57 lines
1.4 KiB
Go
57 lines
1.4 KiB
Go
// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package json
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import (
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"unicode"
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"unicode/utf8"
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)
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// foldName returns a folded string such that foldName(x) == foldName(y)
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// is similar to strings.EqualFold(x, y), but ignores underscore and dashes.
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// This allows foldName to match common naming conventions.
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func foldName(in []byte) []byte {
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// This is inlinable to take advantage of "function outlining".
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// See https://blog.filippo.io/efficient-go-apis-with-the-inliner/
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var arr [32]byte // large enough for most JSON names
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return appendFoldedName(arr[:0], in)
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}
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func appendFoldedName(out, in []byte) []byte {
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for i := 0; i < len(in); {
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// Handle single-byte ASCII.
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if c := in[i]; c < utf8.RuneSelf {
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if c != '_' && c != '-' {
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if 'a' <= c && c <= 'z' {
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c -= 'a' - 'A'
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}
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out = append(out, c)
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}
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i++
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continue
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}
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// Handle multi-byte Unicode.
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r, n := utf8.DecodeRune(in[i:])
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out = utf8.AppendRune(out, foldRune(r))
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i += n
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}
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return out
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}
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// foldRune is a variation on unicode.SimpleFold that returns the same rune
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// for all runes in the same fold set.
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//
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// Invariant:
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//
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// foldRune(x) == foldRune(y) ⇔ strings.EqualFold(string(x), string(y))
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func foldRune(r rune) rune {
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for {
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r2 := unicode.SimpleFold(r)
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if r2 <= r {
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return r2 // smallest character in the fold set
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}
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r = r2
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}
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}
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