ast

package
v1.18.0 Latest Latest
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 Go to latest Published: Sep 26, 2023 License: MIT Imports: 3 Imported by: 0

Documentation

Overview

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

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

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 any, 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. 

package main

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
)

func main() {
	// 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 

func IsExported(name string) bool

IsExported reports whether name starts 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 any) 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. 

package main

import (
	"go/ast"
	"go/parser"
	"go/token"
)

func main() {
	// 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 

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).

Types

type ArrayType 

type ArrayType struct {
	Lbrack token.Pos
	Len    Expr
	Elt    Expr
}

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
	Tok    token.Token
	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
}

A BadDecl node is a placeholder for a declaration containing syntax errors for which a correct declaration node cannot be created.

func (*BadDecl) End 

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

func (*BadDecl) Pos 

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

type BadExpr 

type BadExpr struct {
	From, To token.Pos
}

A BadExpr node is a placeholder for an expression containing syntax errors for which a correct expression node cannot be created.

func (*BadExpr) End 

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

func (*BadExpr) Pos 

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

type BadStmt 

type BadStmt struct {
	From, To token.Pos
}

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

type BasicLit 

type BasicLit struct {
	ValuePos token.Pos
	Kind     token.Token
	Value    string
}

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
	OpPos token.Pos
	Op    token.Token
	Y     Expr
}

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
	List   []Stmt
	Rbrace token.Pos
}

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
	Tok    token.Token
	Label  *Ident
}

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
	Lparen   token.Pos
	Args     []Expr
	Ellipsis token.Pos
	Rparen   token.Pos
}

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
	List  []Expr
	Colon token.Pos
	Body  []Stmt
}

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 a bit mask including one or both of the following constants. 

const (
	SEND ChanDir = 1 << iota
	RECV
)

type ChanType 

type ChanType struct {
	Begin token.Pos
	Arrow token.Pos
	Dir   ChanDir
	Value Expr
}

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
	Comm  Stmt
	Colon token.Pos
	Body  []Stmt
}

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
	Text  string
}

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

The Text field contains the comment text without carriage returns (\r) that may have been present in the source. Because a comment's end position is computed using len(Text), the position reported by End() does not match the true source end position for comments containing carriage returns.

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
}

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. Comment directives like "//line" and "//go:noinline" are also 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 added in v1.1.0 

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. 

package main

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
)

func main() {
	// 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.
	for i, decl := range f.Decls {
		if gen, ok := decl.(*ast.GenDecl); ok && gen.Tok == token.VAR {
			copy(f.Decls[i:], f.Decls[i+1:])
			f.Decls = f.Decls[:len(f.Decls)-1]
			break
		}
	}

	// 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 added in v1.1.0 

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 added in v1.1.0 

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 added in v1.1.0 

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 added in v1.1.0 

func (cmap CommentMap) String() string

func (CommentMap) Update added in v1.1.0 

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
	Lbrace     token.Pos
	Elts       []Expr
	Rbrace     token.Pos
	Incomplete bool
}

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
}

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
	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
	Elt      Expr
}

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
	Implicit  bool
}

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 

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
}

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
	Names   []*Ident
	Type    Expr
	Tag     *BasicLit
	Comment *CommentGroup
}

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. Field.Names is nil for unnamed parameters (parameter lists which only contain types) and embedded struct fields. In the latter case, the field name is the type name.

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
	List    []*Field
	Closing token.Pos
}

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

func (*FieldList) End 

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

func (*FieldList) NumFields 

func (f *FieldList) NumFields() int

NumFields returns the number of parameters or struct fields represented by a FieldList.

func (*FieldList) Pos 

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

type File 

type File struct {
	Doc        *CommentGroup
	Package    token.Pos
	Name       *Ident
	Decls      []Decl
	Scope      *Scope
	Imports    []*ImportSpec
	Unresolved []*Ident
	Comments   []*CommentGroup
}

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).

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
	Init Stmt
	Cond Expr
	Post Stmt
	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
	Recv *FieldList
	Name *Ident
	Type *FuncType
	Body *BlockStmt
}

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
	Body *BlockStmt
}

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
	TypeParams *FieldList
	Params     *FieldList
	Results    *FieldList
}

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
	TokPos token.Pos
	Tok    token.Token
	Lparen token.Pos
	Specs  []Spec
	Rparen token.Pos
}

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 

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

func (*GenDecl) Pos 

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

type GoStmt 

type GoStmt struct {
	Go   token.Pos
	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
	Name    string
	Obj     *Object
}

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 starts with an upper-case 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
	Init Stmt
	Cond Expr
	Body *BlockStmt
	Else Stmt
}

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
	Name    *Ident
	Path    *BasicLit
	Comment *CommentGroup
	EndPos  token.Pos
}

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

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
	Tok    token.Token
}

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
	Lbrack token.Pos
	Index  Expr
	Rbrack token.Pos
}

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 IndexListExpr added in v1.18.0 

type IndexListExpr struct {
	X       Expr
	Lbrack  token.Pos
	Indices []Expr
	Rbrack  token.Pos
}

An IndexListExpr node represents an expression followed by multiple indices.

func (*IndexListExpr) End added in v1.18.0 

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

func (*IndexListExpr) Pos added in v1.18.0 

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

type InterfaceType 

type InterfaceType struct {
	Interface  token.Pos
	Methods    *FieldList
	Incomplete bool
}

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
	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
	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
	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
	End() token.Pos
}

All node types implement the Node interface.

type ObjKind 

type ObjKind int

ObjKind describes what an object represents. 

const (
	Bad ObjKind = iota
	Pkg
	Con
	Typ
	Var
	Fun
	Lbl
)

The list of possible Object kinds.

func (ObjKind) String 

func (kind ObjKind) String() string

type Object 

type Object struct {
	Kind ObjKind
	Name string
	Decl any
	Data any
	Type any
}

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 

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
	Scope   *Scope
	Imports map[string]*Object
	Files   map[string]*File
}

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
	X      Expr
	Rparen token.Pos
}

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
	Key, Value Expr
	TokPos     token.Pos
	Tok        token.Token
	X          Expr
	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
	Results []Expr
}

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
	Body   *BlockStmt
}

A 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
	Sel *Ident
}

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
	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
	Lbrack token.Pos
	Low    Expr
	High   Expr
	Max    Expr
	Slice3 bool
	Rbrack token.Pos
}

A 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
	X    Expr
}

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
	Fields     *FieldList
	Incomplete bool
}

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
	Init   Stmt
	Tag    Expr
	Body   *BlockStmt
}

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
	Lparen token.Pos
	Type   Expr
	Rparen token.Pos
}

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
	Name       *Ident
	TypeParams *FieldList
	Assign     token.Pos
	Type       Expr
	Comment    *CommentGroup
}

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
	Init   Stmt
	Assign Stmt
	Body   *BlockStmt
}

A 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
	Op    token.Token
	X     Expr
}

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
	Names   []*Ident
	Type    Expr
	Values  []Expr
	Comment *CommentGroup
}

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).

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