7 // Set the reader error and return 0.
8 func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
9 parser.error = yaml_READER_ERROR
10 parser.problem = problem
11 parser.problem_offset = offset
12 parser.problem_value = value
18 bom_UTF8 = "\xef\xbb\xbf"
19 bom_UTF16LE = "\xff\xfe"
20 bom_UTF16BE = "\xfe\xff"
23 // Determine the input stream encoding by checking the BOM symbol. If no BOM is
24 // found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
25 func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
26 // Ensure that we had enough bytes in the raw buffer.
27 for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
28 if !yaml_parser_update_raw_buffer(parser) {
33 // Determine the encoding.
34 buf := parser.raw_buffer
35 pos := parser.raw_buffer_pos
36 avail := len(buf) - pos
37 if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
38 parser.encoding = yaml_UTF16LE_ENCODING
39 parser.raw_buffer_pos += 2
41 } else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
42 parser.encoding = yaml_UTF16BE_ENCODING
43 parser.raw_buffer_pos += 2
45 } else if avail >= 3 && buf[pos] == bom_UTF8[0] && buf[pos+1] == bom_UTF8[1] && buf[pos+2] == bom_UTF8[2] {
46 parser.encoding = yaml_UTF8_ENCODING
47 parser.raw_buffer_pos += 3
50 parser.encoding = yaml_UTF8_ENCODING
55 // Update the raw buffer.
56 func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
59 // Return if the raw buffer is full.
60 if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
69 // Move the remaining bytes in the raw buffer to the beginning.
70 if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
71 copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
73 parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
74 parser.raw_buffer_pos = 0
76 // Call the read handler to fill the buffer.
77 size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
78 parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
81 } else if err != nil {
82 return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
87 // Ensure that the buffer contains at least `length` characters.
88 // Return true on success, false on failure.
90 // The length is supposed to be significantly less that the buffer size.
91 func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
92 if parser.read_handler == nil {
93 panic("read handler must be set")
96 // If the EOF flag is set and the raw buffer is empty, do nothing.
97 if parser.eof && parser.raw_buffer_pos == len(parser.raw_buffer) {
101 // Return if the buffer contains enough characters.
102 if parser.unread >= length {
106 // Determine the input encoding if it is not known yet.
107 if parser.encoding == yaml_ANY_ENCODING {
108 if !yaml_parser_determine_encoding(parser) {
113 // Move the unread characters to the beginning of the buffer.
114 buffer_len := len(parser.buffer)
115 if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
116 copy(parser.buffer, parser.buffer[parser.buffer_pos:])
117 buffer_len -= parser.buffer_pos
118 parser.buffer_pos = 0
119 } else if parser.buffer_pos == buffer_len {
121 parser.buffer_pos = 0
124 // Open the whole buffer for writing, and cut it before returning.
125 parser.buffer = parser.buffer[:cap(parser.buffer)]
127 // Fill the buffer until it has enough characters.
129 for parser.unread < length {
131 // Fill the raw buffer if necessary.
132 if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
133 if !yaml_parser_update_raw_buffer(parser) {
134 parser.buffer = parser.buffer[:buffer_len]
140 // Decode the raw buffer.
142 for parser.raw_buffer_pos != len(parser.raw_buffer) {
146 raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
148 // Decode the next character.
149 switch parser.encoding {
150 case yaml_UTF8_ENCODING:
151 // Decode a UTF-8 character. Check RFC 3629
152 // (http://www.ietf.org/rfc/rfc3629.txt) for more details.
154 // The following table (taken from the RFC) is used for
157 // Char. number range | UTF-8 octet sequence
158 // (hexadecimal) | (binary)
159 // --------------------+------------------------------------
160 // 0000 0000-0000 007F | 0xxxxxxx
161 // 0000 0080-0000 07FF | 110xxxxx 10xxxxxx
162 // 0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
163 // 0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
165 // Additionally, the characters in the range 0xD800-0xDFFF
166 // are prohibited as they are reserved for use with UTF-16
169 // Determine the length of the UTF-8 sequence.
170 octet := parser.raw_buffer[parser.raw_buffer_pos]
172 case octet&0x80 == 0x00:
174 case octet&0xE0 == 0xC0:
176 case octet&0xF0 == 0xE0:
178 case octet&0xF8 == 0xF0:
181 // The leading octet is invalid.
182 return yaml_parser_set_reader_error(parser,
183 "invalid leading UTF-8 octet",
184 parser.offset, int(octet))
187 // Check if the raw buffer contains an incomplete character.
188 if width > raw_unread {
190 return yaml_parser_set_reader_error(parser,
191 "incomplete UTF-8 octet sequence",
197 // Decode the leading octet.
199 case octet&0x80 == 0x00:
200 value = rune(octet & 0x7F)
201 case octet&0xE0 == 0xC0:
202 value = rune(octet & 0x1F)
203 case octet&0xF0 == 0xE0:
204 value = rune(octet & 0x0F)
205 case octet&0xF8 == 0xF0:
206 value = rune(octet & 0x07)
211 // Check and decode the trailing octets.
212 for k := 1; k < width; k++ {
213 octet = parser.raw_buffer[parser.raw_buffer_pos+k]
215 // Check if the octet is valid.
216 if (octet & 0xC0) != 0x80 {
217 return yaml_parser_set_reader_error(parser,
218 "invalid trailing UTF-8 octet",
219 parser.offset+k, int(octet))
223 value = (value << 6) + rune(octet&0x3F)
226 // Check the length of the sequence against the value.
229 case width == 2 && value >= 0x80:
230 case width == 3 && value >= 0x800:
231 case width == 4 && value >= 0x10000:
233 return yaml_parser_set_reader_error(parser,
234 "invalid length of a UTF-8 sequence",
238 // Check the range of the value.
239 if value >= 0xD800 && value <= 0xDFFF || value > 0x10FFFF {
240 return yaml_parser_set_reader_error(parser,
241 "invalid Unicode character",
242 parser.offset, int(value))
245 case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
247 if parser.encoding == yaml_UTF16LE_ENCODING {
253 // The UTF-16 encoding is not as simple as one might
254 // naively think. Check RFC 2781
255 // (http://www.ietf.org/rfc/rfc2781.txt).
257 // Normally, two subsequent bytes describe a Unicode
258 // character. However a special technique (called a
259 // surrogate pair) is used for specifying character
260 // values larger than 0xFFFF.
262 // A surrogate pair consists of two pseudo-characters:
263 // high surrogate area (0xD800-0xDBFF)
264 // low surrogate area (0xDC00-0xDFFF)
266 // The following formulas are used for decoding
267 // and encoding characters using surrogate pairs:
269 // U = U' + 0x10000 (0x01 00 00 <= U <= 0x10 FF FF)
270 // U' = yyyyyyyyyyxxxxxxxxxx (0 <= U' <= 0x0F FF FF)
271 // W1 = 110110yyyyyyyyyy
272 // W2 = 110111xxxxxxxxxx
274 // where U is the character value, W1 is the high surrogate
275 // area, W2 is the low surrogate area.
277 // Check for incomplete UTF-16 character.
280 return yaml_parser_set_reader_error(parser,
281 "incomplete UTF-16 character",
287 // Get the character.
288 value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
289 (rune(parser.raw_buffer[parser.raw_buffer_pos+high]) << 8)
291 // Check for unexpected low surrogate area.
292 if value&0xFC00 == 0xDC00 {
293 return yaml_parser_set_reader_error(parser,
294 "unexpected low surrogate area",
295 parser.offset, int(value))
298 // Check for a high surrogate area.
299 if value&0xFC00 == 0xD800 {
302 // Check for incomplete surrogate pair.
305 return yaml_parser_set_reader_error(parser,
306 "incomplete UTF-16 surrogate pair",
312 // Get the next character.
313 value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
314 (rune(parser.raw_buffer[parser.raw_buffer_pos+high+2]) << 8)
316 // Check for a low surrogate area.
317 if value2&0xFC00 != 0xDC00 {
318 return yaml_parser_set_reader_error(parser,
319 "expected low surrogate area",
320 parser.offset+2, int(value2))
323 // Generate the value of the surrogate pair.
324 value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
333 // Check if the character is in the allowed range:
334 // #x9 | #xA | #xD | [#x20-#x7E] (8 bit)
335 // | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD] (16 bit)
336 // | [#x10000-#x10FFFF] (32 bit)
341 case value >= 0x20 && value <= 0x7E:
343 case value >= 0xA0 && value <= 0xD7FF:
344 case value >= 0xE000 && value <= 0xFFFD:
345 case value >= 0x10000 && value <= 0x10FFFF:
347 return yaml_parser_set_reader_error(parser,
348 "control characters are not allowed",
349 parser.offset, int(value))
352 // Move the raw pointers.
353 parser.raw_buffer_pos += width
354 parser.offset += width
356 // Finally put the character into the buffer.
358 // 0000 0000-0000 007F . 0xxxxxxx
359 parser.buffer[buffer_len+0] = byte(value)
361 } else if value <= 0x7FF {
362 // 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
363 parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
364 parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
366 } else if value <= 0xFFFF {
367 // 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
368 parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
369 parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
370 parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
373 // 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
374 parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
375 parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
376 parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
377 parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
384 // On EOF, put NUL into the buffer and return.
386 parser.buffer[buffer_len] = 0
392 parser.buffer = parser.buffer[:buffer_len]