diet-yaml.

Core part of YAML spec is implemented.

author: - Hongxin Liang
license: - Apache License Version 2.0 */

23parse(YAML, PL) :- 24 atom(YAML), !, 25 atom_chars(YAML, YAML0), 26 yaml(PL, YAML0, []). 27 28parse(YAML, PL) :- 29 yaml(PL, YAML, []). 30 31yaml(YAML) --> start, optional_whitespaces, data(YAML), optional_whitespaces, end. 32 33start --> newline, dash, dash, dash, !. 34start --> []. 35 36end --> newline, ['.', '.', '.'], !. 37end --> newline, dash, dash, dash, !. 38end --> []. 39 40data(Data) --> sequence(Data), !. 41data(Data) --> mapping(Data), !. 42data([]) --> ['[', ']'], !. 43data(_{}) --> ['{', '}'], !. 44data(Data) --> optional_whitespaces, scalar(Data), !. 45 46scalar(Scalar) --> string(String), 47 { 48 ( atom(String) 49 -> ( atom_number(String, Scalar) 50 -> true 51 ; ( parse_time(String, iso_8601, T) 52 -> stamp_date_time(T, Scalar, 'UTC') 53 ; ( String = '~' 54 -> Scalar = nil 55 ; Scalar = String 56 ) 57 ) 58 ) 59 ; Scalar = String 60 ) 61 }. 62 63sequence([H|T], ['['|Chars], Rest) :- 64 setup_call_cleanup(asserta(condition(sequence)), 65 ( 66 optional_whitespaces(Chars, Rest1), 67 data(H, Rest1, Rest2), 68 comma_data(T, Rest2, Rest3), 69 optional_whitespaces(Rest3, [']'|Rest]) 70 ), 71 retract(condition(sequence))), !. 72 73sequence([H|T], Chars, Rest) :- 74 optional_spaces(Count, Chars, Rest1), 75 dash(Rest1, Rest2), 76 Count1 is Count + 1, 77 pushback(Count1, Rest2, Rest3), 78 Rest4 = ['\n'|Rest3], 79 whitespaces_with_pushback(Rest4, Rest5), 80 data(H, Rest5, Rest6), 81 dash_data(Count, T, Rest6, Rest). 82 83mapping(Mapping, ['{'|Chars], Rest) :- 84 setup_call_cleanup(asserta(condition(mapping)), 85 ( 86 optional_whitespaces(Chars, Rest1), 87 key(Key, Rest1, Rest2), 88 optional_spaces(_, Rest2, Rest3), 89 colon(Rest3, Rest4), 90 at_least_one_whitespace(Rest4, Rest5), 91 data(Data, Rest5, Rest6), 92 colon_data(Dict, Rest6, Rest7), 93 optional_whitespaces(Rest7, ['}'|Rest]), 94 Mapping = Dict.put(Key, Data) 95 ), 96 retract(condition(mapping))), !. 97 98mapping(Mapping) --> 99 optional_spaces(Count), 100 key(Key), 101 optional_spaces(_), 102 colon, 103 whitespaces_with_pushback, 104 data(Data), 105 tab_data(Count, Dict), 106 { 107 Mapping = Dict.put(Key, Data) 108 }. 109 110optional_spaces(Count) --> space, optional_spaces(X), !, 111 { 112 Count is X + 1 113 }. 114optional_spaces(0) --> []. 115 116string(String) --> ['"'], chars_exclude_trailing_double_quote(Chars), ['"'], !, 117 { 118 atom_string(Chars, String) 119 }. 120 121string(String) --> ['\''], chars_exclude_trailing_single_quote(Chars), ['\''], !, 122 { 123 atom_string(Chars, String) 124 }. 125 126string(String, ['>'|Chars], Rest) :- 127 optional_spaces(_, Chars, ['\n'|Rest1]), 128 optional_spaces(Count, Rest1, Rest2), 129 line(X, Rest2, Rest3), 130 next_line(Y, Count, Rest3, Rest4), !, 131 ( sub_atom(Y, 0, 1, _, '\n') 132 -> atom_concat(X, Y, String) 133 ; atomic_list_concat([X, ' ', Y], String) 134 ), 135 Rest = ['\n'|Rest4]. 136 137string(String, ['|'|Chars], Rest) :- 138 optional_spaces(_, Chars, ['\n'|Rest1]), 139 optional_spaces(Count, Rest1, Rest2), 140 line(X, Rest2, Rest3), 141 next_line_preserving_newline(Y, Count, Rest3, Rest4), !, 142 atomic_list_concat([X, '\n', Y], String), 143 Rest = ['\n'|Rest4]. 144 145string(String) --> valid_start(Char), chars(Chars), 146 { 147 atom_concat(Char, Chars, String) 148 }. 149 150space --> [' ']. 151 152key(Key) --> 153 valid_key_char(X), 154 key(Y), !, 155 { 156 atom_concat(X, Y, Key) 157 }. 158key(Key) --> valid_key_char(Key). 159 160dash --> ['-']. 161colon --> [':']. 162comma --> [',']. 163newline --> ['\n']. 164 165at_least_one_newline --> newline, at_least_one_newline, !. 166at_least_one_newline --> newline. 167 168newlines(V) --> newline, newlines(Y), !, 169 { 170 atom_concat('\n', Y, V) 171 }. 172newlines('\n') --> newline. 173 174optional_whitespaces --> space, optional_whitespaces, !. 175optional_whitespaces --> newline, optional_whitespaces, !. 176optional_whitespaces --> []. 177 178at_least_one_whitespace --> space, optional_whitespaces, !. 179at_least_one_whitespace --> newline, optional_whitespaces. 180 181whitespaces_with_pushback --> space, whitespaces_with_pushback, !. 182whitespaces_with_pushback --> newline, whitespaces_with_pushback0(0), !. 183whitespaces_with_pushback --> space, !. 184whitespaces_with_pushback --> newline. 185 186whitespaces_with_pushback0(Leading) --> space, !, 187 { 188 Leading1 is Leading + 1 189 }, 190 whitespaces_with_pushback0(Leading1). 191whitespaces_with_pushback0(_) --> newline, !, 192 whitespaces_with_pushback0(0). 193whitespaces_with_pushback0(Leading, [H|T], Rest) :- 194 H \= ' ', 195 H \= '\n', 196 pushback(Leading, [H|T], Rest). 197 198pushback(0, List, List) :- !. 199pushback(Count, List0, List) :- 200 List1 = [' '|List0], 201 Count1 is Count - 1, 202 pushback(Count1, List1, List). 203 204comma_data([H|T]) --> comma, optional_whitespaces, data(H), comma_data(T). 205comma_data([]) --> []. 206 207dash_data(Leading, [H|T], Chars, Rest) :- 208 at_least_one_newline(Chars, Rest0), 209 optional_spaces(Leading, Rest0, Rest1), 210 dash(Rest1, Rest2), 211 Count is Leading + 1, 212 pushback(Count, Rest2, Rest3), 213 Rest4 = ['\n'|Rest3], 214 whitespaces_with_pushback(Rest4, Rest5), 215 data(H, Rest5, Rest6), 216 dash_data(Leading, T, Rest6, Rest), !. 217dash_data(_, []) --> []. 218 219colon_data(V) --> 220 comma, 221 optional_whitespaces, 222 key(Key), 223 optional_spaces(_), 224 colon, 225 at_least_one_whitespace, 226 data(Data), 227 colon_data(Dict), !, 228 { 229 V = Dict.put(Key, Data) 230 }. 231colon_data(_{}) --> []. 232 233tab_data(Leading, V) --> 234 at_least_one_newline, 235 optional_spaces(Leading), 236 key(Key), 237 optional_spaces(_), 238 colon, 239 whitespaces_with_pushback, 240 data(Data), 241 tab_data(Leading, Dict), !, 242 { 243 V = Dict.put(Key, Data) 244 }. 245tab_data(_, _{}) --> []. 246 247chars_exclude_trailing_double_quote(V, [H|T], Rest) :- 248 lookahead(T, C), 249 ( C = '"' 250 -> ( H = '\\' 251 -> chars_exclude_trailing_double_quote(X, T, Rest), 252 atom_concat(H, X, V) 253 ; V = H, 254 Rest = T 255 ) 256 ; chars_exclude_trailing_double_quote(X, T, Rest), 257 atom_concat(H, X, V) 258 ), !. 259chars_exclude_trailing_double_quote('') --> []. 260 261chars_exclude_trailing_single_quote(V, [H|T], Rest) :- 262 ( H = '\'' 263 -> T = [C|T1], 264 ( C = '\'' 265 -> chars_exclude_trailing_single_quote(X, T1, Rest), 266 atom_concat('\'', X, V) 267 ; V = '', 268 Rest = [H|T] 269 ) 270 ; chars_exclude_trailing_single_quote(X, T, Rest), 271 atom_concat(H, X, V) 272 ), !. 273chars_exclude_trailing_single_quote('') --> []. 274 275chars(V, [X|Chars], Rest) :- 276 ( condition(sequence), ! 277 -> X \= ']', 278 X \= ',' 279 ; ( condition(mapping), ! 280 -> X \= '}', 281 X \= ',' 282 ; true 283 ) 284 ), 285 X \= '\n', !, 286 chars(Y, Chars, Rest), 287 atom_concat(X, Y, V). 288chars('') --> []. 289 290line(V) --> 291 [X], 292 { 293 X \= '\n' 294 }, 295 line(Y), 296 { 297 atom_concat(X, Y, V) 298 }. 299line('') --> []. 300 301next_line(V, Leading) --> 302 ['\n'], 303 optional_spaces(Leading), 304 line(X), 305 next_line(Y, Leading), !, 306 { 307 ( sub_atom(Y, 0, 1, _, '\n') 308 -> atom_concat(X, Y, V) 309 ; atomic_list_concat([X, ' ', Y], V) 310 ) 311 }. 312next_line(V, Leading, ['\n'|Chars], Rest) :- 313 newlines(X, Chars, Rest1), 314 next_line(Y, Leading, ['\n'|Rest1], Rest), !, 315 atom_concat(X, Y, V). 316next_line('', _) --> []. 317 318next_line_preserving_newline(V, Leading) --> 319 ['\n'], 320 optional_spaces(Leading), 321 line(X), 322 next_line_preserving_newline(Y, Leading), !, 323 { 324 atomic_list_concat([X, '\n', Y], V) 325 }. 326next_line_preserving_newline(V, Leading, ['\n'|Chars], Rest) :- 327 newlines(X, Chars, Rest1), 328 next_line_preserving_newline(Y, Leading, ['\n'|Rest1], Rest), !, 329 atom_concat(X, Y, V). 330next_line_preserving_newline('', _) --> []. 331 332valid_start(V) --> [V], {V \= '-', V \= '[', V \= '{'}. 333 334valid_key_char(V) --> [V], 335 { 336 code_type(V, Type), 337 (Type = csym; Type = period) 338 }. 339 340lookahead([H|_], H)