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Package ast

import "go/ast"
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Examples

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Package ast declares the types used to represent syntax trees for Go packages.

Index ▾

func FileExports(src *File) bool
func FilterDecl(decl Decl, f Filter) bool
func FilterFile(src *File, f Filter) bool
func FilterPackage(pkg *Package, f Filter) bool
func Fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) error
func Inspect(node Node, f func(Node) bool)
func IsExported(name string) bool
func NotNilFilter(_ string, v reflect.Value) bool
func PackageExports(pkg *Package) bool
func Print(fset *token.FileSet, x interface{}) error
func SortImports(fset *token.FileSet, f *File)
func Walk(v Visitor, node Node)
type ArrayType
    func (x *ArrayType) End() token.Pos
    func (x *ArrayType) Pos() token.Pos
type AssignStmt
    func (s *AssignStmt) End() token.Pos
    func (s *AssignStmt) Pos() token.Pos
type BadDecl
    func (d *BadDecl) End() token.Pos
    func (d *BadDecl) Pos() token.Pos
type BadExpr
    func (x *BadExpr) End() token.Pos
    func (x *BadExpr) Pos() token.Pos
type BadStmt
    func (s *BadStmt) End() token.Pos
    func (s *BadStmt) Pos() token.Pos
type BasicLit
    func (x *BasicLit) End() token.Pos
    func (x *BasicLit) Pos() token.Pos
type BinaryExpr
    func (x *BinaryExpr) End() token.Pos
    func (x *BinaryExpr) Pos() token.Pos
type BlockStmt
    func (s *BlockStmt) End() token.Pos
    func (s *BlockStmt) Pos() token.Pos
type BranchStmt
    func (s *BranchStmt) End() token.Pos
    func (s *BranchStmt) Pos() token.Pos
type CallExpr
    func (x *CallExpr) End() token.Pos
    func (x *CallExpr) Pos() token.Pos
type CaseClause
    func (s *CaseClause) End() token.Pos
    func (s *CaseClause) Pos() token.Pos
type ChanDir
type ChanType
    func (x *ChanType) End() token.Pos
    func (x *ChanType) Pos() token.Pos
type CommClause
    func (s *CommClause) End() token.Pos
    func (s *CommClause) Pos() token.Pos
type Comment
    func (c *Comment) End() token.Pos
    func (c *Comment) Pos() token.Pos
type CommentGroup
    func (g *CommentGroup) End() token.Pos
    func (g *CommentGroup) Pos() token.Pos
    func (g *CommentGroup) Text() string
type CommentMap
    func NewCommentMap(fset *token.FileSet, node Node, comments []*CommentGroup) CommentMap
    func (cmap CommentMap) Comments() []*CommentGroup
    func (cmap CommentMap) Filter(node Node) CommentMap
    func (cmap CommentMap) String() string
    func (cmap CommentMap) Update(old, new Node) Node
type CompositeLit
    func (x *CompositeLit) End() token.Pos
    func (x *CompositeLit) Pos() token.Pos
type Decl
type DeclStmt
    func (s *DeclStmt) End() token.Pos
    func (s *DeclStmt) Pos() token.Pos
type DeferStmt
    func (s *DeferStmt) End() token.Pos
    func (s *DeferStmt) Pos() token.Pos
type Ellipsis
    func (x *Ellipsis) End() token.Pos
    func (x *Ellipsis) Pos() token.Pos
type EmptyStmt
    func (s *EmptyStmt) End() token.Pos
    func (s *EmptyStmt) Pos() token.Pos
type Expr
type ExprStmt
    func (s *ExprStmt) End() token.Pos
    func (s *ExprStmt) Pos() token.Pos
type Field
    func (f *Field) End() token.Pos
    func (f *Field) Pos() token.Pos
type FieldFilter
type FieldList
    func (f *FieldList) End() token.Pos
    func (f *FieldList) NumFields() int
    func (f *FieldList) Pos() token.Pos
type File
    func MergePackageFiles(pkg *Package, mode MergeMode) *File
    func (f *File) End() token.Pos
    func (f *File) Pos() token.Pos
type Filter
type ForStmt
    func (s *ForStmt) End() token.Pos
    func (s *ForStmt) Pos() token.Pos
type FuncDecl
    func (d *FuncDecl) End() token.Pos
    func (d *FuncDecl) Pos() token.Pos
type FuncLit
    func (x *FuncLit) End() token.Pos
    func (x *FuncLit) Pos() token.Pos
type FuncType
    func (x *FuncType) End() token.Pos
    func (x *FuncType) Pos() token.Pos
type GenDecl
    func (d *GenDecl) End() token.Pos
    func (d *GenDecl) Pos() token.Pos
type GoStmt
    func (s *GoStmt) End() token.Pos
    func (s *GoStmt) Pos() token.Pos
type Ident
    func NewIdent(name string) *Ident
    func (x *Ident) End() token.Pos
    func (id *Ident) IsExported() bool
    func (x *Ident) Pos() token.Pos
    func (id *Ident) String() string
type IfStmt
    func (s *IfStmt) End() token.Pos
    func (s *IfStmt) Pos() token.Pos
type ImportSpec
    func (s *ImportSpec) End() token.Pos
    func (s *ImportSpec) Pos() token.Pos
type Importer
type IncDecStmt
    func (s *IncDecStmt) End() token.Pos
    func (s *IncDecStmt) Pos() token.Pos
type IndexExpr
    func (x *IndexExpr) End() token.Pos
    func (x *IndexExpr) Pos() token.Pos
type InterfaceType
    func (x *InterfaceType) End() token.Pos
    func (x *InterfaceType) Pos() token.Pos
type KeyValueExpr
    func (x *KeyValueExpr) End() token.Pos
    func (x *KeyValueExpr) Pos() token.Pos
type LabeledStmt
    func (s *LabeledStmt) End() token.Pos
    func (s *LabeledStmt) Pos() token.Pos
type MapType
    func (x *MapType) End() token.Pos
    func (x *MapType) Pos() token.Pos
type MergeMode
type Node
type ObjKind
    func (kind ObjKind) String() string
type Object
    func NewObj(kind ObjKind, name string) *Object
    func (obj *Object) Pos() token.Pos
type Package
    func NewPackage(fset *token.FileSet, files map[string]*File, importer Importer, universe *Scope) (*Package, error)
    func (p *Package) End() token.Pos
    func (p *Package) Pos() token.Pos
type ParenExpr
    func (x *ParenExpr) End() token.Pos
    func (x *ParenExpr) Pos() token.Pos
type RangeStmt
    func (s *RangeStmt) End() token.Pos
    func (s *RangeStmt) Pos() token.Pos
type ReturnStmt
    func (s *ReturnStmt) End() token.Pos
    func (s *ReturnStmt) Pos() token.Pos
type Scope
    func NewScope(outer *Scope) *Scope
    func (s *Scope) Insert(obj *Object) (alt *Object)
    func (s *Scope) Lookup(name string) *Object
    func (s *Scope) String() string
type SelectStmt
    func (s *SelectStmt) End() token.Pos
    func (s *SelectStmt) Pos() token.Pos
type SelectorExpr
    func (x *SelectorExpr) End() token.Pos
    func (x *SelectorExpr) Pos() token.Pos
type SendStmt
    func (s *SendStmt) End() token.Pos
    func (s *SendStmt) Pos() token.Pos
type SliceExpr
    func (x *SliceExpr) End() token.Pos
    func (x *SliceExpr) Pos() token.Pos
type Spec
type StarExpr
    func (x *StarExpr) End() token.Pos
    func (x *StarExpr) Pos() token.Pos
type Stmt
type StructType
    func (x *StructType) End() token.Pos
    func (x *StructType) Pos() token.Pos
type SwitchStmt
    func (s *SwitchStmt) End() token.Pos
    func (s *SwitchStmt) Pos() token.Pos
type TypeAssertExpr
    func (x *TypeAssertExpr) End() token.Pos
    func (x *TypeAssertExpr) Pos() token.Pos
type TypeSpec
    func (s *TypeSpec) End() token.Pos
    func (s *TypeSpec) Pos() token.Pos
type TypeSwitchStmt
    func (s *TypeSwitchStmt) End() token.Pos
    func (s *TypeSwitchStmt) Pos() token.Pos
type UnaryExpr
    func (x *UnaryExpr) End() token.Pos
    func (x *UnaryExpr) Pos() token.Pos
type ValueSpec
    func (s *ValueSpec) End() token.Pos
    func (s *ValueSpec) Pos() token.Pos
type Visitor

Package files

ast.go commentmap.go filter.go import.go print.go resolve.go scope.go walk.go

func FileExports

func FileExports(src *File) bool

FileExports trims the AST for a Go source file in place such that only exported nodes remain: all top-level identifiers which are not exported and their associated information (such as type, initial value, or function body) are removed. Non-exported fields and methods of exported types are stripped. The File.Comments list is not changed.

FileExports reports whether there are exported declarations.

func FilterDecl

func FilterDecl(decl Decl, f Filter) bool

FilterDecl trims the AST for a Go declaration in place by removing all names (including struct field and interface method names, but not from parameter lists) that don't pass through the filter f.

FilterDecl reports whether there are any declared names left after filtering.

func FilterFile

func FilterFile(src *File, f Filter) bool

FilterFile trims the AST for a Go file in place by removing all names from top-level declarations (including struct field and interface method names, but not from parameter lists) that don't pass through the filter f. If the declaration is empty afterwards, the declaration is removed from the AST. Import declarations are always removed. The File.Comments list is not changed.

FilterFile reports whether there are any top-level declarations left after filtering.

func FilterPackage

func FilterPackage(pkg *Package, f Filter) bool

FilterPackage trims the AST for a Go package in place by removing all names from top-level declarations (including struct field and interface method names, but not from parameter lists) that don't pass through the filter f. If the declaration is empty afterwards, the declaration is removed from the AST. The pkg.Files list is not changed, so that file names and top-level package comments don't get lost.

FilterPackage reports whether there are any top-level declarations left after filtering.

func Fprint

func Fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) error

Fprint prints the (sub-)tree starting at AST node x to w. If fset != nil, position information is interpreted relative to that file set. Otherwise positions are printed as integer values (file set specific offsets).

A non-nil FieldFilter f may be provided to control the output: struct fields for which f(fieldname, fieldvalue) is true are printed; all others are filtered from the output. Unexported struct fields are never printed.

func Inspect

func Inspect(node Node, f func(Node) bool)

Inspect traverses an AST in depth-first order: It starts by calling f(node); node must not be nil. If f returns true, Inspect invokes f recursively for each of the non-nil children of node, followed by a call of f(nil).

Example

This example demonstrates how to inspect the AST of a Go program.

src.go:2:9:	p
src.go:3:7:	c
src.go:3:11:	1.0
src.go:4:5:	X
src.go:4:9:	f
src.go:4:11:	3.14
src.go:4:17:	2
src.go:4:21:	c

func IsExported

func IsExported(name string) bool

IsExported reports whether name is an exported Go symbol (that is, whether it begins with an upper-case letter).

func NotNilFilter

func NotNilFilter(_ string, v reflect.Value) bool

NotNilFilter returns true for field values that are not nil; it returns false otherwise.

func PackageExports

func PackageExports(pkg *Package) bool

PackageExports trims the AST for a Go package in place such that only exported nodes remain. The pkg.Files list is not changed, so that file names and top-level package comments don't get lost.

PackageExports reports whether there are exported declarations; it returns false otherwise.

func Print

func Print(fset *token.FileSet, x interface{}) error

Print prints x to standard output, skipping nil fields. Print(fset, x) is the same as Fprint(os.Stdout, fset, x, NotNilFilter).

Example

This example shows what an AST looks like when printed for debugging.

     0  *ast.File {
     1  .  Package: 2:1
     2  .  Name: *ast.Ident {
     3  .  .  NamePos: 2:9
     4  .  .  Name: "main"
     5  .  }
     6  .  Decls: []ast.Decl (len = 1) {
     7  .  .  0: *ast.FuncDecl {
     8  .  .  .  Name: *ast.Ident {
     9  .  .  .  .  NamePos: 3:6
    10  .  .  .  .  Name: "main"
    11  .  .  .  .  Obj: *ast.Object {
    12  .  .  .  .  .  Kind: func
    13  .  .  .  .  .  Name: "main"
    14  .  .  .  .  .  Decl: *(obj @ 7)
    15  .  .  .  .  }
    16  .  .  .  }
    17  .  .  .  Type: *ast.FuncType {
    18  .  .  .  .  Func: 3:1
    19  .  .  .  .  Params: *ast.FieldList {
    20  .  .  .  .  .  Opening: 3:10
    21  .  .  .  .  .  Closing: 3:11
    22  .  .  .  .  }
    23  .  .  .  }
    24  .  .  .  Body: *ast.BlockStmt {
    25  .  .  .  .  Lbrace: 3:13
    26  .  .  .  .  List: []ast.Stmt (len = 1) {
    27  .  .  .  .  .  0: *ast.ExprStmt {
    28  .  .  .  .  .  .  X: *ast.CallExpr {
    29  .  .  .  .  .  .  .  Fun: *ast.Ident {
    30  .  .  .  .  .  .  .  .  NamePos: 4:2
    31  .  .  .  .  .  .  .  .  Name: "println"
    32  .  .  .  .  .  .  .  }
    33  .  .  .  .  .  .  .  Lparen: 4:9
    34  .  .  .  .  .  .  .  Args: []ast.Expr (len = 1) {
    35  .  .  .  .  .  .  .  .  0: *ast.BasicLit {
    36  .  .  .  .  .  .  .  .  .  ValuePos: 4:10
    37  .  .  .  .  .  .  .  .  .  Kind: STRING
    38  .  .  .  .  .  .  .  .  .  Value: "\"Hello, World!\""
    39  .  .  .  .  .  .  .  .  }
    40  .  .  .  .  .  .  .  }
    41  .  .  .  .  .  .  .  Ellipsis: -
    42  .  .  .  .  .  .  .  Rparen: 4:25
    43  .  .  .  .  .  .  }
    44  .  .  .  .  .  }
    45  .  .  .  .  }
    46  .  .  .  .  Rbrace: 5:1
    47  .  .  .  }
    48  .  .  }
    49  .  }
    50  .  Scope: *ast.Scope {
    51  .  .  Objects: map[string]*ast.Object (len = 1) {
    52  .  .  .  "main": *(obj @ 11)
    53  .  .  }
    54  .  }
    55  .  Unresolved: []*ast.Ident (len = 1) {
    56  .  .  0: *(obj @ 29)
    57  .  }
    58  }

func SortImports

func SortImports(fset *token.FileSet, f *File)

SortImports sorts runs of consecutive import lines in import blocks in f. It also removes duplicate imports when it is possible to do so without data loss.

func Walk

func Walk(v Visitor, node Node)

Walk traverses an AST in depth-first order: It starts by calling v.Visit(node); node must not be nil. If the visitor w returned by v.Visit(node) is not nil, Walk is invoked recursively with visitor w for each of the non-nil children of node, followed by a call of w.Visit(nil).

type ArrayType

An ArrayType node represents an array or slice type.

type ArrayType struct {
    Lbrack token.Pos // position of "["
    Len    Expr      // Ellipsis node for [...]T array types, nil for slice types
    Elt    Expr      // element type
}

func (*ArrayType) End

func (x *ArrayType) End() token.Pos

func (*ArrayType) Pos

func (x *ArrayType) Pos() token.Pos

type AssignStmt

An AssignStmt node represents an assignment or a short variable declaration.

type AssignStmt struct {
    Lhs    []Expr
    TokPos token.Pos   // position of Tok
    Tok    token.Token // assignment token, DEFINE
    Rhs    []Expr
}

func (*AssignStmt) End

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

func (*AssignStmt) Pos

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

type BadDecl

A BadDecl node is a placeholder for declarations containing syntax errors for which no correct declaration nodes can be created.

type BadDecl struct {
    From, To token.Pos // position range of bad declaration
}

func (*BadDecl) End

func (d *BadDecl) End() token.Pos

func (*BadDecl) Pos

func (d *BadDecl) Pos() token.Pos

type BadExpr

A BadExpr node is a placeholder for expressions containing syntax errors for which no correct expression nodes can be created.

type BadExpr struct {
    From, To token.Pos // position range of bad expression
}

func (*BadExpr) End

func (x *BadExpr) End() token.Pos

func (*BadExpr) Pos

func (x *BadExpr) Pos() token.Pos

type BadStmt

A BadStmt node is a placeholder for statements containing syntax errors for which no correct statement nodes can be created.

type BadStmt struct {
    From, To token.Pos // position range of bad statement
}

func (*BadStmt) End

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

func (*BadStmt) Pos

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

type BasicLit

A BasicLit node represents a literal of basic type.

type BasicLit struct {
    ValuePos token.Pos   // literal position
    Kind     token.Token // token.INT, token.FLOAT, token.IMAG, token.CHAR, or token.STRING
    Value    string      // literal string; e.g. 42, 0x7f, 3.14, 1e-9, 2.4i, 'a', '\x7f', "foo" or `\m\n\o`
}

func (*BasicLit) End

func (x *BasicLit) End() token.Pos

func (*BasicLit) Pos

func (x *BasicLit) Pos() token.Pos

type BinaryExpr

A BinaryExpr node represents a binary expression.

type BinaryExpr struct {
    X     Expr        // left operand
    OpPos token.Pos   // position of Op
    Op    token.Token // operator
    Y     Expr        // right operand
}

func (*BinaryExpr) End

func (x *BinaryExpr) End() token.Pos

func (*BinaryExpr) Pos

func (x *BinaryExpr) Pos() token.Pos

type BlockStmt

A BlockStmt node represents a braced statement list.

type BlockStmt struct {
    Lbrace token.Pos // position of "{"
    List   []Stmt
    Rbrace token.Pos // position of "}"
}

func (*BlockStmt) End

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

func (*BlockStmt) Pos

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

type BranchStmt

A BranchStmt node represents a break, continue, goto, or fallthrough statement.

type BranchStmt struct {
    TokPos token.Pos   // position of Tok
    Tok    token.Token // keyword token (BREAK, CONTINUE, GOTO, FALLTHROUGH)
    Label  *Ident      // label name; or nil
}

func (*BranchStmt) End

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

func (*BranchStmt) Pos

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

type CallExpr

A CallExpr node represents an expression followed by an argument list.

type CallExpr struct {
    Fun      Expr      // function expression
    Lparen   token.Pos // position of "("
    Args     []Expr    // function arguments; or nil
    Ellipsis token.Pos // position of "..." (token.NoPos if there is no "...")
    Rparen   token.Pos // position of ")"
}

func (*CallExpr) End

func (x *CallExpr) End() token.Pos

func (*CallExpr) Pos

func (x *CallExpr) Pos() token.Pos

type CaseClause

A CaseClause represents a case of an expression or type switch statement.

type CaseClause struct {
    Case  token.Pos // position of "case" or "default" keyword
    List  []Expr    // list of expressions or types; nil means default case
    Colon token.Pos // position of ":"
    Body  []Stmt    // statement list; or nil
}

func (*CaseClause) End

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

func (*CaseClause) Pos

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

type ChanDir

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

type ChanDir int
const (
    SEND ChanDir = 1 << iota
    RECV
)

type ChanType

A ChanType node represents a channel type.

type ChanType struct {
    Begin token.Pos // position of "chan" keyword or "<-" (whichever comes first)
    Arrow token.Pos // position of "<-" (token.NoPos if there is no "<-")
    Dir   ChanDir   // channel direction
    Value Expr      // value type
}

func (*ChanType) End

func (x *ChanType) End() token.Pos

func (*ChanType) Pos

func (x *ChanType) Pos() token.Pos

type CommClause

A CommClause node represents a case of a select statement.

type CommClause struct {
    Case  token.Pos // position of "case" or "default" keyword
    Comm  Stmt      // send or receive statement; nil means default case
    Colon token.Pos // position of ":"
    Body  []Stmt    // statement list; or nil
}

func (*CommClause) End

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

func (*CommClause) Pos

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

type Comment

A Comment node represents a single //-style or /*-style comment.

type Comment struct {
    Slash token.Pos // position of "/" starting the comment
    Text  string    // comment text (excluding '\n' for //-style comments)
}

func (*Comment) End

func (c *Comment) End() token.Pos

func (*Comment) Pos

func (c *Comment) Pos() token.Pos

type CommentGroup

A CommentGroup represents a sequence of comments with no other tokens and no empty lines between.

type CommentGroup struct {
    List []*Comment // len(List) > 0
}

func (*CommentGroup) End

func (g *CommentGroup) End() token.Pos

func (*CommentGroup) Pos

func (g *CommentGroup) Pos() token.Pos

func (*CommentGroup) Text

func (g *CommentGroup) Text() string

Text returns the text of the comment. Comment markers (//, /*, and */), the first space of a line comment, and leading and trailing empty lines are removed. Multiple empty lines are reduced to one, and trailing space on lines is trimmed. Unless the result is empty, it is newline-terminated.

type CommentMap

A CommentMap maps an AST node to a list of comment groups associated with it. See NewCommentMap for a description of the association.

type CommentMap map[Node][]*CommentGroup

Example

This example illustrates how to remove a variable declaration in a Go program while maintaining correct comment association using an ast.CommentMap.

// This is the package comment.
package main

// This comment is associated with the hello constant.
const hello = "Hello, World!" // line comment 1

// This comment is associated with the main function.
func main() {
	fmt.Println(hello) // line comment 3
}

func NewCommentMap

func NewCommentMap(fset *token.FileSet, node Node, comments []*CommentGroup) CommentMap

NewCommentMap creates a new comment map by associating comment groups of the comments list with the nodes of the AST specified by node.

A comment group g is associated with a node n if:

- g starts on the same line as n ends
- g starts on the line immediately following n, and there is
  at least one empty line after g and before the next node
- g starts before n and is not associated to the node before n
  via the previous rules

NewCommentMap tries to associate a comment group to the "largest" node possible: For instance, if the comment is a line comment trailing an assignment, the comment is associated with the entire assignment rather than just the last operand in the assignment.

func (CommentMap) Comments

func (cmap CommentMap) Comments() []*CommentGroup

Comments returns the list of comment groups in the comment map. The result is sorted in source order.

func (CommentMap) Filter

func (cmap CommentMap) Filter(node Node) CommentMap

Filter returns a new comment map consisting of only those entries of cmap for which a corresponding node exists in the AST specified by node.

func (CommentMap) String

func (cmap CommentMap) String() string

func (CommentMap) Update

func (cmap CommentMap) Update(old, new Node) Node

Update replaces an old node in the comment map with the new node and returns the new node. Comments that were associated with the old node are associated with the new node.

type CompositeLit

A CompositeLit node represents a composite literal.

type CompositeLit struct {
    Type   Expr      // literal type; or nil
    Lbrace token.Pos // position of "{"
    Elts   []Expr    // list of composite elements; or nil
    Rbrace token.Pos // position of "}"
}

func (*CompositeLit) End

func (x *CompositeLit) End() token.Pos

func (*CompositeLit) Pos

func (x *CompositeLit) Pos() token.Pos

type Decl

All declaration nodes implement the Decl interface.

type Decl interface {
    Node
    // contains filtered or unexported methods
}

type DeclStmt

A DeclStmt node represents a declaration in a statement list.

type DeclStmt struct {
    Decl Decl // *GenDecl with CONST, TYPE, or VAR token
}

func (*DeclStmt) End

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

func (*DeclStmt) Pos

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

type DeferStmt

A DeferStmt node represents a defer statement.

type DeferStmt struct {
    Defer token.Pos // position of "defer" keyword
    Call  *CallExpr
}

func (*DeferStmt) End

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

func (*DeferStmt) Pos

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

type Ellipsis

An Ellipsis node stands for the "..." type in a parameter list or the "..." length in an array type.

type Ellipsis struct {
    Ellipsis token.Pos // position of "..."
    Elt      Expr      // ellipsis element type (parameter lists only); or nil
}

func (*Ellipsis) End

func (x *Ellipsis) End() token.Pos

func (*Ellipsis) Pos

func (x *Ellipsis) Pos() token.Pos

type EmptyStmt

An EmptyStmt node represents an empty statement. The "position" of the empty statement is the position of the immediately following (explicit or implicit) semicolon.

type EmptyStmt struct {
    Semicolon token.Pos // position of following ";"
    Implicit  bool      // if set, ";" was omitted in the source
}

func (*EmptyStmt) End

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

func (*EmptyStmt) Pos

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

type Expr

All expression nodes implement the Expr interface.

type Expr interface {
    Node
    // contains filtered or unexported methods
}

type ExprStmt

An ExprStmt node represents a (stand-alone) expression in a statement list.

type ExprStmt struct {
    X Expr // expression
}

func (*ExprStmt) End

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

func (*ExprStmt) Pos

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

type Field

A Field represents a Field declaration list in a struct type, a method list in an interface type, or a parameter/result declaration in a signature.

type Field struct {
    Doc     *CommentGroup // associated documentation; or nil
    Names   []*Ident      // field/method/parameter names; or nil if anonymous field
    Type    Expr          // field/method/parameter type
    Tag     *BasicLit     // field tag; or nil
    Comment *CommentGroup // line comments; or nil
}

func (*Field) End

func (f *Field) End() token.Pos

func (*Field) Pos

func (f *Field) Pos() token.Pos

type FieldFilter

A FieldFilter may be provided to Fprint to control the output.

type FieldFilter func(name string, value reflect.Value) bool

type FieldList

A FieldList represents a list of Fields, enclosed by parentheses or braces.

type FieldList struct {
    Opening token.Pos // position of opening parenthesis/brace, if any
    List    []*Field  // field list; or nil
    Closing token.Pos // position of closing parenthesis/brace, if any
}

func (*FieldList) End

func (f *FieldList) End() token.Pos

func (*FieldList) NumFields

func (f *FieldList) NumFields() int

NumFields returns the number of (named and anonymous fields) in a FieldList.

func (*FieldList) Pos

func (f *FieldList) Pos() token.Pos

type File

A File node represents a Go source file.

The Comments list contains all comments in the source file in order of appearance, including the comments that are pointed to from other nodes via Doc and Comment fields.

For correct printing of source code containing comments (using packages go/format and go/printer), special care must be taken to update comments when a File's syntax tree is modified: For printing, comments are interspersed between tokens based on their position. If syntax tree nodes are removed or moved, relevant comments in their vicinity must also be removed (from the File.Comments list) or moved accordingly (by updating their positions). A CommentMap may be used to facilitate some of these operations.

Whether and how a comment is associated with a node depends on the interpretation of the syntax tree by the manipulating program: Except for Doc and Comment comments directly associated with nodes, the remaining comments are "free-floating" (see also issues #18593, #20744).

type File struct {
    Doc        *CommentGroup   // associated documentation; or nil
    Package    token.Pos       // position of "package" keyword
    Name       *Ident          // package name
    Decls      []Decl          // top-level declarations; or nil
    Scope      *Scope          // package scope (this file only)
    Imports    []*ImportSpec   // imports in this file
    Unresolved []*Ident        // unresolved identifiers in this file
    Comments   []*CommentGroup // list of all comments in the source file
}

func MergePackageFiles

func MergePackageFiles(pkg *Package, mode MergeMode) *File

MergePackageFiles creates a file AST by merging the ASTs of the files belonging to a package. The mode flags control merging behavior.

func (*File) End

func (f *File) End() token.Pos

func (*File) Pos

func (f *File) Pos() token.Pos

type Filter

type Filter func(string) bool

type ForStmt

A ForStmt represents a for statement.

type ForStmt struct {
    For  token.Pos // position of "for" keyword
    Init Stmt      // initialization statement; or nil
    Cond Expr      // condition; or nil
    Post Stmt      // post iteration statement; or nil
    Body *BlockStmt
}

func (*ForStmt) End

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

func (*ForStmt) Pos

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

type FuncDecl

A FuncDecl node represents a function declaration.

type FuncDecl struct {
    Doc  *CommentGroup // associated documentation; or nil
    Recv *FieldList    // receiver (methods); or nil (functions)
    Name *Ident        // function/method name
    Type *FuncType     // function signature: parameters, results, and position of "func" keyword
    Body *BlockStmt    // function body; or nil for external (non-Go) function
}

func (*FuncDecl) End

func (d *FuncDecl) End() token.Pos

func (*FuncDecl) Pos

func (d *FuncDecl) Pos() token.Pos

type FuncLit

A FuncLit node represents a function literal.

type FuncLit struct {
    Type *FuncType  // function type
    Body *BlockStmt // function body
}

func (*FuncLit) End

func (x *FuncLit) End() token.Pos

func (*FuncLit) Pos

func (x *FuncLit) Pos() token.Pos

type FuncType

A FuncType node represents a function type.

type FuncType struct {
    Func    token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
    Params  *FieldList // (incoming) parameters; non-nil
    Results *FieldList // (outgoing) results; or nil
}

func (*FuncType) End

func (x *FuncType) End() token.Pos

func (*FuncType) Pos

func (x *FuncType) Pos() token.Pos

type GenDecl

A GenDecl node (generic declaration node) represents an import, constant, type or variable declaration. A valid Lparen position (Lparen.IsValid()) indicates a parenthesized declaration.

Relationship between Tok value and Specs element type:

token.IMPORT  *ImportSpec
token.CONST   *ValueSpec
token.TYPE    *TypeSpec
token.VAR     *ValueSpec
type GenDecl struct {
    Doc    *CommentGroup // associated documentation; or nil
    TokPos token.Pos     // position of Tok
    Tok    token.Token   // IMPORT, CONST, TYPE, VAR
    Lparen token.Pos     // position of '(', if any
    Specs  []Spec
    Rparen token.Pos // position of ')', if any
}

func (*GenDecl) End

func (d *GenDecl) End() token.Pos

func (*GenDecl) Pos

func (d *GenDecl) Pos() token.Pos

type GoStmt

A GoStmt node represents a go statement.

type GoStmt struct {
    Go   token.Pos // position of "go" keyword
    Call *CallExpr
}

func (*GoStmt) End

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

func (*GoStmt) Pos

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

type Ident

An Ident node represents an identifier.

type Ident struct {
    NamePos token.Pos // identifier position
    Name    string    // identifier name
    Obj     *Object   // denoted object; or nil
}

func NewIdent

func NewIdent(name string) *Ident

NewIdent creates a new Ident without position. Useful for ASTs generated by code other than the Go parser.

func (*Ident) End

func (x *Ident) End() token.Pos

func (*Ident) IsExported

func (id *Ident) IsExported() bool

IsExported reports whether id is an exported Go symbol (that is, whether it begins with an uppercase letter).

func (*Ident) Pos

func (x *Ident) Pos() token.Pos

func (*Ident) String

func (id *Ident) String() string

type IfStmt

An IfStmt node represents an if statement.

type IfStmt struct {
    If   token.Pos // position of "if" keyword
    Init Stmt      // initialization statement; or nil
    Cond Expr      // condition
    Body *BlockStmt
    Else Stmt // else branch; or nil
}

func (*IfStmt) End

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

func (*IfStmt) Pos

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

type ImportSpec

An ImportSpec node represents a single package import.

type ImportSpec struct {
    Doc     *CommentGroup // associated documentation; or nil
    Name    *Ident        // local package name (including "."); or nil
    Path    *BasicLit     // import path
    Comment *CommentGroup // line comments; or nil
    EndPos  token.Pos     // end of spec (overrides Path.Pos if nonzero)
}

func (*ImportSpec) End

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

func (*ImportSpec) Pos

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

type Importer

An Importer resolves import paths to package Objects. The imports map records the packages already imported, indexed by package id (canonical import path). An Importer must determine the canonical import path and check the map to see if it is already present in the imports map. If so, the Importer can return the map entry. Otherwise, the Importer should load the package data for the given path into a new *Object (pkg), record pkg in the imports map, and then return pkg.

type Importer func(imports map[string]*Object, path string) (pkg *Object, err error)

type IncDecStmt

An IncDecStmt node represents an increment or decrement statement.

type IncDecStmt struct {
    X      Expr
    TokPos token.Pos   // position of Tok
    Tok    token.Token // INC or DEC
}

func (*IncDecStmt) End

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

func (*IncDecStmt) Pos

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

type IndexExpr

An IndexExpr node represents an expression followed by an index.

type IndexExpr struct {
    X      Expr      // expression
    Lbrack token.Pos // position of "["
    Index  Expr      // index expression
    Rbrack token.Pos // position of "]"
}

func (*IndexExpr) End

func (x *IndexExpr) End() token.Pos

func (*IndexExpr) Pos

func (x *IndexExpr) Pos() token.Pos

type InterfaceType

An InterfaceType node represents an interface type.

type InterfaceType struct {
    Interface  token.Pos  // position of "interface" keyword
    Methods    *FieldList // list of methods
    Incomplete bool       // true if (source) methods are missing in the Methods list
}

func (*InterfaceType) End

func (x *InterfaceType) End() token.Pos

func (*InterfaceType) Pos

func (x *InterfaceType) Pos() token.Pos

type KeyValueExpr

A KeyValueExpr node represents (key : value) pairs in composite literals.

type KeyValueExpr struct {
    Key   Expr
    Colon token.Pos // position of ":"
    Value Expr
}

func (*KeyValueExpr) End

func (x *KeyValueExpr) End() token.Pos

func (*KeyValueExpr) Pos

func (x *KeyValueExpr) Pos() token.Pos

type LabeledStmt

A LabeledStmt node represents a labeled statement.

type LabeledStmt struct {
    Label *Ident
    Colon token.Pos // position of ":"
    Stmt  Stmt
}

func (*LabeledStmt) End

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

func (*LabeledStmt) Pos

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

type MapType

A MapType node represents a map type.

type MapType struct {
    Map   token.Pos // position of "map" keyword
    Key   Expr
    Value Expr
}

func (*MapType) End

func (x *MapType) End() token.Pos

func (*MapType) Pos

func (x *MapType) Pos() token.Pos

type MergeMode

The MergeMode flags control the behavior of MergePackageFiles.

type MergeMode uint
const (
    // If set, duplicate function declarations are excluded.
    FilterFuncDuplicates MergeMode = 1 << iota
    // If set, comments that are not associated with a specific
    // AST node (as Doc or Comment) are excluded.
    FilterUnassociatedComments
    // If set, duplicate import declarations are excluded.
    FilterImportDuplicates
)

type Node

All node types implement the Node interface.

type Node interface {
    Pos() token.Pos // position of first character belonging to the node
    End() token.Pos // position of first character immediately after the node
}

type ObjKind

ObjKind describes what an object represents.

type ObjKind int

The list of possible Object kinds.

const (
    Bad ObjKind = iota // for error handling
    Pkg                // package
    Con                // constant
    Typ                // type
    Var                // variable
    Fun                // function or method
    Lbl                // label
)

func (ObjKind) String

func (kind ObjKind) String() string

type Object

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

The Data fields contains object-specific data:

Kind    Data type         Data value
Pkg     *Scope            package scope
Con     int               iota for the respective declaration
type Object struct {
    Kind ObjKind
    Name string      // declared name
    Decl interface{} // corresponding Field, XxxSpec, FuncDecl, LabeledStmt, AssignStmt, Scope; or nil
    Data interface{} // object-specific data; or nil
    Type interface{} // placeholder for type information; may be nil
}

func NewObj

func NewObj(kind ObjKind, name string) *Object

NewObj creates a new object of a given kind and name.

func (*Object) Pos

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

Pos computes the source position of the declaration of an object name. The result may be an invalid position if it cannot be computed (obj.Decl may be nil or not correct).

type Package

A Package node represents a set of source files collectively building a Go package.

type Package struct {
    Name    string             // package name
    Scope   *Scope             // package scope across all files
    Imports map[string]*Object // map of package id -> package object
    Files   map[string]*File   // Go source files by filename
}

func NewPackage

func NewPackage(fset *token.FileSet, files map[string]*File, importer Importer, universe *Scope) (*Package, error)

NewPackage creates a new Package node from a set of File nodes. It resolves unresolved identifiers across files and updates each file's Unresolved list accordingly. If a non-nil importer and universe scope are provided, they are used to resolve identifiers not declared in any of the package files. Any remaining unresolved identifiers are reported as undeclared. If the files belong to different packages, one package name is selected and files with different package names are reported and then ignored. The result is a package node and a scanner.ErrorList if there were errors.

func (*Package) End

func (p *Package) End() token.Pos

func (*Package) Pos

func (p *Package) Pos() token.Pos

type ParenExpr

A ParenExpr node represents a parenthesized expression.

type ParenExpr struct {
    Lparen token.Pos // position of "("
    X      Expr      // parenthesized expression
    Rparen token.Pos // position of ")"
}

func (*ParenExpr) End

func (x *ParenExpr) End() token.Pos

func (*ParenExpr) Pos

func (x *ParenExpr) Pos() token.Pos

type RangeStmt

A RangeStmt represents a for statement with a range clause.

type RangeStmt struct {
    For        token.Pos   // position of "for" keyword
    Key, Value Expr        // Key, Value may be nil
    TokPos     token.Pos   // position of Tok; invalid if Key == nil
    Tok        token.Token // ILLEGAL if Key == nil, ASSIGN, DEFINE
    X          Expr        // value to range over
    Body       *BlockStmt
}

func (*RangeStmt) End

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

func (*RangeStmt) Pos

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

type ReturnStmt

A ReturnStmt node represents a return statement.

type ReturnStmt struct {
    Return  token.Pos // position of "return" keyword
    Results []Expr    // result expressions; or nil
}

func (*ReturnStmt) End

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

func (*ReturnStmt) Pos

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

type Scope

A Scope maintains the set of named language entities declared in the scope and a link to the immediately surrounding (outer) scope.

type Scope struct {
    Outer   *Scope
    Objects map[string]*Object
}

func NewScope

func NewScope(outer *Scope) *Scope

NewScope creates a new scope nested in the outer scope.

func (*Scope) Insert

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

Insert attempts to insert a named object obj into the scope s. If the scope already contains an object alt with the same name, Insert leaves the scope unchanged and returns alt. Otherwise it inserts obj and returns nil.

func (*Scope) Lookup

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

Lookup returns the object with the given name if it is found in scope s, otherwise it returns nil. Outer scopes are ignored.

func (*Scope) String

func (s *Scope) String() string

Debugging support

type SelectStmt

An SelectStmt node represents a select statement.

type SelectStmt struct {
    Select token.Pos  // position of "select" keyword
    Body   *BlockStmt // CommClauses only
}

func (*SelectStmt) End

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

func (*SelectStmt) Pos

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

type SelectorExpr

A SelectorExpr node represents an expression followed by a selector.

type SelectorExpr struct {
    X   Expr   // expression
    Sel *Ident // field selector
}

func (*SelectorExpr) End

func (x *SelectorExpr) End() token.Pos

func (*SelectorExpr) Pos

func (x *SelectorExpr) Pos() token.Pos

type SendStmt

A SendStmt node represents a send statement.

type SendStmt struct {
    Chan  Expr
    Arrow token.Pos // position of "<-"
    Value Expr
}

func (*SendStmt) End

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

func (*SendStmt) Pos

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

type SliceExpr

An SliceExpr node represents an expression followed by slice indices.

type SliceExpr struct {
    X      Expr      // expression
    Lbrack token.Pos // position of "["
    Low    Expr      // begin of slice range; or nil
    High   Expr      // end of slice range; or nil
    Max    Expr      // maximum capacity of slice; or nil
    Slice3 bool      // true if 3-index slice (2 colons present)
    Rbrack token.Pos // position of "]"
}

func (*SliceExpr) End

func (x *SliceExpr) End() token.Pos

func (*SliceExpr) Pos

func (x *SliceExpr) Pos() token.Pos

type Spec

The Spec type stands for any of *ImportSpec, *ValueSpec, and *TypeSpec.

type Spec interface {
    Node
    // contains filtered or unexported methods
}

type StarExpr

A StarExpr node represents an expression of the form "*" Expression. Semantically it could be a unary "*" expression, or a pointer type.

type StarExpr struct {
    Star token.Pos // position of "*"
    X    Expr      // operand
}

func (*StarExpr) End

func (x *StarExpr) End() token.Pos

func (*StarExpr) Pos

func (x *StarExpr) Pos() token.Pos

type Stmt

All statement nodes implement the Stmt interface.

type Stmt interface {
    Node
    // contains filtered or unexported methods
}

type StructType

A StructType node represents a struct type.

type StructType struct {
    Struct     token.Pos  // position of "struct" keyword
    Fields     *FieldList // list of field declarations
    Incomplete bool       // true if (source) fields are missing in the Fields list
}

func (*StructType) End

func (x *StructType) End() token.Pos

func (*StructType) Pos

func (x *StructType) Pos() token.Pos

type SwitchStmt

A SwitchStmt node represents an expression switch statement.

type SwitchStmt struct {
    Switch token.Pos  // position of "switch" keyword
    Init   Stmt       // initialization statement; or nil
    Tag    Expr       // tag expression; or nil
    Body   *BlockStmt // CaseClauses only
}

func (*SwitchStmt) End

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

func (*SwitchStmt) Pos

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

type TypeAssertExpr

A TypeAssertExpr node represents an expression followed by a type assertion.

type TypeAssertExpr struct {
    X      Expr      // expression
    Lparen token.Pos // position of "("
    Type   Expr      // asserted type; nil means type switch X.(type)
    Rparen token.Pos // position of ")"
}

func (*TypeAssertExpr) End

func (x *TypeAssertExpr) End() token.Pos

func (*TypeAssertExpr) Pos

func (x *TypeAssertExpr) Pos() token.Pos

type TypeSpec

A TypeSpec node represents a type declaration (TypeSpec production).

type TypeSpec struct {
    Doc     *CommentGroup // associated documentation; or nil
    Name    *Ident        // type name
    Assign  token.Pos     // position of '=', if any
    Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
    Comment *CommentGroup // line comments; or nil
}

func (*TypeSpec) End

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

func (*TypeSpec) Pos

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

type TypeSwitchStmt

An TypeSwitchStmt node represents a type switch statement.

type TypeSwitchStmt struct {
    Switch token.Pos  // position of "switch" keyword
    Init   Stmt       // initialization statement; or nil
    Assign Stmt       // x := y.(type) or y.(type)
    Body   *BlockStmt // CaseClauses only
}

func (*TypeSwitchStmt) End

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

func (*TypeSwitchStmt) Pos

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

type UnaryExpr

A UnaryExpr node represents a unary expression. Unary "*" expressions are represented via StarExpr nodes.

type UnaryExpr struct {
    OpPos token.Pos   // position of Op
    Op    token.Token // operator
    X     Expr        // operand
}

func (*UnaryExpr) End

func (x *UnaryExpr) End() token.Pos

func (*UnaryExpr) Pos

func (x *UnaryExpr) Pos() token.Pos

type ValueSpec

A ValueSpec node represents a constant or variable declaration (ConstSpec or VarSpec production).

type ValueSpec struct {
    Doc     *CommentGroup // associated documentation; or nil
    Names   []*Ident      // value names (len(Names) > 0)
    Type    Expr          // value type; or nil
    Values  []Expr        // initial values; or nil
    Comment *CommentGroup // line comments; or nil
}

func (*ValueSpec) End

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

func (*ValueSpec) Pos

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

type Visitor

A Visitor's Visit method is invoked for each node encountered by Walk. If the result visitor w is not nil, Walk visits each of the children of node with the visitor w, followed by a call of w.Visit(nil).

type Visitor interface {
    Visit(node Node) (w Visitor)
}