Imported Upstream version 2011.01.12upstream/2011.01.12

9 files changed, 408 insertions, 33 deletions

diff --git a/src/cmd/gofmt/Makefile b/src/cmd/gofmt/Makefile
index 2294fd1db..5f2f454e8 100644
--- a/src/cmd/gofmt/Makefile
+++ b/src/cmd/gofmt/Makefile
@@ -2,12 +2,13 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-include ../../Make.$(GOARCH)
+include ../../Make.inc
 
 TARG=gofmt
 GOFILES=\
 	gofmt.go\
 	rewrite.go\
+	simplify.go\
 
 include ../../Make.cmd
 
@@ -15,5 +16,4 @@ test: $(TARG)
 	./test.sh
 
 smoketest: $(TARG)
-	./test.sh "$(GOROOT)"/src/pkg/go/parser/parser.go
-
+	(cd testdata; ./test.sh)
diff --git a/src/cmd/gofmt/doc.go b/src/cmd/gofmt/doc.go
index 2e4c40c21..2d2c9ae61 100644
--- a/src/cmd/gofmt/doc.go
+++ b/src/cmd/gofmt/doc.go
@@ -20,6 +20,8 @@ The flags are:
 		unless -w is also set.
 	-r rule
 		apply the rewrite rule to the source before reformatting.
+	-s
+		try to simplify code (after applying the rewrite rule, if any).
 	-w
 		if set, overwrite each input file with its output.
 	-spaces
@@ -33,6 +35,8 @@ Debugging flags:
 
 	-trace
 		print parse trace.
+	-ast
+		print AST (before rewrites).
 	-comments=true
 		print comments; if false, all comments are elided from the output.
 
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index ffec0325f..d7b70c461 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -12,6 +12,7 @@ import (
 	"go/parser"
 	"go/printer"
 	"go/scanner"
+	"go/token"
 	"io/ioutil"
 	"os"
 	pathutil "path"
@@ -24,11 +25,12 @@ var (
 	list        = flag.Bool("l", false, "list files whose formatting differs from gofmt's")
 	write       = flag.Bool("w", false, "write result to (source) file instead of stdout")
 	rewriteRule = flag.String("r", "", "rewrite rule (e.g., 'α[β:len(α)] -> α[β:]')")
+	simplifyAST = flag.Bool("s", false, "simplify code")
 
 	// debugging support
 	comments = flag.Bool("comments", true, "print comments")
-	debug    = flag.Bool("debug", false, "print debugging information")
 	trace    = flag.Bool("trace", false, "print parse trace")
+	printAST = flag.Bool("ast", false, "print AST (before rewrites)")
 
 	// layout control
 	tabWidth  = flag.Int("tabwidth", 8, "tab width")
@@ -38,6 +40,7 @@ var (
 
 
 var (
+	fset        = token.NewFileSet()
 	exitCode    = 0
 	rewrite     func(*ast.File) *ast.File
 	parserMode  uint
@@ -92,22 +95,26 @@ func processFile(f *os.File) os.Error {
 		return err
 	}
 
-	var scope *ast.Scope
-	if *debug {
-		scope = ast.NewScope(nil)
-	}
-	file, err := parser.ParseFile(f.Name(), src, scope, parserMode)
+	file, err := parser.ParseFile(fset, f.Name(), src, parserMode)
 
 	if err != nil {
 		return err
 	}
 
+	if *printAST {
+		ast.Print(file)
+	}
+
 	if rewrite != nil {
 		file = rewrite(file)
 	}
 
+	if *simplifyAST {
+		simplify(file)
+	}
+
 	var res bytes.Buffer
-	_, err = (&printer.Config{printerMode, *tabWidth, nil}).Fprint(&res, file)
+	_, err = (&printer.Config{printerMode, *tabWidth, nil}).Fprint(&res, fset, file)
 	if err != nil {
 		return err
 	}
@@ -133,10 +140,10 @@ func processFile(f *os.File) os.Error {
 }
 
 
-func processFileByName(filename string) (err os.Error) {
+func processFileByName(filename string) os.Error {
 	file, err := os.Open(filename, os.O_RDONLY, 0)
 	if err != nil {
-		return
+		return err
 	}
 	defer file.Close()
 	return processFile(file)
diff --git a/src/cmd/gofmt/rewrite.go b/src/cmd/gofmt/rewrite.go
index a89146ca0..8ea5334e9 100644
--- a/src/cmd/gofmt/rewrite.go
+++ b/src/cmd/gofmt/rewrite.go
@@ -37,7 +37,7 @@ func initRewrite() {
 // 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("input", s, nil)
+	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)
@@ -66,13 +66,19 @@ func rewriteFile(pattern, replace ast.Expr, p *ast.File) *ast.File {
 }
 
 
-var positionType = reflect.Typeof(token.Position{})
-var identType = reflect.Typeof((*ast.Ident)(nil))
-
-
-func isWildcard(s string) bool {
-	rune, size := utf8.DecodeRuneInString(s)
-	return size == len(s) && unicode.IsLower(rune)
+// 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) {
+	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.SetValue(y)
 }
 
 
@@ -86,21 +92,31 @@ func apply(f func(reflect.Value) reflect.Value, val reflect.Value) reflect.Value
 	case *reflect.SliceValue:
 		for i := 0; i < v.Len(); i++ {
 			e := v.Elem(i)
-			e.SetValue(f(e))
+			setValue(e, f(e))
 		}
 	case *reflect.StructValue:
 		for i := 0; i < v.NumField(); i++ {
 			e := v.Field(i)
-			e.SetValue(f(e))
+			setValue(e, f(e))
 		}
 	case *reflect.InterfaceValue:
 		e := v.Elem()
-		v.SetValue(f(e))
+		setValue(v, f(e))
 	}
 	return val
 }
 
 
+var positionType = reflect.Typeof(token.NoPos)
+var identType = reflect.Typeof((*ast.Ident)(nil))
+
+
+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.
@@ -109,17 +125,20 @@ func match(m map[string]reflect.Value, pattern, val reflect.Value) bool {
 	// times in the pattern, it must match the same expression
 	// each time.
 	if m != nil && pattern.Type() == identType {
-		name := pattern.Interface().(*ast.Ident).Name()
+		name := pattern.Interface().(*ast.Ident).Name
 		if isWildcard(name) {
-			if old, ok := m[name]; ok {
-				return match(nil, old, val)
+			// 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
 			}
-			m[name] = val
-			return true
 		}
 	}
 
-	// Otherwise, the expressions must match recursively.
+	// Otherwise, pattern and val must match recursively.
 	if pattern == nil || val == nil {
 		return pattern == nil && val == nil
 	}
@@ -139,7 +158,7 @@ func match(m map[string]reflect.Value, pattern, val reflect.Value) bool {
 		// 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()
+		return p == nil && v == nil || p != nil && v != nil && p.Name == v.Name
 	}
 
 	p := reflect.Indirect(pattern)
@@ -194,7 +213,7 @@ func subst(m map[string]reflect.Value, pattern reflect.Value, pos reflect.Value)
 
 	// Wildcard gets replaced with map value.
 	if m != nil && pattern.Type() == identType {
-		name := pattern.Interface().(*ast.Ident).Name()
+		name := pattern.Interface().(*ast.Ident).Name
 		if isWildcard(name) {
 			if old, ok := m[name]; ok {
 				return subst(nil, old, nil)
@@ -203,6 +222,10 @@ func subst(m map[string]reflect.Value, pattern reflect.Value, pos reflect.Value)
 	}
 
 	if pos != nil && 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
 	}
 
diff --git a/src/cmd/gofmt/simplify.go b/src/cmd/gofmt/simplify.go
new file mode 100644
index 000000000..bcc67c4a6
--- /dev/null
+++ b/src/cmd/gofmt/simplify.go
@@ -0,0 +1,67 @@
+// Copyright 2010 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 (
+	"go/ast"
+	"reflect"
+)
+
+
+type simplifier struct{}
+
+func (s *simplifier) Visit(node ast.Node) ast.Visitor {
+	switch n := node.(type) {
+	case *ast.CompositeLit:
+		// array, slice, and map composite literals may be simplified
+		outer := n
+		var eltType ast.Expr
+		switch typ := outer.Type.(type) {
+		case *ast.ArrayType:
+			eltType = typ.Elt
+		case *ast.MapType:
+			eltType = typ.Value
+		}
+
+		if eltType != nil {
+			typ := reflect.NewValue(eltType)
+			for _, x := range outer.Elts {
+				// look at value of indexed/named elements
+				if t, ok := x.(*ast.KeyValueExpr); ok {
+					x = t.Value
+				}
+				simplify(x)
+				// if the element is a composite literal and its literal type
+				// matches the outer literal's element type exactly, the inner
+				// literal type may be omitted
+				if inner, ok := x.(*ast.CompositeLit); ok {
+					if match(nil, typ, reflect.NewValue(inner.Type)) {
+						inner.Type = nil
+					}
+				}
+			}
+
+			// node was simplified - stop walk (there are no subnodes to simplify)
+			return nil
+		}
+
+	case *ast.RangeStmt:
+		// range of the form: for x, _ = range v {...}
+		// can be simplified to: for x = range v {...}
+		if n.Value != nil {
+			if ident, ok := n.Value.(*ast.Ident); ok && ident.Name == "_" {
+				n.Value = nil
+			}
+		}
+	}
+
+	return s
+}
+
+
+func simplify(node ast.Node) {
+	var s simplifier
+	ast.Walk(&s, node)
+}
diff --git a/src/cmd/gofmt/test.sh b/src/cmd/gofmt/test.sh
index bed46532b..b5f4de1e2 100755
--- a/src/cmd/gofmt/test.sh
+++ b/src/cmd/gofmt/test.sh
@@ -3,7 +3,7 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-. "$GOROOT"/src/Make.$GOARCH
+eval $(gomake --no-print-directory -f ../../Make.inc go-env)
 if [ -z "$O" ]; then
 	echo 'missing $O - maybe no Make.$GOARCH?' 1>&2
 	exit 1
@@ -41,7 +41,8 @@ apply1() {
 	bug106.go | bug121.go | bug125.go | bug133.go | bug160.go | \
 	bug163.go | bug166.go | bug169.go | bug217.go | bug222.go | \
 	bug226.go | bug228.go | bug248.go | bug274.go | bug280.go | \
-	bug282.go ) return ;;
+	bug282.go | bug287.go | bug298.go | bug299.go | bug300.go | \
+	bug302.go | bug306.go ) return ;;
 	esac
 	# the following directories are skipped because they contain test
 	# cases for syntax errors and thus won't parse in the first place:
diff --git a/src/cmd/gofmt/testdata/composites.golden b/src/cmd/gofmt/testdata/composites.golden
new file mode 100644
index 000000000..1fd5847c1
--- /dev/null
+++ b/src/cmd/gofmt/testdata/composites.golden
@@ -0,0 +1,104 @@
+package P
+
+type T struct {
+	x, y int
+}
+
+var _ = [42]T{
+	{},
+	{1, 2},
+	{3, 4},
+}
+
+var _ = [...]T{
+	{},
+	{1, 2},
+	{3, 4},
+}
+
+var _ = []T{
+	{},
+	{1, 2},
+	{3, 4},
+}
+
+var _ = []T{
+	{},
+	10: {1, 2},
+	20: {3, 4},
+}
+
+var _ = []struct {
+	x, y int
+}{
+	{},
+	10: {1, 2},
+	20: {3, 4},
+}
+
+var _ = []interface{}{
+	T{},
+	10: T{1, 2},
+	20: T{3, 4},
+}
+
+var _ = [][]int{
+	{},
+	{1, 2},
+	{3, 4},
+}
+
+var _ = [][]int{
+	([]int{}),
+	([]int{1, 2}),
+	{3, 4},
+}
+
+var _ = [][][]int{
+	{},
+	{
+		{},
+		{0, 1, 2, 3},
+		{4, 5},
+	},
+}
+
+var _ = map[string]T{
+	"foo": {},
+	"bar": {1, 2},
+	"bal": {3, 4},
+}
+
+var _ = map[string]struct {
+	x, y int
+}{
+	"foo": {},
+	"bar": {1, 2},
+	"bal": {3, 4},
+}
+
+var _ = map[string]interface{}{
+	"foo": T{},
+	"bar": T{1, 2},
+	"bal": T{3, 4},
+}
+
+var _ = map[string][]int{
+	"foo": {},
+	"bar": {1, 2},
+	"bal": {3, 4},
+}
+
+var _ = map[string][]int{
+	"foo": ([]int{}),
+	"bar": ([]int{1, 2}),
+	"bal": {3, 4},
+}
+
+// from exp/4s/data.go
+var pieces4 = []Piece{
+	{0, 0, Point{4, 1}, []Point{{0, 0}, {1, 0}, {1, 0}, {1, 0}}, nil, nil},
+	{1, 0, Point{1, 4}, []Point{{0, 0}, {0, 1}, {0, 1}, {0, 1}}, nil, nil},
+	{2, 0, Point{4, 1}, []Point{{0, 0}, {1, 0}, {1, 0}, {1, 0}}, nil, nil},
+	{3, 0, Point{1, 4}, []Point{{0, 0}, {0, 1}, {0, 1}, {0, 1}}, nil, nil},
+}
diff --git a/src/cmd/gofmt/testdata/composites.input b/src/cmd/gofmt/testdata/composites.input
new file mode 100644
index 000000000..15afd9e5c
--- /dev/null
+++ b/src/cmd/gofmt/testdata/composites.input
@@ -0,0 +1,104 @@
+package P
+
+type T struct {
+	x, y int
+}
+
+var _ = [42]T{
+	T{},
+	T{1, 2},
+	T{3, 4},
+}
+
+var _ = [...]T{
+	T{},
+	T{1, 2},
+	T{3, 4},
+}
+
+var _ = []T{
+	T{},
+	T{1, 2},
+	T{3, 4},
+}
+
+var _ = []T{
+	T{},
+	10: T{1, 2},
+	20: T{3, 4},
+}
+
+var _ = []struct {
+	x, y int
+}{
+	struct{ x, y int }{},
+	10: struct{ x, y int }{1, 2},
+	20: struct{ x, y int }{3, 4},
+}
+
+var _ = []interface{}{
+	T{},
+	10: T{1, 2},
+	20: T{3, 4},
+}
+
+var _ = [][]int{
+	[]int{},
+	[]int{1, 2},
+	[]int{3, 4},
+}
+
+var _ = [][]int{
+	([]int{}),
+	([]int{1, 2}),
+	[]int{3, 4},
+}
+
+var _ = [][][]int{
+	[][]int{},
+	[][]int{
+		[]int{},
+		[]int{0, 1, 2, 3},
+		[]int{4, 5},
+	},
+}
+
+var _ = map[string]T{
+	"foo": T{},
+	"bar": T{1, 2},
+	"bal": T{3, 4},
+}
+
+var _ = map[string]struct {
+	x, y int
+}{
+	"foo": struct{ x, y int }{},
+	"bar": struct{ x, y int }{1, 2},
+	"bal": struct{ x, y int }{3, 4},
+}
+
+var _ = map[string]interface{}{
+	"foo": T{},
+	"bar": T{1, 2},
+	"bal": T{3, 4},
+}
+
+var _ = map[string][]int{
+	"foo": []int{},
+	"bar": []int{1, 2},
+	"bal": []int{3, 4},
+}
+
+var _ = map[string][]int{
+	"foo": ([]int{}),
+	"bar": ([]int{1, 2}),
+	"bal": []int{3, 4},
+}
+
+// from exp/4s/data.go
+var pieces4 = []Piece{
+	Piece{0, 0, Point{4, 1}, []Point{Point{0, 0}, Point{1, 0}, Point{1, 0}, Point{1, 0}}, nil, nil},
+	Piece{1, 0, Point{1, 4}, []Point{Point{0, 0}, Point{0, 1}, Point{0, 1}, Point{0, 1}}, nil, nil},
+	Piece{2, 0, Point{4, 1}, []Point{Point{0, 0}, Point{1, 0}, Point{1, 0}, Point{1, 0}}, nil, nil},
+	Piece{3, 0, Point{1, 4}, []Point{Point{0, 0}, Point{0, 1}, Point{0, 1}, Point{0, 1}}, nil, nil},
+}
diff --git a/src/cmd/gofmt/testdata/test.sh b/src/cmd/gofmt/testdata/test.sh
new file mode 100755
index 000000000..a1d5d823e
--- /dev/null
+++ b/src/cmd/gofmt/testdata/test.sh
@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+# Copyright 2010 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.
+
+CMD="../gofmt"
+TMP=test_tmp.go
+COUNT=0
+
+
+cleanup() {
+	rm -f $TMP
+}
+
+
+error() {
+	echo $1
+	exit 1
+}
+
+
+count() {
+	#echo $1
+	let COUNT=$COUNT+1
+	let M=$COUNT%10
+	if [ $M == 0 ]; then
+		echo -n "."
+	fi
+}
+
+
+test() {
+	count $1
+
+	# compare against .golden file
+	cleanup
+	$CMD -s $1 > $TMP
+	cmp -s $TMP $2
+	if [ $? != 0 ]; then
+		diff $TMP $2
+		error "Error: simplified $1 does not match $2"
+	fi
+
+	# make sure .golden is idempotent
+	cleanup
+	$CMD -s $2 > $TMP
+	cmp -s $TMP $2
+	if [ $? != 0 ]; then
+		diff $TMP $2
+		error "Error: $2 is not idempotent"
+	fi
+}
+
+
+runtests() {
+	smoketest=../../../pkg/go/parser/parser.go
+	test $smoketest $smoketest
+	test composites.input composites.golden
+	# add more test cases here
+}
+
+
+runtests
+cleanup
+echo "PASSED ($COUNT tests)"