diff options
Diffstat (limited to 'src/cmd/gofmt/rewrite.go')
-rw-r--r-- | src/cmd/gofmt/rewrite.go | 301 |
1 files changed, 0 insertions, 301 deletions
diff --git a/src/cmd/gofmt/rewrite.go b/src/cmd/gofmt/rewrite.go deleted file mode 100644 index f7f1fe824..000000000 --- a/src/cmd/gofmt/rewrite.go +++ /dev/null @@ -1,301 +0,0 @@ -// 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 main - -import ( - "fmt" - "go/ast" - "go/parser" - "go/token" - "os" - "reflect" - "strings" - "unicode" - "utf8" -) - - -func initRewrite() { - if *rewriteRule == "" { - rewrite = nil // disable any previous rewrite - return - } - f := strings.Split(*rewriteRule, "->") - if len(f) != 2 { - fmt.Fprintf(os.Stderr, "rewrite rule must be of the form 'pattern -> replacement'\n") - os.Exit(2) - } - pattern := parseExpr(f[0], "pattern") - replace := parseExpr(f[1], "replacement") - rewrite = func(p *ast.File) *ast.File { return rewriteFile(pattern, replace, p) } -} - - -// parseExpr parses s as an expression. -// It might make sense to expand this to allow statement patterns, -// but there are problems with preserving formatting and also -// with what a wildcard for a statement looks like. -func parseExpr(s string, what string) ast.Expr { - x, err := parser.ParseExpr(fset, "input", s) - if err != nil { - fmt.Fprintf(os.Stderr, "parsing %s %s: %s\n", what, s, err) - os.Exit(2) - } - return x -} - - -// Keep this function for debugging. -/* -func dump(msg string, val reflect.Value) { - fmt.Printf("%s:\n", msg) - ast.Print(fset, val.Interface()) - fmt.Println() -} -*/ - - -// rewriteFile applies the rewrite rule 'pattern -> replace' to an entire file. -func rewriteFile(pattern, replace ast.Expr, p *ast.File) *ast.File { - m := make(map[string]reflect.Value) - pat := reflect.ValueOf(pattern) - repl := reflect.ValueOf(replace) - var f func(val reflect.Value) reflect.Value // f is recursive - f = func(val reflect.Value) reflect.Value { - // don't bother if val is invalid to start with - if !val.IsValid() { - return reflect.Value{} - } - for k := range m { - m[k] = reflect.Value{}, false - } - val = apply(f, val) - if match(m, pat, val) { - val = subst(m, repl, reflect.ValueOf(val.Interface().(ast.Node).Pos())) - } - return val - } - return apply(f, reflect.ValueOf(p)).Interface().(*ast.File) -} - - -// setValue is a wrapper for x.SetValue(y); it protects -// the caller from panics if x cannot be changed to y. -func setValue(x, y reflect.Value) { - // don't bother if y is invalid to start with - if !y.IsValid() { - return - } - defer func() { - if x := recover(); x != nil { - if s, ok := x.(string); ok && strings.HasPrefix(s, "type mismatch") { - // x cannot be set to y - ignore this rewrite - return - } - panic(x) - } - }() - x.Set(y) -} - - -// Values/types for special cases. -var ( - objectPtrNil = reflect.ValueOf((*ast.Object)(nil)) - scopePtrNil = reflect.ValueOf((*ast.Scope)(nil)) - - identType = reflect.TypeOf((*ast.Ident)(nil)) - objectPtrType = reflect.TypeOf((*ast.Object)(nil)) - positionType = reflect.TypeOf(token.NoPos) - scopePtrType = reflect.TypeOf((*ast.Scope)(nil)) -) - - -// apply replaces each AST field x in val with f(x), returning val. -// To avoid extra conversions, f operates on the reflect.Value form. -func apply(f func(reflect.Value) reflect.Value, val reflect.Value) reflect.Value { - if !val.IsValid() { - return reflect.Value{} - } - - // *ast.Objects introduce cycles and are likely incorrect after - // rewrite; don't follow them but replace with nil instead - if val.Type() == objectPtrType { - return objectPtrNil - } - - // similarly for scopes: they are likely incorrect after a rewrite; - // replace them with nil - if val.Type() == scopePtrType { - return scopePtrNil - } - - switch v := reflect.Indirect(val); v.Kind() { - case reflect.Slice: - for i := 0; i < v.Len(); i++ { - e := v.Index(i) - setValue(e, f(e)) - } - case reflect.Struct: - for i := 0; i < v.NumField(); i++ { - e := v.Field(i) - setValue(e, f(e)) - } - case reflect.Interface: - e := v.Elem() - setValue(v, f(e)) - } - return val -} - - -func isWildcard(s string) bool { - rune, size := utf8.DecodeRuneInString(s) - return size == len(s) && unicode.IsLower(rune) -} - - -// match returns true if pattern matches val, -// recording wildcard submatches in m. -// If m == nil, match checks whether pattern == val. -func match(m map[string]reflect.Value, pattern, val reflect.Value) bool { - // Wildcard matches any expression. If it appears multiple - // times in the pattern, it must match the same expression - // each time. - if m != nil && pattern.IsValid() && pattern.Type() == identType { - name := pattern.Interface().(*ast.Ident).Name - if isWildcard(name) && val.IsValid() { - // wildcards only match expressions - if _, ok := val.Interface().(ast.Expr); ok { - if old, ok := m[name]; ok { - return match(nil, old, val) - } - m[name] = val - return true - } - } - } - - // Otherwise, pattern and val must match recursively. - if !pattern.IsValid() || !val.IsValid() { - return !pattern.IsValid() && !val.IsValid() - } - if pattern.Type() != val.Type() { - return false - } - - // Special cases. - switch pattern.Type() { - case identType: - // For identifiers, only the names need to match - // (and none of the other *ast.Object information). - // This is a common case, handle it all here instead - // of recursing down any further via reflection. - p := pattern.Interface().(*ast.Ident) - v := val.Interface().(*ast.Ident) - return p == nil && v == nil || p != nil && v != nil && p.Name == v.Name - case objectPtrType, positionType: - // object pointers and token positions don't need to match - return true - } - - p := reflect.Indirect(pattern) - v := reflect.Indirect(val) - if !p.IsValid() || !v.IsValid() { - return !p.IsValid() && !v.IsValid() - } - - switch p.Kind() { - case reflect.Slice: - if p.Len() != v.Len() { - return false - } - for i := 0; i < p.Len(); i++ { - if !match(m, p.Index(i), v.Index(i)) { - return false - } - } - return true - - case reflect.Struct: - if p.NumField() != v.NumField() { - return false - } - for i := 0; i < p.NumField(); i++ { - if !match(m, p.Field(i), v.Field(i)) { - return false - } - } - return true - - case reflect.Interface: - return match(m, p.Elem(), v.Elem()) - } - - // Handle token integers, etc. - return p.Interface() == v.Interface() -} - - -// subst returns a copy of pattern with values from m substituted in place -// of wildcards and pos used as the position of tokens from the pattern. -// if m == nil, subst returns a copy of pattern and doesn't change the line -// number information. -func subst(m map[string]reflect.Value, pattern reflect.Value, pos reflect.Value) reflect.Value { - if !pattern.IsValid() { - return reflect.Value{} - } - - // Wildcard gets replaced with map value. - if m != nil && pattern.Type() == identType { - name := pattern.Interface().(*ast.Ident).Name - if isWildcard(name) { - if old, ok := m[name]; ok { - return subst(nil, old, reflect.Value{}) - } - } - } - - if pos.IsValid() && pattern.Type() == positionType { - // use new position only if old position was valid in the first place - if old := pattern.Interface().(token.Pos); !old.IsValid() { - return pattern - } - return pos - } - - // Otherwise copy. - switch p := pattern; p.Kind() { - case reflect.Slice: - v := reflect.MakeSlice(p.Type(), p.Len(), p.Len()) - for i := 0; i < p.Len(); i++ { - v.Index(i).Set(subst(m, p.Index(i), pos)) - } - return v - - case reflect.Struct: - v := reflect.New(p.Type()).Elem() - for i := 0; i < p.NumField(); i++ { - v.Field(i).Set(subst(m, p.Field(i), pos)) - } - return v - - case reflect.Ptr: - v := reflect.New(p.Type()).Elem() - if elem := p.Elem(); elem.IsValid() { - v.Set(subst(m, elem, pos).Addr()) - } - return v - - case reflect.Interface: - v := reflect.New(p.Type()).Elem() - if elem := p.Elem(); elem.IsValid() { - v.Set(subst(m, elem, pos)) - } - return v - } - - return pattern -} |