diff options
Diffstat (limited to 'src/bytes')
| -rw-r--r-- | src/bytes/bytes_test.go | 57 | ||||
| -rw-r--r-- | src/bytes/iter.go | 148 |
2 files changed, 205 insertions, 0 deletions
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go index 6fb6140c18..637880a4f7 100644 --- a/src/bytes/bytes_test.go +++ b/src/bytes/bytes_test.go @@ -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) } diff --git a/src/bytes/iter.go b/src/bytes/iter.go new file mode 100644 index 0000000000..1cf13a94ec --- /dev/null +++ b/src/bytes/iter.go @@ -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)]) + } + } +} |