forked from ebhomengo/niki
56 lines
1.4 KiB
Go
56 lines
1.4 KiB
Go
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package swag
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import "unicode"
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// FieldsFunc split a string s by a func splitter into max n parts
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func FieldsFunc(s string, f func(rune2 rune) bool, n int) []string {
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// A span is used to record a slice of s of the form s[start:end].
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// The start index is inclusive and the end index is exclusive.
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type span struct {
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start int
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end int
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}
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spans := make([]span, 0, 32)
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// Find the field start and end indices.
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// Doing this in a separate pass (rather than slicing the string s
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// and collecting the result substrings right away) is significantly
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// more efficient, possibly due to cache effects.
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start := -1 // valid span start if >= 0
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for end, rune := range s {
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if f(rune) {
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if start >= 0 {
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spans = append(spans, span{start, end})
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// Set start to a negative value.
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// Note: using -1 here consistently and reproducibly
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// slows down this code by a several percent on amd64.
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start = ^start
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}
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} else {
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if start < 0 {
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start = end
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if n > 0 && len(spans)+1 >= n {
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break
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}
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}
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}
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}
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// Last field might end at EOF.
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if start >= 0 {
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spans = append(spans, span{start, len(s)})
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}
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// Create strings from recorded field indices.
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a := make([]string, len(spans))
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for i, span := range spans {
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a[i] = s[span.start:span.end]
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}
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return a
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}
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// FieldsByAnySpace split a string s by any space character into max n parts
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func FieldsByAnySpace(s string, n int) []string {
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return FieldsFunc(s, unicode.IsSpace, n)
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}
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