97 lines
1.7 KiB
C
97 lines
1.7 KiB
C
/* go-rune.c -- rune functions for Go.
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Copyright 2009, 2010 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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#include <stddef.h>
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#include "go-string.h"
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/* Get a character from the UTF-8 string STR, of length LEN. Store
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the Unicode character, if any, in *RUNE. Return the number of
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characters used from STR. */
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int
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__go_get_rune (const unsigned char *str, size_t len, int *rune)
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{
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int c, c1, c2, c3, l;
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/* Default to the "replacement character". */
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*rune = 0xfffd;
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if (len <= 0)
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return 1;
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c = *str;
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if (c <= 0x7f)
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{
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*rune = c;
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return 1;
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}
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if (len <= 1)
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return 1;
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c1 = str[1];
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if ((c & 0xe0) == 0xc0
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&& (c1 & 0xc0) == 0x80)
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{
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l = (((c & 0x1f) << 6) + (c1 & 0x3f));
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if (l <= 0x7f)
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return 1;
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*rune = l;
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return 2;
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}
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if (len <= 2)
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return 1;
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c2 = str[2];
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if ((c & 0xf0) == 0xe0
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&& (c1 & 0xc0) == 0x80
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&& (c2 & 0xc0) == 0x80)
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{
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l = (((c & 0xf) << 12)
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+ ((c1 & 0x3f) << 6)
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+ (c2 & 0x3f));
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if (l <= 0x7ff)
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return 1;
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if (l >= 0xd800 && l < 0xe000)
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{
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/* Invalid surrogate half; return replace character. */
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return 1;
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}
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*rune = l;
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return 3;
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}
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if (len <= 3)
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return 1;
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c3 = str[3];
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if ((c & 0xf8) == 0xf0
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&& (c1 & 0xc0) == 0x80
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&& (c2 & 0xc0) == 0x80
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&& (c3 & 0xc0) == 0x80)
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{
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l = (((c & 0x7) << 18)
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+ ((c1 & 0x3f) << 12)
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+ ((c2 & 0x3f) << 6)
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+ (c3 & 0x3f));
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if (l <= 0xffff || l > 0x10ffff)
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return 1;
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*rune = l;
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return 4;
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}
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/* Invalid encoding. Return 1 so that we advance. */
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return 1;
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}
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