if they do not belong to this package.

type Array

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

An Array represents an array type.

func NewArray

func NewArray(elem Type, len int64) *Array

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

func (*Array) Elem

func (a *Array) Elem() Type

Elem returns element type of array a.

func (*Array) Len

func (a *Array) Len() int64

Len returns the length of array a.

func (*Array) String

func (t *Array) String() string

func (*Array) Underlying

func (t *Array) Underlying() Type

type Basic

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

A Basic represents a basic type.

func (*Basic) Info

func (b *Basic) Info() BasicInfo

Info returns information about properties of basic type b.

func (*Basic) Kind

func (b *Basic) Kind() BasicKind

Kind returns the kind of basic type b.

func (*Basic) Name

func (b *Basic) Name() string

Name returns the name of basic type b.

func (*Basic) String

func (t *Basic) String() string

func (*Basic) Underlying

func (t *Basic) Underlying() Type

type BasicInfo

type BasicInfo int

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

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

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

Properties of basic types.

type BasicKind

type BasicKind int

BasicKind describes the kind of basic type.

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 Builtin

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

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

func (*Builtin) Exported

func (obj *Builtin) Exported() bool

func (*Builtin) Id

func (obj *Builtin) Id() string

func (*Builtin) Name

func (obj *Builtin) Name() string

func (*Builtin) Parent

func (obj *Builtin) Parent() *Scope

func (*Builtin) Pkg

func (obj *Builtin) Pkg() *Package

func (*Builtin) Pos

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

func (*Builtin) String

func (obj *Builtin) String() string

func (*Builtin) Type

func (obj *Builtin) Type() Type

type Chan

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

A Chan represents a channel type.

func NewChan

func NewChan(dir ChanDir, elem Type) *Chan

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

func (*Chan) Dir

func (c *Chan) Dir() ChanDir

Dir returns the direction of channel c.

func (*Chan) Elem

func (c *Chan) Elem() Type

Elem returns the element type of channel c.

func (*Chan) String

func (t *Chan) String() string

func (*Chan) Underlying

func (t *Chan) Underlying() Type

type ChanDir

type ChanDir int

A ChanDir value indicates a channel direction.

const (
    SendRecv ChanDir = iota
    SendOnly
    RecvOnly
)

The direction of a channel is indicated by one of the following constants.

type Config

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

A Config specifies the configuration for type checking. The zero value for Config is a ready-to-use default configuration.

func (*Config) Check

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, 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.

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 Const

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

A Const represents a declared constant.

func NewConst

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

func (*Const) Exported

func (obj *Const) Exported() bool

func (*Const) Id

func (obj *Const) Id() string

func (*Const) Name

func (obj *Const) Name() string

func (*Const) Parent

func (obj *Const) Parent() *Scope

func (*Const) Pkg

func (obj *Const) Pkg() *Package

func (*Const) Pos

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

func (*Const) String

func (obj *Const) String() string

func (*Const) Type

func (obj *Const) Type() Type

func (*Const) Val

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

type Error

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"
}

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.

func (Error) Error

func (err Error) Error() string

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

type Func

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

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.

func MissingMethod

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 NewFunc

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

func (*Func) Exported

func (obj *Func) Exported() bool

func (*Func) FullName

func (obj *Func) FullName() string

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

func (*Func) Id

func (obj *Func) Id() string

func (*Func) Name

func (obj *Func) Name() string

func (*Func) Parent

func (obj *Func) Parent() *Scope

func (*Func) Pkg

func (obj *Func) Pkg() *Package

func (*Func) Pos

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

func (*Func) Scope

func (obj *Func) Scope() *Scope

func (*Func) String

func (obj *Func) String() string

func (*Func) Type

func (obj *Func) Type() Type

type Importer

type Importer func(map[string]*Package, string) (*Package, error)

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.

var DefaultImport Importer

DefaultImport is the default importer invoked if Config.Import == nil. The declaration:

import _ "code.google.com/p/go.tools/go/gcimporter"

in a client of go/types will initialize DefaultImport to gcimporter.Import.

type Info

type Info struct {
    // Types maps expressions to their types, and for constant
    // expressions, their values.
    // Identifiers are collected in Defs and Uses, not Types.
    //
    // For an expression denoting a predeclared built-in function
    // the recorded signature is 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.
    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, blank identifiers on the lhs of assignments, 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 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
}

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 Initializer

type Initializer struct {
    Lhs []*Var // var Lhs = Rhs
    Rhs ast.Expr
}

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.

func (*Initializer) String

func (init *Initializer) String() string

type Interface

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

An Interface represents an interface type.

func NewInterface

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

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

func (*Interface) Embedded

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) Empty

func (t *Interface) Empty() bool

Empty returns true if t is the empty interface.

func (*Interface) ExplicitMethod

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) Method

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) NumEmbeddeds

func (t *Interface) NumEmbeddeds() int

NumEmbeddeds returns the number of embedded types in interface t.

func (*Interface) NumExplicitMethods

func (t *Interface) NumExplicitMethods() int

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

func (*Interface) NumMethods

func (t *Interface) NumMethods() int

NumMethods returns the total number of methods of interface t.

func (*Interface) String

func (t *Interface) String() string

func (*Interface) Underlying

func (t *Interface) Underlying() Type

type Label

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

A Label represents a declared label.

func NewLabel

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

func (*Label) Exported

func (obj *Label) Exported() bool

func (*Label) Id

func (obj *Label) Id() string

func (*Label) Name

func (obj *Label) Name() string

func (*Label) Parent

func (obj *Label) Parent() *Scope

func (*Label) Pkg

func (obj *Label) Pkg() *Package

func (*Label) Pos

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

func (*Label) String

func (obj *Label) String() string

func (*Label) Type

func (obj *Label) Type() Type

type Map

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

A Map represents a map type.

func NewMap

func NewMap(key, elem Type) *Map

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

func (*Map) Elem

func (m *Map) Elem() Type

Elem returns the element type of map m.

func (*Map) Key

func (m *Map) Key() Type

Key returns the key type of map m.

func (*Map) String

func (t *Map) String() string

func (*Map) Underlying

func (t *Map) Underlying() Type

type MethodSet

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

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.

func NewMethodSet

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.

A MethodSetCache handles repeat queries more efficiently.

func (*MethodSet) At

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

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

func (*MethodSet) Len

func (s *MethodSet) Len() int

Len returns the number of methods in s.

func (*MethodSet) Lookup

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) String

func (s *MethodSet) String() string

type MethodSetCache

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

A MethodSetCache records the method set of each type T for which MethodSet(T) is called so that repeat queries are fast. The zero value is a ready-to-use cache instance.

func (*MethodSetCache) MethodSet

func (cache *MethodSetCache) MethodSet(T Type) *MethodSet

MethodSet returns the method set of type T. It is thread-safe.

If cache is nil, this function is equivalent to NewMethodSet(T). Utility functions can thus expose an optional *MethodSetCache parameter to clients that care about performance.

type Named

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

A Named represents a named type.

func NewNamed

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) AddMethod

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) Method

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

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

func (*Named) NumMethods

func (t *Named) NumMethods() int

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

func (*Named) Obj

func (t *Named) Obj() *TypeName

TypeName returns the type name for the named type t.

func (*Named) SetUnderlying

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) String

func (t *Named) String() string

func (*Named) Underlying

func (t *Named) Underlying() Type

type Nil

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

Nil represents the predeclared value nil.

func (*Nil) Exported

func (obj *Nil) Exported() bool

func (*Nil) Id

func (obj *Nil) Id() string

func (*Nil) Name

func (obj *Nil) Name() string

func (*Nil) Parent

func (obj *Nil) Parent() *Scope

func (*Nil) Pkg

func (obj *Nil) Pkg() *Package

func (*Nil) Pos

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

func (*Nil) String

func (obj *Nil) String() string

func (*Nil) Type

func (obj *Nil) Type() Type

type Object

type Object interface {
    Parent() *Scope // scope in which this object is declared
    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
}

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.

func LookupFieldOrMethod

func LookupFieldOrMethod(T Type, 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.

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 embedded 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 sequence points to an ambiguous entry if it exists, or it is nil.

type Package

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

A Package describes a Go package.

func Check

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

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 NewPackage

func NewPackage(path, name string) *Package

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

func (*Package) Complete

func (pkg *Package) Complete() bool

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

func (*Package) Imports

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

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

func (*Package) MarkComplete

func (pkg *Package) MarkComplete()

MarkComplete marks a package as complete.

func (*Package) Name

func (pkg *Package) Name() string

Name returns the package name.

func (*Package) Path

func (pkg *Package) Path() string

Path returns the package path.

func (*Package) Scope

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) SetImports

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) String

func (pkg *Package) String() string

type PkgName

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

A PkgName represents an imported Go package.

func NewPkgName

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

func (*PkgName) Exported

func (obj *PkgName) Exported() bool

func (*PkgName) Id

func (obj *PkgName) Id() string

func (*PkgName) Name

func (obj *PkgName) Name() string

func (*PkgName) Parent

func (obj *PkgName) Parent() *Scope

func (*PkgName) Pkg

func (obj *PkgName) Pkg() *Package

func (*PkgName) Pos

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

func (*PkgName) String

func (obj *PkgName) String() string

func (*PkgName) Type

func (obj *PkgName) Type() Type

type Pointer

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

A Pointer represents a pointer type.

func NewPointer

func NewPointer(elem Type) *Pointer

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

func (*Pointer) Elem

func (p *Pointer) Elem() Type

Elem returns the element type for the given pointer p.

func (*Pointer) String

func (t *Pointer) String() string

func (*Pointer) Underlying

func (t *Pointer) Underlying() Type

type Scope

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

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.

func NewScope

func NewScope(parent *Scope, 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) Child

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

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

func (*Scope) Insert

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) Len

func (s *Scope) Len() int

Len() returns the number of scope elements.

func (*Scope) Lookup

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) LookupParent

func (s *Scope) LookupParent(name string) 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 object. If no such scope exists, the result is nil.

func (*Scope) Names

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

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

func (*Scope) NumChildren

func (s *Scope) NumChildren() int

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

func (*Scope) Parent

func (s *Scope) Parent() *Scope

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

func (*Scope) String

func (s *Scope) String() string

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

func (*Scope) WriteTo

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 Selection

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

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
math.Pi     PackageObj    nil     Pi     untyped numeric    nil       false

func (*Selection) Index

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

Index describes the path from x to f in x.f. The result is nil if x.f is a qualified identifier (PackageObj).

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) Indirect

func (s *Selection) Indirect() bool

Indirect reports whether any pointer indirection was required to get from x to f in x.f. The result is false if x.f is a qualified identifier (PackageObj).

func (*Selection) Kind

func (s *Selection) Kind() SelectionKind

Kind returns the selection kind.

func (*Selection) Obj

func (s *Selection) Obj() Object

Obj returns the object denoted by x.f. The following object types may appear:

Kind          Object

FieldVal      *Var                          field
MethodVal     *Func                         method
MethodExpr    *Func                         method
PackageObj    *Const, *Type, *Var, *Func    imported const, type, var, or func

func (*Selection) Recv

func (s *Selection) Recv() Type

Recv returns the type of x in x.f. The result is nil if x.f is a qualified identifier (PackageObj).

func (*Selection) String

func (s *Selection) String() string

func (*Selection) Type

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 SelectionKind

type SelectionKind int

SelectionKind describes the kind of a selector expression x.f.

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
    PackageObj                      // x.f is a qualified identifier
)

type Signature

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

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

func NewSignature

func NewSignature(scope *Scope, 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) Params

func (s *Signature) Params() *Tuple

Params returns the parameters of signature s, or nil.

func (*Signature) Recv

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) Results

func (s *Signature) Results() *Tuple

Results returns the results of signature s, or nil.

func (*Signature) String

func (t *Signature) String() string

func (*Signature) Underlying

func (t *Signature) Underlying() Type

func (*Signature) Variadic

func (s *Signature) Variadic() bool

Variadic reports whether the signature s is variadic.

type Sizes

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
}

Sizes defines the sizing functions for package unsafe.

type Slice

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

A Slice represents a slice type.

func NewSlice

func NewSlice(elem Type) *Slice

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

func (*Slice) Elem

func (s *Slice) Elem() Type

Elem returns the element type of slice s.

func (*Slice) String

func (t *Slice) String() string

func (*Slice) Underlying

func (t *Slice) Underlying() Type

type StdSizes

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

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.
- 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.

func (*StdSizes) Alignof

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

func (*StdSizes) Offsetsof

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

func (*StdSizes) Sizeof

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

type Struct

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

A Struct represents a struct type.

func NewStruct

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) Field

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

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

func (*Struct) NumFields

func (s *Struct) NumFields() int

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

func (*Struct) String

func (t *Struct) String() string

func (*Struct) Tag

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

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

func (*Struct) Underlying

func (t *Struct) Underlying() Type

type Tuple

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

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.

func NewTuple

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

NewTuple returns a new tuple for the given variables.

func (*Tuple) At

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

At returns the i'th variable of tuple t.

func (*Tuple) Len

func (t *Tuple) Len() int

Len returns the number variables of tuple t.

func (*Tuple) String

func (t *Tuple) String() string

func (*Tuple) Underlying

func (t *Tuple) Underlying() Type

type Type

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

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

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

func Eval

func Eval(str string, pkg *Package, scope *Scope) (typ Type, val exact.Value, err error)

Eval returns the type and, if constant, the value for the expression or type literal string str evaluated in scope. If the expression contains function literals, the function bodies are ignored (though they must be syntactically correct).

If pkg == nil, the Universe scope is used and the provided scope is ignored. Otherwise, the scope must belong to the package (either the package scope, or nested within the package scope).

An error is returned if the scope is incorrect, the string has syntax errors, or if it cannot be evaluated in the scope. Position info for objects in the result type is undefined.

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 EvalNode

func EvalNode(fset *token.FileSet, node ast.Expr, pkg *Package, scope *Scope) (typ Type, val exact.Value, err error)

EvalNode is like Eval but instead of string it accepts an expression node and respective file set.

An error is returned if the scope is incorrect if the node cannot be evaluated in the scope.

func New

func New(str string) Type

New is a convenience function to create a new type from a given expression or type literal string evaluated in Universe scope. New(str) is shorthand for Eval(str, nil, nil), but only returns the type result, and panics in case of an error. Position info for objects in the result type is undefined.

type TypeAndValue

type TypeAndValue struct {
    Type  Type
    Value exact.Value
}

type TypeName

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

A TypeName represents a declared type.

func NewTypeName

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

func (*TypeName) Exported

func (obj *TypeName) Exported() bool

func (*TypeName) Id

func (obj *TypeName) Id() string

func (*TypeName) Name

func (obj *TypeName) Name() string

func (*TypeName) Parent

func (obj *TypeName) Parent() *Scope

func (*TypeName) Pkg

func (obj *TypeName) Pkg() *Package

func (*TypeName) Pos

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

func (*TypeName) String

func (obj *TypeName) String() string

func (*TypeName) Type

func (obj *TypeName) Type() Type

type Var

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

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

func NewField

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

func NewParam

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

func NewVar

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

func (*Var) Anonymous

func (obj *Var) Anonymous() bool

func (*Var) Exported

func (obj *Var) Exported() bool

func (*Var) Id

func (obj *Var) Id() string

func (*Var) IsField

func (obj *Var) IsField() bool

func (*Var) Name

func (obj *Var) Name() string

func (*Var) Parent

func (obj *Var) Parent() *Scope

func (*Var) Pkg

func (obj *Var) Pkg() *Package

func (*Var) Pos

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

func (*Var) String

func (obj *Var) String() string

func (*Var) Type

func (obj *Var) Type() Type

Directories

PathSynopsis
typeutilPackage typeutil defines various utilities for types, such as Map, a mapping from types.Type to interface{} values.

Package types imports 14 packages (graph) and is imported by 48 packages. Updated 2014-04-19. Refresh now. Tools for package owners.