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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) (err 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 returns true if there are exported declarations; it returns false otherwise.

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 returns true if there are any declared names left after filtering; it returns false otherwise.

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. The File.Comments list is not changed.

FilterFile returns true if there are any top-level declarations left after filtering; it returns false otherwise.

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 returns true if there are any top-level declarations left after filtering; it returns false otherwise.

func Fprint

func Fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) (err 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 for all the non-nil children of node, recursively.

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 returns true if 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

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

An ArrayType node represents an array or slice type.

func (*ArrayType) End

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

func (*ArrayType) Pos

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

type AssignStmt

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

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

func (*AssignStmt) End

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

func (*AssignStmt) Pos

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

type BadDecl

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

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

func (*BadDecl) End

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

func (*BadDecl) Pos

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

Pos and End implementations for declaration nodes.

type BadExpr

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

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

func (*BadExpr) End

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

func (*BadExpr) Pos

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

Pos and End implementations for expression/type nodes.

type BadStmt

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

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

func (*BadStmt) End

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

func (*BadStmt) Pos

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

Pos and End implementations for statement nodes.

type BasicLit

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`
}

A BasicLit node represents a literal of basic type.

func (*BasicLit) End

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

func (*BasicLit) Pos

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

type BinaryExpr

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

A BinaryExpr node represents a binary expression.

func (*BinaryExpr) End

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

func (*BinaryExpr) Pos

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

type BlockStmt

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

A BlockStmt node represents a braced statement list.

func (*BlockStmt) End

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

func (*BlockStmt) Pos

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

type BranchStmt

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

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

func (*BranchStmt) End

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

func (*BranchStmt) Pos

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

type CallExpr

type CallExpr struct {
        Fun      Expr      // function expression
        Lparen   token.Pos // position of "("
        Args     []Expr    // function arguments; or nil
        Ellipsis token.Pos // position of "...", if any
        Rparen   token.Pos // position of ")"
}

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

func (*CallExpr) End

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

func (*CallExpr) Pos

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

type CaseClause

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
}

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

func (*CaseClause) End

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

func (*CaseClause) Pos

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

type ChanDir

type ChanDir int

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

const (
        SEND ChanDir = 1 << iota
        RECV
)

type ChanType

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
}

A ChanType node represents a channel type.

func (*ChanType) End

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

func (*ChanType) Pos

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

type CommClause

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
}

A CommClause node represents a case of a select statement.

func (*CommClause) End

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

func (*CommClause) Pos

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

type Comment

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

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

func (*Comment) End

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

func (*Comment) Pos

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

type CommentGroup

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

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

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

type CommentMap map[Node][]*CommentGroup

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

Example

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

Code:

// src is the input for which we create the AST that we
    // are going to manipulate.
    src := `
// 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 foo variable.
var foo = hello // line comment 2 

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

    // Create the AST by parsing src.
    fset := token.NewFileSet() // positions are relative to fset
    f, err := parser.ParseFile(fset, "src.go", src, parser.ParseComments)
    if err != nil {
            panic(err)
    }

    // Create an ast.CommentMap from the ast.File's comments.
    // This helps keeping the association between comments
    // and AST nodes.
    cmap := ast.NewCommentMap(fset, f, f.Comments)

    // Remove the first variable declaration from the list of declarations.
    f.Decls = removeFirstVarDecl(f.Decls)

    // Use the comment map to filter comments that don't belong anymore
    // (the comments associated with the variable declaration), and create
    // the new comments list.
    f.Comments = cmap.Filter(f).Comments()

    // Print the modified AST.
    var buf bytes.Buffer
    if err := format.Node(&buf, fset, f); err != nil {
            panic(err)
    }
    fmt.Printf("%s", buf.Bytes())

    

Output:

// 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 is 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

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 "}"
}

A CompositeLit node represents a composite literal.

func (*CompositeLit) End

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

func (*CompositeLit) Pos

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

type Decl

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

All declaration nodes implement the Decl interface.

type DeclStmt

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

A DeclStmt node represents a declaration in a statement list.

func (*DeclStmt) End

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

func (*DeclStmt) Pos

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

type DeferStmt

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

A DeferStmt node represents a defer statement.

func (*DeferStmt) End

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

func (*DeferStmt) Pos

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

type Ellipsis

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

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

func (*Ellipsis) End

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

func (*Ellipsis) Pos

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

type EmptyStmt

type EmptyStmt struct {
        Semicolon token.Pos // position of preceding ";"
}

An EmptyStmt node represents an empty statement. The "position" of the empty statement is the position of the immediately preceding semicolon.

func (*EmptyStmt) End

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

func (*EmptyStmt) Pos

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

type Expr

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

All expression nodes implement the Expr interface.

type ExprStmt

type ExprStmt struct {
        X Expr // expression
}

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

func (*ExprStmt) End

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

func (*ExprStmt) Pos

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

type Field

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
}

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.

func (*Field) End

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

func (*Field) Pos

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

type FieldFilter

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

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

type FieldList

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
}

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

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

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
}

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.

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

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
}

A ForStmt represents a for statement.

func (*ForStmt) End

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

func (*ForStmt) Pos

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

type FuncDecl

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 (forward declaration)
}

A FuncDecl node represents a function declaration.

func (*FuncDecl) End

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

func (*FuncDecl) Pos

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

type FuncLit

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

A FuncLit node represents a function literal.

func (*FuncLit) End

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

func (*FuncLit) Pos

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

type FuncType

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
}

A FuncType node represents a function type.

func (*FuncType) End

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

func (*FuncType) Pos

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

type GenDecl

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
}

A GenDecl node (generic declaration node) represents an import, constant, type or variable declaration. A valid Lparen position (Lparen.Line > 0) indicates a parenthesized declaration.

Relationship between Tok value and Specs element type:

token.IMPORT  *ImportSpec
token.CONST   *ValueSpec
token.TYPE    *TypeSpec
token.VAR     *ValueSpec

func (*GenDecl) End

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

func (*GenDecl) Pos

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

type GoStmt

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

A GoStmt node represents a go statement.

func (*GoStmt) End

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

func (*GoStmt) Pos

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

type Ident

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

An Ident node represents an identifier.

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

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
}

An IfStmt node represents an if statement.

func (*IfStmt) End

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

func (*IfStmt) Pos

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

type ImportSpec

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)
}

An ImportSpec node represents a single package import.

func (*ImportSpec) End

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

func (*ImportSpec) Pos

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

Pos and End implementations for spec nodes.

type Importer

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

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 IncDecStmt

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

An IncDecStmt node represents an increment or decrement statement.

func (*IncDecStmt) End

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

func (*IncDecStmt) Pos

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

type IndexExpr

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

An IndexExpr node represents an expression followed by an index.

func (*IndexExpr) End

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

func (*IndexExpr) Pos

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

type InterfaceType

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
}

An InterfaceType node represents an interface type.

func (*InterfaceType) End

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

func (*InterfaceType) Pos

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

type KeyValueExpr

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

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

func (*KeyValueExpr) End

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

func (*KeyValueExpr) Pos

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

type LabeledStmt

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

A LabeledStmt node represents a labeled statement.

func (*LabeledStmt) End

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

func (*LabeledStmt) Pos

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

type MapType

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

A MapType node represents a map type.

func (*MapType) End

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

func (*MapType) Pos

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

type MergeMode

type MergeMode uint

The MergeMode flags control the behavior of MergePackageFiles.

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

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
}

All node types implement the Node interface.

type ObjKind

type ObjKind int

ObjKind describes what an object represents.

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

The list of possible Object kinds.

func (ObjKind) String

func (kind ObjKind) String() string

type Object

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
}

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	*types.Package    package scope
Con     int               iota for the respective declaration
Con     != nil            constant value
Typ     *Scope            (used as method scope during type checking - transient)

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

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
}

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

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

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

A ParenExpr node represents a parenthesized expression.

func (*ParenExpr) End

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

func (*ParenExpr) Pos

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

type RangeStmt

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
}

A RangeStmt represents a for statement with a range clause.

func (*RangeStmt) End

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

func (*RangeStmt) Pos

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

type ReturnStmt

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

A ReturnStmt node represents a return statement.

func (*ReturnStmt) End

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

func (*ReturnStmt) Pos

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

type Scope

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

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

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

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

An SelectStmt node represents a select statement.

func (*SelectStmt) End

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

func (*SelectStmt) Pos

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

type SelectorExpr

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

A SelectorExpr node represents an expression followed by a selector.

func (*SelectorExpr) End

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

func (*SelectorExpr) Pos

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

type SendStmt

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

A SendStmt node represents a send statement.

func (*SendStmt) End

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

func (*SendStmt) Pos

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

type SliceExpr

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 "]"
}

An SliceExpr node represents an expression followed by slice indices.

func (*SliceExpr) End

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

func (*SliceExpr) Pos

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

type Spec

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

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

type StarExpr

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

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

func (*StarExpr) End

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

func (*StarExpr) Pos

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

type Stmt

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

All statement nodes implement the Stmt interface.

type StructType

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
}

A StructType node represents a struct type.

func (*StructType) End

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

func (*StructType) Pos

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

type SwitchStmt

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
}

A SwitchStmt node represents an expression switch statement.

func (*SwitchStmt) End

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

func (*SwitchStmt) Pos

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

type TypeAssertExpr

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 ")"
}

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

func (*TypeAssertExpr) End

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

func (*TypeAssertExpr) Pos

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

type TypeSpec

type TypeSpec struct {
        Doc     *CommentGroup // associated documentation; or nil
        Name    *Ident        // type name
        Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
        Comment *CommentGroup // line comments; or nil
}

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

func (*TypeSpec) End

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

func (*TypeSpec) Pos

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

type TypeSwitchStmt

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
}

An TypeSwitchStmt node represents a type switch statement.

func (*TypeSwitchStmt) End

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

func (*TypeSwitchStmt) Pos

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

type UnaryExpr

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

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

func (*UnaryExpr) End

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

func (*UnaryExpr) Pos

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

type ValueSpec

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
}

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

func (*ValueSpec) End

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

func (*ValueSpec) Pos

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

type Visitor

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