538 lines
13 KiB
Go
538 lines
13 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Parse input AST and prepare Prog structure.
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package main
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import (
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"fmt"
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"go/ast"
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"go/parser"
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"go/scanner"
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"go/token"
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"os"
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"strings"
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)
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func parse(name string, src []byte, flags parser.Mode) *ast.File {
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ast1, err := parser.ParseFile(fset, name, src, flags)
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if err != nil {
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if list, ok := err.(scanner.ErrorList); ok {
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// If err is a scanner.ErrorList, its String will print just
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// the first error and then (+n more errors).
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// Instead, turn it into a new Error that will return
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// details for all the errors.
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for _, e := range list {
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fmt.Fprintln(os.Stderr, e)
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}
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os.Exit(2)
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}
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fatalf("parsing %s: %s", name, err)
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}
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return ast1
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}
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func sourceLine(n ast.Node) int {
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return fset.Position(n.Pos()).Line
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}
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// ParseGo populates f with information learned from the Go source code
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// which was read from the named file. It gathers the C preamble
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// attached to the import "C" comment, a list of references to C.xxx,
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// a list of exported functions, and the actual AST, to be rewritten and
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// printed.
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func (f *File) ParseGo(abspath string, src []byte) {
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// Two different parses: once with comments, once without.
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// The printer is not good enough at printing comments in the
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// right place when we start editing the AST behind its back,
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// so we use ast1 to look for the doc comments on import "C"
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// and on exported functions, and we use ast2 for translating
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// and reprinting.
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// In cgo mode, we ignore ast2 and just apply edits directly
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// the text behind ast1. In godefs mode we modify and print ast2.
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ast1 := parse(abspath, src, parser.ParseComments)
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ast2 := parse(abspath, src, 0)
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f.Package = ast1.Name.Name
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f.Name = make(map[string]*Name)
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f.NamePos = make(map[*Name]token.Pos)
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// In ast1, find the import "C" line and get any extra C preamble.
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sawC := false
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for _, decl := range ast1.Decls {
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d, ok := decl.(*ast.GenDecl)
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if !ok {
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continue
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}
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for _, spec := range d.Specs {
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s, ok := spec.(*ast.ImportSpec)
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if !ok || s.Path.Value != `"C"` {
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continue
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}
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sawC = true
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if s.Name != nil {
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error_(s.Path.Pos(), `cannot rename import "C"`)
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}
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cg := s.Doc
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if cg == nil && len(d.Specs) == 1 {
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cg = d.Doc
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}
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if cg != nil {
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f.Preamble += fmt.Sprintf("#line %d %q\n", sourceLine(cg), abspath)
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f.Preamble += commentText(cg) + "\n"
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f.Preamble += "#line 1 \"cgo-generated-wrapper\"\n"
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}
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}
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}
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if !sawC {
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error_(ast1.Package, `cannot find import "C"`)
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}
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// In ast2, strip the import "C" line.
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if *godefs {
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w := 0
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for _, decl := range ast2.Decls {
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d, ok := decl.(*ast.GenDecl)
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if !ok {
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ast2.Decls[w] = decl
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w++
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continue
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}
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ws := 0
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for _, spec := range d.Specs {
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s, ok := spec.(*ast.ImportSpec)
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if !ok || s.Path.Value != `"C"` {
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d.Specs[ws] = spec
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ws++
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}
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}
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if ws == 0 {
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continue
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}
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d.Specs = d.Specs[0:ws]
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ast2.Decls[w] = d
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w++
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}
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ast2.Decls = ast2.Decls[0:w]
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} else {
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for _, decl := range ast2.Decls {
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d, ok := decl.(*ast.GenDecl)
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if !ok {
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continue
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}
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for _, spec := range d.Specs {
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if s, ok := spec.(*ast.ImportSpec); ok && s.Path.Value == `"C"` {
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// Replace "C" with _ "unsafe", to keep program valid.
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// (Deleting import statement or clause is not safe if it is followed
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// in the source by an explicit semicolon.)
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f.Edit.Replace(f.offset(s.Path.Pos()), f.offset(s.Path.End()), `_ "unsafe"`)
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}
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}
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}
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}
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// Accumulate pointers to uses of C.x.
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if f.Ref == nil {
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f.Ref = make([]*Ref, 0, 8)
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}
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f.walk(ast2, ctxProg, (*File).validateIdents)
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f.walk(ast2, ctxProg, (*File).saveExprs)
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// Accumulate exported functions.
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// The comments are only on ast1 but we need to
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// save the function bodies from ast2.
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// The first walk fills in ExpFunc, and the
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// second walk changes the entries to
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// refer to ast2 instead.
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f.walk(ast1, ctxProg, (*File).saveExport)
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f.walk(ast2, ctxProg, (*File).saveExport2)
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f.Comments = ast1.Comments
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f.AST = ast2
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}
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// Like ast.CommentGroup's Text method but preserves
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// leading blank lines, so that line numbers line up.
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func commentText(g *ast.CommentGroup) string {
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var pieces []string
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for _, com := range g.List {
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c := com.Text
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// Remove comment markers.
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// The parser has given us exactly the comment text.
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switch c[1] {
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case '/':
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//-style comment (no newline at the end)
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c = c[2:] + "\n"
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case '*':
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/*-style comment */
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c = c[2 : len(c)-2]
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}
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pieces = append(pieces, c)
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}
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return strings.Join(pieces, "")
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}
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func (f *File) validateIdents(x interface{}, context astContext) {
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if x, ok := x.(*ast.Ident); ok {
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if f.isMangledName(x.Name) {
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error_(x.Pos(), "identifier %q may conflict with identifiers generated by cgo", x.Name)
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}
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}
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}
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// Save various references we are going to need later.
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func (f *File) saveExprs(x interface{}, context astContext) {
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switch x := x.(type) {
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case *ast.Expr:
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switch (*x).(type) {
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case *ast.SelectorExpr:
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f.saveRef(x, context)
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}
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case *ast.CallExpr:
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f.saveCall(x, context)
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}
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}
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// Save references to C.xxx for later processing.
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func (f *File) saveRef(n *ast.Expr, context astContext) {
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sel := (*n).(*ast.SelectorExpr)
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// For now, assume that the only instance of capital C is when
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// used as the imported package identifier.
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// The parser should take care of scoping in the future, so
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// that we will be able to distinguish a "top-level C" from a
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// local C.
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if l, ok := sel.X.(*ast.Ident); !ok || l.Name != "C" {
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return
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}
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if context == ctxAssign2 {
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context = ctxExpr
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}
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if context == ctxEmbedType {
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error_(sel.Pos(), "cannot embed C type")
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}
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goname := sel.Sel.Name
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if goname == "errno" {
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error_(sel.Pos(), "cannot refer to errno directly; see documentation")
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return
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}
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if goname == "_CMalloc" {
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error_(sel.Pos(), "cannot refer to C._CMalloc; use C.malloc")
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return
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}
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if goname == "malloc" {
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goname = "_CMalloc"
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}
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name := f.Name[goname]
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if name == nil {
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name = &Name{
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Go: goname,
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}
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f.Name[goname] = name
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f.NamePos[name] = sel.Pos()
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}
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f.Ref = append(f.Ref, &Ref{
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Name: name,
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Expr: n,
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Context: context,
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})
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}
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// Save calls to C.xxx for later processing.
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func (f *File) saveCall(call *ast.CallExpr, context astContext) {
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sel, ok := call.Fun.(*ast.SelectorExpr)
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if !ok {
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return
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}
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if l, ok := sel.X.(*ast.Ident); !ok || l.Name != "C" {
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return
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}
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c := &Call{Call: call, Deferred: context == ctxDefer}
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f.Calls = append(f.Calls, c)
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}
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// If a function should be exported add it to ExpFunc.
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func (f *File) saveExport(x interface{}, context astContext) {
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n, ok := x.(*ast.FuncDecl)
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if !ok {
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return
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}
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if n.Doc == nil {
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return
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}
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for _, c := range n.Doc.List {
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if !strings.HasPrefix(c.Text, "//export ") {
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continue
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}
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name := strings.TrimSpace(c.Text[9:])
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if name == "" {
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error_(c.Pos(), "export missing name")
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}
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if name != n.Name.Name {
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error_(c.Pos(), "export comment has wrong name %q, want %q", name, n.Name.Name)
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}
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doc := ""
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for _, c1 := range n.Doc.List {
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if c1 != c {
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doc += c1.Text + "\n"
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}
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}
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f.ExpFunc = append(f.ExpFunc, &ExpFunc{
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Func: n,
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ExpName: name,
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Doc: doc,
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})
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break
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}
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}
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// Make f.ExpFunc[i] point at the Func from this AST instead of the other one.
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func (f *File) saveExport2(x interface{}, context astContext) {
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n, ok := x.(*ast.FuncDecl)
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if !ok {
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return
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}
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for _, exp := range f.ExpFunc {
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if exp.Func.Name.Name == n.Name.Name {
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exp.Func = n
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break
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}
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}
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}
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type astContext int
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const (
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ctxProg astContext = iota
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ctxEmbedType
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ctxType
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ctxStmt
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ctxExpr
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ctxField
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ctxParam
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ctxAssign2 // assignment of a single expression to two variables
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ctxSwitch
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ctxTypeSwitch
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ctxFile
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ctxDecl
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ctxSpec
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ctxDefer
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ctxCall // any function call other than ctxCall2
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ctxCall2 // function call whose result is assigned to two variables
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ctxSelector
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)
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// walk walks the AST x, calling visit(f, x, context) for each node.
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func (f *File) walk(x interface{}, context astContext, visit func(*File, interface{}, astContext)) {
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visit(f, x, context)
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switch n := x.(type) {
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case *ast.Expr:
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f.walk(*n, context, visit)
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// everything else just recurs
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default:
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f.walkUnexpected(x, context, visit)
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case nil:
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// These are ordered and grouped to match ../../go/ast/ast.go
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case *ast.Field:
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if len(n.Names) == 0 && context == ctxField {
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f.walk(&n.Type, ctxEmbedType, visit)
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} else {
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f.walk(&n.Type, ctxType, visit)
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}
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case *ast.FieldList:
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for _, field := range n.List {
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f.walk(field, context, visit)
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}
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case *ast.BadExpr:
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case *ast.Ident:
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case *ast.Ellipsis:
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f.walk(&n.Elt, ctxType, visit)
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case *ast.BasicLit:
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case *ast.FuncLit:
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f.walk(n.Type, ctxType, visit)
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f.walk(n.Body, ctxStmt, visit)
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case *ast.CompositeLit:
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f.walk(&n.Type, ctxType, visit)
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f.walk(n.Elts, ctxExpr, visit)
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case *ast.ParenExpr:
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f.walk(&n.X, context, visit)
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case *ast.SelectorExpr:
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f.walk(&n.X, ctxSelector, visit)
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case *ast.IndexExpr:
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f.walk(&n.X, ctxExpr, visit)
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f.walk(&n.Index, ctxExpr, visit)
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case *ast.SliceExpr:
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f.walk(&n.X, ctxExpr, visit)
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if n.Low != nil {
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f.walk(&n.Low, ctxExpr, visit)
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}
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if n.High != nil {
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f.walk(&n.High, ctxExpr, visit)
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}
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if n.Max != nil {
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f.walk(&n.Max, ctxExpr, visit)
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}
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case *ast.TypeAssertExpr:
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f.walk(&n.X, ctxExpr, visit)
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f.walk(&n.Type, ctxType, visit)
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case *ast.CallExpr:
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if context == ctxAssign2 {
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f.walk(&n.Fun, ctxCall2, visit)
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} else {
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f.walk(&n.Fun, ctxCall, visit)
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}
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f.walk(n.Args, ctxExpr, visit)
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case *ast.StarExpr:
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f.walk(&n.X, context, visit)
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case *ast.UnaryExpr:
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f.walk(&n.X, ctxExpr, visit)
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case *ast.BinaryExpr:
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f.walk(&n.X, ctxExpr, visit)
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f.walk(&n.Y, ctxExpr, visit)
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case *ast.KeyValueExpr:
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f.walk(&n.Key, ctxExpr, visit)
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f.walk(&n.Value, ctxExpr, visit)
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case *ast.ArrayType:
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f.walk(&n.Len, ctxExpr, visit)
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f.walk(&n.Elt, ctxType, visit)
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case *ast.StructType:
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f.walk(n.Fields, ctxField, visit)
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case *ast.FuncType:
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f.walk(n.Params, ctxParam, visit)
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if n.Results != nil {
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f.walk(n.Results, ctxParam, visit)
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}
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case *ast.InterfaceType:
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f.walk(n.Methods, ctxField, visit)
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case *ast.MapType:
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f.walk(&n.Key, ctxType, visit)
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f.walk(&n.Value, ctxType, visit)
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case *ast.ChanType:
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f.walk(&n.Value, ctxType, visit)
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case *ast.BadStmt:
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case *ast.DeclStmt:
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f.walk(n.Decl, ctxDecl, visit)
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case *ast.EmptyStmt:
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case *ast.LabeledStmt:
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f.walk(n.Stmt, ctxStmt, visit)
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case *ast.ExprStmt:
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f.walk(&n.X, ctxExpr, visit)
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case *ast.SendStmt:
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f.walk(&n.Chan, ctxExpr, visit)
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f.walk(&n.Value, ctxExpr, visit)
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case *ast.IncDecStmt:
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f.walk(&n.X, ctxExpr, visit)
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case *ast.AssignStmt:
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f.walk(n.Lhs, ctxExpr, visit)
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if len(n.Lhs) == 2 && len(n.Rhs) == 1 {
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f.walk(n.Rhs, ctxAssign2, visit)
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} else {
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f.walk(n.Rhs, ctxExpr, visit)
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}
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case *ast.GoStmt:
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f.walk(n.Call, ctxExpr, visit)
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case *ast.DeferStmt:
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f.walk(n.Call, ctxDefer, visit)
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case *ast.ReturnStmt:
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f.walk(n.Results, ctxExpr, visit)
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case *ast.BranchStmt:
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case *ast.BlockStmt:
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f.walk(n.List, context, visit)
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case *ast.IfStmt:
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f.walk(n.Init, ctxStmt, visit)
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f.walk(&n.Cond, ctxExpr, visit)
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f.walk(n.Body, ctxStmt, visit)
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f.walk(n.Else, ctxStmt, visit)
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case *ast.CaseClause:
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if context == ctxTypeSwitch {
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context = ctxType
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} else {
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context = ctxExpr
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}
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f.walk(n.List, context, visit)
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f.walk(n.Body, ctxStmt, visit)
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case *ast.SwitchStmt:
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f.walk(n.Init, ctxStmt, visit)
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f.walk(&n.Tag, ctxExpr, visit)
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f.walk(n.Body, ctxSwitch, visit)
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case *ast.TypeSwitchStmt:
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f.walk(n.Init, ctxStmt, visit)
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f.walk(n.Assign, ctxStmt, visit)
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f.walk(n.Body, ctxTypeSwitch, visit)
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case *ast.CommClause:
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f.walk(n.Comm, ctxStmt, visit)
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f.walk(n.Body, ctxStmt, visit)
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case *ast.SelectStmt:
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f.walk(n.Body, ctxStmt, visit)
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case *ast.ForStmt:
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f.walk(n.Init, ctxStmt, visit)
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f.walk(&n.Cond, ctxExpr, visit)
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f.walk(n.Post, ctxStmt, visit)
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f.walk(n.Body, ctxStmt, visit)
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case *ast.RangeStmt:
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f.walk(&n.Key, ctxExpr, visit)
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f.walk(&n.Value, ctxExpr, visit)
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f.walk(&n.X, ctxExpr, visit)
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f.walk(n.Body, ctxStmt, visit)
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case *ast.ImportSpec:
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case *ast.ValueSpec:
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f.walk(&n.Type, ctxType, visit)
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if len(n.Names) == 2 && len(n.Values) == 1 {
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f.walk(&n.Values[0], ctxAssign2, visit)
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} else {
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f.walk(n.Values, ctxExpr, visit)
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}
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case *ast.TypeSpec:
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f.walk(&n.Type, ctxType, visit)
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case *ast.BadDecl:
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case *ast.GenDecl:
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f.walk(n.Specs, ctxSpec, visit)
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case *ast.FuncDecl:
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if n.Recv != nil {
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f.walk(n.Recv, ctxParam, visit)
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}
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f.walk(n.Type, ctxType, visit)
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if n.Body != nil {
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f.walk(n.Body, ctxStmt, visit)
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}
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case *ast.File:
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f.walk(n.Decls, ctxDecl, visit)
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case *ast.Package:
|
|
for _, file := range n.Files {
|
|
f.walk(file, ctxFile, visit)
|
|
}
|
|
|
|
case []ast.Decl:
|
|
for _, d := range n {
|
|
f.walk(d, context, visit)
|
|
}
|
|
case []ast.Expr:
|
|
for i := range n {
|
|
f.walk(&n[i], context, visit)
|
|
}
|
|
case []ast.Stmt:
|
|
for _, s := range n {
|
|
f.walk(s, context, visit)
|
|
}
|
|
case []ast.Spec:
|
|
for _, s := range n {
|
|
f.walk(s, context, visit)
|
|
}
|
|
}
|
|
}
|