diff options
Diffstat (limited to 'vendor/golang.org/x/text/internal/utf8internal/utf8internal.go')
-rw-r--r-- | vendor/golang.org/x/text/internal/utf8internal/utf8internal.go | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/internal/utf8internal/utf8internal.go b/vendor/golang.org/x/text/internal/utf8internal/utf8internal.go new file mode 100644 index 00000000..575cea87 --- /dev/null +++ b/vendor/golang.org/x/text/internal/utf8internal/utf8internal.go @@ -0,0 +1,87 @@ +// Copyright 2015 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 utf8internal contains low-level utf8-related constants, tables, etc. +// that are used internally by the text package. +package utf8internal + +// The default lowest and highest continuation byte. +const ( + LoCB = 0x80 // 1000 0000 + HiCB = 0xBF // 1011 1111 +) + +// Constants related to getting information of first bytes of UTF-8 sequences. +const ( + // ASCII identifies a UTF-8 byte as ASCII. + ASCII = as + + // FirstInvalid indicates a byte is invalid as a first byte of a UTF-8 + // sequence. + FirstInvalid = xx + + // SizeMask is a mask for the size bits. Use use x&SizeMask to get the size. + SizeMask = 7 + + // AcceptShift is the right-shift count for the first byte info byte to get + // the index into the AcceptRanges table. See AcceptRanges. + AcceptShift = 4 + + // The names of these constants are chosen to give nice alignment in the + // table below. The first nibble is an index into acceptRanges or F for + // special one-byte cases. The second nibble is the Rune length or the + // Status for the special one-byte case. + xx = 0xF1 // invalid: size 1 + as = 0xF0 // ASCII: size 1 + s1 = 0x02 // accept 0, size 2 + s2 = 0x13 // accept 1, size 3 + s3 = 0x03 // accept 0, size 3 + s4 = 0x23 // accept 2, size 3 + s5 = 0x34 // accept 3, size 4 + s6 = 0x04 // accept 0, size 4 + s7 = 0x44 // accept 4, size 4 +) + +// First is information about the first byte in a UTF-8 sequence. +var First = [256]uint8{ + // 1 2 3 4 5 6 7 8 9 A B C D E F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x00-0x0F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x10-0x1F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x20-0x2F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x30-0x3F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x40-0x4F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x50-0x5F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x60-0x6F + as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, as, // 0x70-0x7F + // 1 2 3 4 5 6 7 8 9 A B C D E F + xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0x80-0x8F + xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0x90-0x9F + xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0xA0-0xAF + xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0xB0-0xBF + xx, xx, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, // 0xC0-0xCF + s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, s1, // 0xD0-0xDF + s2, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s3, s4, s3, s3, // 0xE0-0xEF + s5, s6, s6, s6, s7, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, // 0xF0-0xFF +} + +// AcceptRange gives the range of valid values for the second byte in a UTF-8 +// sequence for any value for First that is not ASCII or FirstInvalid. +type AcceptRange struct { + Lo uint8 // lowest value for second byte. + Hi uint8 // highest value for second byte. +} + +// AcceptRanges is a slice of AcceptRange values. For a given byte sequence b +// +// AcceptRanges[First[b[0]]>>AcceptShift] +// +// will give the value of AcceptRange for the multi-byte UTF-8 sequence starting +// at b[0]. +var AcceptRanges = [...]AcceptRange{ + 0: {LoCB, HiCB}, + 1: {0xA0, HiCB}, + 2: {LoCB, 0x9F}, + 3: {0x90, HiCB}, + 4: {LoCB, 0x8F}, +} |