various: avoid func compare

R=gri, r, bradfitz
CC=golang-dev
https://golang.org/cl/5371074

7 files changed, 128 insertions, 101 deletions

diff --git a/src/pkg/bytes/bytes_test.go b/src/pkg/bytes/bytes_test.go
index 9256b18427..21a1a4f580 100644
--- a/src/pkg/bytes/bytes_test.go
+++ b/src/pkg/bytes/bytes_test.go
@@ -662,48 +662,49 @@ func TestRunes(t *testing.T) {
 }
 
 type TrimTest struct {
-	f               func([]byte, string) []byte
+	f               string
 	in, cutset, out string
 }
 
 var trimTests = []TrimTest{
-	{Trim, "abba", "a", "bb"},
-	{Trim, "abba", "ab", ""},
-	{TrimLeft, "abba", "ab", ""},
-	{TrimRight, "abba", "ab", ""},
-	{TrimLeft, "abba", "a", "bba"},
-	{TrimRight, "abba", "a", "abb"},
-	{Trim, "<tag>", "<>", "tag"},
-	{Trim, "* listitem", " *", "listitem"},
-	{Trim, `"quote"`, `"`, "quote"},
-	{Trim, "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
+	{"Trim", "abba", "a", "bb"},
+	{"Trim", "abba", "ab", ""},
+	{"TrimLeft", "abba", "ab", ""},
+	{"TrimRight", "abba", "ab", ""},
+	{"TrimLeft", "abba", "a", "bba"},
+	{"TrimRight", "abba", "a", "abb"},
+	{"Trim", "<tag>", "<>", "tag"},
+	{"Trim", "* listitem", " *", "listitem"},
+	{"Trim", `"quote"`, `"`, "quote"},
+	{"Trim", "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
 	//empty string tests
-	{Trim, "abba", "", "abba"},
-	{Trim, "", "123", ""},
-	{Trim, "", "", ""},
-	{TrimLeft, "abba", "", "abba"},
-	{TrimLeft, "", "123", ""},
-	{TrimLeft, "", "", ""},
-	{TrimRight, "abba", "", "abba"},
-	{TrimRight, "", "123", ""},
-	{TrimRight, "", "", ""},
-	{TrimRight, "☺\xc0", "☺", "☺\xc0"},
+	{"Trim", "abba", "", "abba"},
+	{"Trim", "", "123", ""},
+	{"Trim", "", "", ""},
+	{"TrimLeft", "abba", "", "abba"},
+	{"TrimLeft", "", "123", ""},
+	{"TrimLeft", "", "", ""},
+	{"TrimRight", "abba", "", "abba"},
+	{"TrimRight", "", "123", ""},
+	{"TrimRight", "", "", ""},
+	{"TrimRight", "☺\xc0", "☺", "☺\xc0"},
 }
 
 func TestTrim(t *testing.T) {
 	for _, tc := range trimTests {
-		actual := string(tc.f([]byte(tc.in), tc.cutset))
-		var name string
-		switch tc.f {
-		case Trim:
-			name = "Trim"
-		case TrimLeft:
-			name = "TrimLeft"
-		case TrimRight:
-			name = "TrimRight"
+		name := tc.f
+		var f func([]byte, string) []byte
+		switch name {
+		case "Trim":
+			f = Trim
+		case "TrimLeft":
+			f = TrimLeft
+		case "TrimRight":
+			f = TrimRight
 		default:
-			t.Error("Undefined trim function")
+			t.Error("Undefined trim function %s", name)
 		}
+		actual := string(f([]byte(tc.in), tc.cutset))
 		if actual != tc.out {
 			t.Errorf("%s(%q, %q) = %q; want %q", name, tc.in, tc.cutset, actual, tc.out)
 		}
diff --git a/src/pkg/compress/lzw/writer.go b/src/pkg/compress/lzw/writer.go
index 642bfc481e..488ba6428d 100644
--- a/src/pkg/compress/lzw/writer.go
+++ b/src/pkg/compress/lzw/writer.go
@@ -48,8 +48,9 @@ const (
 type encoder struct {
 	// w is the writer that compressed bytes are written to.
 	w writer
-	// write, bits, nBits and width are the state for converting a code stream
-	// into a byte stream.
+	// order, write, bits, nBits and width are the state for
+	// converting a code stream into a byte stream.
+	order Order
 	write func(*encoder, uint32) error
 	bits  uint32
 	nBits uint
@@ -213,7 +214,7 @@ func (e *encoder) Close() error {
 	}
 	// Write the final bits.
 	if e.nBits > 0 {
-		if e.write == (*encoder).writeMSB {
+		if e.order == MSB {
 			e.bits >>= 24
 		}
 		if err := e.w.WriteByte(uint8(e.bits)); err != nil {
@@ -249,6 +250,7 @@ func NewWriter(w io.Writer, order Order, litWidth int) io.WriteCloser {
 	lw := uint(litWidth)
 	return &encoder{
 		w:         bw,
+		order:     order,
 		write:     write,
 		width:     1 + lw,
 		litWidth:  lw,
diff --git a/src/pkg/encoding/json/decode.go b/src/pkg/encoding/json/decode.go
index 41295d2d24..e786075455 100644
--- a/src/pkg/encoding/json/decode.go
+++ b/src/pkg/encoding/json/decode.go
@@ -227,7 +227,7 @@ func (d *decodeState) value(v reflect.Value) {
 		// d.scan thinks we're still at the beginning of the item.
 		// Feed in an empty string - the shortest, simplest value -
 		// so that it knows we got to the end of the value.
-		if d.scan.step == stateRedo {
+		if d.scan.redo {
 			panic("redo")
 		}
 		d.scan.step(&d.scan, '"')
diff --git a/src/pkg/encoding/json/scanner.go b/src/pkg/encoding/json/scanner.go
index 179690464b..2661f410e0 100644
--- a/src/pkg/encoding/json/scanner.go
+++ b/src/pkg/encoding/json/scanner.go
@@ -80,6 +80,9 @@ type scanner struct {
 	// on a 64-bit Mac Mini, and it's nicer to read.
 	step func(*scanner, int) int
 
+	// Reached end of top-level value.
+	endTop bool
+
 	// Stack of what we're in the middle of - array values, object keys, object values.
 	parseState []int
 
@@ -87,6 +90,7 @@ type scanner struct {
 	err error
 
 	// 1-byte redo (see undo method)
+	redo      bool
 	redoCode  int
 	redoState func(*scanner, int) int
 
@@ -135,6 +139,8 @@ func (s *scanner) reset() {
 	s.step = stateBeginValue
 	s.parseState = s.parseState[0:0]
 	s.err = nil
+	s.redo = false
+	s.endTop = false
 }
 
 // eof tells the scanner that the end of input has been reached.
@@ -143,11 +149,11 @@ func (s *scanner) eof() int {
 	if s.err != nil {
 		return scanError
 	}
-	if s.step == stateEndTop {
+	if s.endTop {
 		return scanEnd
 	}
 	s.step(s, ' ')
-	if s.step == stateEndTop {
+	if s.endTop {
 		return scanEnd
 	}
 	if s.err == nil {
@@ -166,8 +172,10 @@ func (s *scanner) pushParseState(p int) {
 func (s *scanner) popParseState() {
 	n := len(s.parseState) - 1
 	s.parseState = s.parseState[0:n]
+	s.redo = false
 	if n == 0 {
 		s.step = stateEndTop
+		s.endTop = true
 	} else {
 		s.step = stateEndValue
 	}
@@ -269,6 +277,7 @@ func stateEndValue(s *scanner, c int) int {
 	if n == 0 {
 		// Completed top-level before the current byte.
 		s.step = stateEndTop
+		s.endTop = true
 		return stateEndTop(s, c)
 	}
 	if c <= ' ' && (c == ' ' || c == '\t' || c == '\r' || c == '\n') {
@@ -606,16 +615,18 @@ func quoteChar(c int) string {
 // undo causes the scanner to return scanCode from the next state transition.
 // This gives callers a simple 1-byte undo mechanism.
 func (s *scanner) undo(scanCode int) {
-	if s.step == stateRedo {
-		panic("invalid use of scanner")
+	if s.redo {
+		panic("json: invalid use of scanner")
 	}
 	s.redoCode = scanCode
 	s.redoState = s.step
 	s.step = stateRedo
+	s.redo = true
 }
 
 // stateRedo helps implement the scanner's 1-byte undo.
 func stateRedo(s *scanner, c int) int {
+	s.redo = false
 	s.step = s.redoState
 	return s.redoCode
 }
diff --git a/src/pkg/go/ast/filter.go b/src/pkg/go/ast/filter.go
index d7d4b4b6b6..bec235e2f9 100644
--- a/src/pkg/go/ast/filter.go
+++ b/src/pkg/go/ast/filter.go
@@ -24,7 +24,7 @@ func exportFilter(name string) bool {
 // it returns false otherwise.
 //
 func FileExports(src *File) bool {
-	return FilterFile(src, exportFilter)
+	return filterFile(src, exportFilter, true)
 }
 
 // PackageExports trims the AST for a Go package in place such that
@@ -35,7 +35,7 @@ func FileExports(src *File) bool {
 // it returns false otherwise.
 //
 func PackageExports(pkg *Package) bool {
-	return FilterPackage(pkg, exportFilter)
+	return filterPackage(pkg, exportFilter, true)
 }
 
 // ----------------------------------------------------------------------------
@@ -72,7 +72,7 @@ func fieldName(x Expr) *Ident {
 	return nil
 }
 
-func filterFieldList(fields *FieldList, filter Filter) (removedFields bool) {
+func filterFieldList(fields *FieldList, filter Filter, export bool) (removedFields bool) {
 	if fields == nil {
 		return false
 	}
@@ -93,8 +93,8 @@ func filterFieldList(fields *FieldList, filter Filter) (removedFields bool) {
 			keepField = len(f.Names) > 0
 		}
 		if keepField {
-			if filter == exportFilter {
-				filterType(f.Type, filter)
+			if export {
+				filterType(f.Type, filter, export)
 			}
 			list[j] = f
 			j++
@@ -107,84 +107,84 @@ func filterFieldList(fields *FieldList, filter Filter) (removedFields bool) {
 	return
 }
 
-func filterParamList(fields *FieldList, filter Filter) bool {
+func filterParamList(fields *FieldList, filter Filter, export bool) bool {
 	if fields == nil {
 		return false
 	}
 	var b bool
 	for _, f := range fields.List {
-		if filterType(f.Type, filter) {
+		if filterType(f.Type, filter, export) {
 			b = true
 		}
 	}
 	return b
 }
 
-func filterType(typ Expr, f Filter) bool {
+func filterType(typ Expr, f Filter, export bool) bool {
 	switch t := typ.(type) {
 	case *Ident:
 		return f(t.Name)
 	case *ParenExpr:
-		return filterType(t.X, f)
+		return filterType(t.X, f, export)
 	case *ArrayType:
-		return filterType(t.Elt, f)
+		return filterType(t.Elt, f, export)
 	case *StructType:
-		if filterFieldList(t.Fields, f) {
+		if filterFieldList(t.Fields, f, export) {
 			t.Incomplete = true
 		}
 		return len(t.Fields.List) > 0
 	case *FuncType:
-		b1 := filterParamList(t.Params, f)
-		b2 := filterParamList(t.Results, f)
+		b1 := filterParamList(t.Params, f, export)
+		b2 := filterParamList(t.Results, f, export)
 		return b1 || b2
 	case *InterfaceType:
-		if filterFieldList(t.Methods, f) {
+		if filterFieldList(t.Methods, f, export) {
 			t.Incomplete = true
 		}
 		return len(t.Methods.List) > 0
 	case *MapType:
-		b1 := filterType(t.Key, f)
-		b2 := filterType(t.Value, f)
+		b1 := filterType(t.Key, f, export)
+		b2 := filterType(t.Value, f, export)
 		return b1 || b2
 	case *ChanType:
-		return filterType(t.Value, f)
+		return filterType(t.Value, f, export)
 	}
 	return false
 }
 
-func filterSpec(spec Spec, f Filter) bool {
+func filterSpec(spec Spec, f Filter, export bool) bool {
 	switch s := spec.(type) {
 	case *ValueSpec:
 		s.Names = filterIdentList(s.Names, f)
 		if len(s.Names) > 0 {
-			if f == exportFilter {
-				filterType(s.Type, f)
+			if export {
+				filterType(s.Type, f, export)
 			}
 			return true
 		}
 	case *TypeSpec:
 		if f(s.Name.Name) {
-			if f == exportFilter {
-				filterType(s.Type, f)
+			if export {
+				filterType(s.Type, f, export)
 			}
 			return true
 		}
-		if f != exportFilter {
+		if !export {
 			// For general filtering (not just exports),
 			// filter type even if name is not filtered
 			// out.
 			// If the type contains filtered elements,
 			// keep the declaration.
-			return filterType(s.Type, f)
+			return filterType(s.Type, f, export)
 		}
 	}
 	return false
 }
 
-func filterSpecList(list []Spec, f Filter) []Spec {
+func filterSpecList(list []Spec, f Filter, export bool) []Spec {
 	j := 0
 	for _, s := range list {
-		if filterSpec(s, f) {
+		if filterSpec(s, f, export) {
 			list[j] = s
 			j++
 		}
@@ -200,9 +200,13 @@ func filterSpecList(list []Spec, f Filter) []Spec {
 // filtering; it returns false otherwise.
 //
 func FilterDecl(decl Decl, f Filter) bool {
+	return filterDecl(decl, f, false)
+}
+
+func filterDecl(decl Decl, f Filter, export bool) bool {
 	switch d := decl.(type) {
 	case *GenDecl:
-		d.Specs = filterSpecList(d.Specs, f)
+		d.Specs = filterSpecList(d.Specs, f, export)
 		return len(d.Specs) > 0
 	case *FuncDecl:
 		return f(d.Name.Name)
@@ -221,9 +225,13 @@ func FilterDecl(decl Decl, f Filter) bool {
 // left after filtering; it returns false otherwise.
 //
 func FilterFile(src *File, f Filter) bool {
+	return filterFile(src, f, false)
+}
+
+func filterFile(src *File, f Filter, export bool) bool {
 	j := 0
 	for _, d := range src.Decls {
-		if FilterDecl(d, f) {
+		if filterDecl(d, f, export) {
 			src.Decls[j] = d
 			j++
 		}
@@ -244,9 +252,13 @@ func FilterFile(src *File, f Filter) bool {
 // left after filtering; it returns false otherwise.
 //
 func FilterPackage(pkg *Package, f Filter) bool {
+	return filterPackage(pkg, f, false)
+}
+
+func filterPackage(pkg *Package, f Filter, export bool) bool {
 	hasDecls := false
 	for _, src := range pkg.Files {
-		if FilterFile(src, f) {
+		if filterFile(src, f, export) {
 			hasDecls = true
 		}
 	}
diff --git a/src/pkg/net/ipsock.go b/src/pkg/net/ipsock.go
index 716454d8a9..9234f5aff6 100644
--- a/src/pkg/net/ipsock.go
+++ b/src/pkg/net/ipsock.go
@@ -9,7 +9,7 @@ package net
 var supportsIPv6, supportsIPv4map = probeIPv6Stack()
 
 func firstFavoriteAddr(filter func(IP) IP, addrs []string) (addr IP) {
-	if filter == anyaddr {
+	if filter == nil {
 		// We'll take any IP address, but since the dialing code
 		// does not yet try multiple addresses, prefer to use
 		// an IPv4 address if possible.  This is especially relevant
@@ -113,7 +113,7 @@ func hostPortToIP(net, hostport string) (ip IP, iport int, err error) {
 		// Try as an IP address.
 		addr = ParseIP(host)
 		if addr == nil {
-			filter := anyaddr
+			var filter func(IP) IP
 			if net != "" && net[len(net)-1] == '4' {
 				filter = ipv4only
 			}
diff --git a/src/pkg/strings/strings_test.go b/src/pkg/strings/strings_test.go
index 304d69a19d..96207f5a2d 100644
--- a/src/pkg/strings/strings_test.go
+++ b/src/pkg/strings/strings_test.go
@@ -489,46 +489,47 @@ func TestSpecialCase(t *testing.T) {
 func TestTrimSpace(t *testing.T) { runStringTests(t, TrimSpace, "TrimSpace", trimSpaceTests) }
 
 var trimTests = []struct {
-	f               func(string, string) string
+	f               string
 	in, cutset, out string
 }{
-	{Trim, "abba", "a", "bb"},
-	{Trim, "abba", "ab", ""},
-	{TrimLeft, "abba", "ab", ""},
-	{TrimRight, "abba", "ab", ""},
-	{TrimLeft, "abba", "a", "bba"},
-	{TrimRight, "abba", "a", "abb"},
-	{Trim, "<tag>", "<>", "tag"},
-	{Trim, "* listitem", " *", "listitem"},
-	{Trim, `"quote"`, `"`, "quote"},
-	{Trim, "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
+	{"Trim", "abba", "a", "bb"},
+	{"Trim", "abba", "ab", ""},
+	{"TrimLeft", "abba", "ab", ""},
+	{"TrimRight", "abba", "ab", ""},
+	{"TrimLeft", "abba", "a", "bba"},
+	{"TrimRight", "abba", "a", "abb"},
+	{"Trim", "<tag>", "<>", "tag"},
+	{"Trim", "* listitem", " *", "listitem"},
+	{"Trim", `"quote"`, `"`, "quote"},
+	{"Trim", "\u2C6F\u2C6F\u0250\u0250\u2C6F\u2C6F", "\u2C6F", "\u0250\u0250"},
 	//empty string tests
-	{Trim, "abba", "", "abba"},
-	{Trim, "", "123", ""},
-	{Trim, "", "", ""},
-	{TrimLeft, "abba", "", "abba"},
-	{TrimLeft, "", "123", ""},
-	{TrimLeft, "", "", ""},
-	{TrimRight, "abba", "", "abba"},
-	{TrimRight, "", "123", ""},
-	{TrimRight, "", "", ""},
-	{TrimRight, "☺\xc0", "☺", "☺\xc0"},
+	{"Trim", "abba", "", "abba"},
+	{"Trim", "", "123", ""},
+	{"Trim", "", "", ""},
+	{"TrimLeft", "abba", "", "abba"},
+	{"TrimLeft", "", "123", ""},
+	{"TrimLeft", "", "", ""},
+	{"TrimRight", "abba", "", "abba"},
+	{"TrimRight", "", "123", ""},
+	{"TrimRight", "", "", ""},
+	{"TrimRight", "☺\xc0", "☺", "☺\xc0"},
 }
 
 func TestTrim(t *testing.T) {
 	for _, tc := range trimTests {
-		actual := tc.f(tc.in, tc.cutset)
-		var name string
-		switch tc.f {
-		case Trim:
-			name = "Trim"
-		case TrimLeft:
-			name = "TrimLeft"
-		case TrimRight:
-			name = "TrimRight"
+		name := tc.f
+		var f func(string, string) string
+		switch name {
+		case "Trim":
+			f = Trim
+		case "TrimLeft":
+			f = TrimLeft
+		case "TrimRight":
+			f = TrimRight
 		default:
-			t.Error("Undefined trim function")
+			t.Error("Undefined trim function %s", name)
 		}
+		actual := f(tc.in, tc.cutset)
 		if actual != tc.out {
 			t.Errorf("%s(%q, %q) = %q; want %q", name, tc.in, tc.cutset, actual, tc.out)
 		}