Package ast

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).

// 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
})

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 IsGenerated ¶ 1.21

func IsGenerated(file *File) bool

IsGenerated reports whether the file was generated by a program, not handwritten, by detecting the special comment described at https://go.dev/s/generatedcode.

The syntax tree must have been parsed with the [parser.ParseComments] flag. Example:

f, err := parser.ParseFile(fset, filename, src, parser.ParseComments|parser.PackageClauseOnly)
if err != nil { ... }
gen := ast.IsGenerated(f)

func NotNilFilter ¶

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

NotNilFilter is a FieldFilter that 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 Preorder ¶ 1.23

func Preorder(root Node) iter.Seq[Node]

Preorder returns an iterator over all the nodes of the syntax tree beneath (and including) the specified root, in depth-first preorder.

For greater control over the traversal of each subtree, use Inspect.

src := `
package p

func f(x, y int) {
    print(x + y)
}
`

fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "", src, 0)
if err != nil {
    panic(err)
}

// Print identifiers in order
for n := range ast.Preorder(f) {
    id, ok := n.(*ast.Ident)
    if !ok {
        continue
    }
    fmt.Println(id.Name)
}

p
f
x
y
int
print
x
y

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).

// 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)

     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  .  FileStart: 1:1
    51  .  FileEnd: 5:3
    52  .  Scope: *ast.Scope {
    53  .  .  Objects: map[string]*ast.Object (len = 1) {
    54  .  .  .  "main": *(obj @ 11)
    55  .  .  }
    56  .  }
    57  .  Unresolved: []*ast.Ident (len = 1) {
    58  .  .  0: *(obj @ 29)
    59  .  }
    60  .  GoVersion: ""
    61  }

func SortImports ¶

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

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

func Walk ¶

func Walk(v Visitor, node Node)

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

type ArrayType ¶

An ArrayType node represents an array or slice type.

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

func (*ArrayType) End ¶

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

func (*ArrayType) Pos ¶

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

type AssignStmt ¶

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

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

func (*AssignStmt) End ¶

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

func (*AssignStmt) Pos ¶

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

type BadDecl ¶

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

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

func (*BadDecl) End ¶

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

func (*BadDecl) Pos ¶

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

type BadExpr ¶

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

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

func (*BadExpr) End ¶

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

func (*BadExpr) Pos ¶

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

type BadStmt ¶

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

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

func (*BadStmt) End ¶

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

func (*BadStmt) Pos ¶

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

type BasicLit ¶

A BasicLit node represents a literal of basic type.

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

func (*BasicLit) End ¶

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

func (*BasicLit) Pos ¶

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

type BinaryExpr ¶

A BinaryExpr node represents a binary expression.

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

func (*BinaryExpr) End ¶

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

func (*BinaryExpr) Pos ¶

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

type BlockStmt ¶

A BlockStmt node represents a braced statement list.

type BlockStmt struct {
    Lbrace token.Pos // position of "{"
    List   []Stmt
    Rbrace token.Pos // position of "}", if any (may be absent due to syntax error)
}

func (*BlockStmt) End ¶

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

func (*BlockStmt) Pos ¶

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

type BranchStmt ¶

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

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

func (*BranchStmt) End ¶

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

func (*BranchStmt) Pos ¶

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

type CallExpr ¶

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

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

func (*CallExpr) End ¶

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

func (*CallExpr) Pos ¶

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

type CaseClause ¶

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

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

func (*CaseClause) End ¶

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

func (*CaseClause) Pos ¶

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

type ChanDir ¶

The direction of a channel type is indicated by a bit mask including one or both of the following constants.

type ChanDir int

const (
    SEND ChanDir = 1 << iota
    RECV
)

type ChanType ¶

A ChanType node represents a channel type.

type ChanType struct {
    Begin token.Pos // position of "chan" keyword or "<-" (whichever comes first)
    Arrow token.Pos // position of "<-" (token.NoPos if there is no "<-"); added in Go 1.1
    Dir   ChanDir   // channel direction
    Value Expr      // value type
}

func (*ChanType) End ¶

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

func (*ChanType) Pos ¶

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

type CommClause ¶

A CommClause node represents a case of a select statement.

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

func (*CommClause) End ¶

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

func (*CommClause) Pos ¶

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

type Comment ¶

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

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 Comment.End does not match the true source end position for comments containing carriage returns.

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

func (*Comment) End ¶

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

func (*Comment) Pos ¶

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

type CommentGroup ¶

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

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

func (*CommentGroup) End ¶

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

func (*CommentGroup) Pos ¶

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

func (*CommentGroup) Text ¶

func (g *CommentGroup) Text() string

Text returns the text of the comment. Comment markers (//, /*, and */), the first space of a line comment, and leading and trailing empty lines are removed. 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 ¶ 1.1

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

type CommentMap map[Node][]*CommentGroup

// 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 strings.Builder
if err := format.Node(&buf, fset, f); err != nil {
    panic(err)
}
fmt.Printf("%s", buf.String())

// 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 ¶ 1.1

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 ¶ 1.1

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 ¶ 1.1

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 ¶ 1.1

func (cmap CommentMap) String() string

func (CommentMap) Update ¶ 1.1

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

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

type CompositeLit ¶

A CompositeLit node represents a composite literal.

type CompositeLit struct {
    Type       Expr      // literal type; or nil
    Lbrace     token.Pos // position of "{"
    Elts       []Expr    // list of composite elements; or nil
    Rbrace     token.Pos // position of "}"
    Incomplete bool      // true if (source) expressions are missing in the Elts list; added in Go 1.11
}

func (*CompositeLit) End ¶

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

func (*CompositeLit) Pos ¶

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

type Decl ¶

All declaration nodes implement the Decl interface.

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

type DeclStmt ¶

A DeclStmt node represents a declaration in a statement list.

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

func (*DeclStmt) End ¶

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

func (*DeclStmt) Pos ¶

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

type DeferStmt ¶

A DeferStmt node represents a defer statement.

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

func (*DeferStmt) End ¶

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

func (*DeferStmt) Pos ¶

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

type Ellipsis ¶

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

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

func (*Ellipsis) End ¶

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

func (*Ellipsis) Pos ¶

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

type EmptyStmt ¶

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

type EmptyStmt struct {
    Semicolon token.Pos // position of following ";"
    Implicit  bool      // if set, ";" was omitted in the source; added in Go 1.5
}

func (*EmptyStmt) End ¶

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

func (*EmptyStmt) Pos ¶

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

type Expr ¶

All expression nodes implement the Expr interface.

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

func Unparen ¶ 1.22

func Unparen(e Expr) Expr

Unparen returns the expression with any enclosing parentheses removed.

type ExprStmt ¶

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

type ExprStmt struct {
    X Expr // expression
}

func (*ExprStmt) End ¶

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

func (*ExprStmt) Pos ¶

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

type Field ¶

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

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

func (*Field) End ¶

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

func (*Field) Pos ¶

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

type FieldFilter ¶

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

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

type FieldList ¶

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

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

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 ¶

A File node represents a Go source file.

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

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

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

type File struct {
    Doc     *CommentGroup // associated documentation; or nil
    Package token.Pos     // position of "package" keyword
    Name    *Ident        // package name
    Decls   []Decl        // top-level declarations; or nil

    FileStart, FileEnd token.Pos       // start and end of entire file; added in Go 1.20
    Scope              *Scope          // package scope (this file only). Deprecated: see Object
    Imports            []*ImportSpec   // imports in this file
    Unresolved         []*Ident        // unresolved identifiers in this file. Deprecated: see Object
    Comments           []*CommentGroup // list of all comments in the source file
    GoVersion          string          // minimum Go version required by //go:build or // +build directives; added in Go 1.21
}

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

End returns the end of the last declaration in the file. (Use FileEnd for the end of the entire file.)

func (*File) Pos ¶

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

Pos returns the position of the package declaration. (Use FileStart for the start of the entire file.)

type Filter ¶

type Filter func(string) bool

type ForStmt ¶

A ForStmt represents a for statement.

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

func (*ForStmt) End ¶

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

func (*ForStmt) Pos ¶

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

type FuncDecl ¶

A FuncDecl node represents a function declaration.

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

func (*FuncDecl) End ¶

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

func (*FuncDecl) Pos ¶

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

type FuncLit ¶

A FuncLit node represents a function literal.

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

func (*FuncLit) End ¶

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

func (*FuncLit) Pos ¶

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

type FuncType ¶

A FuncType node represents a function type.

type FuncType struct {
    Func       token.Pos  // position of "func" keyword (token.NoPos if there is no "func")
    TypeParams *FieldList // type parameters; or nil; added in Go 1.18
    Params     *FieldList // (incoming) parameters; non-nil
    Results    *FieldList // (outgoing) results; or nil
}

func (*FuncType) End ¶

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

func (*FuncType) Pos ¶

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

type GenDecl ¶

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

Relationship between Tok value and Specs element type:

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

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

func (*GenDecl) End ¶

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

func (*GenDecl) Pos ¶

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

type GoStmt ¶

A GoStmt node represents a go statement.

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

func (*GoStmt) End ¶

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

func (*GoStmt) Pos ¶

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

type Ident ¶

An Ident node represents an identifier.

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

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 ¶

An IfStmt node represents an if statement.

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

func (*IfStmt) End ¶

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

func (*IfStmt) Pos ¶

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

type ImportSpec ¶

An ImportSpec node represents a single package import.

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

func (*ImportSpec) End ¶

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

func (*ImportSpec) Pos ¶

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

type Importer ¶

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

Deprecated: use the type checker go/types instead; see Object.

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

type IncDecStmt ¶

An IncDecStmt node represents an increment or decrement statement.

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

func (*IncDecStmt) End ¶

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

func (*IncDecStmt) Pos ¶

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

type IndexExpr ¶

An IndexExpr node represents an expression followed by an index.

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

func (*IndexExpr) End ¶

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

func (*IndexExpr) Pos ¶

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

type IndexListExpr ¶ 1.18

An IndexListExpr node represents an expression followed by multiple indices.

type IndexListExpr struct {
    X       Expr      // expression
    Lbrack  token.Pos // position of "["
    Indices []Expr    // index expressions
    Rbrack  token.Pos // position of "]"
}

func (*IndexListExpr) End ¶ 1.18

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

func (*IndexListExpr) Pos ¶ 1.18

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

type InterfaceType ¶

An InterfaceType node represents an interface type.

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

func (*InterfaceType) End ¶

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

func (*InterfaceType) Pos ¶

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

type KeyValueExpr ¶

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

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

func (*KeyValueExpr) End ¶

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

func (*KeyValueExpr) Pos ¶

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

type LabeledStmt ¶

A LabeledStmt node represents a labeled statement.

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

func (*LabeledStmt) End ¶

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

func (*LabeledStmt) Pos ¶

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

type MapType ¶

A MapType node represents a map type.

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

func (*MapType) End ¶

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

func (*MapType) Pos ¶

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

type MergeMode ¶

The MergeMode flags control the behavior of MergePackageFiles.

type MergeMode uint

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

type Node ¶

All node types implement the Node interface.

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

type ObjKind ¶

ObjKind describes what an Object represents.

type ObjKind int

The list of possible Object kinds.

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

func (ObjKind) String ¶

func (kind ObjKind) String() string

type Object ¶

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

The Data fields contains object-specific data:

Kind    Data type         Data value
Pkg     *Scope            package scope
Con     int               iota for the respective declaration

Deprecated: The relationship between Idents and Objects cannot be correctly computed without type information. For example, the expression T{K: 0} may denote a struct, map, slice, or array literal, depending on the type of T. If T is a struct, then K refers to a field of T, whereas for the other types it refers to a value in the environment.

New programs should set the [parser.SkipObjectResolution] parser flag to disable syntactic object resolution (which also saves CPU and memory), and instead use the type checker go/types if object resolution is desired. See the Defs, Uses, and Implicits fields of the [types.Info] struct for details.

type Object struct {
    Kind ObjKind
    Name string // declared name
    Decl any    // corresponding Field, XxxSpec, FuncDecl, LabeledStmt, AssignStmt, Scope; or nil
    Data any    // object-specific data; or nil
    Type any    // placeholder for type information; may be nil
}

func NewObj ¶

func NewObj(kind ObjKind, name string) *Object

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

func (*Object) Pos ¶

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

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

type Package ¶

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

Deprecated: use the type checker go/types instead; see Object.

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

func NewPackage ¶

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

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

Deprecated: use the type checker go/types instead; see Object.

func (*Package) End ¶

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

func (*Package) Pos ¶

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

type ParenExpr ¶

A ParenExpr node represents a parenthesized expression.

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

func (*ParenExpr) End ¶

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

func (*ParenExpr) Pos ¶

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

type RangeStmt ¶

A RangeStmt represents a for statement with a range clause.

type RangeStmt struct {
    For        token.Pos   // position of "for" keyword
    Key, Value Expr        // Key, Value may be nil
    TokPos     token.Pos   // position of Tok; invalid if Key == nil
    Tok        token.Token // ILLEGAL if Key == nil, ASSIGN, DEFINE
    Range      token.Pos   // position of "range" keyword; added in Go 1.20
    X          Expr        // value to range over
    Body       *BlockStmt
}

func (*RangeStmt) End ¶

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

func (*RangeStmt) Pos ¶

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

type ReturnStmt ¶

A ReturnStmt node represents a return statement.

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

func (*ReturnStmt) End ¶

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

func (*ReturnStmt) Pos ¶

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

type Scope ¶

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

Deprecated: use the type checker go/types instead; see Object.

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

func NewScope ¶

func NewScope(outer *Scope) *Scope

NewScope creates a new scope nested in the outer scope.

func (*Scope) Insert ¶

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

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

func (*Scope) Lookup ¶

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

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

func (*Scope) String ¶

func (s *Scope) String() string

Debugging support

type SelectStmt ¶

A SelectStmt node represents a select statement.

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

func (*SelectStmt) End ¶

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

func (*SelectStmt) Pos ¶

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

type SelectorExpr ¶

A SelectorExpr node represents an expression followed by a selector.

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

func (*SelectorExpr) End ¶

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

func (*SelectorExpr) Pos ¶

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

type SendStmt ¶

A SendStmt node represents a send statement.

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

func (*SendStmt) End ¶

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

func (*SendStmt) Pos ¶

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

type SliceExpr ¶

A SliceExpr node represents an expression followed by slice indices.

type SliceExpr struct {
    X      Expr      // expression
    Lbrack token.Pos // position of "["
    Low    Expr      // begin of slice range; or nil
    High   Expr      // end of slice range; or nil
    Max    Expr      // maximum capacity of slice; or nil; added in Go 1.2
    Slice3 bool      // true if 3-index slice (2 colons present); added in Go 1.2
    Rbrack token.Pos // position of "]"
}

func (*SliceExpr) End ¶

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

func (*SliceExpr) Pos ¶

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

type Spec ¶

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

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

type StarExpr ¶

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

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

func (*StarExpr) End ¶

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

func (*StarExpr) Pos ¶

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

type Stmt ¶

All statement nodes implement the Stmt interface.

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

type StructType ¶

A StructType node represents a struct type.

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

func (*StructType) End ¶

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

func (*StructType) Pos ¶

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

type SwitchStmt ¶

A SwitchStmt node represents an expression switch statement.

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

func (*SwitchStmt) End ¶

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

func (*SwitchStmt) Pos ¶

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

type TypeAssertExpr ¶

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

type TypeAssertExpr struct {
    X      Expr      // expression
    Lparen token.Pos // position of "("; added in Go 1.2
    Type   Expr      // asserted type; nil means type switch X.(type)
    Rparen token.Pos // position of ")"; added in Go 1.2
}

func (*TypeAssertExpr) End ¶

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

func (*TypeAssertExpr) Pos ¶

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

type TypeSpec ¶

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

type TypeSpec struct {
    Doc        *CommentGroup // associated documentation; or nil
    Name       *Ident        // type name
    TypeParams *FieldList    // type parameters; or nil; added in Go 1.18
    Assign     token.Pos     // position of '=', if any; added in Go 1.9
    Type       Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
    Comment    *CommentGroup // line comments; or nil
}

func (*TypeSpec) End ¶

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

func (*TypeSpec) Pos ¶

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

type TypeSwitchStmt ¶

A TypeSwitchStmt node represents a type switch statement.

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

func (*TypeSwitchStmt) End ¶

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

func (*TypeSwitchStmt) Pos ¶

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

type UnaryExpr ¶

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

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

func (*UnaryExpr) End ¶

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

func (*UnaryExpr) Pos ¶

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

type ValueSpec ¶

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

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

func (*ValueSpec) End ¶

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

func (*ValueSpec) Pos ¶

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

type Visitor ¶

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

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