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Merge pull request #14090 from colega/improve-zeroOrOneCharacterStringMatcher-Matches
Improve `zeroOrOneCharacterStringMatcher` by using `utf8.DecodeRuneInString`
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commit
1e0b0e250a
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@ -828,7 +828,12 @@ type zeroOrOneCharacterStringMatcher struct {
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}
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}
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func (m *zeroOrOneCharacterStringMatcher) Matches(s string) bool {
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func (m *zeroOrOneCharacterStringMatcher) Matches(s string) bool {
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if moreThanOneRune(s) {
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// If there's more than one rune in the string, then it can't match.
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if r, size := utf8.DecodeRuneInString(s); r == utf8.RuneError {
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// Size is 0 for empty strings, 1 for invalid rune.
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// Empty string matches, invalid rune matches if there isn't anything else.
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return size == len(s)
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} else if size < len(s) {
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return false
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return false
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}
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}
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@ -840,27 +845,6 @@ func (m *zeroOrOneCharacterStringMatcher) Matches(s string) bool {
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return s[0] != '\n'
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return s[0] != '\n'
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}
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}
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// moreThanOneRune returns true if there are more than one runes in the string.
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// It doesn't check whether the string is valid UTF-8.
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// The return value should be always equal to utf8.RuneCountInString(s) > 1,
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// but the function is optimized for the common case where the string prefix is ASCII.
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func moreThanOneRune(s string) bool {
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// If len(s) is exactly one or zero, there can't be more than one rune.
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// Exit through this path quickly.
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if len(s) <= 1 {
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return false
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}
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// There's one or more bytes:
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// If first byte is ASCII then there are multiple runes if there are more bytes after that.
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if s[0] < utf8.RuneSelf {
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return len(s) > 1
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}
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// Less common case: first is a multibyte rune.
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return utf8.RuneCountInString(s) > 1
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}
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// trueMatcher is a stringMatcher which matches any string (always returns true).
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// trueMatcher is a stringMatcher which matches any string (always returns true).
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type trueMatcher struct{}
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type trueMatcher struct{}
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@ -19,6 +19,7 @@ import (
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"strings"
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"strings"
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"testing"
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"testing"
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"time"
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"time"
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"unicode/utf8"
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"github.com/grafana/regexp"
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"github.com/grafana/regexp"
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"github.com/grafana/regexp/syntax"
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"github.com/grafana/regexp/syntax"
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@ -36,6 +37,7 @@ var (
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".*foo",
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".*foo",
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"^.*foo$",
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"^.*foo$",
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"^.+foo$",
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"^.+foo$",
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".?",
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".*",
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".*",
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".+",
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".+",
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"foo.+",
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"foo.+",
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@ -88,6 +90,12 @@ var (
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// Values matching / not matching the test regexps on long alternations.
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// Values matching / not matching the test regexps on long alternations.
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"zQPbMkNO", "zQPbMkNo", "jyyfj00j0061", "jyyfj00j006", "jyyfj00j00612", "NNSPdvMi", "NNSPdvMiXXX", "NNSPdvMixxx", "nnSPdvMi", "nnSPdvMiXXX",
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"zQPbMkNO", "zQPbMkNo", "jyyfj00j0061", "jyyfj00j006", "jyyfj00j00612", "NNSPdvMi", "NNSPdvMiXXX", "NNSPdvMixxx", "nnSPdvMi", "nnSPdvMiXXX",
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// Invalid utf8
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"\xfefoo",
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"foo\xfe",
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"\xfd",
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"\xff\xff",
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}
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}
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)
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)
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@ -926,19 +934,91 @@ func BenchmarkOptimizeEqualStringMatchers(b *testing.B) {
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}
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}
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func TestZeroOrOneCharacterStringMatcher(t *testing.T) {
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func TestZeroOrOneCharacterStringMatcher(t *testing.T) {
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matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
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t.Run("match newline", func(t *testing.T) {
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require.True(t, matcher.Matches(""))
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matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
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require.True(t, matcher.Matches("x"))
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require.True(t, matcher.Matches(""))
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require.True(t, matcher.Matches("\n"))
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require.True(t, matcher.Matches("x"))
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require.False(t, matcher.Matches("xx"))
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require.True(t, matcher.Matches("\n"))
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require.False(t, matcher.Matches("\n\n"))
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require.False(t, matcher.Matches("xx"))
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require.False(t, matcher.Matches("\n\n"))
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})
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matcher = &zeroOrOneCharacterStringMatcher{matchNL: false}
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t.Run("do not match newline", func(t *testing.T) {
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require.True(t, matcher.Matches(""))
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matcher := &zeroOrOneCharacterStringMatcher{matchNL: false}
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require.True(t, matcher.Matches("x"))
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require.True(t, matcher.Matches(""))
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require.False(t, matcher.Matches("\n"))
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require.True(t, matcher.Matches("x"))
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require.False(t, matcher.Matches("xx"))
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require.False(t, matcher.Matches("\n"))
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require.False(t, matcher.Matches("\n\n"))
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require.False(t, matcher.Matches("xx"))
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require.False(t, matcher.Matches("\n\n"))
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})
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t.Run("unicode", func(t *testing.T) {
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// Just for documentation purposes, emoji1 is 1 rune, emoji2 is 2 runes.
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// Having this in mind, will make future readers fixing tests easier.
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emoji1 := "😀"
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emoji2 := "❤️"
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require.Equal(t, 1, utf8.RuneCountInString(emoji1))
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require.Equal(t, 2, utf8.RuneCountInString(emoji2))
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matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
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require.True(t, matcher.Matches(emoji1))
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require.False(t, matcher.Matches(emoji2))
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require.False(t, matcher.Matches(emoji1+emoji1))
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require.False(t, matcher.Matches("x"+emoji1))
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require.False(t, matcher.Matches(emoji1+"x"))
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require.False(t, matcher.Matches(emoji1+emoji2))
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})
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t.Run("invalid unicode", func(t *testing.T) {
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// Just for reference, we also compare to what `^.?$` regular expression matches.
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re := regexp.MustCompile("^.?$")
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matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
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requireMatches := func(s string, expected bool) {
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t.Helper()
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require.Equal(t, expected, matcher.Matches(s))
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require.Equal(t, re.MatchString(s), matcher.Matches(s))
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}
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requireMatches("\xff", true)
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requireMatches("x\xff", false)
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requireMatches("\xffx", false)
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requireMatches("\xff\xfe", false)
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})
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}
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func BenchmarkZeroOrOneCharacterStringMatcher(b *testing.B) {
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type benchCase struct {
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str string
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matches bool
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}
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emoji1 := "😀"
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emoji2 := "❤️"
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cases := []benchCase{
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{"", true},
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{"x", true},
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{"\n", true},
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{"xx", false},
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{"\n\n", false},
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{emoji1, true},
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{emoji2, false},
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{emoji1 + emoji1, false},
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{strings.Repeat("x", 100), false},
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{strings.Repeat(emoji1, 100), false},
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{strings.Repeat(emoji2, 100), false},
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}
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matcher := &zeroOrOneCharacterStringMatcher{matchNL: true}
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b.ResetTimer()
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for n := 0; n < b.N; n++ {
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c := cases[n%len(cases)]
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got := matcher.Matches(c.str)
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if got != c.matches {
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b.Fatalf("unexpected result for %q: got %t, want %t", c.str, got, c.matches)
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}
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}
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}
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}
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func TestLiteralPrefixStringMatcher(t *testing.T) {
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func TestLiteralPrefixStringMatcher(t *testing.T) {
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