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https://github.com/golang/go
synced 2024-11-12 09:20:22 -07:00
bytes, strings: add new function Fields
R=rsc, r, phf CC=golang-dev https://golang.org/cl/170046
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@ -163,6 +163,44 @@ func SplitAfter(s, sep []byte, n int) [][]byte {
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return genSplit(s, sep, len(sep), n)
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}
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// Fields splits the array s around each instance of one or more consecutive white space
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// characters, returning a slice of subarrays of s or an empty list if s contains only white space.
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func Fields(s []byte) [][]byte {
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n := 0
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inField := false
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for i := 0; i < len(s); {
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rune, size := utf8.DecodeRune(s[i:])
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wasInField := inField
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inField = !unicode.IsSpace(rune)
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if inField && !wasInField {
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n++
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}
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i += size
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}
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a := make([][]byte, n)
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na := 0
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fieldStart := -1
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for i := 0; i <= len(s) && na < n; {
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rune, size := utf8.DecodeRune(s[i:])
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if fieldStart < 0 && size > 0 && !unicode.IsSpace(rune) {
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fieldStart = i
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i += size
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continue
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}
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if fieldStart >= 0 && (size == 0 || unicode.IsSpace(rune)) {
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a[na] = s[fieldStart:i]
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na++
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fieldStart = -1
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}
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if size == 0 {
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break
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}
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i += size
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}
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return a[0:na]
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}
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// Join concatenates the elements of a to create a single byte array. The separator
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// sep is placed between elements in the resulting array.
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func Join(a [][]byte, sep []byte) []byte {
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@ -254,6 +254,36 @@ func TestSplitAfter(t *testing.T) {
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}
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}
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type FieldsTest struct {
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s string
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a []string
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}
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var fieldstests = []FieldsTest{
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FieldsTest{"", []string{}},
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FieldsTest{" ", []string{}},
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FieldsTest{" \t ", []string{}},
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FieldsTest{" abc ", []string{"abc"}},
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FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
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FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
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FieldsTest{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
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FieldsTest{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
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FieldsTest{"\u2000\u2001\u2002", []string{}},
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FieldsTest{"\n™\t™\n", []string{"™", "™"}},
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FieldsTest{faces, []string{faces}},
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}
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func TestFields(t *testing.T) {
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for _, tt := range fieldstests {
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a := Fields(strings.Bytes(tt.s))
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result := arrayOfString(a)
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if !eq(result, tt.a) {
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t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
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continue
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}
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}
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}
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// Test case for any function which accepts and returns a byte array.
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// For ease of creation, we write the byte arrays as strings.
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type StringTest struct {
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@ -134,6 +134,40 @@ func SplitAfter(s, sep string, n int) []string {
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return genSplit(s, sep, len(sep), n)
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}
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// Fields splits the string s around each instance of one or more consecutive white space
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// characters, returning an array of substrings of s or an empty list if s contains only white space.
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func Fields(s string) []string {
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n := 0
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inField := false
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for _, rune := range s {
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wasInField := inField
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inField = !unicode.IsSpace(rune)
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if inField && !wasInField {
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n++
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}
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}
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a := make([]string, n)
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na := 0
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fieldStart := -1
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for i, rune := range s {
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if unicode.IsSpace(rune) {
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if fieldStart >= 0 {
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a[na] = s[fieldStart:i]
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na++
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fieldStart = -1
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}
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} else if fieldStart == -1 {
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fieldStart = i
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}
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}
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if fieldStart != -1 {
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a[na] = s[fieldStart:]
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na++
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}
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return a[0:na]
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}
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// Join concatenates the elements of a to create a single string. The separator string
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// sep is placed between elements in the resulting string.
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func Join(a []string, sep string) string {
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@ -180,6 +180,36 @@ func TestSplitAfter(t *testing.T) {
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}
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}
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type FieldsTest struct {
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s string
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a []string
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}
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var fieldstests = []FieldsTest{
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FieldsTest{"", []string{}},
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FieldsTest{" ", []string{}},
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FieldsTest{" \t ", []string{}},
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FieldsTest{" abc ", []string{"abc"}},
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FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
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FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
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FieldsTest{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
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FieldsTest{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
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FieldsTest{"\u2000\u2001\u2002", []string{}},
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FieldsTest{"\n™\t™\n", []string{"™", "™"}},
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FieldsTest{faces, []string{faces}},
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}
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func TestFields(t *testing.T) {
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for _, tt := range fieldstests {
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a := Fields(tt.s)
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if !eq(a, tt.a) {
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t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
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continue
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}
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}
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}
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// Test case for any function which accepts and returns a single string.
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type StringTest struct {
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in, out string
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