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strings: add EqualFold
Case-insensitive strcmp without using ToLower. (Using ToLower is not always correct, and it allocates.) R=golang-dev, r CC=golang-dev https://golang.org/cl/5143044
This commit is contained in:
Russ Cox
parent
1fa87ada55
commit
a8a18f6566
@ -583,3 +583,57 @@ func Replace(s, old, new string, n int) string {
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w += copy(t[w:], s[start:])
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return string(t[0:w])
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}
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// EqualFold returns true if s and t are equal under Unicode case-folding.
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func EqualFold(s, t string) bool {
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for s != "" && t != "" {
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// Extract first rune from each string.
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var sr, tr int
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if s[0] < utf8.RuneSelf {
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sr, s = int(s[0]), s[1:]
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} else {
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r, size := utf8.DecodeRuneInString(s)
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sr, s = r, s[size:]
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}
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if t[0] < utf8.RuneSelf {
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tr, t = int(t[0]), t[1:]
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} else {
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r, size := utf8.DecodeRuneInString(t)
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tr, t = r, t[size:]
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}
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// If they match, keep going; if not, return false.
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// Easy case.
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if tr == sr {
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continue
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}
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// Make sr < tr to simplify what follows.
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if tr < sr {
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tr, sr = sr, tr
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}
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// Fast check for ASCII.
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if tr < utf8.RuneSelf && 'A' <= sr && sr <= 'Z' {
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// ASCII, and sr is upper case. tr must be lower case.
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if tr == sr+'a'-'A' {
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continue
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}
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return false
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}
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// General case. SimpleFold(x) returns the next equivalent rune > x
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// or wraps around to smaller values.
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r := unicode.SimpleFold(sr)
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for r != sr && r < tr {
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r = unicode.SimpleFold(r)
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}
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if r == tr {
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continue
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}
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return false
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}
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// One string is empty. Are both?
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return s == t
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}
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@ -120,13 +120,11 @@ func TestLastIndex(t *testing.T) { runIndexTests(t, LastIndex, "LastIndex", l
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func TestIndexAny(t *testing.T) { runIndexTests(t, IndexAny, "IndexAny", indexAnyTests) }
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func TestLastIndexAny(t *testing.T) { runIndexTests(t, LastIndexAny, "LastIndexAny", lastIndexAnyTests) }
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type IndexRuneTest struct {
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var indexRuneTests = []struct {
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s string
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rune int
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out int
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}
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var indexRuneTests = []IndexRuneTest{
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}{
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{"a A x", 'A', 2},
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{"some_text=some_value", '=', 9},
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{"☺a", 'a', 3},
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@ -170,13 +168,11 @@ func BenchmarkIndex(b *testing.B) {
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}
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}
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type ExplodeTest struct {
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var explodetests = []struct {
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s string
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n int
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a []string
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}
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var explodetests = []ExplodeTest{
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}{
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{"", -1, []string{}},
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{abcd, 4, []string{"a", "b", "c", "d"}},
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{faces, 3, []string{"☺", "☻", "☹"}},
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@ -308,15 +304,16 @@ func TestFields(t *testing.T) {
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}
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}
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func TestFieldsFunc(t *testing.T) {
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pred := func(c int) bool { return c == 'X' }
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var fieldsFuncTests = []FieldsTest{
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var FieldsFuncTests = []FieldsTest{
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{"", []string{}},
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{"XX", []string{}},
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{"XXhiXXX", []string{"hi"}},
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{"aXXbXXXcX", []string{"a", "b", "c"}},
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}
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for _, tt := range fieldsFuncTests {
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func TestFieldsFunc(t *testing.T) {
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pred := func(c int) bool { return c == 'X' }
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for _, tt := range FieldsFuncTests {
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a := FieldsFunc(tt.s, pred)
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if !eq(a, tt.a) {
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t.Errorf("FieldsFunc(%q) = %v, want %v", tt.s, a, tt.a)
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@ -491,12 +488,10 @@ func TestSpecialCase(t *testing.T) {
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func TestTrimSpace(t *testing.T) { runStringTests(t, TrimSpace, "TrimSpace", trimSpaceTests) }
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type TrimTest struct {
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var trimTests = []struct {
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f func(string, string) string
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in, cutset, out string
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}
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var trimTests = []TrimTest{
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}{
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{Trim, "abba", "a", "bb"},
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{Trim, "abba", "ab", ""},
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{TrimLeft, "abba", "ab", ""},
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@ -555,11 +550,6 @@ var isValidRune = predicate{
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"IsValidRune",
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}
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type TrimFuncTest struct {
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f predicate
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in, out string
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}
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func not(p predicate) predicate {
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return predicate{
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func(r int) bool {
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@ -569,7 +559,10 @@ func not(p predicate) predicate {
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}
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}
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var trimFuncTests = []TrimFuncTest{
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var trimFuncTests = []struct {
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f predicate
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in, out string
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}{
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{isSpace, space + " hello " + space, "hello"},
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{isDigit, "\u0e50\u0e5212hello34\u0e50\u0e51", "hello"},
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{isUpper, "\u2C6F\u2C6F\u2C6F\u2C6FABCDhelloEF\u2C6F\u2C6FGH\u2C6F\u2C6F", "hello"},
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@ -588,13 +581,11 @@ func TestTrimFunc(t *testing.T) {
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}
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}
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type IndexFuncTest struct {
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var indexFuncTests = []struct {
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in string
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f predicate
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first, last int
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}
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var indexFuncTests = []IndexFuncTest{
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}{
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{"", isValidRune, -1, -1},
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{"abc", isDigit, -1, -1},
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{"0123", isDigit, 0, 3},
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@ -692,12 +683,10 @@ func TestCaseConsistency(t *testing.T) {
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*/
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}
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type RepeatTest struct {
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var RepeatTests = []struct {
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in, out string
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count int
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}
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var RepeatTests = []RepeatTest{
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}{
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{"", "", 0},
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{"", "", 1},
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{"", "", 2},
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@ -729,13 +718,11 @@ func runesEqual(a, b []int) bool {
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return true
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}
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type RunesTest struct {
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var RunesTests = []struct {
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in string
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out []int
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lossy bool
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}
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var RunesTests = []RunesTest{
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}{
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{"", []int{}, false},
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{" ", []int{32}, false},
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{"ABC", []int{65, 66, 67}, false},
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@ -846,14 +833,12 @@ func TestReadRune(t *testing.T) {
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}
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}
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type ReplaceTest struct {
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var ReplaceTests = []struct {
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in string
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old, new string
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n int
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out string
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}
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var ReplaceTests = []ReplaceTest{
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}{
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{"hello", "l", "L", 0, "hello"},
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{"hello", "l", "L", -1, "heLLo"},
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{"hello", "x", "X", -1, "hello"},
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@ -883,11 +868,9 @@ func TestReplace(t *testing.T) {
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}
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}
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type TitleTest struct {
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var TitleTests = []struct {
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in, out string
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}
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var TitleTests = []TitleTest{
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}{
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{"", ""},
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{"a", "A"},
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{" aaa aaa aaa ", " Aaa Aaa Aaa "},
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@ -905,12 +888,10 @@ func TestTitle(t *testing.T) {
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}
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}
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type ContainsTest struct {
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var ContainsTests = []struct {
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str, substr string
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expected bool
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}
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var ContainsTests = []ContainsTest{
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}{
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{"abc", "bc", true},
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{"abc", "bcd", false},
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{"abc", "", true},
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@ -925,3 +906,31 @@ func TestContains(t *testing.T) {
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}
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}
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}
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var EqualFoldTests = []struct {
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s, t string
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out bool
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}{
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{"abc", "abc", true},
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{"ABcd", "ABcd", true},
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{"123abc", "123ABC", true},
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{"αβδ", "ΑΒΔ", true},
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{"abc", "xyz", false},
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{"abc", "XYZ", false},
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{"abcdefghijk", "abcdefghijX", false},
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{"abcdefghijk", "abcdefghij\u212A", true},
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{"abcdefghijK", "abcdefghij\u212A", true},
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{"abcdefghijkz", "abcdefghij\u212Ay", false},
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{"abcdefghijKz", "abcdefghij\u212Ay", false},
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}
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func TestEqualFold(t *testing.T) {
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for _, tt := range EqualFoldTests {
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if out := EqualFold(tt.s, tt.t); out != tt.out {
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t.Errorf("EqualFold(%#q, %#q) = %v, want %v", tt.s, tt.t, out, tt.out)
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}
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if out := EqualFold(tt.t, tt.s); out != tt.out {
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t.Errorf("EqualFold(%#q, %#q) = %v, want %v", tt.t, tt.s, out, tt.out)
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}
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}
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}
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