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bytes, strings: add new function Fields

R=rsc, r, phf
CC=golang-dev
https://golang.org/cl/170046
This commit is contained in:
Andrey Mirtchovski 2009-12-15 21:09:55 -08:00 committed by Russ Cox
parent d5bcf7bf41
commit 7f501c06f7
4 changed files with 132 additions and 0 deletions

View File

@ -163,6 +163,44 @@ func SplitAfter(s, sep []byte, n int) [][]byte {
return genSplit(s, sep, len(sep), n) return genSplit(s, sep, len(sep), n)
} }
// 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 {
n := 0
inField := false
for i := 0; i < len(s); {
rune, size := utf8.DecodeRune(s[i:])
wasInField := inField
inField = !unicode.IsSpace(rune)
if inField && !wasInField {
n++
}
i += size
}
a := make([][]byte, n)
na := 0
fieldStart := -1
for i := 0; i <= len(s) && na < n; {
rune, size := utf8.DecodeRune(s[i:])
if fieldStart < 0 && size > 0 && !unicode.IsSpace(rune) {
fieldStart = i
i += size
continue
}
if fieldStart >= 0 && (size == 0 || unicode.IsSpace(rune)) {
a[na] = s[fieldStart:i]
na++
fieldStart = -1
}
if size == 0 {
break
}
i += size
}
return a[0:na]
}
// Join concatenates the elements of a to create a single byte array. The separator // Join concatenates the elements of a to create a single byte array. The separator
// sep is placed between elements in the resulting array. // sep is placed between elements in the resulting array.
func Join(a [][]byte, sep []byte) []byte { func Join(a [][]byte, sep []byte) []byte {

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@ -254,6 +254,36 @@ func TestSplitAfter(t *testing.T) {
} }
} }
type FieldsTest struct {
s string
a []string
}
var fieldstests = []FieldsTest{
FieldsTest{"", []string{}},
FieldsTest{" ", []string{}},
FieldsTest{" \t ", []string{}},
FieldsTest{" abc ", []string{"abc"}},
FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
FieldsTest{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
FieldsTest{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
FieldsTest{"\u2000\u2001\u2002", []string{}},
FieldsTest{"\n™\t™\n", []string{"™", "™"}},
FieldsTest{faces, []string{faces}},
}
func TestFields(t *testing.T) {
for _, tt := range fieldstests {
a := Fields(strings.Bytes(tt.s))
result := arrayOfString(a)
if !eq(result, tt.a) {
t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
continue
}
}
}
// Test case for any function which accepts and returns a byte array. // Test case for any function which accepts and returns a byte array.
// For ease of creation, we write the byte arrays as strings. // For ease of creation, we write the byte arrays as strings.
type StringTest struct { type StringTest struct {

View File

@ -134,6 +134,40 @@ func SplitAfter(s, sep string, n int) []string {
return genSplit(s, sep, len(sep), n) return genSplit(s, sep, len(sep), n)
} }
// 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 {
n := 0
inField := false
for _, rune := range s {
wasInField := inField
inField = !unicode.IsSpace(rune)
if inField && !wasInField {
n++
}
}
a := make([]string, n)
na := 0
fieldStart := -1
for i, rune := range s {
if unicode.IsSpace(rune) {
if fieldStart >= 0 {
a[na] = s[fieldStart:i]
na++
fieldStart = -1
}
} else if fieldStart == -1 {
fieldStart = i
}
}
if fieldStart != -1 {
a[na] = s[fieldStart:]
na++
}
return a[0:na]
}
// Join concatenates the elements of a to create a single string. The separator string // Join concatenates the elements of a to create a single string. The separator string
// sep is placed between elements in the resulting string. // sep is placed between elements in the resulting string.
func Join(a []string, sep string) string { func Join(a []string, sep string) string {

View File

@ -180,6 +180,36 @@ func TestSplitAfter(t *testing.T) {
} }
} }
type FieldsTest struct {
s string
a []string
}
var fieldstests = []FieldsTest{
FieldsTest{"", []string{}},
FieldsTest{" ", []string{}},
FieldsTest{" \t ", []string{}},
FieldsTest{" abc ", []string{"abc"}},
FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
FieldsTest{"1 2 3 4", []string{"1", "2", "3", "4"}},
FieldsTest{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
FieldsTest{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
FieldsTest{"\u2000\u2001\u2002", []string{}},
FieldsTest{"\n™\t™\n", []string{"™", "™"}},
FieldsTest{faces, []string{faces}},
}
func TestFields(t *testing.T) {
for _, tt := range fieldstests {
a := Fields(tt.s)
if !eq(a, tt.a) {
t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
continue
}
}
}
// Test case for any function which accepts and returns a single string. // Test case for any function which accepts and returns a single string.
type StringTest struct { type StringTest struct {
in, out string in, out string