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mirror of https://github.com/golang/go synced 2024-11-11 17:11:36 -07:00

bytes, strings: add Lines, SplitSeq, SplitAfterSeq, FieldsSeq, FieldsFuncSeq

Fixes #61901.

Change-Id: I4db21c91fd21079f2aa3bc81fb03dd6f40423a38
GitHub-Last-Rev: ed3df560a4
GitHub-Pull-Request: golang/go#67543
Reviewed-on: https://go-review.googlesource.com/c/go/+/587095
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
This commit is contained in:
aimuz 2024-08-09 07:33:36 +00:00 committed by Gopher Robot
parent 3e3ce20df8
commit 9becf401de
7 changed files with 439 additions and 0 deletions

10
api/next/61901.txt Normal file
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@ -0,0 +1,10 @@
pkg bytes, func FieldsFuncSeq([]uint8, func(int32) bool) iter.Seq[[]uint8] #61901
pkg bytes, func FieldsSeq([]uint8) iter.Seq[[]uint8] #61901
pkg bytes, func Lines([]uint8) iter.Seq[[]uint8] #61901
pkg bytes, func SplitAfterSeq([]uint8, []uint8) iter.Seq[[]uint8] #61901
pkg bytes, func SplitSeq([]uint8, []uint8) iter.Seq[[]uint8] #61901
pkg strings, func FieldsFuncSeq(string, func(int32) bool) iter.Seq[string] #61901
pkg strings, func FieldsSeq(string) iter.Seq[string] #61901
pkg strings, func Lines(string) iter.Seq[string] #61901
pkg strings, func SplitAfterSeq(string, string) iter.Seq[string] #61901
pkg strings, func SplitSeq(string, string) iter.Seq[string] #61901

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@ -0,0 +1,12 @@
The [bytes] package adds several functions that work with iterators:
- [Lines] returns an iterator over the
newline-terminated lines in the byte slice s.
- [SplitSeq] returns an iterator over
all substrings of s separated by sep.
- [SplitAfterSeq] returns an iterator
over substrings of s split after each instance of sep.
- [FieldsSeq] returns an iterator over
substrings of s split around runs of whitespace characters,
as defined by unicode.IsSpace.
- [FieldsFuncSeq] returns an iterator
over substrings of s split around runs of Unicode code points satisfying f(c).

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@ -0,0 +1,12 @@
The [strings] package adds several functions that work with iterators:
- [Lines] returns an iterator over
the newline-terminated lines in the string s.
- [SplitSeq] returns an iterator over
all substrings of s separated by sep.
- [SplitAfterSeq] returns an iterator
over substrings of s split after each instance of sep.
- [FieldsSeq] returns an iterator over
substrings of s split around runs of whitespace characters,
as defined by unicode.IsSpace.
- [FieldsFuncSeq] returns an iterator
over substrings of s split around runs of Unicode code points satisfying f(c).

View File

@ -8,6 +8,7 @@ import (
. "bytes"
"fmt"
"internal/testenv"
"iter"
"math"
"math/rand"
"slices"
@ -26,6 +27,37 @@ func sliceOfString(s [][]byte) []string {
return result
}
func collect(t *testing.T, seq iter.Seq[[]byte]) [][]byte {
out := slices.Collect(seq)
out1 := slices.Collect(seq)
if !slices.Equal(sliceOfString(out), sliceOfString(out1)) {
t.Fatalf("inconsistent seq:\n%s\n%s", out, out1)
}
return out
}
type LinesTest struct {
a string
b []string
}
var linesTests = []LinesTest{
{a: "abc\nabc\n", b: []string{"abc\n", "abc\n"}},
{a: "abc\r\nabc", b: []string{"abc\r\n", "abc"}},
{a: "abc\r\n", b: []string{"abc\r\n"}},
{a: "\nabc", b: []string{"\n", "abc"}},
{a: "\nabc\n\n", b: []string{"\n", "abc\n", "\n"}},
}
func TestLines(t *testing.T) {
for _, s := range linesTests {
result := sliceOfString(slices.Collect(Lines([]byte(s.a))))
if !slices.Equal(result, s.b) {
t.Errorf(`slices.Collect(Lines(%q)) = %q; want %q`, s.a, result, s.b)
}
}
}
// For ease of reading, the test cases use strings that are converted to byte
// slices before invoking the functions.
@ -800,6 +832,14 @@ func TestSplit(t *testing.T) {
t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, result, tt.a)
continue
}
if tt.n < 0 {
b := sliceOfString(slices.Collect(SplitSeq([]byte(tt.s), []byte(tt.sep))))
if !slices.Equal(b, tt.a) {
t.Errorf(`collect(SplitSeq(%q, %q)) = %v; want %v`, tt.s, tt.sep, b, tt.a)
}
}
if tt.n == 0 || len(a) == 0 {
continue
}
@ -859,6 +899,13 @@ func TestSplitAfter(t *testing.T) {
continue
}
if tt.n < 0 {
b := sliceOfString(slices.Collect(SplitAfterSeq([]byte(tt.s), []byte(tt.sep))))
if !slices.Equal(b, tt.a) {
t.Errorf(`collect(SplitAfterSeq(%q, %q)) = %v; want %v`, tt.s, tt.sep, b, tt.a)
}
}
if want := tt.a[len(tt.a)-1] + "z"; string(x) != want {
t.Errorf("last appended result was %s; want %s", x, want)
}
@ -912,6 +959,11 @@ func TestFields(t *testing.T) {
continue
}
result2 := sliceOfString(collect(t, FieldsSeq([]byte(tt.s))))
if !slices.Equal(result2, tt.a) {
t.Errorf(`collect(FieldsSeq(%q)) = %v; want %v`, tt.s, result2, tt.a)
}
if string(b) != tt.s {
t.Errorf("slice changed to %s; want %s", string(b), tt.s)
}
@ -954,6 +1006,11 @@ func TestFieldsFunc(t *testing.T) {
t.Errorf("FieldsFunc(%q) = %v, want %v", tt.s, a, tt.a)
}
result2 := sliceOfString(collect(t, FieldsFuncSeq([]byte(tt.s), pred)))
if !slices.Equal(result2, tt.a) {
t.Errorf(`collect(FieldsFuncSeq(%q)) = %v; want %v`, tt.s, result2, tt.a)
}
if string(b) != tt.s {
t.Errorf("slice changed to %s; want %s", b, tt.s)
}

148
src/bytes/iter.go Normal file
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@ -0,0 +1,148 @@
// Copyright 2024 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 bytes
import (
"iter"
"unicode"
"unicode/utf8"
)
// Lines returns an iterator over the newline-terminated lines in the byte slice s.
// The lines yielded by the iterator include their terminating newlines.
// If s is empty, the iterator yields no lines at all.
// If s does not end in a newline, the final yielded line will not end in a newline.
// It returns a single-use iterator.
func Lines(s []byte) iter.Seq[[]byte] {
return func(yield func([]byte) bool) {
for len(s) > 0 {
var line []byte
if i := IndexByte(s, '\n'); i >= 0 {
line, s = s[:i+1], s[i+1:]
} else {
line, s = s, nil
}
if !yield(line[:len(line):len(line)]) {
return
}
}
return
}
}
// explodeSeq returns an iterator over the runes in s.
func explodeSeq(s []byte) iter.Seq[[]byte] {
return func(yield func([]byte) bool) {
for len(s) > 0 {
_, size := utf8.DecodeRune(s)
if !yield(s[:size:size]) {
return
}
s = s[size:]
}
}
}
// splitSeq is SplitSeq or SplitAfterSeq, configured by how many
// bytes of sep to include in the results (none or all).
func splitSeq(s, sep []byte, sepSave int) iter.Seq[[]byte] {
if len(sep) == 0 {
return explodeSeq(s)
}
return func(yield func([]byte) bool) {
for {
i := Index(s, sep)
if i < 0 {
break
}
frag := s[:i+sepSave]
if !yield(frag[:len(frag):len(frag)]) {
return
}
s = s[i+len(sep):]
}
yield(s[:len(s):len(s)])
}
}
// SplitSeq returns an iterator over all substrings of s separated by sep.
// The iterator yields the same strings that would be returned by Split(s, sep),
// but without constructing the slice.
// It returns a single-use iterator.
func SplitSeq(s, sep []byte) iter.Seq[[]byte] {
return splitSeq(s, sep, 0)
}
// SplitAfterSeq returns an iterator over substrings of s split after each instance of sep.
// The iterator yields the same strings that would be returned by SplitAfter(s, sep),
// but without constructing the slice.
// It returns a single-use iterator.
func SplitAfterSeq(s, sep []byte) iter.Seq[[]byte] {
return splitSeq(s, sep, len(sep))
}
// FieldsSeq returns an iterator over substrings of s split around runs of
// whitespace characters, as defined by unicode.IsSpace.
// The iterator yields the same strings that would be returned by Fields(s),
// but without constructing the slice.
func FieldsSeq(s []byte) iter.Seq[[]byte] {
return func(yield func([]byte) bool) {
start := -1
for i := 0; i < len(s); {
size := 1
r := rune(s[i])
isSpace := asciiSpace[s[i]] != 0
if r >= utf8.RuneSelf {
r, size = utf8.DecodeRune(s[i:])
isSpace = unicode.IsSpace(r)
}
if isSpace {
if start >= 0 {
if !yield(s[start:i:i]) {
return
}
start = -1
}
} else if start < 0 {
start = i
}
i += size
}
if start >= 0 {
yield(s[start:len(s):len(s)])
}
}
}
// FieldsFuncSeq returns an iterator over substrings of s split around runs of
// Unicode code points satisfying f(c).
// The iterator yields the same strings that would be returned by FieldsFunc(s),
// but without constructing the slice.
func FieldsFuncSeq(s []byte, f func(rune) bool) iter.Seq[[]byte] {
return func(yield func([]byte) bool) {
start := -1
for i := 0; i < len(s); {
size := 1
r := rune(s[i])
if r >= utf8.RuneSelf {
r, size = utf8.DecodeRune(s[i:])
}
if f(r) {
if start >= 0 {
if !yield(s[start:i:i]) {
return
}
start = -1
}
} else if start < 0 {
start = i
}
i += size
}
if start >= 0 {
yield(s[start:len(s):len(s)])
}
}
}

148
src/strings/iter.go Normal file
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@ -0,0 +1,148 @@
// Copyright 2024 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 strings
import (
"iter"
"unicode"
"unicode/utf8"
)
// Lines returns an iterator over the newline-terminated lines in the string s.
// The lines yielded by the iterator include their terminating newlines.
// If s is empty, the iterator yields no lines at all.
// If s does not end in a newline, the final yielded line will not end in a newline.
// It returns a single-use iterator.
func Lines(s string) iter.Seq[string] {
return func(yield func(string) bool) {
for len(s) > 0 {
var line string
if i := IndexByte(s, '\n'); i >= 0 {
line, s = s[:i+1], s[i+1:]
} else {
line, s = s, ""
}
if !yield(line) {
return
}
}
return
}
}
// explodeSeq returns an iterator over the runes in s.
func explodeSeq(s string) iter.Seq[string] {
return func(yield func(string) bool) {
for len(s) > 0 {
_, size := utf8.DecodeRuneInString(s)
if !yield(s[:size]) {
return
}
s = s[size:]
}
}
}
// splitSeq is SplitSeq or SplitAfterSeq, configured by how many
// bytes of sep to include in the results (none or all).
func splitSeq(s, sep string, sepSave int) iter.Seq[string] {
if len(sep) == 0 {
return explodeSeq(s)
}
return func(yield func(string) bool) {
for {
i := Index(s, sep)
if i < 0 {
break
}
frag := s[:i+sepSave]
if !yield(frag) {
return
}
s = s[i+len(sep):]
}
yield(s)
}
}
// SplitSeq returns an iterator over all substrings of s separated by sep.
// The iterator yields the same strings that would be returned by Split(s, sep),
// but without constructing the slice.
// It returns a single-use iterator.
func SplitSeq(s, sep string) iter.Seq[string] {
return splitSeq(s, sep, 0)
}
// SplitAfterSeq returns an iterator over substrings of s split after each instance of sep.
// The iterator yields the same strings that would be returned by SplitAfter(s, sep),
// but without constructing the slice.
// It returns a single-use iterator.
func SplitAfterSeq(s, sep string) iter.Seq[string] {
return splitSeq(s, sep, len(sep))
}
// FieldsSeq returns an iterator over substrings of s split around runs of
// whitespace characters, as defined by unicode.IsSpace.
// The iterator yields the same strings that would be returned by Fields(s),
// but without constructing the slice.
func FieldsSeq(s string) iter.Seq[string] {
return func(yield func(string) bool) {
start := -1
for i := 0; i < len(s); {
size := 1
r := rune(s[i])
isSpace := asciiSpace[s[i]] != 0
if r >= utf8.RuneSelf {
r, size = utf8.DecodeRuneInString(s[i:])
isSpace = unicode.IsSpace(r)
}
if isSpace {
if start >= 0 {
if !yield(s[start:i]) {
return
}
start = -1
}
} else if start < 0 {
start = i
}
i += size
}
if start >= 0 {
yield(s[start:])
}
}
}
// FieldsFuncSeq returns an iterator over substrings of s split around runs of
// Unicode code points satisfying f(c).
// The iterator yields the same strings that would be returned by FieldsFunc(s),
// but without constructing the slice.
func FieldsFuncSeq(s string, f func(rune) bool) iter.Seq[string] {
return func(yield func(string) bool) {
start := -1
for i := 0; i < len(s); {
size := 1
r := rune(s[i])
if r >= utf8.RuneSelf {
r, size = utf8.DecodeRuneInString(s[i:])
}
if f(r) {
if start >= 0 {
if !yield(s[start:i]) {
return
}
start = -1
}
} else if start < 0 {
start = i
}
i += size
}
if start >= 0 {
yield(s[start:])
}
}
}

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@ -8,6 +8,7 @@ import (
"bytes"
"fmt"
"io"
"iter"
"math"
"math/rand"
"slices"
@ -19,6 +20,37 @@ import (
"unsafe"
)
func collect(t *testing.T, seq iter.Seq[string]) []string {
out := slices.Collect(seq)
out1 := slices.Collect(seq)
if !slices.Equal(out, out1) {
t.Fatalf("inconsistent seq:\n%s\n%s", out, out1)
}
return out
}
type LinesTest struct {
a string
b []string
}
var linesTests = []LinesTest{
{a: "abc\nabc\n", b: []string{"abc\n", "abc\n"}},
{a: "abc\r\nabc", b: []string{"abc\r\n", "abc"}},
{a: "abc\r\n", b: []string{"abc\r\n"}},
{a: "\nabc", b: []string{"\n", "abc"}},
{a: "\nabc\n\n", b: []string{"\n", "abc\n", "\n"}},
}
func TestLines(t *testing.T) {
for _, s := range linesTests {
result := slices.Collect(Lines(s.a))
if !slices.Equal(result, s.b) {
t.Errorf(`slices.Collect(Lines(%q)) = %q; want %q`, s.a, result, s.b)
}
}
}
var abcd = "abcd"
var faces = "☺☻☹"
var commas = "1,2,3,4"
@ -410,6 +442,12 @@ func TestSplit(t *testing.T) {
t.Errorf("Split(%q, %q, %d) = %v; want %v", tt.s, tt.sep, tt.n, a, tt.a)
continue
}
if tt.n < 0 {
a2 := slices.Collect(SplitSeq(tt.s, tt.sep))
if !slices.Equal(a2, tt.a) {
t.Errorf(`collect(SplitSeq(%q, %q)) = %v; want %v`, tt.s, tt.sep, a2, tt.a)
}
}
if tt.n == 0 {
continue
}
@ -449,6 +487,12 @@ func TestSplitAfter(t *testing.T) {
t.Errorf(`Split(%q, %q, %d) = %v; want %v`, tt.s, tt.sep, tt.n, a, tt.a)
continue
}
if tt.n < 0 {
a2 := slices.Collect(SplitAfterSeq(tt.s, tt.sep))
if !slices.Equal(a2, tt.a) {
t.Errorf(`collect(SplitAfterSeq(%q, %q)) = %v; want %v`, tt.s, tt.sep, a2, tt.a)
}
}
s := Join(a, "")
if s != tt.s {
t.Errorf(`Join(Split(%q, %q, %d), %q) = %q`, tt.s, tt.sep, tt.n, tt.sep, s)
@ -492,6 +536,10 @@ func TestFields(t *testing.T) {
t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
continue
}
a2 := collect(t, FieldsSeq(tt.s))
if !slices.Equal(a2, tt.a) {
t.Errorf(`collect(FieldsSeq(%q)) = %v; want %v`, tt.s, a2, tt.a)
}
}
}
@ -516,6 +564,10 @@ func TestFieldsFunc(t *testing.T) {
if !slices.Equal(a, tt.a) {
t.Errorf("FieldsFunc(%q) = %v, want %v", tt.s, a, tt.a)
}
a2 := collect(t, FieldsFuncSeq(tt.s, pred))
if !slices.Equal(a2, tt.a) {
t.Errorf(`collect(FieldsFuncSeq(%q)) = %v; want %v`, tt.s, a2, tt.a)
}
}
}