diff options
Diffstat (limited to 'src/cmd/cgo/ast.go')
-rw-r--r-- | src/cmd/cgo/ast.go | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/src/cmd/cgo/ast.go b/src/cmd/cgo/ast.go new file mode 100644 index 000000000..73b7313d6 --- /dev/null +++ b/src/cmd/cgo/ast.go @@ -0,0 +1,414 @@ +// 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. + +// Parse input AST and prepare Prog structure. + +package main + +import ( + "fmt" + "go/ast" + "go/doc" + "go/parser" + "go/scanner" + "go/token" + "os" + "strings" +) + +func parse(name string, flags uint) *ast.File { + ast1, err := parser.ParseFile(fset, name, nil, flags) + if err != nil { + if list, ok := err.(scanner.ErrorList); ok { + // If err is a scanner.ErrorList, its String will print just + // the first error and then (+n more errors). + // Instead, turn it into a new Error that will return + // details for all the errors. + for _, e := range list { + fmt.Fprintln(os.Stderr, e) + } + os.Exit(2) + } + fatalf("parsing %s: %s", name, err) + } + return ast1 +} + +func sourceLine(n ast.Node) int { + return fset.Position(n.Pos()).Line +} + +// ReadGo populates f with information learned from reading the +// Go source file with the given file name. It gathers the C preamble +// attached to the import "C" comment, a list of references to C.xxx, +// a list of exported functions, and the actual AST, to be rewritten and +// printed. +func (f *File) ReadGo(name string) { + // Two different parses: once with comments, once without. + // The printer is not good enough at printing comments in the + // right place when we start editing the AST behind its back, + // so we use ast1 to look for the doc comments on import "C" + // and on exported functions, and we use ast2 for translating + // and reprinting. + ast1 := parse(name, parser.ParseComments) + ast2 := parse(name, 0) + + f.Package = ast1.Name.Name + f.Name = make(map[string]*Name) + + // In ast1, find the import "C" line and get any extra C preamble. + sawC := false + for _, decl := range ast1.Decls { + d, ok := decl.(*ast.GenDecl) + if !ok { + continue + } + for _, spec := range d.Specs { + s, ok := spec.(*ast.ImportSpec) + if !ok || string(s.Path.Value) != `"C"` { + continue + } + sawC = true + if s.Name != nil { + error(s.Path.Pos(), `cannot rename import "C"`) + } + cg := s.Doc + if cg == nil && len(d.Specs) == 1 { + cg = d.Doc + } + if cg != nil { + f.Preamble += fmt.Sprintf("#line %d %q\n", sourceLine(cg), name) + f.Preamble += doc.CommentText(cg) + "\n" + } + } + } + if !sawC { + error(token.NoPos, `cannot find import "C"`) + } + + // In ast2, strip the import "C" line. + w := 0 + for _, decl := range ast2.Decls { + d, ok := decl.(*ast.GenDecl) + if !ok { + ast2.Decls[w] = decl + w++ + continue + } + ws := 0 + for _, spec := range d.Specs { + s, ok := spec.(*ast.ImportSpec) + if !ok || string(s.Path.Value) != `"C"` { + d.Specs[ws] = spec + ws++ + } + } + if ws == 0 { + continue + } + d.Specs = d.Specs[0:ws] + ast2.Decls[w] = d + w++ + } + ast2.Decls = ast2.Decls[0:w] + + // Accumulate pointers to uses of C.x. + if f.Ref == nil { + f.Ref = make([]*Ref, 0, 8) + } + f.walk(ast2, "prog", (*File).saveRef) + + // Accumulate exported functions. + // The comments are only on ast1 but we need to + // save the function bodies from ast2. + // The first walk fills in ExpFunc, and the + // second walk changes the entries to + // refer to ast2 instead. + f.walk(ast1, "prog", (*File).saveExport) + f.walk(ast2, "prog", (*File).saveExport2) + + f.AST = ast2 +} + +// Save references to C.xxx for later processing. +func (f *File) saveRef(x interface{}, context string) { + n, ok := x.(*ast.Expr) + if !ok { + return + } + if sel, ok := (*n).(*ast.SelectorExpr); ok { + // For now, assume that the only instance of capital C is + // when used as the imported package identifier. + // The parser should take care of scoping in the future, + // so that we will be able to distinguish a "top-level C" + // from a local C. + if l, ok := sel.X.(*ast.Ident); ok && l.Name == "C" { + if context == "as2" { + context = "expr" + } + goname := sel.Sel.Name + if goname == "errno" { + error(sel.Pos(), "cannot refer to errno directly; see documentation") + return + } + name := f.Name[goname] + if name == nil { + name = &Name{ + Go: goname, + } + f.Name[goname] = name + } + f.Ref = append(f.Ref, &Ref{ + Name: name, + Expr: n, + Context: context, + }) + return + } + } +} + +// If a function should be exported add it to ExpFunc. +func (f *File) saveExport(x interface{}, context string) { + n, ok := x.(*ast.FuncDecl) + if !ok { + return + } + + if n.Doc == nil { + return + } + for _, c := range n.Doc.List { + if !strings.HasPrefix(string(c.Text), "//export ") { + continue + } + + name := strings.TrimSpace(string(c.Text[9:])) + if name == "" { + error(c.Pos(), "export missing name") + } + + if name != n.Name.Name { + error(c.Pos(), "export comment has wrong name %q, want %q", name, n.Name.Name) + } + + f.ExpFunc = append(f.ExpFunc, &ExpFunc{ + Func: n, + ExpName: name, + }) + break + } +} + +// Make f.ExpFunc[i] point at the Func from this AST instead of the other one. +func (f *File) saveExport2(x interface{}, context string) { + n, ok := x.(*ast.FuncDecl) + if !ok { + return + } + + for _, exp := range f.ExpFunc { + if exp.Func.Name.Name == n.Name.Name { + exp.Func = n + break + } + } +} + +// walk walks the AST x, calling visit(f, x, context) for each node. +func (f *File) walk(x interface{}, context string, visit func(*File, interface{}, string)) { + visit(f, x, context) + switch n := x.(type) { + case *ast.Expr: + f.walk(*n, context, visit) + + // everything else just recurs + default: + error(token.NoPos, "unexpected type %T in walk", x, visit) + panic("unexpected type") + + case nil: + + // These are ordered and grouped to match ../../pkg/go/ast/ast.go + case *ast.Field: + f.walk(&n.Type, "type", visit) + case *ast.FieldList: + for _, field := range n.List { + f.walk(field, context, visit) + } + case *ast.BadExpr: + case *ast.Ident: + case *ast.Ellipsis: + case *ast.BasicLit: + case *ast.FuncLit: + f.walk(n.Type, "type", visit) + f.walk(n.Body, "stmt", visit) + case *ast.CompositeLit: + f.walk(&n.Type, "type", visit) + f.walk(n.Elts, "expr", visit) + case *ast.ParenExpr: + f.walk(&n.X, context, visit) + case *ast.SelectorExpr: + f.walk(&n.X, "selector", visit) + case *ast.IndexExpr: + f.walk(&n.X, "expr", visit) + f.walk(&n.Index, "expr", visit) + case *ast.SliceExpr: + f.walk(&n.X, "expr", visit) + if n.Low != nil { + f.walk(&n.Low, "expr", visit) + } + if n.High != nil { + f.walk(&n.High, "expr", visit) + } + case *ast.TypeAssertExpr: + f.walk(&n.X, "expr", visit) + f.walk(&n.Type, "type", visit) + case *ast.CallExpr: + if context == "as2" { + f.walk(&n.Fun, "call2", visit) + } else { + f.walk(&n.Fun, "call", visit) + } + f.walk(n.Args, "expr", visit) + case *ast.StarExpr: + f.walk(&n.X, context, visit) + case *ast.UnaryExpr: + f.walk(&n.X, "expr", visit) + case *ast.BinaryExpr: + f.walk(&n.X, "expr", visit) + f.walk(&n.Y, "expr", visit) + case *ast.KeyValueExpr: + f.walk(&n.Key, "expr", visit) + f.walk(&n.Value, "expr", visit) + + case *ast.ArrayType: + f.walk(&n.Len, "expr", visit) + f.walk(&n.Elt, "type", visit) + case *ast.StructType: + f.walk(n.Fields, "field", visit) + case *ast.FuncType: + f.walk(n.Params, "field", visit) + if n.Results != nil { + f.walk(n.Results, "field", visit) + } + case *ast.InterfaceType: + f.walk(n.Methods, "field", visit) + case *ast.MapType: + f.walk(&n.Key, "type", visit) + f.walk(&n.Value, "type", visit) + case *ast.ChanType: + f.walk(&n.Value, "type", visit) + + case *ast.BadStmt: + case *ast.DeclStmt: + f.walk(n.Decl, "decl", visit) + case *ast.EmptyStmt: + case *ast.LabeledStmt: + f.walk(n.Stmt, "stmt", visit) + case *ast.ExprStmt: + f.walk(&n.X, "expr", visit) + case *ast.SendStmt: + f.walk(&n.Chan, "expr", visit) + f.walk(&n.Value, "expr", visit) + case *ast.IncDecStmt: + f.walk(&n.X, "expr", visit) + case *ast.AssignStmt: + f.walk(n.Lhs, "expr", visit) + if len(n.Lhs) == 2 && len(n.Rhs) == 1 { + f.walk(n.Rhs, "as2", visit) + } else { + f.walk(n.Rhs, "expr", visit) + } + case *ast.GoStmt: + f.walk(n.Call, "expr", visit) + case *ast.DeferStmt: + f.walk(n.Call, "expr", visit) + case *ast.ReturnStmt: + f.walk(n.Results, "expr", visit) + case *ast.BranchStmt: + case *ast.BlockStmt: + f.walk(n.List, context, visit) + case *ast.IfStmt: + f.walk(n.Init, "stmt", visit) + f.walk(&n.Cond, "expr", visit) + f.walk(n.Body, "stmt", visit) + f.walk(n.Else, "stmt", visit) + case *ast.CaseClause: + if context == "typeswitch" { + context = "type" + } else { + context = "expr" + } + f.walk(n.List, context, visit) + f.walk(n.Body, "stmt", visit) + case *ast.SwitchStmt: + f.walk(n.Init, "stmt", visit) + f.walk(&n.Tag, "expr", visit) + f.walk(n.Body, "switch", visit) + case *ast.TypeSwitchStmt: + f.walk(n.Init, "stmt", visit) + f.walk(n.Assign, "stmt", visit) + f.walk(n.Body, "typeswitch", visit) + case *ast.CommClause: + f.walk(n.Comm, "stmt", visit) + f.walk(n.Body, "stmt", visit) + case *ast.SelectStmt: + f.walk(n.Body, "stmt", visit) + case *ast.ForStmt: + f.walk(n.Init, "stmt", visit) + f.walk(&n.Cond, "expr", visit) + f.walk(n.Post, "stmt", visit) + f.walk(n.Body, "stmt", visit) + case *ast.RangeStmt: + f.walk(&n.Key, "expr", visit) + f.walk(&n.Value, "expr", visit) + f.walk(&n.X, "expr", visit) + f.walk(n.Body, "stmt", visit) + + case *ast.ImportSpec: + case *ast.ValueSpec: + f.walk(&n.Type, "type", visit) + f.walk(n.Values, "expr", visit) + case *ast.TypeSpec: + f.walk(&n.Type, "type", visit) + + case *ast.BadDecl: + case *ast.GenDecl: + f.walk(n.Specs, "spec", visit) + case *ast.FuncDecl: + if n.Recv != nil { + f.walk(n.Recv, "field", visit) + } + f.walk(n.Type, "type", visit) + if n.Body != nil { + f.walk(n.Body, "stmt", visit) + } + + case *ast.File: + f.walk(n.Decls, "decl", visit) + + case *ast.Package: + for _, file := range n.Files { + f.walk(file, "file", 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) + } + } +} |