parser.go

/*
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package candiedyaml

import (
	"bytes"
)

/*
 * The parser implements the following grammar:
 *
 * stream               ::= STREAM-START implicit_document? explicit_document* STREAM-END
 * implicit_document    ::= block_node DOCUMENT-END*
 * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
 * block_node_or_indentless_sequence    ::=
 *                          ALIAS
 *                          | properties (block_content | indentless_block_sequence)?
 *                          | block_content
 *                          | indentless_block_sequence
 * block_node           ::= ALIAS
 *                          | properties block_content?
 *                          | block_content
 * flow_node            ::= ALIAS
 *                          | properties flow_content?
 *                          | flow_content
 * properties           ::= TAG ANCHOR? | ANCHOR TAG?
 * block_content        ::= block_collection | flow_collection | SCALAR
 * flow_content         ::= flow_collection | SCALAR
 * block_collection     ::= block_sequence | block_mapping
 * flow_collection      ::= flow_sequence | flow_mapping
 * block_sequence       ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
 * indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
 * block_mapping        ::= BLOCK-MAPPING_START
 *                          ((KEY block_node_or_indentless_sequence?)?
 *                          (VALUE block_node_or_indentless_sequence?)?)*
 *                          BLOCK-END
 * flow_sequence        ::= FLOW-SEQUENCE-START
 *                          (flow_sequence_entry FLOW-ENTRY)*
 *                          flow_sequence_entry?
 *                          FLOW-SEQUENCE-END
 * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 * flow_mapping         ::= FLOW-MAPPING-START
 *                          (flow_mapping_entry FLOW-ENTRY)*
 *                          flow_mapping_entry?
 *                          FLOW-MAPPING-END
 * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 */

/*
 * Peek the next token in the token queue.
 */
func peek_token(parser *yaml_parser_t) *yaml_token_t {
	if parser.token_available || yaml_parser_fetch_more_tokens(parser) {
		return &parser.tokens[parser.tokens_head]
	}
	return nil
}

/*
 * Remove the next token from the queue (must be called after peek_token).
 */
func skip_token(parser *yaml_parser_t) {
	parser.token_available = false
	parser.tokens_parsed++
	parser.stream_end_produced = parser.tokens[parser.tokens_head].token_type == yaml_STREAM_END_TOKEN
	parser.tokens_head++
}

/*
 * Get the next event.
 */

func yaml_parser_parse(parser *yaml_parser_t, event *yaml_event_t) bool {
	/* Erase the event object. */
	*event = yaml_event_t{}

	/* No events after the end of the stream or error. */

	if parser.stream_end_produced || parser.error != yaml_NO_ERROR ||
		parser.state == yaml_PARSE_END_STATE {
		return true
	}

	/* Generate the next event. */

	return yaml_parser_state_machine(parser, event)
}

/*
 * Set parser error.
 */

func yaml_parser_set_parser_error(parser *yaml_parser_t,
	problem string, problem_mark YAML_mark_t) bool {
	parser.error = yaml_PARSER_ERROR
	parser.problem = problem
	parser.problem_mark = problem_mark

	return false
}

func yaml_parser_set_parser_error_context(parser *yaml_parser_t,
	context string, context_mark YAML_mark_t,
	problem string, problem_mark YAML_mark_t) bool {
	parser.error = yaml_PARSER_ERROR
	parser.context = context
	parser.context_mark = context_mark
	parser.problem = problem
	parser.problem_mark = problem_mark

	return false
}

/*
 * State dispatcher.
 */

func yaml_parser_state_machine(parser *yaml_parser_t, event *yaml_event_t) bool {
	switch parser.state {
	case yaml_PARSE_STREAM_START_STATE:
		return yaml_parser_parse_stream_start(parser, event)

	case yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE:
		return yaml_parser_parse_document_start(parser, event, true)

	case yaml_PARSE_DOCUMENT_START_STATE:
		return yaml_parser_parse_document_start(parser, event, false)

	case yaml_PARSE_DOCUMENT_CONTENT_STATE:
		return yaml_parser_parse_document_content(parser, event)

	case yaml_PARSE_DOCUMENT_END_STATE:
		return yaml_parser_parse_document_end(parser, event)

	case yaml_PARSE_BLOCK_NODE_STATE:
		return yaml_parser_parse_node(parser, event, true, false)

	case yaml_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE:
		return yaml_parser_parse_node(parser, event, true, true)

	case yaml_PARSE_FLOW_NODE_STATE:
		return yaml_parser_parse_node(parser, event, false, false)

	case yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE:
		return yaml_parser_parse_block_sequence_entry(parser, event, true)

	case yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE:
		return yaml_parser_parse_block_sequence_entry(parser, event, false)

	case yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE:
		return yaml_parser_parse_indentless_sequence_entry(parser, event)

	case yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE:
		return yaml_parser_parse_block_mapping_key(parser, event, true)

	case yaml_PARSE_BLOCK_MAPPING_KEY_STATE:
		return yaml_parser_parse_block_mapping_key(parser, event, false)

	case yaml_PARSE_BLOCK_MAPPING_VALUE_STATE:
		return yaml_parser_parse_block_mapping_value(parser, event)

	case yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE:
		return yaml_parser_parse_flow_sequence_entry(parser, event, true)

	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE:
		return yaml_parser_parse_flow_sequence_entry(parser, event, false)

	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE:
		return yaml_parser_parse_flow_sequence_entry_mapping_key(parser, event)

	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE:
		return yaml_parser_parse_flow_sequence_entry_mapping_value(parser, event)

	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE:
		return yaml_parser_parse_flow_sequence_entry_mapping_end(parser, event)

	case yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE:
		return yaml_parser_parse_flow_mapping_key(parser, event, true)

	case yaml_PARSE_FLOW_MAPPING_KEY_STATE:
		return yaml_parser_parse_flow_mapping_key(parser, event, false)

	case yaml_PARSE_FLOW_MAPPING_VALUE_STATE:
		return yaml_parser_parse_flow_mapping_value(parser, event, false)

	case yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE:
		return yaml_parser_parse_flow_mapping_value(parser, event, true)
	}

	panic("invalid parser state")
}

/*
 * Parse the production:
 * stream   ::= STREAM-START implicit_document? explicit_document* STREAM-END
 *              ************
 */

func yaml_parser_parse_stream_start(parser *yaml_parser_t, event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type != yaml_STREAM_START_TOKEN {
		return yaml_parser_set_parser_error(parser,
			"did not find expected <stream-start>", token.start_mark)
	}

	parser.state = yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE
	*event = yaml_event_t{
		event_type: yaml_STREAM_START_EVENT,
		start_mark: token.start_mark,
		end_mark:   token.end_mark,
		encoding:   token.encoding,
	}
	skip_token(parser)

	return true
}

/*
 * Parse the productions:
 * implicit_document    ::= block_node DOCUMENT-END*
 *                          *
 * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
 *                          *************************
 */

func yaml_parser_parse_document_start(parser *yaml_parser_t, event *yaml_event_t,
	implicit bool) bool {

	token := peek_token(parser)
	if token == nil {
		return false
	}

	/* Parse extra document end indicators. */

	if !implicit {
		for token.token_type == yaml_DOCUMENT_END_TOKEN {
			skip_token(parser)
			token = peek_token(parser)
			if token == nil {
				return false
			}
		}
	}

	/* Parse an implicit document. */

	if implicit && token.token_type != yaml_VERSION_DIRECTIVE_TOKEN &&
		token.token_type != yaml_TAG_DIRECTIVE_TOKEN &&
		token.token_type != yaml_DOCUMENT_START_TOKEN &&
		token.token_type != yaml_STREAM_END_TOKEN {
		if !yaml_parser_process_directives(parser, nil, nil) {
			return false
		}

		parser.states = append(parser.states, yaml_PARSE_DOCUMENT_END_STATE)
		parser.state = yaml_PARSE_BLOCK_NODE_STATE

		*event = yaml_event_t{
			event_type: yaml_DOCUMENT_START_EVENT,
			implicit:   true,
			start_mark: token.start_mark,
			end_mark:   token.end_mark,
		}
	} else if token.token_type != yaml_STREAM_END_TOKEN {
		/* Parse an explicit document. */
		var version_directive *yaml_version_directive_t
		var tag_directives []yaml_tag_directive_t

		start_mark := token.start_mark
		if !yaml_parser_process_directives(parser, &version_directive,
			&tag_directives) {
			return false
		}
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_DOCUMENT_START_TOKEN {
			yaml_parser_set_parser_error(parser,
				"did not find expected <document start>", token.start_mark)
			return false
		}

		parser.states = append(parser.states, yaml_PARSE_DOCUMENT_END_STATE)
		parser.state = yaml_PARSE_DOCUMENT_CONTENT_STATE

		end_mark := token.end_mark

		*event = yaml_event_t{
			event_type:        yaml_DOCUMENT_START_EVENT,
			start_mark:        start_mark,
			end_mark:          end_mark,
			version_directive: version_directive,
			tag_directives:    tag_directives,
			implicit:          false,
		}
		skip_token(parser)
	} else {
		/* Parse the stream end. */
		parser.state = yaml_PARSE_END_STATE

		*event = yaml_event_t{
			event_type: yaml_STREAM_END_EVENT,
			start_mark: token.start_mark,
			end_mark:   token.end_mark,
		}
		skip_token(parser)
	}
	return true
}

/*
 * Parse the productions:
 * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
 *                                                    ***********
 */

func yaml_parser_parse_document_content(parser *yaml_parser_t, event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_VERSION_DIRECTIVE_TOKEN ||
		token.token_type == yaml_TAG_DIRECTIVE_TOKEN ||
		token.token_type == yaml_DOCUMENT_START_TOKEN ||
		token.token_type == yaml_DOCUMENT_END_TOKEN ||
		token.token_type == yaml_STREAM_END_TOKEN {
		parser.state = parser.states[len(parser.states)-1]
		parser.states = parser.states[:len(parser.states)-1]
		return yaml_parser_process_empty_scalar(parser, event,
			token.start_mark)
	} else {
		return yaml_parser_parse_node(parser, event, true, false)
	}
}

/*
 * Parse the productions:
 * implicit_document    ::= block_node DOCUMENT-END*
 *                                     *************
 * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
 *                                                                *************
 */

func yaml_parser_parse_document_end(parser *yaml_parser_t, event *yaml_event_t) bool {
	implicit := true

	token := peek_token(parser)
	if token == nil {
		return false
	}

	start_mark, end_mark := token.start_mark, token.start_mark

	if token.token_type == yaml_DOCUMENT_END_TOKEN {
		end_mark = token.end_mark
		skip_token(parser)
		implicit = false
	}

	parser.tag_directives = parser.tag_directives[:0]

	parser.state = yaml_PARSE_DOCUMENT_START_STATE
	*event = yaml_event_t{
		event_type: yaml_DOCUMENT_END_EVENT,
		start_mark: start_mark,
		end_mark:   end_mark,
		implicit:   implicit,
	}

	return true
}

/*
 * Parse the productions:
 * block_node_or_indentless_sequence    ::=
 *                          ALIAS
 *                          *****
 *                          | properties (block_content | indentless_block_sequence)?
 *                            **********  *
 *                          | block_content | indentless_block_sequence
 *                            *
 * block_node           ::= ALIAS
 *                          *****
 *                          | properties block_content?
 *                            ********** *
 *                          | block_content
 *                            *
 * flow_node            ::= ALIAS
 *                          *****
 *                          | properties flow_content?
 *                            ********** *
 *                          | flow_content
 *                            *
 * properties           ::= TAG ANCHOR? | ANCHOR TAG?
 *                          *************************
 * block_content        ::= block_collection | flow_collection | SCALAR
 *                                                               ******
 * flow_content         ::= flow_collection | SCALAR
 *                                            ******
 */

func yaml_parser_parse_node(parser *yaml_parser_t, event *yaml_event_t,
	block bool, indentless_sequence bool) bool {

	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_ALIAS_TOKEN {
		parser.state = parser.states[len(parser.states)-1]
		parser.states = parser.states[:len(parser.states)-1]

		*event = yaml_event_t{
			event_type: yaml_ALIAS_EVENT,
			start_mark: token.start_mark,
			end_mark:   token.end_mark,
			anchor:     token.value,
		}
		skip_token(parser)
		return true
	} else {
		start_mark, end_mark := token.start_mark, token.start_mark

		var tag_handle []byte
		var tag_suffix, anchor []byte
		var tag_mark YAML_mark_t
		if token.token_type == yaml_ANCHOR_TOKEN {
			anchor = token.value
			start_mark = token.start_mark
			end_mark = token.end_mark
			skip_token(parser)
			token = peek_token(parser)
			if token == nil {
				return false
			}
			if token.token_type == yaml_TAG_TOKEN {
				tag_handle = token.value
				tag_suffix = token.suffix
				tag_mark = token.start_mark
				end_mark = token.end_mark
				skip_token(parser)
				token = peek_token(parser)
				if token == nil {
					return false
				}
			}
		} else if token.token_type == yaml_TAG_TOKEN {
			tag_handle = token.value
			tag_suffix = token.suffix
			start_mark, tag_mark = token.start_mark, token.start_mark
			end_mark = token.end_mark
			skip_token(parser)
			token = peek_token(parser)
			if token == nil {
				return false
			}
			if token.token_type == yaml_ANCHOR_TOKEN {
				anchor = token.value
				end_mark = token.end_mark
				skip_token(parser)
				token = peek_token(parser)
				if token == nil {
					return false
				}

			}
		}

		var tag []byte
		if tag_handle != nil {
			if len(tag_handle) == 0 {
				tag = tag_suffix
				tag_handle = nil
				tag_suffix = nil
			} else {
				for i := range parser.tag_directives {
					tag_directive := &parser.tag_directives[i]
					if bytes.Equal(tag_directive.handle, tag_handle) {
						tag = append([]byte(nil), tag_directive.prefix...)
						tag = append(tag, tag_suffix...)
						tag_handle = nil
						tag_suffix = nil
						break
					}
				}
				if len(tag) == 0 {
					yaml_parser_set_parser_error_context(parser,
						"while parsing a node", start_mark,
						"found undefined tag handle", tag_mark)
					return false
				}
			}
		}

		implicit := len(tag) == 0
		if indentless_sequence && token.token_type == yaml_BLOCK_ENTRY_TOKEN {
			end_mark = token.end_mark
			parser.state = yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE

			*event = yaml_event_t{
				event_type: yaml_SEQUENCE_START_EVENT,
				start_mark: start_mark,
				end_mark:   end_mark,
				anchor:     anchor,
				tag:        tag,
				implicit:   implicit,
				style:      yaml_style_t(yaml_BLOCK_SEQUENCE_STYLE),
			}

			return true
		} else {
			if token.token_type == yaml_SCALAR_TOKEN {
				plain_implicit := false
				quoted_implicit := false
				end_mark = token.end_mark
				if (token.style == yaml_PLAIN_SCALAR_STYLE && len(tag) == 0) ||
					(len(tag) == 1 && tag[0] == '!') {
					plain_implicit = true
				} else if len(tag) == 0 {
					quoted_implicit = true
				}

				parser.state = parser.states[len(parser.states)-1]
				parser.states = parser.states[:len(parser.states)-1]

				*event = yaml_event_t{
					event_type:      yaml_SCALAR_EVENT,
					start_mark:      start_mark,
					end_mark:        end_mark,
					anchor:          anchor,
					tag:             tag,
					value:           token.value,
					implicit:        plain_implicit,
					quoted_implicit: quoted_implicit,
					style:           yaml_style_t(token.style),
				}

				skip_token(parser)
				return true
			} else if token.token_type == yaml_FLOW_SEQUENCE_START_TOKEN {
				end_mark = token.end_mark
				parser.state = yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE

				*event = yaml_event_t{
					event_type: yaml_SEQUENCE_START_EVENT,
					start_mark: start_mark,
					end_mark:   end_mark,
					anchor:     anchor,
					tag:        tag,
					implicit:   implicit,
					style:      yaml_style_t(yaml_FLOW_SEQUENCE_STYLE),
				}

				return true
			} else if token.token_type == yaml_FLOW_MAPPING_START_TOKEN {
				end_mark = token.end_mark
				parser.state = yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE

				*event = yaml_event_t{
					event_type: yaml_MAPPING_START_EVENT,
					start_mark: start_mark,
					end_mark:   end_mark,
					anchor:     anchor,
					tag:        tag,
					implicit:   implicit,
					style:      yaml_style_t(yaml_FLOW_MAPPING_STYLE),
				}

				return true
			} else if block && token.token_type == yaml_BLOCK_SEQUENCE_START_TOKEN {
				end_mark = token.end_mark
				parser.state = yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE

				*event = yaml_event_t{
					event_type: yaml_SEQUENCE_START_EVENT,
					start_mark: start_mark,
					end_mark:   end_mark,
					anchor:     anchor,
					tag:        tag,
					implicit:   implicit,
					style:      yaml_style_t(yaml_BLOCK_SEQUENCE_STYLE),
				}

				return true
			} else if block && token.token_type == yaml_BLOCK_MAPPING_START_TOKEN {
				end_mark = token.end_mark
				parser.state = yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE

				*event = yaml_event_t{
					event_type: yaml_MAPPING_START_EVENT,
					start_mark: start_mark,
					end_mark:   end_mark,
					anchor:     anchor,
					tag:        tag,
					implicit:   implicit,
					style:      yaml_style_t(yaml_BLOCK_MAPPING_STYLE),
				}
				return true
			} else if len(anchor) > 0 || len(tag) > 0 {

				parser.state = parser.states[len(parser.states)-1]
				parser.states = parser.states[:len(parser.states)-1]

				*event = yaml_event_t{
					event_type:      yaml_SCALAR_EVENT,
					start_mark:      start_mark,
					end_mark:        end_mark,
					anchor:          anchor,
					tag:             tag,
					implicit:        implicit,
					quoted_implicit: false,
					style:           yaml_style_t(yaml_PLAIN_SCALAR_STYLE),
				}
				return true
			} else {
				msg := "while parsing a block node"
				if !block {
					msg = "while parsing a flow node"
				}
				yaml_parser_set_parser_error_context(parser, msg, start_mark,
					"did not find expected node content", token.start_mark)
				return false
			}
		}
	}

	return false
}

/*
 * Parse the productions:
 * block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
 *                    ********************  *********** *             *********
 */

func yaml_parser_parse_block_sequence_entry(parser *yaml_parser_t,
	event *yaml_event_t, first bool) bool {
	if first {
		token := peek_token(parser)
		parser.marks = append(parser.marks, token.start_mark)
		skip_token(parser)
	}

	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_BLOCK_ENTRY_TOKEN {
		mark := token.end_mark
		skip_token(parser)
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_BLOCK_ENTRY_TOKEN &&
			token.token_type != yaml_BLOCK_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE)
			return yaml_parser_parse_node(parser, event, true, false)
		} else {
			parser.state = yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE
			return yaml_parser_process_empty_scalar(parser, event, mark)
		}
	} else if token.token_type == yaml_BLOCK_END_TOKEN {
		parser.state = parser.states[len(parser.states)-1]
		parser.states = parser.states[:len(parser.states)-1]
		parser.marks = parser.marks[:len(parser.marks)-1]

		*event = yaml_event_t{
			event_type: yaml_SEQUENCE_END_EVENT,
			start_mark: token.start_mark,
			end_mark:   token.end_mark,
		}

		skip_token(parser)
		return true
	} else {
		mark := parser.marks[len(parser.marks)-1]
		parser.marks = parser.marks[:len(parser.marks)-1]

		return yaml_parser_set_parser_error_context(parser,
			"while parsing a block collection", mark,
			"did not find expected '-' indicator", token.start_mark)
	}
}

/*
 * Parse the productions:
 * indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
 *                           *********** *
 */

func yaml_parser_parse_indentless_sequence_entry(parser *yaml_parser_t,
	event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_BLOCK_ENTRY_TOKEN {
		mark := token.end_mark
		skip_token(parser)
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_BLOCK_ENTRY_TOKEN &&
			token.token_type != yaml_KEY_TOKEN &&
			token.token_type != yaml_VALUE_TOKEN &&
			token.token_type != yaml_BLOCK_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE)
			return yaml_parser_parse_node(parser, event, true, false)
		} else {
			parser.state = yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE
			return yaml_parser_process_empty_scalar(parser, event, mark)
		}
	} else {
		parser.state = parser.states[len(parser.states)-1]
		parser.states = parser.states[:len(parser.states)-1]

		*event = yaml_event_t{
			event_type: yaml_SEQUENCE_END_EVENT,
			start_mark: token.start_mark,
			end_mark:   token.start_mark,
		}
		return true
	}
}

/*
 * Parse the productions:
 * block_mapping        ::= BLOCK-MAPPING_START
 *                          *******************
 *                          ((KEY block_node_or_indentless_sequence?)?
 *                            *** *
 *                          (VALUE block_node_or_indentless_sequence?)?)*
 *
 *                          BLOCK-END
 *                          *********
 */

func yaml_parser_parse_block_mapping_key(parser *yaml_parser_t,
	event *yaml_event_t, first bool) bool {
	if first {
		token := peek_token(parser)
		parser.marks = append(parser.marks, token.start_mark)
		skip_token(parser)
	}

	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_KEY_TOKEN {
		mark := token.end_mark
		skip_token(parser)
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_KEY_TOKEN &&
			token.token_type != yaml_VALUE_TOKEN &&
			token.token_type != yaml_BLOCK_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_BLOCK_MAPPING_VALUE_STATE)
			return yaml_parser_parse_node(parser, event, true, true)
		} else {
			parser.state = yaml_PARSE_BLOCK_MAPPING_VALUE_STATE
			return yaml_parser_process_empty_scalar(parser, event, mark)
		}
	} else if token.token_type == yaml_BLOCK_END_TOKEN {
		parser.state = parser.states[len(parser.states)-1]
		parser.states = parser.states[:len(parser.states)-1]
		parser.marks = parser.marks[:len(parser.marks)-1]
		*event = yaml_event_t{
			event_type: yaml_MAPPING_END_EVENT,
			start_mark: token.start_mark,
			end_mark:   token.end_mark,
		}
		skip_token(parser)
		return true
	} else {
		mark := parser.marks[len(parser.marks)-1]
		parser.marks = parser.marks[:len(parser.marks)-1]

		return yaml_parser_set_parser_error_context(parser,
			"while parsing a block mapping", mark,
			"did not find expected key", token.start_mark)
	}
}

/*
 * Parse the productions:
 * block_mapping        ::= BLOCK-MAPPING_START
 *
 *                          ((KEY block_node_or_indentless_sequence?)?
 *
 *                          (VALUE block_node_or_indentless_sequence?)?)*
 *                           ***** *
 *                          BLOCK-END
 *
 */

func yaml_parser_parse_block_mapping_value(parser *yaml_parser_t,
	event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_VALUE_TOKEN {
		mark := token.end_mark
		skip_token(parser)
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_KEY_TOKEN &&
			token.token_type != yaml_VALUE_TOKEN &&
			token.token_type != yaml_BLOCK_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_BLOCK_MAPPING_KEY_STATE)
			return yaml_parser_parse_node(parser, event, true, true)
		} else {
			parser.state = yaml_PARSE_BLOCK_MAPPING_KEY_STATE
			return yaml_parser_process_empty_scalar(parser, event, mark)
		}
	} else {
		parser.state = yaml_PARSE_BLOCK_MAPPING_KEY_STATE
		return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
	}
}

/*
 * Parse the productions:
 * flow_sequence        ::= FLOW-SEQUENCE-START
 *                          *******************
 *                          (flow_sequence_entry FLOW-ENTRY)*
 *                           *                   **********
 *                          flow_sequence_entry?
 *                          *
 *                          FLOW-SEQUENCE-END
 *                          *****************
 * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 *                          *
 */

func yaml_parser_parse_flow_sequence_entry(parser *yaml_parser_t,
	event *yaml_event_t, first bool) bool {
	if first {
		token := peek_token(parser)
		parser.marks = append(parser.marks, token.start_mark)
		skip_token(parser)
	}

	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type != yaml_FLOW_SEQUENCE_END_TOKEN {
		if !first {
			if token.token_type == yaml_FLOW_ENTRY_TOKEN {
				skip_token(parser)
				token = peek_token(parser)
				if token == nil {
					return false
				}
			} else {
				mark := parser.marks[len(parser.marks)-1]
				parser.marks = parser.marks[:len(parser.marks)-1]

				return yaml_parser_set_parser_error_context(parser,
					"while parsing a flow sequence", mark,
					"did not find expected ',' or ']'", token.start_mark)
			}
		}

		if token.token_type == yaml_KEY_TOKEN {
			parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE
			*event = yaml_event_t{
				event_type: yaml_MAPPING_START_EVENT,
				start_mark: token.start_mark,
				end_mark:   token.end_mark,
				implicit:   true,
				style:      yaml_style_t(yaml_FLOW_MAPPING_STYLE),
			}

			skip_token(parser)
			return true
		} else if token.token_type != yaml_FLOW_SEQUENCE_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE)
			return yaml_parser_parse_node(parser, event, false, false)
		}
	}

	parser.state = parser.states[len(parser.states)-1]
	parser.states = parser.states[:len(parser.states)-1]
	parser.marks = parser.marks[:len(parser.marks)-1]

	*event = yaml_event_t{
		event_type: yaml_SEQUENCE_END_EVENT,
		start_mark: token.start_mark,
		end_mark:   token.end_mark,
	}

	skip_token(parser)
	return true
}

/*
 * Parse the productions:
 * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 *                                      *** *
 */

func yaml_parser_parse_flow_sequence_entry_mapping_key(parser *yaml_parser_t,
	event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type != yaml_VALUE_TOKEN &&
		token.token_type != yaml_FLOW_ENTRY_TOKEN &&
		token.token_type != yaml_FLOW_SEQUENCE_END_TOKEN {
		parser.states = append(parser.states, yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE)
		return yaml_parser_parse_node(parser, event, false, false)
	} else {
		mark := token.end_mark
		skip_token(parser)
		parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE
		return yaml_parser_process_empty_scalar(parser, event, mark)
	}
}

/*
 * Parse the productions:
 * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 *                                                      ***** *
 */

func yaml_parser_parse_flow_sequence_entry_mapping_value(parser *yaml_parser_t,
	event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type == yaml_VALUE_TOKEN {
		skip_token(parser)
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_FLOW_ENTRY_TOKEN &&
			token.token_type != yaml_FLOW_SEQUENCE_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE)
			return yaml_parser_parse_node(parser, event, false, false)
		}
	}
	parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE
	return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
}

/*
 * Parse the productions:
 * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 *                                                                      *
 */

func yaml_parser_parse_flow_sequence_entry_mapping_end(parser *yaml_parser_t,
	event *yaml_event_t) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE
	*event = yaml_event_t{
		event_type: yaml_MAPPING_END_EVENT,
		start_mark: token.start_mark,
		end_mark:   token.start_mark,
	}

	return true
}

/*
 * Parse the productions:
 * flow_mapping         ::= FLOW-MAPPING-START
 *                          ******************
 *                          (flow_mapping_entry FLOW-ENTRY)*
 *                           *                  **********
 *                          flow_mapping_entry?
 *                          ******************
 *                          FLOW-MAPPING-END
 *                          ****************
 * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 *                          *           *** *
 */

func yaml_parser_parse_flow_mapping_key(parser *yaml_parser_t,
	event *yaml_event_t, first bool) bool {
	if first {
		token := peek_token(parser)
		parser.marks = append(parser.marks, token.start_mark)
		skip_token(parser)
	}

	token := peek_token(parser)
	if token == nil {
		return false
	}

	if token.token_type != yaml_FLOW_MAPPING_END_TOKEN {
		if !first {
			if token.token_type == yaml_FLOW_ENTRY_TOKEN {
				skip_token(parser)
				token = peek_token(parser)
				if token == nil {
					return false
				}
			} else {
				mark := parser.marks[len(parser.marks)-1]
				parser.marks = parser.marks[:len(parser.marks)-1]

				return yaml_parser_set_parser_error_context(parser,
					"while parsing a flow mapping", mark,
					"did not find expected ',' or '}'", token.start_mark)
			}
		}

		if token.token_type == yaml_KEY_TOKEN {
			skip_token(parser)
			token = peek_token(parser)
			if token == nil {
				return false
			}
			if token.token_type != yaml_VALUE_TOKEN &&
				token.token_type != yaml_FLOW_ENTRY_TOKEN &&
				token.token_type != yaml_FLOW_MAPPING_END_TOKEN {
				parser.states = append(parser.states, yaml_PARSE_FLOW_MAPPING_VALUE_STATE)
				return yaml_parser_parse_node(parser, event, false, false)
			} else {
				parser.state = yaml_PARSE_FLOW_MAPPING_VALUE_STATE
				return yaml_parser_process_empty_scalar(parser, event,
					token.start_mark)
			}
		} else if token.token_type != yaml_FLOW_MAPPING_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE)
			return yaml_parser_parse_node(parser, event, false, false)
		}
	}

	parser.state = parser.states[len(parser.states)-1]
	parser.states = parser.states[:len(parser.states)-1]
	parser.marks = parser.marks[:len(parser.marks)-1]
	*event = yaml_event_t{
		event_type: yaml_MAPPING_END_EVENT,
		start_mark: token.start_mark,
		end_mark:   token.end_mark,
	}

	skip_token(parser)
	return true
}

/*
 * Parse the productions:
 * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
 *                                   *                  ***** *
 */

func yaml_parser_parse_flow_mapping_value(parser *yaml_parser_t,
	event *yaml_event_t, empty bool) bool {
	token := peek_token(parser)
	if token == nil {
		return false
	}

	if empty {
		parser.state = yaml_PARSE_FLOW_MAPPING_KEY_STATE
		return yaml_parser_process_empty_scalar(parser, event,
			token.start_mark)
	}

	if token.token_type == yaml_VALUE_TOKEN {
		skip_token(parser)
		token = peek_token(parser)
		if token == nil {
			return false
		}
		if token.token_type != yaml_FLOW_ENTRY_TOKEN &&
			token.token_type != yaml_FLOW_MAPPING_END_TOKEN {
			parser.states = append(parser.states, yaml_PARSE_FLOW_MAPPING_KEY_STATE)
			return yaml_parser_parse_node(parser, event, false, false)
		}
	}

	parser.state = yaml_PARSE_FLOW_MAPPING_KEY_STATE
	return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
}

/*
 * Generate an empty scalar event.
 */

func yaml_parser_process_empty_scalar(parser *yaml_parser_t, event *yaml_event_t,
	mark YAML_mark_t) bool {
	*event = yaml_event_t{
		event_type: yaml_SCALAR_EVENT,
		start_mark: mark,
		end_mark:   mark,
		value:      nil,
		implicit:   true,
		style:      yaml_style_t(yaml_PLAIN_SCALAR_STYLE),
	}

	return true
}

/*
 * Parse directives.
 */

func yaml_parser_process_directives(parser *yaml_parser_t,
	version_directive_ref **yaml_version_directive_t,
	tag_directives_ref *[]yaml_tag_directive_t) bool {

	token := peek_token(parser)
	if token == nil {
		return false
	}

	var version_directive *yaml_version_directive_t
	var tag_directives []yaml_tag_directive_t

	for token.token_type == yaml_VERSION_DIRECTIVE_TOKEN ||
		token.token_type == yaml_TAG_DIRECTIVE_TOKEN {
		if token.token_type == yaml_VERSION_DIRECTIVE_TOKEN {
			if version_directive != nil {
				yaml_parser_set_parser_error(parser,
					"found duplicate %YAML directive", token.start_mark)
				return false
			}
			if token.major != 1 ||
				token.minor != 1 {
				yaml_parser_set_parser_error(parser,
					"found incompatible YAML document", token.start_mark)
				return false
			}
			version_directive = &yaml_version_directive_t{
				major: token.major,
				minor: token.minor,
			}
		} else if token.token_type == yaml_TAG_DIRECTIVE_TOKEN {
			value := yaml_tag_directive_t{
				handle: token.value,
				prefix: token.prefix,
			}

			if !yaml_parser_append_tag_directive(parser, value, false,
				token.start_mark) {
				return false
			}
			tag_directives = append(tag_directives, value)
		}

		skip_token(parser)
		token := peek_token(parser)
		if token == nil {
			return false
		}
	}

	for i := range default_tag_directives {
		if !yaml_parser_append_tag_directive(parser, default_tag_directives[i], true, token.start_mark) {
			return false
		}
	}

	if version_directive_ref != nil {
		*version_directive_ref = version_directive
	}
	if tag_directives_ref != nil {
		*tag_directives_ref = tag_directives
	}

	return true
}

/*
 * Append a tag directive to the directives stack.
 */

func yaml_parser_append_tag_directive(parser *yaml_parser_t,
	value yaml_tag_directive_t, allow_duplicates bool, mark YAML_mark_t) bool {
	for i := range parser.tag_directives {
		tag := &parser.tag_directives[i]
		if bytes.Equal(value.handle, tag.handle) {
			if allow_duplicates {
				return true
			}
			return yaml_parser_set_parser_error(parser, "found duplicate %TAG directive", mark)
		}
	}

	parser.tag_directives = append(parser.tag_directives, value)
	return true
}