Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1063 insertions, 0 deletions

diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
new file mode 100644
index 0000000..300966a
--- /dev/null
+++ b/src/go/ast/ast.go
@@ -0,0 +1,1063 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ast declares the types used to represent syntax trees for Go
+// packages.
+//
+package ast
+
+import (
+	"go/token"
+	"strings"
+)
+
+// ----------------------------------------------------------------------------
+// Interfaces
+//
+// There are 3 main classes of nodes: Expressions and type nodes,
+// statement nodes, and declaration nodes. The node names usually
+// match the corresponding Go spec production names to which they
+// correspond. The node fields correspond to the individual parts
+// of the respective productions.
+//
+// All nodes contain position information marking the beginning of
+// the corresponding source text segment; it is accessible via the
+// Pos accessor method. Nodes may contain additional position info
+// for language constructs where comments may be found between parts
+// of the construct (typically any larger, parenthesized subpart).
+// That position information is needed to properly position comments
+// when printing the construct.
+
+// 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
+}
+
+// All expression nodes implement the Expr interface.
+type Expr interface {
+	Node
+	exprNode()
+}
+
+// All statement nodes implement the Stmt interface.
+type Stmt interface {
+	Node
+	stmtNode()
+}
+
+// All declaration nodes implement the Decl interface.
+type Decl interface {
+	Node
+	declNode()
+}
+
+// ----------------------------------------------------------------------------
+// Comments
+
+// 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.
+type Comment struct {
+	Slash token.Pos // position of "/" starting the comment
+	Text  string    // comment text (excluding '\n' for //-style comments)
+}
+
+func (c *Comment) Pos() token.Pos { return c.Slash }
+func (c *Comment) End() token.Pos { return token.Pos(int(c.Slash) + len(c.Text)) }
+
+// 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 (g *CommentGroup) Pos() token.Pos { return g.List[0].Pos() }
+func (g *CommentGroup) End() token.Pos { return g.List[len(g.List)-1].End() }
+
+func isWhitespace(ch byte) bool { return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r' }
+
+func stripTrailingWhitespace(s string) string {
+	i := len(s)
+	for i > 0 && isWhitespace(s[i-1]) {
+		i--
+	}
+	return s[0:i]
+}
+
+// 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.
+func (g *CommentGroup) Text() string {
+	if g == nil {
+		return ""
+	}
+	comments := make([]string, len(g.List))
+	for i, c := range g.List {
+		comments[i] = c.Text
+	}
+
+	lines := make([]string, 0, 10) // most comments are less than 10 lines
+	for _, c := range comments {
+		// Remove comment markers.
+		// The parser has given us exactly the comment text.
+		switch c[1] {
+		case '/':
+			//-style comment (no newline at the end)
+			c = c[2:]
+			if len(c) == 0 {
+				// empty line
+				break
+			}
+			if c[0] == ' ' {
+				// strip first space - required for Example tests
+				c = c[1:]
+				break
+			}
+			if isDirective(c) {
+				// Ignore //go:noinline, //line, and so on.
+				continue
+			}
+		case '*':
+			/*-style comment */
+			c = c[2 : len(c)-2]
+		}
+
+		// Split on newlines.
+		cl := strings.Split(c, "\n")
+
+		// Walk lines, stripping trailing white space and adding to list.
+		for _, l := range cl {
+			lines = append(lines, stripTrailingWhitespace(l))
+		}
+	}
+
+	// Remove leading blank lines; convert runs of
+	// interior blank lines to a single blank line.
+	n := 0
+	for _, line := range lines {
+		if line != "" || n > 0 && lines[n-1] != "" {
+			lines[n] = line
+			n++
+		}
+	}
+	lines = lines[0:n]
+
+	// Add final "" entry to get trailing newline from Join.
+	if n > 0 && lines[n-1] != "" {
+		lines = append(lines, "")
+	}
+
+	return strings.Join(lines, "\n")
+}
+
+// isDirective reports whether c is a comment directive.
+func isDirective(c string) bool {
+	// "//line " is a line directive.
+	// (The // has been removed.)
+	if strings.HasPrefix(c, "line ") {
+		return true
+	}
+
+	// "//[a-z0-9]+:[a-z0-9]"
+	// (The // has been removed.)
+	colon := strings.Index(c, ":")
+	if colon <= 0 || colon+1 >= len(c) {
+		return false
+	}
+	for i := 0; i <= colon+1; i++ {
+		if i == colon {
+			continue
+		}
+		b := c[i]
+		if !('a' <= b && b <= 'z' || '0' <= b && b <= '9') {
+			return false
+		}
+	}
+	return true
+}
+
+// ----------------------------------------------------------------------------
+// Expressions and types
+
+// 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/parameter names; or nil
+	Type    Expr          // field/method/parameter type
+	Tag     *BasicLit     // field tag; or nil
+	Comment *CommentGroup // line comments; or nil
+}
+
+func (f *Field) Pos() token.Pos {
+	if len(f.Names) > 0 {
+		return f.Names[0].Pos()
+	}
+	return f.Type.Pos()
+}
+
+func (f *Field) End() token.Pos {
+	if f.Tag != nil {
+		return f.Tag.End()
+	}
+	return f.Type.End()
+}
+
+// A FieldList represents a list of Fields, enclosed by parentheses or braces.
+type FieldList struct {
+	Opening token.Pos // position of opening parenthesis/brace, if any
+	List    []*Field  // field list; or nil
+	Closing token.Pos // position of closing parenthesis/brace, if any
+}
+
+func (f *FieldList) Pos() token.Pos {
+	if f.Opening.IsValid() {
+		return f.Opening
+	}
+	// the list should not be empty in this case;
+	// be conservative and guard against bad ASTs
+	if len(f.List) > 0 {
+		return f.List[0].Pos()
+	}
+	return token.NoPos
+}
+
+func (f *FieldList) End() token.Pos {
+	if f.Closing.IsValid() {
+		return f.Closing + 1
+	}
+	// the list should not be empty in this case;
+	// be conservative and guard against bad ASTs
+	if n := len(f.List); n > 0 {
+		return f.List[n-1].End()
+	}
+	return token.NoPos
+}
+
+// NumFields returns the number of parameters or struct fields represented by a FieldList.
+func (f *FieldList) NumFields() int {
+	n := 0
+	if f != nil {
+		for _, g := range f.List {
+			m := len(g.Names)
+			if m == 0 {
+				m = 1
+			}
+			n += m
+		}
+	}
+	return n
+}
+
+// An expression is represented by a tree consisting of one
+// or more of the following concrete expression nodes.
+//
+type (
+	// A BadExpr node is a placeholder for an expression containing
+	// syntax errors for which a correct expression node cannot be
+	// created.
+	//
+	BadExpr struct {
+		From, To token.Pos // position range of bad expression
+	}
+
+	// An Ident node represents an identifier.
+	Ident struct {
+		NamePos token.Pos // identifier position
+		Name    string    // identifier name
+		Obj     *Object   // denoted object; or nil
+	}
+
+	// An Ellipsis node stands for the "..." type in a
+	// parameter list or the "..." length in an array type.
+	//
+	Ellipsis struct {
+		Ellipsis token.Pos // position of "..."
+		Elt      Expr      // ellipsis element type (parameter lists only); or nil
+	}
+
+	// A BasicLit node represents a literal of basic type.
+	//
+	// Note that for the CHAR and STRING kinds, the literal is stored
+	// with its quotes. For example, for a double-quoted STRING, the
+	// first and the last rune in the Value field will be ". The
+	// Unquote and UnquoteChar functions in the strconv package can be
+	// used to unquote STRING and CHAR values, respectively.
+	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 FuncLit node represents a function literal.
+	FuncLit struct {
+		Type *FuncType  // function type
+		Body *BlockStmt // function body
+	}
+
+	// A CompositeLit node represents a composite literal.
+	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
+	}
+
+	// A ParenExpr node represents a parenthesized expression.
+	ParenExpr struct {
+		Lparen token.Pos // position of "("
+		X      Expr      // parenthesized expression
+		Rparen token.Pos // position of ")"
+	}
+
+	// A SelectorExpr node represents an expression followed by a selector.
+	SelectorExpr struct {
+		X   Expr   // expression
+		Sel *Ident // field selector
+	}
+
+	// An IndexExpr node represents an expression followed by an index.
+	IndexExpr struct {
+		X      Expr      // expression
+		Lbrack token.Pos // position of "["
+		Index  Expr      // index expression
+		Rbrack token.Pos // position of "]"
+	}
+
+	// A SliceExpr node represents an expression followed by slice indices.
+	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 "]"
+	}
+
+	// A TypeAssertExpr node represents an expression followed by a
+	// type assertion.
+	//
+	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 CallExpr node represents an expression followed by an argument list.
+	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 StarExpr node represents an expression of the form "*" Expression.
+	// Semantically it could be a unary "*" expression, or a pointer type.
+	//
+	StarExpr struct {
+		Star token.Pos // position of "*"
+		X    Expr      // operand
+	}
+
+	// A UnaryExpr node represents a unary expression.
+	// Unary "*" expressions are represented via StarExpr nodes.
+	//
+	UnaryExpr struct {
+		OpPos token.Pos   // position of Op
+		Op    token.Token // operator
+		X     Expr        // operand
+	}
+
+	// A BinaryExpr node represents a binary expression.
+	BinaryExpr struct {
+		X     Expr        // left operand
+		OpPos token.Pos   // position of Op
+		Op    token.Token // operator
+		Y     Expr        // right operand
+	}
+
+	// A KeyValueExpr node represents (key : value) pairs
+	// in composite literals.
+	//
+	KeyValueExpr struct {
+		Key   Expr
+		Colon token.Pos // position of ":"
+		Value Expr
+	}
+)
+
+// 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
+)
+
+// A type is represented by a tree consisting of one
+// or more of the following type-specific expression
+// nodes.
+//
+type (
+	// An ArrayType node represents an array or slice type.
+	ArrayType struct {
+		Lbrack token.Pos // position of "["
+		Len    Expr      // Ellipsis node for [...]T array types, nil for slice types
+		Elt    Expr      // element type
+	}
+
+	// A StructType node represents a struct 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
+	}
+
+	// Pointer types are represented via StarExpr nodes.
+
+	// A FuncType node represents a function 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
+	}
+
+	// An InterfaceType node represents an interface 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
+	}
+
+	// A MapType node represents a map type.
+	MapType struct {
+		Map   token.Pos // position of "map" keyword
+		Key   Expr
+		Value Expr
+	}
+
+	// A ChanType node represents a channel 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
+	}
+)
+
+// Pos and End implementations for expression/type nodes.
+
+func (x *BadExpr) Pos() token.Pos  { return x.From }
+func (x *Ident) Pos() token.Pos    { return x.NamePos }
+func (x *Ellipsis) Pos() token.Pos { return x.Ellipsis }
+func (x *BasicLit) Pos() token.Pos { return x.ValuePos }
+func (x *FuncLit) Pos() token.Pos  { return x.Type.Pos() }
+func (x *CompositeLit) Pos() token.Pos {
+	if x.Type != nil {
+		return x.Type.Pos()
+	}
+	return x.Lbrace
+}
+func (x *ParenExpr) Pos() token.Pos      { return x.Lparen }
+func (x *SelectorExpr) Pos() token.Pos   { return x.X.Pos() }
+func (x *IndexExpr) Pos() token.Pos      { return x.X.Pos() }
+func (x *SliceExpr) Pos() token.Pos      { return x.X.Pos() }
+func (x *TypeAssertExpr) Pos() token.Pos { return x.X.Pos() }
+func (x *CallExpr) Pos() token.Pos       { return x.Fun.Pos() }
+func (x *StarExpr) Pos() token.Pos       { return x.Star }
+func (x *UnaryExpr) Pos() token.Pos      { return x.OpPos }
+func (x *BinaryExpr) Pos() token.Pos     { return x.X.Pos() }
+func (x *KeyValueExpr) Pos() token.Pos   { return x.Key.Pos() }
+func (x *ArrayType) Pos() token.Pos      { return x.Lbrack }
+func (x *StructType) Pos() token.Pos     { return x.Struct }
+func (x *FuncType) Pos() token.Pos {
+	if x.Func.IsValid() || x.Params == nil { // see issue 3870
+		return x.Func
+	}
+	return x.Params.Pos() // interface method declarations have no "func" keyword
+}
+func (x *InterfaceType) Pos() token.Pos { return x.Interface }
+func (x *MapType) Pos() token.Pos       { return x.Map }
+func (x *ChanType) Pos() token.Pos      { return x.Begin }
+
+func (x *BadExpr) End() token.Pos { return x.To }
+func (x *Ident) End() token.Pos   { return token.Pos(int(x.NamePos) + len(x.Name)) }
+func (x *Ellipsis) End() token.Pos {
+	if x.Elt != nil {
+		return x.Elt.End()
+	}
+	return x.Ellipsis + 3 // len("...")
+}
+func (x *BasicLit) End() token.Pos       { return token.Pos(int(x.ValuePos) + len(x.Value)) }
+func (x *FuncLit) End() token.Pos        { return x.Body.End() }
+func (x *CompositeLit) End() token.Pos   { return x.Rbrace + 1 }
+func (x *ParenExpr) End() token.Pos      { return x.Rparen + 1 }
+func (x *SelectorExpr) End() token.Pos   { return x.Sel.End() }
+func (x *IndexExpr) End() token.Pos      { return x.Rbrack + 1 }
+func (x *SliceExpr) End() token.Pos      { return x.Rbrack + 1 }
+func (x *TypeAssertExpr) End() token.Pos { return x.Rparen + 1 }
+func (x *CallExpr) End() token.Pos       { return x.Rparen + 1 }
+func (x *StarExpr) End() token.Pos       { return x.X.End() }
+func (x *UnaryExpr) End() token.Pos      { return x.X.End() }
+func (x *BinaryExpr) End() token.Pos     { return x.Y.End() }
+func (x *KeyValueExpr) End() token.Pos   { return x.Value.End() }
+func (x *ArrayType) End() token.Pos      { return x.Elt.End() }
+func (x *StructType) End() token.Pos     { return x.Fields.End() }
+func (x *FuncType) End() token.Pos {
+	if x.Results != nil {
+		return x.Results.End()
+	}
+	return x.Params.End()
+}
+func (x *InterfaceType) End() token.Pos { return x.Methods.End() }
+func (x *MapType) End() token.Pos       { return x.Value.End() }
+func (x *ChanType) End() token.Pos      { return x.Value.End() }
+
+// exprNode() ensures that only expression/type nodes can be
+// assigned to an Expr.
+//
+func (*BadExpr) exprNode()        {}
+func (*Ident) exprNode()          {}
+func (*Ellipsis) exprNode()       {}
+func (*BasicLit) exprNode()       {}
+func (*FuncLit) exprNode()        {}
+func (*CompositeLit) exprNode()   {}
+func (*ParenExpr) exprNode()      {}
+func (*SelectorExpr) exprNode()   {}
+func (*IndexExpr) exprNode()      {}
+func (*SliceExpr) exprNode()      {}
+func (*TypeAssertExpr) exprNode() {}
+func (*CallExpr) exprNode()       {}
+func (*StarExpr) exprNode()       {}
+func (*UnaryExpr) exprNode()      {}
+func (*BinaryExpr) exprNode()     {}
+func (*KeyValueExpr) exprNode()   {}
+
+func (*ArrayType) exprNode()     {}
+func (*StructType) exprNode()    {}
+func (*FuncType) exprNode()      {}
+func (*InterfaceType) exprNode() {}
+func (*MapType) exprNode()       {}
+func (*ChanType) exprNode()      {}
+
+// ----------------------------------------------------------------------------
+// Convenience functions for Idents
+
+// NewIdent creates a new Ident without position.
+// Useful for ASTs generated by code other than the Go parser.
+//
+func NewIdent(name string) *Ident { return &Ident{token.NoPos, name, nil} }
+
+// IsExported reports whether name starts with an upper-case letter.
+//
+func IsExported(name string) bool { return token.IsExported(name) }
+
+// IsExported reports whether id starts with an upper-case letter.
+//
+func (id *Ident) IsExported() bool { return token.IsExported(id.Name) }
+
+func (id *Ident) String() string {
+	if id != nil {
+		return id.Name
+	}
+	return "<nil>"
+}
+
+// ----------------------------------------------------------------------------
+// Statements
+
+// A statement is represented by a tree consisting of one
+// or more of the following concrete statement nodes.
+//
+type (
+	// A BadStmt node is a placeholder for statements containing
+	// syntax errors for which no correct statement nodes can be
+	// created.
+	//
+	BadStmt struct {
+		From, To token.Pos // position range of bad statement
+	}
+
+	// A DeclStmt node represents a declaration in a statement list.
+	DeclStmt struct {
+		Decl Decl // *GenDecl with CONST, TYPE, or VAR token
+	}
+
+	// An EmptyStmt node represents an empty statement.
+	// The "position" of the empty statement is the position
+	// of the immediately following (explicit or implicit) semicolon.
+	//
+	EmptyStmt struct {
+		Semicolon token.Pos // position of following ";"
+		Implicit  bool      // if set, ";" was omitted in the source
+	}
+
+	// A LabeledStmt node represents a labeled statement.
+	LabeledStmt struct {
+		Label *Ident
+		Colon token.Pos // position of ":"
+		Stmt  Stmt
+	}
+
+	// An ExprStmt node represents a (stand-alone) expression
+	// in a statement list.
+	//
+	ExprStmt struct {
+		X Expr // expression
+	}
+
+	// A SendStmt node represents a send statement.
+	SendStmt struct {
+		Chan  Expr
+		Arrow token.Pos // position of "<-"
+		Value Expr
+	}
+
+	// An IncDecStmt node represents an increment or decrement statement.
+	IncDecStmt struct {
+		X      Expr
+		TokPos token.Pos   // position of Tok
+		Tok    token.Token // INC or DEC
+	}
+
+	// An AssignStmt node represents an assignment or
+	// a short variable declaration.
+	//
+	AssignStmt struct {
+		Lhs    []Expr
+		TokPos token.Pos   // position of Tok
+		Tok    token.Token // assignment token, DEFINE
+		Rhs    []Expr
+	}
+
+	// A GoStmt node represents a go statement.
+	GoStmt struct {
+		Go   token.Pos // position of "go" keyword
+		Call *CallExpr
+	}
+
+	// A DeferStmt node represents a defer statement.
+	DeferStmt struct {
+		Defer token.Pos // position of "defer" keyword
+		Call  *CallExpr
+	}
+
+	// A ReturnStmt node represents a return statement.
+	ReturnStmt struct {
+		Return  token.Pos // position of "return" keyword
+		Results []Expr    // result expressions; or nil
+	}
+
+	// A BranchStmt node represents a break, continue, goto,
+	// or fallthrough statement.
+	//
+	BranchStmt struct {
+		TokPos token.Pos   // position of Tok
+		Tok    token.Token // keyword token (BREAK, CONTINUE, GOTO, FALLTHROUGH)
+		Label  *Ident      // label name; or nil
+	}
+
+	// A BlockStmt node represents a braced statement list.
+	BlockStmt struct {
+		Lbrace token.Pos // position of "{"
+		List   []Stmt
+		Rbrace token.Pos // position of "}", if any (may be absent due to syntax error)
+	}
+
+	// An IfStmt node represents an if statement.
+	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
+	}
+
+	// A CaseClause represents a case of an expression or type switch statement.
+	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 SwitchStmt node represents an expression switch statement.
+	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 TypeSwitchStmt node represents a type switch statement.
+	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
+	}
+
+	// A CommClause node represents a case of a select statement.
+	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 SelectStmt node represents a select statement.
+	SelectStmt struct {
+		Select token.Pos  // position of "select" keyword
+		Body   *BlockStmt // CommClauses only
+	}
+
+	// A ForStmt represents a for statement.
+	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 RangeStmt represents a for statement with a range clause.
+	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
+	}
+)
+
+// Pos and End implementations for statement nodes.
+
+func (s *BadStmt) Pos() token.Pos        { return s.From }
+func (s *DeclStmt) Pos() token.Pos       { return s.Decl.Pos() }
+func (s *EmptyStmt) Pos() token.Pos      { return s.Semicolon }
+func (s *LabeledStmt) Pos() token.Pos    { return s.Label.Pos() }
+func (s *ExprStmt) Pos() token.Pos       { return s.X.Pos() }
+func (s *SendStmt) Pos() token.Pos       { return s.Chan.Pos() }
+func (s *IncDecStmt) Pos() token.Pos     { return s.X.Pos() }
+func (s *AssignStmt) Pos() token.Pos     { return s.Lhs[0].Pos() }
+func (s *GoStmt) Pos() token.Pos         { return s.Go }
+func (s *DeferStmt) Pos() token.Pos      { return s.Defer }
+func (s *ReturnStmt) Pos() token.Pos     { return s.Return }
+func (s *BranchStmt) Pos() token.Pos     { return s.TokPos }
+func (s *BlockStmt) Pos() token.Pos      { return s.Lbrace }
+func (s *IfStmt) Pos() token.Pos         { return s.If }
+func (s *CaseClause) Pos() token.Pos     { return s.Case }
+func (s *SwitchStmt) Pos() token.Pos     { return s.Switch }
+func (s *TypeSwitchStmt) Pos() token.Pos { return s.Switch }
+func (s *CommClause) Pos() token.Pos     { return s.Case }
+func (s *SelectStmt) Pos() token.Pos     { return s.Select }
+func (s *ForStmt) Pos() token.Pos        { return s.For }
+func (s *RangeStmt) Pos() token.Pos      { return s.For }
+
+func (s *BadStmt) End() token.Pos  { return s.To }
+func (s *DeclStmt) End() token.Pos { return s.Decl.End() }
+func (s *EmptyStmt) End() token.Pos {
+	if s.Implicit {
+		return s.Semicolon
+	}
+	return s.Semicolon + 1 /* len(";") */
+}
+func (s *LabeledStmt) End() token.Pos { return s.Stmt.End() }
+func (s *ExprStmt) End() token.Pos    { return s.X.End() }
+func (s *SendStmt) End() token.Pos    { return s.Value.End() }
+func (s *IncDecStmt) End() token.Pos {
+	return s.TokPos + 2 /* len("++") */
+}
+func (s *AssignStmt) End() token.Pos { return s.Rhs[len(s.Rhs)-1].End() }
+func (s *GoStmt) End() token.Pos     { return s.Call.End() }
+func (s *DeferStmt) End() token.Pos  { return s.Call.End() }
+func (s *ReturnStmt) End() token.Pos {
+	if n := len(s.Results); n > 0 {
+		return s.Results[n-1].End()
+	}
+	return s.Return + 6 // len("return")
+}
+func (s *BranchStmt) End() token.Pos {
+	if s.Label != nil {
+		return s.Label.End()
+	}
+	return token.Pos(int(s.TokPos) + len(s.Tok.String()))
+}
+func (s *BlockStmt) End() token.Pos {
+	if s.Rbrace.IsValid() {
+		return s.Rbrace + 1
+	}
+	if n := len(s.List); n > 0 {
+		return s.List[n-1].End()
+	}
+	return s.Lbrace + 1
+}
+func (s *IfStmt) End() token.Pos {
+	if s.Else != nil {
+		return s.Else.End()
+	}
+	return s.Body.End()
+}
+func (s *CaseClause) End() token.Pos {
+	if n := len(s.Body); n > 0 {
+		return s.Body[n-1].End()
+	}
+	return s.Colon + 1
+}
+func (s *SwitchStmt) End() token.Pos     { return s.Body.End() }
+func (s *TypeSwitchStmt) End() token.Pos { return s.Body.End() }
+func (s *CommClause) End() token.Pos {
+	if n := len(s.Body); n > 0 {
+		return s.Body[n-1].End()
+	}
+	return s.Colon + 1
+}
+func (s *SelectStmt) End() token.Pos { return s.Body.End() }
+func (s *ForStmt) End() token.Pos    { return s.Body.End() }
+func (s *RangeStmt) End() token.Pos  { return s.Body.End() }
+
+// stmtNode() ensures that only statement nodes can be
+// assigned to a Stmt.
+//
+func (*BadStmt) stmtNode()        {}
+func (*DeclStmt) stmtNode()       {}
+func (*EmptyStmt) stmtNode()      {}
+func (*LabeledStmt) stmtNode()    {}
+func (*ExprStmt) stmtNode()       {}
+func (*SendStmt) stmtNode()       {}
+func (*IncDecStmt) stmtNode()     {}
+func (*AssignStmt) stmtNode()     {}
+func (*GoStmt) stmtNode()         {}
+func (*DeferStmt) stmtNode()      {}
+func (*ReturnStmt) stmtNode()     {}
+func (*BranchStmt) stmtNode()     {}
+func (*BlockStmt) stmtNode()      {}
+func (*IfStmt) stmtNode()         {}
+func (*CaseClause) stmtNode()     {}
+func (*SwitchStmt) stmtNode()     {}
+func (*TypeSwitchStmt) stmtNode() {}
+func (*CommClause) stmtNode()     {}
+func (*SelectStmt) stmtNode()     {}
+func (*ForStmt) stmtNode()        {}
+func (*RangeStmt) stmtNode()      {}
+
+// ----------------------------------------------------------------------------
+// Declarations
+
+// A Spec node represents a single (non-parenthesized) import,
+// constant, type, or variable declaration.
+//
+type (
+	// The Spec type stands for any of *ImportSpec, *ValueSpec, and *TypeSpec.
+	Spec interface {
+		Node
+		specNode()
+	}
+
+	// An ImportSpec node represents a single package import.
+	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)
+	}
+
+	// A ValueSpec node represents a constant or variable declaration
+	// (ConstSpec or VarSpec production).
+	//
+	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 TypeSpec node represents a type declaration (TypeSpec production).
+	TypeSpec struct {
+		Doc     *CommentGroup // associated documentation; or nil
+		Name    *Ident        // type name
+		Assign  token.Pos     // position of '=', if any
+		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
+		Comment *CommentGroup // line comments; or nil
+	}
+)
+
+// Pos and End implementations for spec nodes.
+
+func (s *ImportSpec) Pos() token.Pos {
+	if s.Name != nil {
+		return s.Name.Pos()
+	}
+	return s.Path.Pos()
+}
+func (s *ValueSpec) Pos() token.Pos { return s.Names[0].Pos() }
+func (s *TypeSpec) Pos() token.Pos  { return s.Name.Pos() }
+
+func (s *ImportSpec) End() token.Pos {
+	if s.EndPos != 0 {
+		return s.EndPos
+	}
+	return s.Path.End()
+}
+
+func (s *ValueSpec) End() token.Pos {
+	if n := len(s.Values); n > 0 {
+		return s.Values[n-1].End()
+	}
+	if s.Type != nil {
+		return s.Type.End()
+	}
+	return s.Names[len(s.Names)-1].End()
+}
+func (s *TypeSpec) End() token.Pos { return s.Type.End() }
+
+// specNode() ensures that only spec nodes can be
+// assigned to a Spec.
+//
+func (*ImportSpec) specNode() {}
+func (*ValueSpec) specNode()  {}
+func (*TypeSpec) specNode()   {}
+
+// A declaration is represented by one of the following declaration nodes.
+//
+type (
+	// A BadDecl node is a placeholder for a declaration containing
+	// syntax errors for which a correct declaration node cannot be
+	// created.
+	//
+	BadDecl struct {
+		From, To token.Pos // position range of bad declaration
+	}
+
+	// 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
+	//
+	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 FuncDecl node represents a function declaration.
+	FuncDecl struct {
+		Doc  *CommentGroup // associated documentation; or nil
+		Recv *FieldList    // receiver (methods); or nil (functions)
+		Name *Ident        // function/method name
+		Type *FuncType     // function signature: parameters, results, and position of "func" keyword
+		Body *BlockStmt    // function body; or nil for external (non-Go) function
+	}
+)
+
+// Pos and End implementations for declaration nodes.
+
+func (d *BadDecl) Pos() token.Pos  { return d.From }
+func (d *GenDecl) Pos() token.Pos  { return d.TokPos }
+func (d *FuncDecl) Pos() token.Pos { return d.Type.Pos() }
+
+func (d *BadDecl) End() token.Pos { return d.To }
+func (d *GenDecl) End() token.Pos {
+	if d.Rparen.IsValid() {
+		return d.Rparen + 1
+	}
+	return d.Specs[0].End()
+}
+func (d *FuncDecl) End() token.Pos {
+	if d.Body != nil {
+		return d.Body.End()
+	}
+	return d.Type.End()
+}
+
+// declNode() ensures that only declaration nodes can be
+// assigned to a Decl.
+//
+func (*BadDecl) declNode()  {}
+func (*GenDecl) declNode()  {}
+func (*FuncDecl) declNode() {}
+
+// ----------------------------------------------------------------------------
+// Files and packages
+
+// A File node represents a Go source file.
+//
+// The Comments list contains all comments in the source file in order of
+// appearance, including the comments that are pointed to from other nodes
+// via Doc and Comment fields.
+//
+// For correct printing of source code containing comments (using packages
+// go/format and go/printer), special care must be taken to update comments
+// when a File's syntax tree is modified: For printing, comments are interspersed
+// between tokens based on their position. If syntax tree nodes are
+// removed or moved, relevant comments in their vicinity must also be removed
+// (from the File.Comments list) or moved accordingly (by updating their
+// positions). A CommentMap may be used to facilitate some of these operations.
+//
+// Whether and how a comment is associated with a node depends on the
+// interpretation of the syntax tree by the manipulating program: Except for Doc
+// and Comment comments directly associated with nodes, the remaining comments
+// are "free-floating" (see also issues #18593, #20744).
+//
+type File struct {
+	Doc        *CommentGroup   // associated documentation; or nil
+	Package    token.Pos       // position of "package" keyword
+	Name       *Ident          // package name
+	Decls      []Decl          // top-level declarations; or nil
+	Scope      *Scope          // package scope (this file only)
+	Imports    []*ImportSpec   // imports in this file
+	Unresolved []*Ident        // unresolved identifiers in this file
+	Comments   []*CommentGroup // list of all comments in the source file
+}
+
+func (f *File) Pos() token.Pos { return f.Package }
+func (f *File) End() token.Pos {
+	if n := len(f.Decls); n > 0 {
+		return f.Decls[n-1].End()
+	}
+	return f.Name.End()
+}
+
+// A Package node represents a set of source files
+// collectively building a Go package.
+//
+type Package struct {
+	Name    string             // package name
+	Scope   *Scope             // package scope across all files
+	Imports map[string]*Object // map of package id -> package object
+	Files   map[string]*File   // Go source files by filename
+}
+
+func (p *Package) Pos() token.Pos { return token.NoPos }
+func (p *Package) End() token.Pos { return token.NoPos }