strings.Split: make the default to split all.

Change the signature of Split to have no count,
assuming a full split, and rename the existing
Split with a count to SplitN.
Do the same to package bytes.
Add a gofix module.

R=adg, dsymonds, alex.brainman, rsc
CC=golang-dev
https://golang.org/cl/4661051

misc/dashboard/builder/main.go

@@ -161,7 +161,7 @@ func NewBuilder(builder string) (*Builder, os.Error) {
 	b := &Builder{name: builder}
 
 	// get goos/goarch from builder string
-	s := strings.Split(builder, "-", 3)
+	s := strings.SplitN(builder, "-", 3)
 	if len(s) >= 2 {
 		b.goos, b.goarch = s[0], s[1]
 	} else {
@@ -177,7 +177,7 @@ func NewBuilder(builder string) (*Builder, os.Error) {
 	if err != nil {
 		return nil, fmt.Errorf("readKeys %s (%s): %s", b.name, fn, err)
 	}
-	v := strings.Split(string(c), "\n", -1)
+	v := strings.Split(string(c), "\n")
 	b.key = v[0]
 	if len(v) >= 3 {
 		b.codeUsername, b.codePassword = v[1], v[2]
@@ -392,7 +392,7 @@ func (b *Builder) envvWindows() []string {
 		skip[name] = true
 	}
 	for _, kv := range os.Environ() {
-		s := strings.Split(kv, "=", 2)
+		s := strings.SplitN(kv, "=", 2)
 		name := strings.ToUpper(s[0])
 		switch {
 		case name == "":
@@ -602,7 +602,7 @@ var revisionRe = regexp.MustCompile(`^([^ ]+) +[0-9]+:([0-9a-f]+)$`)
 // firstTag returns the hash and tag of the most recent tag matching re.
 func firstTag(re *regexp.Regexp) (hash string, tag string, err os.Error) {
 	o, _, err := runLog(nil, "", goroot, "hg", "tags")
-	for _, l := range strings.Split(o, "\n", -1) {
+	for _, l := range strings.Split(o, "\n") {
 		if l == "" {
 			continue
 		}

src/cmd/cgo/gcc.go

@@ -66,7 +66,7 @@ func cname(s string) string {
 // preamble. Multiple occurrences are concatenated with a separating space,
 // even across files.
 func (p *Package) ParseFlags(f *File, srcfile string) {
-	linesIn := strings.Split(f.Preamble, "\n", -1)
+	linesIn := strings.Split(f.Preamble, "\n")
 	linesOut := make([]string, 0, len(linesIn))
 
 NextLine:
@@ -78,7 +78,7 @@ NextLine:
 		}
 
 		l = strings.TrimSpace(l[4:])
-		fields := strings.Split(l, ":", 2)
+		fields := strings.SplitN(l, ":", 2)
 		if len(fields) != 2 {
 			fatalf("%s: bad #cgo line: %s", srcfile, line)
 		}
@@ -275,7 +275,7 @@ func (p *Package) loadDefines(f *File) {
 	b.WriteString(f.Preamble)
 	stdout := p.gccDefines(b.Bytes())
 
-	for _, line := range strings.Split(stdout, "\n", -1) {
+	for _, line := range strings.Split(stdout, "\n") {
 		if len(line) < 9 || line[0:7] != "#define" {
 			continue
 		}
@@ -397,7 +397,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 		isConst[i] = true // until proven otherwise
 	}
 
-	for _, line := range strings.Split(stderr, "\n", -1) {
+	for _, line := range strings.Split(stderr, "\n") {
 		if len(line) < 9 || line[0:9] != "cgo-test:" {
 			// the user will see any compiler errors when the code is compiled later.
 			continue
@@ -1188,7 +1188,7 @@ func (c *typeConv) Type(dtype dwarf.Type) *Type {
 			if ss, ok := dwarfToName[s]; ok {
 				s = ss
 			}
-			s = strings.Join(strings.Split(s, " ", -1), "") // strip spaces
+			s = strings.Join(strings.Split(s, " "), "") // strip spaces
 			name := c.Ident("_Ctype_" + s)
 			typedef[name.Name] = t.Go
 			t.Go = name

src/cmd/cgo/out.go

@@ -148,7 +148,7 @@ func dynimport(obj string) {
 			fatalf("cannot load imported symbols from PE file %s: %v", obj, err)
 		}
 		for _, s := range sym {
-			ss := strings.Split(s, ":", -1)
+			ss := strings.Split(s, ":")
 			fmt.Printf("#pragma dynimport %s %s %q\n", ss[0], ss[0], strings.ToLower(ss[1]))
 		}
 		return

src/cmd/godoc/dirtrees.go

@@ -267,8 +267,8 @@ func (dir *Directory) lookupLocal(name string) *Directory {
 
 // lookup looks for the *Directory for a given path, relative to dir.
 func (dir *Directory) lookup(path string) *Directory {
-	d := strings.Split(dir.Path, string(filepath.Separator), -1)
-	p := strings.Split(path, string(filepath.Separator), -1)
+	d := strings.Split(dir.Path, string(filepath.Separator))
+	p := strings.Split(path, string(filepath.Separator))
 	i := 0
 	for i < len(d) {
 		if i >= len(p) || d[i] != p[i] {

src/cmd/godoc/godoc.go

@@ -160,7 +160,7 @@ func readDirList(filename string) ([]string, os.Error) {
 		}
 		return e == nil && isPkgDir(d)
 	}
-	list := canonicalizePaths(strings.Split(string(contents), "\n", -1), filter)
+	list := canonicalizePaths(strings.Split(string(contents), "\n"), filter)
 	// for each parent path, remove all it's children q
 	// (requirement for binary search to work when filtering)
 	i := 0

src/cmd/godoc/index.go

@@ -901,7 +901,7 @@ func isIdentifier(s string) bool {
 // identifier, Lookup returns a LookupResult, and a list of alternative
 // spellings, if any. If the query syntax is wrong, an error is reported.
 func (x *Index) Lookup(query string) (match *LookupResult, alt *AltWords, err os.Error) {
-	ss := strings.Split(query, ".", -1)
+	ss := strings.Split(query, ".")
 
 	// check query syntax
 	for _, s := range ss {

src/cmd/gofix/Makefile

@@ -19,6 +19,7 @@ GOFILES=\
 	procattr.go\
 	reflect.go\
 	sortslice.go\
+	stringssplit.go\
 	typecheck.go\
 
 include ../../Make.cmd

src/cmd/gofix/main.go

@@ -53,7 +53,7 @@ func main() {
 
 	if *allowedRewrites != "" {
 		allowed = make(map[string]bool)
-		for _, f := range strings.Split(*allowedRewrites, ",", -1) {
+		for _, f := range strings.Split(*allowedRewrites, ",") {
 			allowed[f] = true
 		}
 	}

src/cmd/gofix/stringssplit.go

+// Copyright 2011 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"
+	"go/token"
+)
+
+var stringssplitFix = fix{
+	"stringssplit",
+	stringssplit,
+	`Restore strings.Split to its original meaning and add strings.SplitN. Bytes too.
+
+http://codereview.appspot.com/4661051
+`,
+}
+
+func init() {
+	register(stringssplitFix)
+}
+
+func stringssplit(f *ast.File) bool {
+	if !imports(f, "bytes") && !imports(f, "strings") {
+		return false
+	}
+
+	fixed := false
+	walk(f, func(n interface{}) {
+		call, ok := n.(*ast.CallExpr)
+		// func Split(s, sep string, n int) []string
+		// func SplitAfter(s, sep string, n int) []string
+		if !ok || len(call.Args) != 3 {
+			return
+		}
+		// Is this our function?
+		switch {
+		case isPkgDot(call.Fun, "bytes", "Split"):
+		case isPkgDot(call.Fun, "bytes", "SplitAfter"):
+		case isPkgDot(call.Fun, "strings", "Split"):
+		case isPkgDot(call.Fun, "strings", "SplitAfter"):
+		default:
+			return
+		}
+
+		sel := call.Fun.(*ast.SelectorExpr)
+		args := call.Args
+		fixed = true // We're committed.
+
+		// Is the last argument -1? If so, drop the arg.
+		// (Actually we just look for a negative integer literal.)
+		// Otherwise, Split->SplitN and keep the arg.
+		final := args[2]
+		if unary, ok := final.(*ast.UnaryExpr); ok && unary.Op == token.SUB {
+			if lit, ok := unary.X.(*ast.BasicLit); ok {
+				// Is it an integer? If so, it's a negative integer and that's what we're after.
+				if lit.Kind == token.INT {
+					// drop the last arg.
+					call.Args = args[0:2]
+					return
+				}
+			}
+		}
+
+		// If not, rename and keep the argument list.
+		sel.Sel.Name += "N"
+	})
+	return fixed
+}

src/cmd/gofix/stringssplit_test.go

+// Copyright 2011 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
+
+func init() {
+	addTestCases(stringssplitTests)
+}
+
+var stringssplitTests = []testCase{
+	{
+		Name: "stringssplit.0",
+		In: `package main
+
+import (
+	"bytes"
+	"strings"
+)
+
+func f() {
+	bytes.Split(a, b, c)
+	bytes.Split(a, b, -1)
+	bytes.SplitAfter(a, b, c)
+	bytes.SplitAfter(a, b, -1)
+	strings.Split(a, b, c)
+	strings.Split(a, b, -1)
+	strings.SplitAfter(a, b, c)
+	strings.SplitAfter(a, b, -1)
+}
+`,
+		Out: `package main
+
+import (
+	"bytes"
+	"strings"
+)
+
+func f() {
+	bytes.SplitN(a, b, c)
+	bytes.Split(a, b)
+	bytes.SplitAfterN(a, b, c)
+	bytes.SplitAfter(a, b)
+	strings.SplitN(a, b, c)
+	strings.Split(a, b)
+	strings.SplitAfterN(a, b, c)
+	strings.SplitAfter(a, b)
+}
+`,
+	},
+}

src/cmd/gofix/testdata/reflect.template.go.in

@@ -444,7 +444,7 @@ func (t *Template) newVariable(words []string) *variableElement {
 	bar := strings.IndexRune(lastWord, '|')
 	if bar >= 0 {
 		words[len(words)-1] = lastWord[0:bar]
-		formatters = strings.Split(lastWord[bar+1:], "|", -1)
+		formatters = strings.Split(lastWord[bar+1:], "|")
 	}
 
 	// We could remember the function address here and avoid the lookup later,
@@ -705,7 +705,7 @@ func (t *Template) findVar(st *state, s string) reflect.Value {
 	if s == "@" {
 		return indirectPtr(data, numStars)
 	}
-	for _, elem := range strings.Split(s, ".", -1) {
+	for _, elem := range strings.Split(s, ".") {
 		// Look up field; data must be a struct or map.
 		data = t.lookup(st, data, elem)
 		if data == nil {

src/cmd/gofix/testdata/reflect.template.go.out

@@ -444,7 +444,7 @@ func (t *Template) newVariable(words []string) *variableElement {
 	bar := strings.IndexRune(lastWord, '|')
 	if bar >= 0 {
 		words[len(words)-1] = lastWord[0:bar]
-		formatters = strings.Split(lastWord[bar+1:], "|", -1)
+		formatters = strings.Split(lastWord[bar+1:], "|")
 	}
 
 	// We could remember the function address here and avoid the lookup later,
@@ -705,7 +705,7 @@ func (t *Template) findVar(st *state, s string) reflect.Value {
 	if s == "@" {
 		return indirectPtr(data, numStars)
 	}
-	for _, elem := range strings.Split(s, ".", -1) {
+	for _, elem := range strings.Split(s, ".") {
 		// Look up field; data must be a struct or map.
 		data = t.lookup(st, data, elem)
 		if !data.IsValid() {

src/cmd/gofmt/gofmt_test.go

@@ -20,8 +20,8 @@ func runTest(t *testing.T, dirname, in, out, flags string) {
 	// process flags
 	*simplifyAST = false
 	*rewriteRule = ""
-	for _, flag := range strings.Split(flags, " ", -1) {
-		elts := strings.Split(flag, "=", 2)
+	for _, flag := range strings.Split(flags, " ") {
+		elts := strings.SplitN(flag, "=", 2)
 		name := elts[0]
 		value := ""
 		if len(elts) == 2 {

src/cmd/gofmt/rewrite.go

@@ -22,7 +22,7 @@ func initRewrite() {
 		rewrite = nil // disable any previous rewrite
 		return
 	}
-	f := strings.Split(*rewriteRule, "->", -1)
+	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)

src/cmd/goinstall/download.go

@@ -146,11 +146,11 @@ var vcsList = []*vcs{&git, &hg, &bzr, &svn}
 // hostname - i.e. contains at least one '.' and the last part is at least 2
 // characters.
 func isRemote(pkg string) bool {
-	parts := strings.Split(pkg, "/", 2)
+	parts := strings.SplitN(pkg, "/", 2)
 	if len(parts) != 2 {
 		return false
 	}
-	parts = strings.Split(parts[0], ".", -1)
+	parts = strings.Split(parts[0], ".")
 	if len(parts) < 2 || len(parts[len(parts)-1]) < 2 {
 		return false
 	}

src/cmd/govet/govet.go

@@ -50,7 +50,7 @@ func main() {
 	flag.Parse()
 
 	if *printfuncs != "" {
-		for _, name := range strings.Split(*printfuncs, ",", -1) {
+		for _, name := range strings.Split(*printfuncs, ",") {
 			if len(name) == 0 {
 				flag.Usage()
 			}

src/cmd/goyacc/goyacc.go

@@ -2834,7 +2834,7 @@ func others() {
 	// copy yaccpar
 	fmt.Fprintf(ftable, "\n//line yaccpar:1\n")
 
-	parts := strings.Split(yaccpar, prefix+"run()", 2)
+	parts := strings.SplitN(yaccpar, prefix+"run()", 2)
 	fmt.Fprintf(ftable, "%v", parts[0])
 	ftable.Write(fcode.Bytes())
 	fmt.Fprintf(ftable, "%v", parts[1])

src/cmd/hgpatch/main.go

@@ -282,7 +282,7 @@ func hgModified() ([]string, os.Error) {
 	if err != nil {
 		return nil, err
 	}
-	return strings.Split(strings.TrimSpace(out), "\n", -1), nil
+	return strings.Split(strings.TrimSpace(out), "\n"), nil
 }
 
 // hgAdd adds name to the repository.

src/pkg/asn1/common.go

@@ -83,7 +83,7 @@ type fieldParameters struct {
 // parseFieldParameters will parse it into a fieldParameters structure,
 // ignoring unknown parts of the string.
 func parseFieldParameters(str string) (ret fieldParameters) {
-	for _, part := range strings.Split(str, ",", -1) {
+	for _, part := range strings.Split(str, ",") {
 		switch {
 		case part == "optional":
 			ret.optional = true

src/pkg/bytes/bytes.go

@@ -212,26 +212,40 @@ func genSplit(s, sep []byte, sepSave, n int) [][]byte {
 	return a[0 : na+1]
 }
 
-// Split slices s into subslices separated by sep and returns a slice of
+// SplitN slices s into subslices separated by sep and returns a slice of
 // the subslices between those separators.
-// If sep is empty, Split splits after each UTF-8 sequence.
+// If sep is empty, SplitN splits after each UTF-8 sequence.
 // The count determines the number of subslices to return:
 //   n > 0: at most n subslices; the last subslice will be the unsplit remainder.
 //   n == 0: the result is nil (zero subslices)
 //   n < 0: all subslices
-func Split(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }
+func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }
 
-// SplitAfter slices s into subslices after each instance of sep and
+// SplitAfterN slices s into subslices after each instance of sep and
 // returns a slice of those subslices.
-// If sep is empty, Split splits after each UTF-8 sequence.
+// If sep is empty, SplitAfterN splits after each UTF-8 sequence.
 // The count determines the number of subslices to return:
 //   n > 0: at most n subslices; the last subslice will be the unsplit remainder.
 //   n == 0: the result is nil (zero subslices)
 //   n < 0: all subslices
-func SplitAfter(s, sep []byte, n int) [][]byte {
+func SplitAfterN(s, sep []byte, n int) [][]byte {
 	return genSplit(s, sep, len(sep), n)
 }
 
+// Split slices s into all subslices separated by sep and returns a slice of
+// the subslices between those separators.
+// If sep is empty, Split splits after each UTF-8 sequence.
+// It is equivalent to SplitN with a count of -1.
+func Split(s, sep []byte) [][]byte { return genSplit(s, sep, 0, -1) }
+
+// SplitAfter slices s into all subslices after each instance of sep and
+// returns a slice of those subslices.
+// If sep is empty, SplitAfter splits after each UTF-8 sequence.
+// It is equivalent to SplitAfterN with a count of -1.
+func SplitAfter(s, sep []byte) [][]byte {
+	return genSplit(s, sep, len(sep), -1)
+}
+
 // Fields splits the array s around each instance of one or more consecutive white space
 // characters, returning a slice of subarrays of s or an empty list if s contains only white space.
 func Fields(s []byte) [][]byte {

src/pkg/bytes/bytes_test.go

@@ -6,6 +6,7 @@ package bytes_test
 
 import (
 	. "bytes"
+	"reflect"
 	"testing"
 	"unicode"
 	"utf8"
@@ -315,7 +316,7 @@ var explodetests = []ExplodeTest{
 
 func TestExplode(t *testing.T) {
 	for _, tt := range explodetests {
-		a := Split([]byte(tt.s), nil, tt.n)
+		a := SplitN([]byte(tt.s), nil, tt.n)
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf(`Explode("%s", %d) = %v; want %v`, tt.s, tt.n, result, tt.a)
@@ -354,7 +355,7 @@ var splittests = []SplitTest{
 
 func TestSplit(t *testing.T) {
 	for _, tt := range splittests {
-		a := Split([]byte(tt.s), []byte(tt.sep), tt.n)
+		a := SplitN([]byte(tt.s), []byte(tt.sep), tt.n)
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
@@ -367,6 +368,12 @@ func TestSplit(t *testing.T) {
 		if string(s) != tt.s {
 			t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
 		}
+		if tt.n < 0 {
+			b := Split([]byte(tt.s), []byte(tt.sep))
+			if !reflect.DeepEqual(a, b) {
+				t.Errorf("Split disagrees withSplitN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
+			}
+		}
 	}
 }
 
@@ -388,7 +395,7 @@ var splitaftertests = []SplitTest{
 
 func TestSplitAfter(t *testing.T) {
 	for _, tt := range splitaftertests {
-		a := SplitAfter([]byte(tt.s), []byte(tt.sep), tt.n)
+		a := SplitAfterN([]byte(tt.s), []byte(tt.sep), tt.n)
 		result := arrayOfString(a)
 		if !eq(result, tt.a) {
 			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
@@ -398,6 +405,12 @@ func TestSplitAfter(t *testing.T) {
 		if string(s) != tt.s {
 			t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
 		}
+		if tt.n < 0 {
+			b := SplitAfter([]byte(tt.s), []byte(tt.sep))
+			if !reflect.DeepEqual(a, b) {
+				t.Errorf("SplitAfter disagrees withSplitAfterN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
+			}
+		}
 	}
 }
 

src/pkg/compress/lzw/reader_test.go

@@ -84,7 +84,7 @@ var lzwTests = []lzwTest{
 func TestReader(t *testing.T) {
 	b := bytes.NewBuffer(nil)
 	for _, tt := range lzwTests {
-		d := strings.Split(tt.desc, ";", -1)
+		d := strings.Split(tt.desc, ";")
 		var order Order
 		switch d[1] {
 		case "LSB":

src/pkg/crypto/x509/verify.go

@@ -202,8 +202,8 @@ func matchHostnames(pattern, host string) bool {
 		return false
 	}
 
-	patternParts := strings.Split(pattern, ".", -1)
-	hostParts := strings.Split(host, ".", -1)
+	patternParts := strings.Split(pattern, ".")
+	hostParts := strings.Split(host, ".")
 
 	if len(patternParts) != len(hostParts) {
 		return false

src/pkg/debug/proc/proc_linux.go

@@ -1229,7 +1229,7 @@ func (p *process) attachAllThreads() os.Error {
 					return err
 				}
 
-				statParts := strings.Split(string(statFile), " ", 4)
+				statParts := strings.SplitN(string(statFile), " ", 4)
 				if len(statParts) > 2 && statParts[2] == "Z" {
 					// tid is a zombie
 					p.logTrace("thread %d is a zombie", tid)

src/pkg/exec/exec_test.go

@@ -55,7 +55,7 @@ func TestCatGoodAndBadFile(t *testing.T) {
 		t.Errorf("expected Waitmsg from cat combined; got %T: %v", err, err)
 	}
 	s := string(bs)
-	sp := strings.Split(s, "\n", 2)
+	sp := strings.SplitN(s, "\n", 2)
 	if len(sp) != 2 {
 		t.Fatalf("expected two lines from cat; got %q", s)
 	}

src/pkg/exec/lp_plan9.go

@@ -42,7 +42,7 @@ func LookPath(file string) (string, os.Error) {
 	}
 
 	path := os.Getenv("path")
-	for _, dir := range strings.Split(path, "\000", -1) {
+	for _, dir := range strings.Split(path, "\000") {
 		if err := findExecutable(dir + "/" + file); err == nil {
 			return dir + "/" + file, nil
 		}

src/pkg/exec/lp_unix.go

@@ -39,7 +39,7 @@ func LookPath(file string) (string, os.Error) {
 		return "", &Error{file, err}
 	}
 	pathenv := os.Getenv("PATH")
-	for _, dir := range strings.Split(pathenv, ":", -1) {
+	for _, dir := range strings.Split(pathenv, ":") {
 		if dir == "" {
 			// Unix shell semantics: path element "" means "."
 			dir = "."

src/pkg/exec/lp_windows.go

@@ -47,7 +47,7 @@ func LookPath(file string) (f string, err os.Error) {
 		x = `.COM;.EXE;.BAT;.CMD`
 	}
 	exts := []string{}
-	for _, e := range strings.Split(strings.ToLower(x), `;`, -1) {
+	for _, e := range strings.Split(strings.ToLower(x), `;`) {
 		if e == "" {
 			continue
 		}
@@ -67,7 +67,7 @@ func LookPath(file string) (f string, err os.Error) {
 			return
 		}
 	} else {
-		for _, dir := range strings.Split(pathenv, `;`, -1) {
+		for _, dir := range strings.Split(pathenv, `;`) {
 			if f, err = findExecutable(dir+`\`+file, exts); err == nil {
 				return
 			}

src/pkg/exp/ogle/cmd.go

@@ -154,7 +154,7 @@ func cmdLoad(args []byte) os.Error {
 		}
 		println("Attached to", pid)
 	} else {
-		parts := strings.Split(path, " ", -1)
+		parts := strings.Split(path, " ")
 		if len(parts) == 0 {
 			fname = ""
 		} else {

src/pkg/go/ast/print_test.go

@@ -53,7 +53,7 @@ var tests = []struct {
 // Split s into lines, trim whitespace from all lines, and return
 // the concatenated non-empty lines.
 func trim(s string) string {
-	lines := strings.Split(s, "\n", -1)
+	lines := strings.Split(s, "\n")
 	i := 0
 	for _, line := range lines {
 		line = strings.TrimSpace(line)

src/pkg/go/build/dir.go

@@ -139,7 +139,7 @@ func goodOSArch(filename string) bool {
 	if dot := strings.Index(filename, "."); dot != -1 {
 		filename = filename[:dot]
 	}
-	l := strings.Split(filename, "_", -1)
+	l := strings.Split(filename, "_")
 	n := len(l)
 	if n == 0 {
 		return true

src/pkg/go/doc/comment.go

@@ -58,7 +58,7 @@ func CommentText(comment *ast.CommentGroup) string {
 		}
 
 		// Split on newlines.
-		cl := strings.Split(c, "\n", -1)
+		cl := strings.Split(c, "\n")
 
 		// Walk lines, stripping trailing white space and adding to list.
 		for _, l := range cl {

src/pkg/html/token_test.go

@@ -161,7 +161,7 @@ func TestTokenizer(t *testing.T) {
 loop:
 	for _, tt := range tokenTests {
 		z := NewTokenizer(bytes.NewBuffer([]byte(tt.html)))
-		for i, s := range strings.Split(tt.golden, "$", -1) {
+		for i, s := range strings.Split(tt.golden, "$") {
 			if z.Next() == ErrorToken {
 				t.Errorf("%s token %d: want %q got error %v", tt.desc, i, s, z.Error())
 				continue loop

src/pkg/http/cgi/host.go

@@ -197,7 +197,7 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		if len(line) == 0 {
 			break
 		}
-		parts := strings.Split(string(line), ":", 2)
+		parts := strings.SplitN(string(line), ":", 2)
 		if len(parts) < 2 {
 			h.printf("cgi: bogus header line: %s", string(line))
 			continue

src/pkg/http/cgi/host_test.go

@@ -46,7 +46,7 @@ readlines:
 		}
 		linesRead++
 		trimmedLine := strings.TrimRight(line, "\r\n")
-		split := strings.Split(trimmedLine, "=", 2)
+		split := strings.SplitN(trimmedLine, "=", 2)
 		if len(split) != 2 {
 			t.Fatalf("Unexpected %d parts from invalid line number %v: %q; existing map=%v",
 				len(split), linesRead, line, m)

src/pkg/http/cookie.go

@@ -41,7 +41,7 @@ type Cookie struct {
 func readSetCookies(h Header) []*Cookie {
 	cookies := []*Cookie{}
 	for _, line := range h["Set-Cookie"] {
-		parts := strings.Split(strings.TrimSpace(line), ";", -1)
+		parts := strings.Split(strings.TrimSpace(line), ";")
 		if len(parts) == 1 && parts[0] == "" {
 			continue
 		}
@@ -175,7 +175,7 @@ func readCookies(h Header, filter string) []*Cookie {
 	}
 
 	for _, line := range lines {
-		parts := strings.Split(strings.TrimSpace(line), ";", -1)
+		parts := strings.Split(strings.TrimSpace(line), ";")
 		if len(parts) == 1 && parts[0] == "" {
 			continue
 		}

src/pkg/http/fs.go

@@ -259,7 +259,7 @@ func parseRange(s string, size int64) ([]httpRange, os.Error) {
 		return nil, os.NewError("invalid range")
 	}
 	var ranges []httpRange
-	for _, ra := range strings.Split(s[len(b):], ",", -1) {
+	for _, ra := range strings.Split(s[len(b):], ",") {
 		i := strings.Index(ra, "-")
 		if i < 0 {
 			return nil, os.NewError("invalid range")

src/pkg/http/request.go

@@ -543,7 +543,7 @@ func ReadRequest(b *bufio.Reader) (req *Request, err os.Error) {
 	}
 
 	var f []string
-	if f = strings.Split(s, " ", 3); len(f) < 3 {
+	if f = strings.SplitN(s, " ", 3); len(f) < 3 {
 		return nil, &badStringError{"malformed HTTP request", s}
 	}
 	req.Method, req.RawURL, req.Proto = f[0], f[1], f[2]
@@ -662,11 +662,11 @@ func ParseQuery(query string) (m Values, err os.Error) {
 }
 
 func parseQuery(m Values, query string) (err os.Error) {
-	for _, kv := range strings.Split(query, "&", -1) {
+	for _, kv := range strings.Split(query, "&") {
 		if len(kv) == 0 {
 			continue
 		}
-		kvPair := strings.Split(kv, "=", 2)
+		kvPair := strings.SplitN(kv, "=", 2)
 
 		var key, value string
 		var e os.Error
@@ -703,7 +703,7 @@ func (r *Request) ParseForm() (err os.Error) {
 			return os.NewError("missing form body")
 		}
 		ct := r.Header.Get("Content-Type")
-		switch strings.Split(ct, ";", 2)[0] {
+		switch strings.SplitN(ct, ";", 2)[0] {
 		case "text/plain", "application/x-www-form-urlencoded", "":
 			const maxFormSize = int64(10 << 20) // 10 MB is a lot of text.
 			b, e := ioutil.ReadAll(io.LimitReader(r.Body, maxFormSize+1))

src/pkg/http/response.go

@@ -95,7 +95,7 @@ func ReadResponse(r *bufio.Reader, req *Request) (resp *Response, err os.Error)
 		}
 		return nil, err
 	}
-	f := strings.Split(line, " ", 3)
+	f := strings.SplitN(line, " ", 3)
 	if len(f) < 2 {
 		return nil, &badStringError{"malformed HTTP response", line}
 	}

src/pkg/http/server.go

@@ -421,7 +421,7 @@ func errorKludge(w *response) {
 	msg += " would ignore this error page if this text weren't here.\n"
 
 	// Is it text?  ("Content-Type" is always in the map)
-	baseType := strings.Split(w.header.Get("Content-Type"), ";", 2)[0]
+	baseType := strings.SplitN(w.header.Get("Content-Type"), ";", 2)[0]
 	switch baseType {
 	case "text/html":
 		io.WriteString(w, "<!-- ")

src/pkg/http/spdy/read.go

@@ -174,7 +174,7 @@ func parseHeaderValueBlock(r io.Reader, streamId uint32) (http.Header, os.Error)
 		if _, err := io.ReadFull(r, value); err != nil {
 			return nil, err
 		}
-		valueList := strings.Split(string(value), "\x00", -1)
+		valueList := strings.Split(string(value), "\x00")
 		for _, v := range valueList {
 			h.Add(name, v)
 		}

src/pkg/http/transfer.go

@@ -334,7 +334,7 @@ func fixTransferEncoding(requestMethod string, header Header) ([]string, os.Erro
 		return nil, nil
 	}
 
-	encodings := strings.Split(raw[0], ",", -1)
+	encodings := strings.Split(raw[0], ",")
 	te := make([]string, 0, len(encodings))
 	// TODO: Even though we only support "identity" and "chunked"
 	// encodings, the loop below is designed with foresight. One
@@ -450,7 +450,7 @@ func fixTrailer(header Header, te []string) (Header, os.Error) {
 
 	header.Del("Trailer")
 	trailer := make(Header)
-	keys := strings.Split(raw, ",", -1)
+	keys := strings.Split(raw, ",")
 	for _, key := range keys {
 		key = CanonicalHeaderKey(strings.TrimSpace(key))
 		switch key {

src/pkg/http/transport.go

@@ -329,7 +329,7 @@ func (t *Transport) getConn(cm *connectMethod) (*persistConn, os.Error) {
 			return nil, err
 		}
 		if resp.StatusCode != 200 {
-			f := strings.Split(resp.Status, " ", 2)
+			f := strings.SplitN(resp.Status, " ", 2)
 			conn.Close()
 			return nil, os.NewError(f[1])
 		}
@@ -383,7 +383,7 @@ func useProxy(addr string) bool {
 		addr = addr[:strings.LastIndex(addr, ":")]
 	}
 
-	for _, p := range strings.Split(no_proxy, ",", -1) {
+	for _, p := range strings.Split(no_proxy, ",") {
 		p = strings.ToLower(strings.TrimSpace(p))
 		if len(p) == 0 {
 			continue

src/pkg/http/url.go

@@ -508,8 +508,8 @@ func (v Values) Encode() string {
 // resolvePath applies special path segments from refs and applies
 // them to base, per RFC 2396.
 func resolvePath(basepath string, refpath string) string {
-	base := strings.Split(basepath, "/", -1)
-	refs := strings.Split(refpath, "/", -1)
+	base := strings.Split(basepath, "/")
+	refs := strings.Split(refpath, "/")
 	if len(base) == 0 {
 		base = []string{""}
 	}

src/pkg/mail/message.go

@@ -425,7 +425,7 @@ func (p *addrParser) len() int {
 }
 
 func decodeRFC2047Word(s string) (string, os.Error) {
-	fields := strings.Split(s, "?", -1)
+	fields := strings.Split(s, "?")
 	if len(fields) != 5 || fields[0] != "=" || fields[4] != "=" {
 		return "", os.NewError("mail: address not RFC 2047 encoded")
 	}

src/pkg/mime/mediatype.go

@@ -134,7 +134,7 @@ func ParseMediaType(v string) (mediatype string, params map[string]string) {
 }
 
 func decode2231Enc(v string) string {
-	sv := strings.Split(v, "'", 3)
+	sv := strings.SplitN(v, "'", 3)
 	if len(sv) != 3 {
 		return ""
 	}

src/pkg/patch/patch.go

@@ -319,4 +319,4 @@ func hasPrefix(s []byte, t string) bool {
 
 // splitLines returns the result of splitting s into lines.
 // The \n on each line is preserved.
-func splitLines(s []byte) [][]byte { return bytes.SplitAfter(s, newline, -1) }
+func splitLines(s []byte) [][]byte { return bytes.SplitAfter(s, newline) }

src/pkg/path/filepath/path.go

@@ -136,7 +136,7 @@ func SplitList(path string) []string {
 	if path == "" {
 		return []string{}
 	}
-	return strings.Split(path, string(ListSeparator), -1)
+	return strings.Split(path, string(ListSeparator))
 }
 
 // Split splits path immediately following the final Separator,

src/pkg/rpc/server.go

@@ -495,7 +495,7 @@ func (server *Server) readRequest(codec ServerCodec) (req *Request, service *ser
 		return
 	}
 
-	serviceMethod := strings.Split(req.ServiceMethod, ".", -1)
+	serviceMethod := strings.Split(req.ServiceMethod, ".")
 	if len(serviceMethod) != 2 {
 		err = os.NewError("rpc: service/method request ill-formed: " + req.ServiceMethod)
 		return

src/pkg/runtime/debug/stack.go

@@ -52,7 +52,7 @@ func stack() []byte {
 			if err != nil {
 				continue
 			}
-			lines = bytes.Split(data, []byte{'\n'}, -1)
+			lines = bytes.Split(data, []byte{'\n'})
 			lastFile = file
 		}
 		line-- // in stack trace, lines are 1-indexed but our array is 0-indexed

src/pkg/runtime/debug/stack_test.go

@@ -35,7 +35,7 @@ func (t T) method() []byte {
 */
 func TestStack(t *testing.T) {
 	b := T(0).method()
-	lines := strings.Split(string(b), "\n", -1)
+	lines := strings.Split(string(b), "\n")
 	if len(lines) <= 6 {
 		t.Fatal("too few lines")
 	}

src/pkg/smtp/smtp.go

@@ -93,11 +93,11 @@ func (c *Client) ehlo() os.Error {
 		return err
 	}
 	ext := make(map[string]string)
-	extList := strings.Split(msg, "\n", -1)
+	extList := strings.Split(msg, "\n")
 	if len(extList) > 1 {
 		extList = extList[1:]
 		for _, line := range extList {
-			args := strings.Split(line, " ", 2)
+			args := strings.SplitN(line, " ", 2)
 			if len(args) > 1 {
 				ext[args[0]] = args[1]
 			} else {
@@ -106,7 +106,7 @@ func (c *Client) ehlo() os.Error {
 		}
 	}
 	if mechs, ok := ext["AUTH"]; ok {
-		c.auth = strings.Split(mechs, " ", -1)
+		c.auth = strings.Split(mechs, " ")
 	}
 	c.ext = ext
 	return err

src/pkg/smtp/smtp_test.go

@@ -64,8 +64,8 @@ func (f faker) Close() os.Error {
 }
 
 func TestBasic(t *testing.T) {
-	basicServer = strings.Join(strings.Split(basicServer, "\n", -1), "\r\n")
-	basicClient = strings.Join(strings.Split(basicClient, "\n", -1), "\r\n")
+	basicServer = strings.Join(strings.Split(basicServer, "\n"), "\r\n")
+	basicClient = strings.Join(strings.Split(basicClient, "\n"), "\r\n")
 
 	var cmdbuf bytes.Buffer
 	bcmdbuf := bufio.NewWriter(&cmdbuf)

src/pkg/strconv/fp_test.go

@@ -28,7 +28,7 @@ func pow2(i int) float64 {
 // Wrapper around strconv.Atof64.  Handles dddddp+ddd (binary exponent)
 // itself, passes the rest on to strconv.Atof64.
 func myatof64(s string) (f float64, ok bool) {
-	a := strings.Split(s, "p", 2)
+	a := strings.SplitN(s, "p", 2)
 	if len(a) == 2 {
 		n, err := strconv.Atoi64(a[0])
 		if err != nil {
@@ -72,7 +72,7 @@ func myatof64(s string) (f float64, ok bool) {
 // Wrapper around strconv.Atof32.  Handles dddddp+ddd (binary exponent)
 // itself, passes the rest on to strconv.Atof32.
 func myatof32(s string) (f float32, ok bool) {
-	a := strings.Split(s, "p", 2)
+	a := strings.SplitN(s, "p", 2)
 	if len(a) == 2 {
 		n, err := strconv.Atoi(a[0])
 		if err != nil {
@@ -116,7 +116,7 @@ func TestFp(t *testing.T) {
 		if len(line) == 0 || line[0] == '#' {
 			continue
 		}
-		a := strings.Split(line, " ", -1)
+		a := strings.Split(line, " ")
 		if len(a) != 4 {
 			t.Error("testfp.txt:", lineno, ": wrong field count")
 			continue

src/pkg/strings/strings.go

@@ -198,26 +198,40 @@ func genSplit(s, sep string, sepSave, n int) []string {
 	return a[0 : na+1]
 }
 
-// Split slices s into substrings separated by sep and returns a slice of
+// SplitN slices s into substrings separated by sep and returns a slice of
 // the substrings between those separators.
-// If sep is empty, Split splits after each UTF-8 sequence.
+// If sep is empty, SplitN splits after each UTF-8 sequence.
 // The count determines the number of substrings to return:
 //   n > 0: at most n substrings; the last substring will be the unsplit remainder.
 //   n == 0: the result is nil (zero substrings)
 //   n < 0: all substrings
-func Split(s, sep string, n int) []string { return genSplit(s, sep, 0, n) }
+func SplitN(s, sep string, n int) []string { return genSplit(s, sep, 0, n) }
 
-// SplitAfter slices s into substrings after each instance of sep and
+// SplitAfterN slices s into substrings after each instance of sep and
 // returns a slice of those substrings.
-// If sep is empty, Split splits after each UTF-8 sequence.
+// If sep is empty, SplitAfterN splits after each UTF-8 sequence.
 // The count determines the number of substrings to return:
 //   n > 0: at most n substrings; the last substring will be the unsplit remainder.
 //   n == 0: the result is nil (zero substrings)
 //   n < 0: all substrings
-func SplitAfter(s, sep string, n int) []string {
+func SplitAfterN(s, sep string, n int) []string {
 	return genSplit(s, sep, len(sep), n)
 }
 
+// Split slices s into all substrings separated by sep and returns a slice of
+// the substrings between those separators.
+// If sep is empty, Split splits after each UTF-8 sequence.
+// It is equivalent to SplitN with a count of -1.
+func Split(s, sep string) []string { return genSplit(s, sep, 0, -1) }
+
+// SplitAfter slices s into all substrings after each instance of sep and
+// returns a slice of those substrings.
+// If sep is empty, SplitAfter splits after each UTF-8 sequence.
+// It is equivalent to SplitAfterN with a count of -1.
+func SplitAfter(s, sep string) []string {
+	return genSplit(s, sep, len(sep), -1)
+}
+
 // Fields splits the string s around each instance of one or more consecutive white space
 // characters, returning an array of substrings of s or an empty list if s contains only white space.
 func Fields(s string) []string {

src/pkg/strings/strings_test.go

@@ -186,7 +186,7 @@ var explodetests = []ExplodeTest{
 
 func TestExplode(t *testing.T) {
 	for _, tt := range explodetests {
-		a := Split(tt.s, "", tt.n)
+		a := SplitN(tt.s, "", tt.n)
 		if !eq(a, tt.a) {
 			t.Errorf("explode(%q, %d) = %v; want %v", tt.s, tt.n, a, tt.a)
 			continue
@@ -223,7 +223,7 @@ var splittests = []SplitTest{
 
 func TestSplit(t *testing.T) {
 	for _, tt := range splittests {
-		a := Split(tt.s, tt.sep, tt.n)
+		a := SplitN(tt.s, tt.sep, tt.n)
 		if !eq(a, tt.a) {
 			t.Errorf("Split(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, a, tt.a)
 			continue
@@ -235,6 +235,12 @@ func TestSplit(t *testing.T) {
 		if s != tt.s {
 			t.Errorf("Join(Split(%q, %q, %d), %q) = %q", tt.s, tt.sep, tt.n, tt.sep, s)
 		}
+		if tt.n < 0 {
+			b := Split(tt.s, tt.sep)
+			if !reflect.DeepEqual(a, b) {
+				t.Errorf("Split disagrees with SplitN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
+			}
+		}
 	}
 }
 
@@ -256,7 +262,7 @@ var splitaftertests = []SplitTest{
 
 func TestSplitAfter(t *testing.T) {
 	for _, tt := range splitaftertests {
-		a := SplitAfter(tt.s, tt.sep, tt.n)
+		a := SplitAfterN(tt.s, tt.sep, tt.n)
 		if !eq(a, tt.a) {
 			t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, a, tt.a)
 			continue
@@ -265,6 +271,12 @@ func TestSplitAfter(t *testing.T) {
 		if s != tt.s {
 			t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
 		}
+		if tt.n < 0 {
+			b := SplitAfter(tt.s, tt.sep)
+			if !reflect.DeepEqual(a, b) {
+				t.Errorf("SplitAfter disagrees with SplitAfterN(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, b, a)
+			}
+		}
 	}
 }
 
@@ -623,8 +635,8 @@ func equal(m string, s1, s2 string, t *testing.T) bool {
 	if s1 == s2 {
 		return true
 	}
-	e1 := Split(s1, "", -1)
-	e2 := Split(s2, "", -1)
+	e1 := Split(s1, "")
+	e2 := Split(s2, "")
 	for i, c1 := range e1 {
 		if i > len(e2) {
 			break

src/pkg/template/execute.go

@@ -114,7 +114,7 @@ func (t *Template) findVar(st *state, s string) reflect.Value {
 	if s == "@" {
 		return indirectPtr(data, numStars)
 	}
-	for _, elem := range strings.Split(s, ".", -1) {
+	for _, elem := range strings.Split(s, ".") {
 		// Look up field; data must be a struct or map.
 		data = t.lookup(st, data, elem)
 		if !data.IsValid() {

src/pkg/template/parse.go

@@ -483,7 +483,7 @@ func extractFormatters(words []string) (formatters []string) {
 		}
 	}
 	words[len(words)-1] = lastWord[0:bar]
-	formatters = strings.Split(lastWord[bar+1:], "|", -1)
+	formatters = strings.Split(lastWord[bar+1:], "|")
 	return
 }
 

src/pkg/testing/testing.go

@@ -287,7 +287,7 @@ func parseCpuList() {
 	if len(*cpuListStr) == 0 {
 		cpuList = append(cpuList, runtime.GOMAXPROCS(-1))
 	} else {
-		for _, val := range strings.Split(*cpuListStr, ",", -1) {
+		for _, val := range strings.Split(*cpuListStr, ",") {
 			cpu, err := strconv.Atoi(val)
 			if err != nil || cpu <= 0 {
 				println("invalid value for -test.cpu")

src/pkg/unicode/maketables.go

@@ -156,7 +156,7 @@ const (
 )
 
 func parseCategory(line string) (state State) {
-	field := strings.Split(line, ";", -1)
+	field := strings.Split(line, ";")
 	if len(field) != NumField {
 		logger.Fatalf("%5s: %d fields (expected %d)\n", line, len(field), NumField)
 	}
@@ -253,7 +253,7 @@ func all(scripts map[string][]Script) []string {
 // Extract the version number from the URL
 func version() string {
 	// Break on slashes and look for the first numeric field
-	fields := strings.Split(*url, "/", -1)
+	fields := strings.Split(*url, "/")
 	for _, f := range fields {
 		if len(f) > 0 && '0' <= f[0] && f[0] <= '9' {
 			return f
@@ -336,7 +336,7 @@ func loadCasefold() {
 		if line[0] == '#' {
 			continue
 		}
-		field := strings.Split(line, "; ", -1)
+		field := strings.Split(line, "; ")
 		if len(field) != 4 {
 			logger.Fatalf("CaseFolding.txt %.5s...: %d fields (expected %d)\n", line, len(field), 4)
 		}
@@ -372,7 +372,7 @@ func printCategories() {
 		return
 	}
 	// Find out which categories to dump
-	list := strings.Split(*tablelist, ",", -1)
+	list := strings.Split(*tablelist, ",")
 	if *tablelist == "all" {
 		list = allCategories()
 	}
@@ -588,7 +588,7 @@ func parseScript(line string, scripts map[string][]Script) {
 	if len(line) == 0 {
 		return
 	}
-	field := strings.Split(line, ";", -1)
+	field := strings.Split(line, ";")
 	if len(field) != 2 {
 		logger.Fatalf("%s: %d fields (expected 2)\n", line, len(field))
 	}
@@ -685,7 +685,7 @@ func printScriptOrProperty(doProps bool) {
 	resp.Body.Close()
 
 	// Find out which scripts to dump
-	list := strings.Split(flaglist, ",", -1)
+	list := strings.Split(flaglist, ",")
 	if flaglist == "all" {
 		list = all(table)
 	}