1// 
  2// Copyright (c) 2011-2019 Canonical Ltd
  3// Copyright (c) 2006-2010 Kirill Simonov
  4// 
  5// Permission is hereby granted, free of charge, to any person obtaining a copy of
  6// this software and associated documentation files (the "Software"), to deal in
  7// the Software without restriction, including without limitation the rights to
  8// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
  9// of the Software, and to permit persons to whom the Software is furnished to do
 10// so, subject to the following conditions:
 11// 
 12// The above copyright notice and this permission notice shall be included in all
 13// copies or substantial portions of the Software.
 14// 
 15// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 18// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 19// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 20// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 21// SOFTWARE.
 22
 23package yaml
 24
 25const (
 26	// The size of the input raw buffer.
 27	input_raw_buffer_size = 512
 28
 29	// The size of the input buffer.
 30	// It should be possible to decode the whole raw buffer.
 31	input_buffer_size = input_raw_buffer_size * 3
 32
 33	// The size of the output buffer.
 34	output_buffer_size = 128
 35
 36	// The size of the output raw buffer.
 37	// It should be possible to encode the whole output buffer.
 38	output_raw_buffer_size = (output_buffer_size*2 + 2)
 39
 40	// The size of other stacks and queues.
 41	initial_stack_size  = 16
 42	initial_queue_size  = 16
 43	initial_string_size = 16
 44)
 45
 46// Check if the character at the specified position is an alphabetical
 47// character, a digit, '_', or '-'.
 48func is_alpha(b []byte, i int) bool {
 49	return b[i] >= '0' && b[i] <= '9' || b[i] >= 'A' && b[i] <= 'Z' || b[i] >= 'a' && b[i] <= 'z' || b[i] == '_' || b[i] == '-'
 50}
 51
 52// Check if the character at the specified position is a digit.
 53func is_digit(b []byte, i int) bool {
 54	return b[i] >= '0' && b[i] <= '9'
 55}
 56
 57// Get the value of a digit.
 58func as_digit(b []byte, i int) int {
 59	return int(b[i]) - '0'
 60}
 61
 62// Check if the character at the specified position is a hex-digit.
 63func is_hex(b []byte, i int) bool {
 64	return b[i] >= '0' && b[i] <= '9' || b[i] >= 'A' && b[i] <= 'F' || b[i] >= 'a' && b[i] <= 'f'
 65}
 66
 67// Get the value of a hex-digit.
 68func as_hex(b []byte, i int) int {
 69	bi := b[i]
 70	if bi >= 'A' && bi <= 'F' {
 71		return int(bi) - 'A' + 10
 72	}
 73	if bi >= 'a' && bi <= 'f' {
 74		return int(bi) - 'a' + 10
 75	}
 76	return int(bi) - '0'
 77}
 78
 79// Check if the character is ASCII.
 80func is_ascii(b []byte, i int) bool {
 81	return b[i] <= 0x7F
 82}
 83
 84// Check if the character at the start of the buffer can be printed unescaped.
 85func is_printable(b []byte, i int) bool {
 86	return ((b[i] == 0x0A) || // . == #x0A
 87		(b[i] >= 0x20 && b[i] <= 0x7E) || // #x20 <= . <= #x7E
 88		(b[i] == 0xC2 && b[i+1] >= 0xA0) || // #0xA0 <= . <= #xD7FF
 89		(b[i] > 0xC2 && b[i] < 0xED) ||
 90		(b[i] == 0xED && b[i+1] < 0xA0) ||
 91		(b[i] == 0xEE) ||
 92		(b[i] == 0xEF && // #xE000 <= . <= #xFFFD
 93			!(b[i+1] == 0xBB && b[i+2] == 0xBF) && // && . != #xFEFF
 94			!(b[i+1] == 0xBF && (b[i+2] == 0xBE || b[i+2] == 0xBF))))
 95}
 96
 97// Check if the character at the specified position is NUL.
 98func is_z(b []byte, i int) bool {
 99	return b[i] == 0x00
100}
101
102// Check if the beginning of the buffer is a BOM.
103func is_bom(b []byte, i int) bool {
104	return b[0] == 0xEF && b[1] == 0xBB && b[2] == 0xBF
105}
106
107// Check if the character at the specified position is space.
108func is_space(b []byte, i int) bool {
109	return b[i] == ' '
110}
111
112// Check if the character at the specified position is tab.
113func is_tab(b []byte, i int) bool {
114	return b[i] == '\t'
115}
116
117// Check if the character at the specified position is blank (space or tab).
118func is_blank(b []byte, i int) bool {
119	//return is_space(b, i) || is_tab(b, i)
120	return b[i] == ' ' || b[i] == '\t'
121}
122
123// Check if the character at the specified position is a line break.
124func is_break(b []byte, i int) bool {
125	return (b[i] == '\r' || // CR (#xD)
126		b[i] == '\n' || // LF (#xA)
127		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
128		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
129		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9) // PS (#x2029)
130}
131
132func is_crlf(b []byte, i int) bool {
133	return b[i] == '\r' && b[i+1] == '\n'
134}
135
136// Check if the character is a line break or NUL.
137func is_breakz(b []byte, i int) bool {
138	//return is_break(b, i) || is_z(b, i)
139	return (
140		// is_break:
141		b[i] == '\r' || // CR (#xD)
142		b[i] == '\n' || // LF (#xA)
143		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
144		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
145		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9 || // PS (#x2029)
146		// is_z:
147		b[i] == 0)
148}
149
150// Check if the character is a line break, space, or NUL.
151func is_spacez(b []byte, i int) bool {
152	//return is_space(b, i) || is_breakz(b, i)
153	return (
154		// is_space:
155		b[i] == ' ' ||
156		// is_breakz:
157		b[i] == '\r' || // CR (#xD)
158		b[i] == '\n' || // LF (#xA)
159		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
160		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
161		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9 || // PS (#x2029)
162		b[i] == 0)
163}
164
165// Check if the character is a line break, space, tab, or NUL.
166func is_blankz(b []byte, i int) bool {
167	//return is_blank(b, i) || is_breakz(b, i)
168	return (
169		// is_blank:
170		b[i] == ' ' || b[i] == '\t' ||
171		// is_breakz:
172		b[i] == '\r' || // CR (#xD)
173		b[i] == '\n' || // LF (#xA)
174		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
175		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
176		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9 || // PS (#x2029)
177		b[i] == 0)
178}
179
180// Determine the width of the character.
181func width(b byte) int {
182	// Don't replace these by a switch without first
183	// confirming that it is being inlined.
184	if b&0x80 == 0x00 {
185		return 1
186	}
187	if b&0xE0 == 0xC0 {
188		return 2
189	}
190	if b&0xF0 == 0xE0 {
191		return 3
192	}
193	if b&0xF8 == 0xF0 {
194		return 4
195	}
196	return 0
197
198}