src/parser.c

   1
   2 /*
   3  * The parser implements the following grammar:
   4  *
   5  * stream               ::= STREAM-START implicit_document? explicit_document* STREAM-END
   6  * implicit_document    ::= block_node DOCUMENT-END*
   7  * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
   8  * block_node_or_indentless_sequence    ::=
   9  *                          ALIAS
  10  *                          | properties (block_content | indentless_block_sequence)?
  11  *                          | block_content
  12  *                          | indentless_block_sequence
  13  * block_node           ::= ALIAS
  14  *                          | properties block_content?
  15  *                          | block_content
  16  * flow_node            ::= ALIAS
  17  *                          | properties flow_content?
  18  *                          | flow_content
  19  * properties           ::= TAG ANCHOR? | ANCHOR TAG?
  20  * block_content        ::= block_collection | flow_collection | SCALAR
  21  * flow_content         ::= flow_collection | SCALAR
  22  * block_collection     ::= block_sequence | block_mapping
  23  * flow_collection      ::= flow_sequence | flow_mapping
  24  * block_sequence       ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
  25  * indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
  26  * block_mapping        ::= BLOCK-MAPPING_START
  27  *                          ((KEY block_node_or_indentless_sequence?)?
  28  *                          (VALUE block_node_or_indentless_sequence?)?)*
  29  *                          BLOCK-END
  30  * flow_sequence        ::= FLOW-SEQUENCE-START
  31  *                          (flow_sequence_entry FLOW-ENTRY)*
  32  *                          flow_sequence_entry?
  33  *                          FLOW-SEQUENCE-END
  34  * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
  35  * flow_mapping         ::= FLOW-MAPPING-START
  36  *                          (flow_mapping_entry FLOW-ENTRY)*
  37  *                          flow_mapping_entry?
  38  *                          FLOW-MAPPING-END
  39  * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
  40  */
  41
  42 #if HAVE_CONFIG_H
  43 #include <config.h>
  44 #endif
  45
  46 #include <yaml.h>
  47
  48 #include <assert.h>
  49
  50 /*
  51  * Public API declarations.
  52  */
  53
  54 YAML_DECLARE(yaml_event_t *)
  55 yaml_parser_get_event(yaml_parser_t *parser);
  56
  57 YAML_DECLARE(yaml_event_t *)
  58 yaml_parser_peek_event(yaml_parser_t *parser);
  59
  60 /*
  61  * State functions.
  62  */
  63
  64 static yaml_event_t *
  65 yaml_parser_state_machine(yaml_parser_t *parser);
  66
  67 static yaml_event_t *
  68 yaml_parser_parse_stream_start(yaml_parser_t *parser);
  69
  70 static yaml_event_t *
  71 yaml_parser_parse_document_start(yaml_parser_t *parser, int implicit);
  72
  73 static yaml_event_t *
  74 yaml_parser_parse_document_content(yaml_parser_t *parser);
  75
  76 static yaml_event_t *
  77 yaml_parser_parse_document_end(yaml_parser_t *parser);
  78
  79 static yaml_event_t *
  80 yaml_parser_parse_node(yaml_parser_t *parser,
  81         int block, int indentless_sequence);
  82
  83 static yaml_event_t *
  84 yaml_parser_parse_block_sequence_entry(yaml_parser_t *parser, int first);
  85
  86 static yaml_event_t *
  87 yaml_parser_parse_indentless_sequence_entry(yaml_parser_t *parser);
  88
  89 static yaml_event_t *
  90 yaml_parser_parse_block_mapping_key(yaml_parser_t *parser, int first);
  91
  92 static yaml_event_t *
  93 yaml_parser_parse_block_mapping_value(yaml_parser_t *parser);
  94
  95 static yaml_event_t *
  96 yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser, int first);
  97
  98 static yaml_event_t *
  99 yaml_parser_parse_flow_sequence_entry_mapping_key(yaml_parser_t *parser);
 100
 101 static yaml_event_t *
 102 yaml_parser_parse_flow_sequence_entry_mapping_value(yaml_parser_t *parser);
 103
 104 static yaml_event_t *
 105 yaml_parser_parse_flow_sequence_entry_mapping_end(yaml_parser_t *parser);
 106
 107 static yaml_event_t *
 108 yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser, int first);
 109
 110 static yaml_event_t *
 111 yaml_parser_parse_flow_mapping_value(yaml_parser_t *parser, int empty);
 112
 113 /*
 114  * Get the next event and advance the parser.
 115  */
 116
 117 YAML_DECLARE(yaml_event_t *)
 118 yaml_parser_get_event(yaml_parser_t *parser)
 119 {
 120     yaml_event_t *value;
 121
 122     /* Update the current event if needed. */
 123
 124     if (!parser->current_event) {
 125         parser->current_event = yaml_parser_state_machine(parser);
 126     }
 127
 128     /* Return and clear the current event. */
 129
 130     value = parser->current_event;
 131     parser->current_event = NULL;
 132     return value;
 133 }
 134
 135 /*
 136  * Peek the next event.
 137  */
 138
 139 YAML_DECLARE(yaml_event_t *)
 140 yaml_parser_peek_event(yaml_parser_t *parser)
 141 {
 142     yaml_event_t *value;
 143
 144     /* Update the current event if needed. */
 145
 146     if (!parser->current_event) {
 147         parser->current_event = yaml_parser_state_machine(parser);
 148     }
 149
 150     /* Return the current event. */
 151
 152     return parser->current_event;
 153 }
 154
 155 /*
 156  * State dispatcher.
 157  */
 158
 159 static yaml_event_t *
 160 yaml_parser_state_machine(yaml_parser_t *parser)
 161 {
 162     assert (parser->state != YAML_PARSE_END_STATE);
 163
 164     switch (parser->state)
 165     {
 166         case YAML_PARSE_STREAM_START_STATE:
 167             return yaml_parser_parse_stream_start(parser);
 168
 169         case YAML_PARSE_IMPLICIT_DOCUMENT_START_STATE:
 170             return yaml_parser_parse_document_start(parser, 1);
 171
 172         case YAML_PARSE_DOCUMENT_START_STATE:
 173             return yaml_parser_parse_document_start(parser, 0);
 174
 175         case YAML_PARSE_DOCUMENT_CONTENT_STATE:
 176             return yaml_parser_parse_document_content(parser);
 177
 178         case YAML_PARSE_DOCUMENT_END_STATE:
 179             return yaml_parser_parse_document_end(parser);
 180
 181         case YAML_PARSE_BLOCK_NODE_STATE:
 182             return yaml_parser_parse_node(parser, 1, 0);
 183
 184         case YAML_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE:
 185             return yaml_parser_parse_node(parser, 1, 1);
 186
 187         case YAML_PARSE_FLOW_NODE_STATE:
 188             return yaml_parser_parse_node(parser, 0, 0);
 189
 190         case YAML_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE:
 191             return yaml_parser_parse_block_sequence_entry(parser, 1);
 192
 193         case YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE:
 194             return yaml_parser_parse_block_sequence_entry(parser, 0);
 195
 196         case YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE:
 197             return yaml_parser_parse_indentless_sequence_entry(parser);
 198
 199         case YAML_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE:
 200             return yaml_parser_parse_block_mapping_key(parser, 1);
 201
 202         case YAML_PARSE_BLOCK_MAPPING_KEY_STATE:
 203             return yaml_parser_parse_block_mapping_key(parser, 0);
 204
 205         case YAML_PARSE_BLOCK_MAPPING_VALUE_STATE:
 206             return yaml_parser_parse_block_mapping_value(parser);
 207
 208         case YAML_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE:
 209             return yaml_parser_parse_flow_sequence_entry(parser, 1);
 210
 211         case YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE:
 212             return yaml_parser_parse_flow_sequence_entry(parser, 0);
 213
 214         case YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE:
 215             return yaml_parser_parse_flow_sequence_entry_mapping_key(parser);
 216
 217         case YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE:
 218             return yaml_parser_parse_flow_sequence_entry_mapping_value(parser);
 219
 220         case YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE:
 221             return yaml_parser_parse_flow_sequence_entry_mapping_end(parser);
 222
 223         case YAML_PARSE_FLOW_MAPPING_FIRST_KEY_STATE:
 224             return yaml_parser_parse_flow_mapping_key(parser, 1);
 225
 226         case YAML_PARSE_FLOW_MAPPING_KEY_STATE:
 227             return yaml_parser_parse_flow_mapping_key(parser, 0);
 228
 229         case YAML_PARSE_FLOW_MAPPING_VALUE_STATE:
 230             return yaml_parser_parse_flow_mapping_value(parser, 0);
 231
 232         case YAML_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE:
 233             return yaml_parser_parse_flow_mapping_value(parser, 1);
 234     }
 235     assert(1);
 236 }
 237