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ast

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2023-12-01

import "go/ast"

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

Index

Examples

Package Files

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

func FileExports Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
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.

Code:play  

// src is the input for which we want to inspect the AST.
src := `
package p
const c = 1.0
var X = f(3.14)*2 + c
`

// Create the AST by parsing src.
fset := token.NewFileSet() // positions are relative to fset
f, err := parser.ParseFile(fset, "src.go", src, 0)
if err != nil {
    panic(err)
}

// Inspect the AST and print all identifiers and literals.
ast.Inspect(f, func(n ast.Node) bool {
    var s string
    switch x := n.(type) {
    case *ast.BasicLit:
        s = x.Value
    case *ast.Ident:
        s = x.Name
    }
    if s != "" {
        fmt.Printf("%s:\t%s\n", fset.Position(n.Pos()), s)
    }
    return true
})

Output:

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 Uses

❖
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 Uses

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

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

func PackageExports Uses

❖
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 Uses

❖
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.

Code:play  

// src is the input for which we want to print the AST.
src := `
package main
func main() {
	println("Hello, World!")
}
`

// Create the AST by parsing src.
fset := token.NewFileSet() // positions are relative to fset
f, err := parser.ParseFile(fset, "", src, 0)
if err != nil {
    panic(err)
}

// Print the AST.
ast.Print(fset, f)

Output:

     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 Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
func (x *ArrayType) End() token.Pos

func (*ArrayType) Pos Uses

❖
func (x *ArrayType) Pos() token.Pos

type AssignStmt Uses

❖
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 Uses

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

func (*AssignStmt) Pos Uses

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

type BadDecl Uses

❖
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 Uses

❖
func (d *BadDecl) End() token.Pos

func (*BadDecl) Pos Uses

❖
func (d *BadDecl) Pos() token.Pos

type BadExpr Uses

❖
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 Uses

❖
func (x *BadExpr) End() token.Pos

func (*BadExpr) Pos Uses

❖
func (x *BadExpr) Pos() token.Pos

type BadStmt Uses

❖
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 Uses

❖
func (s *BadStmt) End() token.Pos

func (*BadStmt) Pos Uses

❖
func (s *BadStmt) Pos() token.Pos

type BasicLit Uses

❖
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 Uses

❖
func (x *BasicLit) End() token.Pos

func (*BasicLit) Pos Uses

❖
func (x *BasicLit) Pos() token.Pos

type BinaryExpr Uses

❖
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 Uses

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

func (*BinaryExpr) Pos Uses

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

type BlockStmt Uses

❖
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 Uses

❖
func (s *BlockStmt) End() token.Pos

func (*BlockStmt) Pos Uses

❖
func (s *BlockStmt) Pos() token.Pos

type BranchStmt Uses

❖
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 Uses

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

func (*BranchStmt) Pos Uses

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

type CallExpr Uses

❖
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 ")"
}

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

func (*CallExpr) End Uses

❖
func (x *CallExpr) End() token.Pos

func (*CallExpr) Pos Uses

❖
func (x *CallExpr) Pos() token.Pos

type CaseClause Uses

❖
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 Uses

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

func (*CaseClause) Pos Uses

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

type ChanDir Uses

❖
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 Uses

❖
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 Uses

❖
func (x *ChanType) End() token.Pos

func (*ChanType) Pos Uses

❖
func (x *ChanType) Pos() token.Pos

type CommClause Uses

❖
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 Uses

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

func (*CommClause) Pos Uses

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

type Comment Uses

❖
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 Uses

❖
func (c *Comment) End() token.Pos

func (*Comment) Pos Uses

❖
func (c *Comment) Pos() token.Pos

type CommentGroup Uses

❖
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 Uses

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

func (*CommentGroup) Pos Uses

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

func (*CommentGroup) Text Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
func (cmap CommentMap) String() string

func (CommentMap) Update Uses

❖
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 Uses

❖
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 Uses

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

func (*CompositeLit) Pos Uses

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

type Decl Uses

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

All declaration nodes implement the Decl interface.

type DeclStmt Uses

❖
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 Uses

❖
func (s *DeclStmt) End() token.Pos

func (*DeclStmt) Pos Uses

❖
func (s *DeclStmt) Pos() token.Pos

type DeferStmt Uses

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

A DeferStmt node represents a defer statement.

func (*DeferStmt) End Uses

❖
func (s *DeferStmt) End() token.Pos

func (*DeferStmt) Pos Uses

❖
func (s *DeferStmt) Pos() token.Pos

type Ellipsis Uses

❖
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 Uses

❖
func (x *Ellipsis) End() token.Pos

func (*Ellipsis) Pos Uses

❖
func (x *Ellipsis) Pos() token.Pos

type EmptyStmt Uses

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

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

func (*EmptyStmt) End Uses

❖
func (s *EmptyStmt) End() token.Pos

func (*EmptyStmt) Pos Uses

❖
func (s *EmptyStmt) Pos() token.Pos

type Expr Uses

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

All expression nodes implement the Expr interface.

type ExprStmt Uses

❖
type ExprStmt struct {
    X Expr // expression
}

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

func (*ExprStmt) End Uses

❖
func (s *ExprStmt) End() token.Pos

func (*ExprStmt) Pos Uses

❖
func (s *ExprStmt) Pos() token.Pos

type Field Uses

❖
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 Uses

❖
func (f *Field) End() token.Pos

func (*Field) Pos Uses

❖
func (f *Field) Pos() token.Pos

type FieldFilter Uses

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

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

type FieldList Uses

❖
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 Uses

❖
func (f *FieldList) End() token.Pos

func (*FieldList) NumFields Uses

❖
func (f *FieldList) NumFields() int

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

func (*FieldList) Pos Uses

❖
func (f *FieldList) Pos() token.Pos

type File Uses

❖
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 Uses

❖
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 Uses

❖
func (f *File) End() token.Pos

func (*File) Pos Uses

❖
func (f *File) Pos() token.Pos

type Filter Uses

❖
type Filter func(string) bool

type ForStmt Uses

❖
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 Uses

❖
func (s *ForStmt) End() token.Pos

func (*ForStmt) Pos Uses

❖
func (s *ForStmt) Pos() token.Pos

type FuncDecl Uses

❖
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 Uses

❖
func (d *FuncDecl) End() token.Pos

func (*FuncDecl) Pos Uses

❖
func (d *FuncDecl) Pos() token.Pos

type FuncLit Uses

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

A FuncLit node represents a function literal.

func (*FuncLit) End Uses

❖
func (x *FuncLit) End() token.Pos

func (*FuncLit) Pos Uses

❖
func (x *FuncLit) Pos() token.Pos

type FuncType Uses

❖
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 Uses

❖
func (x *FuncType) End() token.Pos

func (*FuncType) Pos Uses

❖
func (x *FuncType) Pos() token.Pos

type GenDecl Uses

❖
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.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

func (*GenDecl) End Uses

❖
func (d *GenDecl) End() token.Pos

func (*GenDecl) Pos Uses

❖
func (d *GenDecl) Pos() token.Pos

type GoStmt Uses

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

A GoStmt node represents a go statement.

func (*GoStmt) End Uses

❖
func (s *GoStmt) End() token.Pos

func (*GoStmt) Pos Uses

❖
func (s *GoStmt) Pos() token.Pos

type Ident Uses

❖
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 Uses

❖
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 Uses

❖
func (x *Ident) End() token.Pos

func (*Ident) IsExported Uses

❖
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 Uses

❖
func (x *Ident) Pos() token.Pos

func (*Ident) String Uses

❖
func (id *Ident) String() string

type IfStmt Uses

❖
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 Uses

❖
func (s *IfStmt) End() token.Pos

func (*IfStmt) Pos Uses

❖
func (s *IfStmt) Pos() token.Pos

type ImportSpec Uses

❖
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 Uses

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

func (*ImportSpec) Pos Uses

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

type Importer Uses

❖
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 Uses

❖
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 Uses

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

func (*IncDecStmt) Pos Uses

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

type IndexExpr Uses

❖
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 Uses

❖
func (x *IndexExpr) End() token.Pos

func (*IndexExpr) Pos Uses

❖
func (x *IndexExpr) Pos() token.Pos

type InterfaceType Uses

❖
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 Uses

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

func (*InterfaceType) Pos Uses

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

type KeyValueExpr Uses

❖
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 Uses

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

func (*KeyValueExpr) Pos Uses

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

type LabeledStmt Uses

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

A LabeledStmt node represents a labeled statement.

func (*LabeledStmt) End Uses

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

func (*LabeledStmt) Pos Uses

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

type MapType Uses

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

A MapType node represents a map type.

func (*MapType) End Uses

❖
func (x *MapType) End() token.Pos

func (*MapType) Pos Uses

❖
func (x *MapType) Pos() token.Pos

type MergeMode Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
func (kind ObjKind) String() string

type Object Uses

❖
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     *Scope            package scope
Con     int               iota for the respective declaration

func NewObj Uses

❖
func NewObj(kind ObjKind, name string) *Object

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

func (*Object) Pos Uses

❖
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 Uses

❖
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 Uses

❖
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 Uses

❖
func (p *Package) End() token.Pos

func (*Package) Pos Uses

❖
func (p *Package) Pos() token.Pos

type ParenExpr Uses

❖
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 Uses

❖
func (x *ParenExpr) End() token.Pos

func (*ParenExpr) Pos Uses

❖
func (x *ParenExpr) Pos() token.Pos

type RangeStmt Uses

❖
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 Uses

❖
func (s *RangeStmt) End() token.Pos

func (*RangeStmt) Pos Uses

❖
func (s *RangeStmt) Pos() token.Pos

type ReturnStmt Uses

❖
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 Uses

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

func (*ReturnStmt) Pos Uses

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

type Scope Uses

❖
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 Uses

❖
func NewScope(outer *Scope) *Scope

NewScope creates a new scope nested in the outer scope.

func (*Scope) Insert Uses

❖
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 Uses

❖
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 Uses

❖
func (s *Scope) String() string

Debugging support

type SelectStmt Uses

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

An SelectStmt node represents a select statement.

func (*SelectStmt) End Uses

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

func (*SelectStmt) Pos Uses

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

type SelectorExpr Uses

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

A SelectorExpr node represents an expression followed by a selector.

func (*SelectorExpr) End Uses

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

func (*SelectorExpr) Pos Uses

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

type SendStmt Uses

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

A SendStmt node represents a send statement.

func (*SendStmt) End Uses

❖
func (s *SendStmt) End() token.Pos

func (*SendStmt) Pos Uses

❖
func (s *SendStmt) Pos() token.Pos

type SliceExpr Uses

❖
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 Uses

❖
func (x *SliceExpr) End() token.Pos

func (*SliceExpr) Pos Uses

❖
func (x *SliceExpr) Pos() token.Pos

type Spec Uses

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

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

type StarExpr Uses

❖
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 Uses

❖
func (x *StarExpr) End() token.Pos

func (*StarExpr) Pos Uses

❖
func (x *StarExpr) Pos() token.Pos

type Stmt Uses

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

All statement nodes implement the Stmt interface.

type StructType Uses

❖
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 Uses

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

func (*StructType) Pos Uses

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

type SwitchStmt Uses

❖
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 Uses

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

func (*SwitchStmt) Pos Uses

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

type TypeAssertExpr Uses

❖
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 Uses

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

func (*TypeAssertExpr) Pos Uses

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

type TypeSpec Uses

❖
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 Uses

❖
func (s *TypeSpec) End() token.Pos

func (*TypeSpec) Pos Uses

❖
func (s *TypeSpec) Pos() token.Pos

type TypeSwitchStmt Uses

❖
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 Uses

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

func (*TypeSwitchStmt) Pos Uses

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

type UnaryExpr Uses

❖
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 Uses

❖
func (x *UnaryExpr) End() token.Pos

func (*UnaryExpr) Pos Uses

❖
func (x *UnaryExpr) Pos() token.Pos

type ValueSpec Uses

❖
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 Uses

❖
func (s *ValueSpec) End() token.Pos

func (*ValueSpec) Pos Uses

❖
func (s *ValueSpec) Pos() token.Pos

type Visitor Uses

❖
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).

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