github.com/mfpierre/corectl@v0.5.6/Godeps/_workspace/src/gopkg.in/yaml.v2/emitterc.go (about)

     1  package yaml
     2  
     3  import (
     4  	"bytes"
     5  )
     6  
     7  // Flush the buffer if needed.
     8  func flush(emitter *yaml_emitter_t) bool {
     9  	if emitter.buffer_pos+5 >= len(emitter.buffer) {
    10  		return yaml_emitter_flush(emitter)
    11  	}
    12  	return true
    13  }
    14  
    15  // Put a character to the output buffer.
    16  func put(emitter *yaml_emitter_t, value byte) bool {
    17  	if emitter.buffer_pos+5 >= len(emitter.buffer) && !yaml_emitter_flush(emitter) {
    18  		return false
    19  	}
    20  	emitter.buffer[emitter.buffer_pos] = value
    21  	emitter.buffer_pos++
    22  	emitter.column++
    23  	return true
    24  }
    25  
    26  // Put a line break to the output buffer.
    27  func put_break(emitter *yaml_emitter_t) bool {
    28  	if emitter.buffer_pos+5 >= len(emitter.buffer) && !yaml_emitter_flush(emitter) {
    29  		return false
    30  	}
    31  	switch emitter.line_break {
    32  	case yaml_CR_BREAK:
    33  		emitter.buffer[emitter.buffer_pos] = '\r'
    34  		emitter.buffer_pos += 1
    35  	case yaml_LN_BREAK:
    36  		emitter.buffer[emitter.buffer_pos] = '\n'
    37  		emitter.buffer_pos += 1
    38  	case yaml_CRLN_BREAK:
    39  		emitter.buffer[emitter.buffer_pos+0] = '\r'
    40  		emitter.buffer[emitter.buffer_pos+1] = '\n'
    41  		emitter.buffer_pos += 2
    42  	default:
    43  		panic("unknown line break setting")
    44  	}
    45  	emitter.column = 0
    46  	emitter.line++
    47  	return true
    48  }
    49  
    50  // Copy a character from a string into buffer.
    51  func write(emitter *yaml_emitter_t, s []byte, i *int) bool {
    52  	if emitter.buffer_pos+5 >= len(emitter.buffer) && !yaml_emitter_flush(emitter) {
    53  		return false
    54  	}
    55  	p := emitter.buffer_pos
    56  	w := width(s[*i])
    57  	switch w {
    58  	case 4:
    59  		emitter.buffer[p+3] = s[*i+3]
    60  		fallthrough
    61  	case 3:
    62  		emitter.buffer[p+2] = s[*i+2]
    63  		fallthrough
    64  	case 2:
    65  		emitter.buffer[p+1] = s[*i+1]
    66  		fallthrough
    67  	case 1:
    68  		emitter.buffer[p+0] = s[*i+0]
    69  	default:
    70  		panic("unknown character width")
    71  	}
    72  	emitter.column++
    73  	emitter.buffer_pos += w
    74  	*i += w
    75  	return true
    76  }
    77  
    78  // Write a whole string into buffer.
    79  func write_all(emitter *yaml_emitter_t, s []byte) bool {
    80  	for i := 0; i < len(s); {
    81  		if !write(emitter, s, &i) {
    82  			return false
    83  		}
    84  	}
    85  	return true
    86  }
    87  
    88  // Copy a line break character from a string into buffer.
    89  func write_break(emitter *yaml_emitter_t, s []byte, i *int) bool {
    90  	if s[*i] == '\n' {
    91  		if !put_break(emitter) {
    92  			return false
    93  		}
    94  		*i++
    95  	} else {
    96  		if !write(emitter, s, i) {
    97  			return false
    98  		}
    99  		emitter.column = 0
   100  		emitter.line++
   101  	}
   102  	return true
   103  }
   104  
   105  // Set an emitter error and return false.
   106  func yaml_emitter_set_emitter_error(emitter *yaml_emitter_t, problem string) bool {
   107  	emitter.error = yaml_EMITTER_ERROR
   108  	emitter.problem = problem
   109  	return false
   110  }
   111  
   112  // Emit an event.
   113  func yaml_emitter_emit(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   114  	emitter.events = append(emitter.events, *event)
   115  	for !yaml_emitter_need_more_events(emitter) {
   116  		event := &emitter.events[emitter.events_head]
   117  		if !yaml_emitter_analyze_event(emitter, event) {
   118  			return false
   119  		}
   120  		if !yaml_emitter_state_machine(emitter, event) {
   121  			return false
   122  		}
   123  		yaml_event_delete(event)
   124  		emitter.events_head++
   125  	}
   126  	return true
   127  }
   128  
   129  // Check if we need to accumulate more events before emitting.
   130  //
   131  // We accumulate extra
   132  //  - 1 event for DOCUMENT-START
   133  //  - 2 events for SEQUENCE-START
   134  //  - 3 events for MAPPING-START
   135  //
   136  func yaml_emitter_need_more_events(emitter *yaml_emitter_t) bool {
   137  	if emitter.events_head == len(emitter.events) {
   138  		return true
   139  	}
   140  	var accumulate int
   141  	switch emitter.events[emitter.events_head].typ {
   142  	case yaml_DOCUMENT_START_EVENT:
   143  		accumulate = 1
   144  		break
   145  	case yaml_SEQUENCE_START_EVENT:
   146  		accumulate = 2
   147  		break
   148  	case yaml_MAPPING_START_EVENT:
   149  		accumulate = 3
   150  		break
   151  	default:
   152  		return false
   153  	}
   154  	if len(emitter.events)-emitter.events_head > accumulate {
   155  		return false
   156  	}
   157  	var level int
   158  	for i := emitter.events_head; i < len(emitter.events); i++ {
   159  		switch emitter.events[i].typ {
   160  		case yaml_STREAM_START_EVENT, yaml_DOCUMENT_START_EVENT, yaml_SEQUENCE_START_EVENT, yaml_MAPPING_START_EVENT:
   161  			level++
   162  		case yaml_STREAM_END_EVENT, yaml_DOCUMENT_END_EVENT, yaml_SEQUENCE_END_EVENT, yaml_MAPPING_END_EVENT:
   163  			level--
   164  		}
   165  		if level == 0 {
   166  			return false
   167  		}
   168  	}
   169  	return true
   170  }
   171  
   172  // Append a directive to the directives stack.
   173  func yaml_emitter_append_tag_directive(emitter *yaml_emitter_t, value *yaml_tag_directive_t, allow_duplicates bool) bool {
   174  	for i := 0; i < len(emitter.tag_directives); i++ {
   175  		if bytes.Equal(value.handle, emitter.tag_directives[i].handle) {
   176  			if allow_duplicates {
   177  				return true
   178  			}
   179  			return yaml_emitter_set_emitter_error(emitter, "duplicate %TAG directive")
   180  		}
   181  	}
   182  
   183  	// [Go] Do we actually need to copy this given garbage collection
   184  	// and the lack of deallocating destructors?
   185  	tag_copy := yaml_tag_directive_t{
   186  		handle: make([]byte, len(value.handle)),
   187  		prefix: make([]byte, len(value.prefix)),
   188  	}
   189  	copy(tag_copy.handle, value.handle)
   190  	copy(tag_copy.prefix, value.prefix)
   191  	emitter.tag_directives = append(emitter.tag_directives, tag_copy)
   192  	return true
   193  }
   194  
   195  // Increase the indentation level.
   196  func yaml_emitter_increase_indent(emitter *yaml_emitter_t, flow, indentless bool) bool {
   197  	emitter.indents = append(emitter.indents, emitter.indent)
   198  	if emitter.indent < 0 {
   199  		if flow {
   200  			emitter.indent = emitter.best_indent
   201  		} else {
   202  			emitter.indent = 0
   203  		}
   204  	} else if !indentless {
   205  		emitter.indent += emitter.best_indent
   206  	}
   207  	return true
   208  }
   209  
   210  // State dispatcher.
   211  func yaml_emitter_state_machine(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   212  	switch emitter.state {
   213  	default:
   214  	case yaml_EMIT_STREAM_START_STATE:
   215  		return yaml_emitter_emit_stream_start(emitter, event)
   216  
   217  	case yaml_EMIT_FIRST_DOCUMENT_START_STATE:
   218  		return yaml_emitter_emit_document_start(emitter, event, true)
   219  
   220  	case yaml_EMIT_DOCUMENT_START_STATE:
   221  		return yaml_emitter_emit_document_start(emitter, event, false)
   222  
   223  	case yaml_EMIT_DOCUMENT_CONTENT_STATE:
   224  		return yaml_emitter_emit_document_content(emitter, event)
   225  
   226  	case yaml_EMIT_DOCUMENT_END_STATE:
   227  		return yaml_emitter_emit_document_end(emitter, event)
   228  
   229  	case yaml_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE:
   230  		return yaml_emitter_emit_flow_sequence_item(emitter, event, true)
   231  
   232  	case yaml_EMIT_FLOW_SEQUENCE_ITEM_STATE:
   233  		return yaml_emitter_emit_flow_sequence_item(emitter, event, false)
   234  
   235  	case yaml_EMIT_FLOW_MAPPING_FIRST_KEY_STATE:
   236  		return yaml_emitter_emit_flow_mapping_key(emitter, event, true)
   237  
   238  	case yaml_EMIT_FLOW_MAPPING_KEY_STATE:
   239  		return yaml_emitter_emit_flow_mapping_key(emitter, event, false)
   240  
   241  	case yaml_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE:
   242  		return yaml_emitter_emit_flow_mapping_value(emitter, event, true)
   243  
   244  	case yaml_EMIT_FLOW_MAPPING_VALUE_STATE:
   245  		return yaml_emitter_emit_flow_mapping_value(emitter, event, false)
   246  
   247  	case yaml_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE:
   248  		return yaml_emitter_emit_block_sequence_item(emitter, event, true)
   249  
   250  	case yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE:
   251  		return yaml_emitter_emit_block_sequence_item(emitter, event, false)
   252  
   253  	case yaml_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE:
   254  		return yaml_emitter_emit_block_mapping_key(emitter, event, true)
   255  
   256  	case yaml_EMIT_BLOCK_MAPPING_KEY_STATE:
   257  		return yaml_emitter_emit_block_mapping_key(emitter, event, false)
   258  
   259  	case yaml_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE:
   260  		return yaml_emitter_emit_block_mapping_value(emitter, event, true)
   261  
   262  	case yaml_EMIT_BLOCK_MAPPING_VALUE_STATE:
   263  		return yaml_emitter_emit_block_mapping_value(emitter, event, false)
   264  
   265  	case yaml_EMIT_END_STATE:
   266  		return yaml_emitter_set_emitter_error(emitter, "expected nothing after STREAM-END")
   267  	}
   268  	panic("invalid emitter state")
   269  }
   270  
   271  // Expect STREAM-START.
   272  func yaml_emitter_emit_stream_start(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   273  	if event.typ != yaml_STREAM_START_EVENT {
   274  		return yaml_emitter_set_emitter_error(emitter, "expected STREAM-START")
   275  	}
   276  	if emitter.encoding == yaml_ANY_ENCODING {
   277  		emitter.encoding = event.encoding
   278  		if emitter.encoding == yaml_ANY_ENCODING {
   279  			emitter.encoding = yaml_UTF8_ENCODING
   280  		}
   281  	}
   282  	if emitter.best_indent < 2 || emitter.best_indent > 9 {
   283  		emitter.best_indent = 2
   284  	}
   285  	if emitter.best_width >= 0 && emitter.best_width <= emitter.best_indent*2 {
   286  		emitter.best_width = 80
   287  	}
   288  	if emitter.best_width < 0 {
   289  		emitter.best_width = 1<<31 - 1
   290  	}
   291  	if emitter.line_break == yaml_ANY_BREAK {
   292  		emitter.line_break = yaml_LN_BREAK
   293  	}
   294  
   295  	emitter.indent = -1
   296  	emitter.line = 0
   297  	emitter.column = 0
   298  	emitter.whitespace = true
   299  	emitter.indention = true
   300  
   301  	if emitter.encoding != yaml_UTF8_ENCODING {
   302  		if !yaml_emitter_write_bom(emitter) {
   303  			return false
   304  		}
   305  	}
   306  	emitter.state = yaml_EMIT_FIRST_DOCUMENT_START_STATE
   307  	return true
   308  }
   309  
   310  // Expect DOCUMENT-START or STREAM-END.
   311  func yaml_emitter_emit_document_start(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
   312  
   313  	if event.typ == yaml_DOCUMENT_START_EVENT {
   314  
   315  		if event.version_directive != nil {
   316  			if !yaml_emitter_analyze_version_directive(emitter, event.version_directive) {
   317  				return false
   318  			}
   319  		}
   320  
   321  		for i := 0; i < len(event.tag_directives); i++ {
   322  			tag_directive := &event.tag_directives[i]
   323  			if !yaml_emitter_analyze_tag_directive(emitter, tag_directive) {
   324  				return false
   325  			}
   326  			if !yaml_emitter_append_tag_directive(emitter, tag_directive, false) {
   327  				return false
   328  			}
   329  		}
   330  
   331  		for i := 0; i < len(default_tag_directives); i++ {
   332  			tag_directive := &default_tag_directives[i]
   333  			if !yaml_emitter_append_tag_directive(emitter, tag_directive, true) {
   334  				return false
   335  			}
   336  		}
   337  
   338  		implicit := event.implicit
   339  		if !first || emitter.canonical {
   340  			implicit = false
   341  		}
   342  
   343  		if emitter.open_ended && (event.version_directive != nil || len(event.tag_directives) > 0) {
   344  			if !yaml_emitter_write_indicator(emitter, []byte("..."), true, false, false) {
   345  				return false
   346  			}
   347  			if !yaml_emitter_write_indent(emitter) {
   348  				return false
   349  			}
   350  		}
   351  
   352  		if event.version_directive != nil {
   353  			implicit = false
   354  			if !yaml_emitter_write_indicator(emitter, []byte("%YAML"), true, false, false) {
   355  				return false
   356  			}
   357  			if !yaml_emitter_write_indicator(emitter, []byte("1.1"), true, false, false) {
   358  				return false
   359  			}
   360  			if !yaml_emitter_write_indent(emitter) {
   361  				return false
   362  			}
   363  		}
   364  
   365  		if len(event.tag_directives) > 0 {
   366  			implicit = false
   367  			for i := 0; i < len(event.tag_directives); i++ {
   368  				tag_directive := &event.tag_directives[i]
   369  				if !yaml_emitter_write_indicator(emitter, []byte("%TAG"), true, false, false) {
   370  					return false
   371  				}
   372  				if !yaml_emitter_write_tag_handle(emitter, tag_directive.handle) {
   373  					return false
   374  				}
   375  				if !yaml_emitter_write_tag_content(emitter, tag_directive.prefix, true) {
   376  					return false
   377  				}
   378  				if !yaml_emitter_write_indent(emitter) {
   379  					return false
   380  				}
   381  			}
   382  		}
   383  
   384  		if yaml_emitter_check_empty_document(emitter) {
   385  			implicit = false
   386  		}
   387  		if !implicit {
   388  			if !yaml_emitter_write_indent(emitter) {
   389  				return false
   390  			}
   391  			if !yaml_emitter_write_indicator(emitter, []byte("---"), true, false, false) {
   392  				return false
   393  			}
   394  			if emitter.canonical {
   395  				if !yaml_emitter_write_indent(emitter) {
   396  					return false
   397  				}
   398  			}
   399  		}
   400  
   401  		emitter.state = yaml_EMIT_DOCUMENT_CONTENT_STATE
   402  		return true
   403  	}
   404  
   405  	if event.typ == yaml_STREAM_END_EVENT {
   406  		if emitter.open_ended {
   407  			if !yaml_emitter_write_indicator(emitter, []byte("..."), true, false, false) {
   408  				return false
   409  			}
   410  			if !yaml_emitter_write_indent(emitter) {
   411  				return false
   412  			}
   413  		}
   414  		if !yaml_emitter_flush(emitter) {
   415  			return false
   416  		}
   417  		emitter.state = yaml_EMIT_END_STATE
   418  		return true
   419  	}
   420  
   421  	return yaml_emitter_set_emitter_error(emitter, "expected DOCUMENT-START or STREAM-END")
   422  }
   423  
   424  // Expect the root node.
   425  func yaml_emitter_emit_document_content(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   426  	emitter.states = append(emitter.states, yaml_EMIT_DOCUMENT_END_STATE)
   427  	return yaml_emitter_emit_node(emitter, event, true, false, false, false)
   428  }
   429  
   430  // Expect DOCUMENT-END.
   431  func yaml_emitter_emit_document_end(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   432  	if event.typ != yaml_DOCUMENT_END_EVENT {
   433  		return yaml_emitter_set_emitter_error(emitter, "expected DOCUMENT-END")
   434  	}
   435  	if !yaml_emitter_write_indent(emitter) {
   436  		return false
   437  	}
   438  	if !event.implicit {
   439  		// [Go] Allocate the slice elsewhere.
   440  		if !yaml_emitter_write_indicator(emitter, []byte("..."), true, false, false) {
   441  			return false
   442  		}
   443  		if !yaml_emitter_write_indent(emitter) {
   444  			return false
   445  		}
   446  	}
   447  	if !yaml_emitter_flush(emitter) {
   448  		return false
   449  	}
   450  	emitter.state = yaml_EMIT_DOCUMENT_START_STATE
   451  	emitter.tag_directives = emitter.tag_directives[:0]
   452  	return true
   453  }
   454  
   455  // Expect a flow item node.
   456  func yaml_emitter_emit_flow_sequence_item(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
   457  	if first {
   458  		if !yaml_emitter_write_indicator(emitter, []byte{'['}, true, true, false) {
   459  			return false
   460  		}
   461  		if !yaml_emitter_increase_indent(emitter, true, false) {
   462  			return false
   463  		}
   464  		emitter.flow_level++
   465  	}
   466  
   467  	if event.typ == yaml_SEQUENCE_END_EVENT {
   468  		emitter.flow_level--
   469  		emitter.indent = emitter.indents[len(emitter.indents)-1]
   470  		emitter.indents = emitter.indents[:len(emitter.indents)-1]
   471  		if emitter.canonical && !first {
   472  			if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
   473  				return false
   474  			}
   475  			if !yaml_emitter_write_indent(emitter) {
   476  				return false
   477  			}
   478  		}
   479  		if !yaml_emitter_write_indicator(emitter, []byte{']'}, false, false, false) {
   480  			return false
   481  		}
   482  		emitter.state = emitter.states[len(emitter.states)-1]
   483  		emitter.states = emitter.states[:len(emitter.states)-1]
   484  
   485  		return true
   486  	}
   487  
   488  	if !first {
   489  		if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
   490  			return false
   491  		}
   492  	}
   493  
   494  	if emitter.canonical || emitter.column > emitter.best_width {
   495  		if !yaml_emitter_write_indent(emitter) {
   496  			return false
   497  		}
   498  	}
   499  	emitter.states = append(emitter.states, yaml_EMIT_FLOW_SEQUENCE_ITEM_STATE)
   500  	return yaml_emitter_emit_node(emitter, event, false, true, false, false)
   501  }
   502  
   503  // Expect a flow key node.
   504  func yaml_emitter_emit_flow_mapping_key(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
   505  	if first {
   506  		if !yaml_emitter_write_indicator(emitter, []byte{'{'}, true, true, false) {
   507  			return false
   508  		}
   509  		if !yaml_emitter_increase_indent(emitter, true, false) {
   510  			return false
   511  		}
   512  		emitter.flow_level++
   513  	}
   514  
   515  	if event.typ == yaml_MAPPING_END_EVENT {
   516  		emitter.flow_level--
   517  		emitter.indent = emitter.indents[len(emitter.indents)-1]
   518  		emitter.indents = emitter.indents[:len(emitter.indents)-1]
   519  		if emitter.canonical && !first {
   520  			if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
   521  				return false
   522  			}
   523  			if !yaml_emitter_write_indent(emitter) {
   524  				return false
   525  			}
   526  		}
   527  		if !yaml_emitter_write_indicator(emitter, []byte{'}'}, false, false, false) {
   528  			return false
   529  		}
   530  		emitter.state = emitter.states[len(emitter.states)-1]
   531  		emitter.states = emitter.states[:len(emitter.states)-1]
   532  		return true
   533  	}
   534  
   535  	if !first {
   536  		if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
   537  			return false
   538  		}
   539  	}
   540  	if emitter.canonical || emitter.column > emitter.best_width {
   541  		if !yaml_emitter_write_indent(emitter) {
   542  			return false
   543  		}
   544  	}
   545  
   546  	if !emitter.canonical && yaml_emitter_check_simple_key(emitter) {
   547  		emitter.states = append(emitter.states, yaml_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE)
   548  		return yaml_emitter_emit_node(emitter, event, false, false, true, true)
   549  	}
   550  	if !yaml_emitter_write_indicator(emitter, []byte{'?'}, true, false, false) {
   551  		return false
   552  	}
   553  	emitter.states = append(emitter.states, yaml_EMIT_FLOW_MAPPING_VALUE_STATE)
   554  	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
   555  }
   556  
   557  // Expect a flow value node.
   558  func yaml_emitter_emit_flow_mapping_value(emitter *yaml_emitter_t, event *yaml_event_t, simple bool) bool {
   559  	if simple {
   560  		if !yaml_emitter_write_indicator(emitter, []byte{':'}, false, false, false) {
   561  			return false
   562  		}
   563  	} else {
   564  		if emitter.canonical || emitter.column > emitter.best_width {
   565  			if !yaml_emitter_write_indent(emitter) {
   566  				return false
   567  			}
   568  		}
   569  		if !yaml_emitter_write_indicator(emitter, []byte{':'}, true, false, false) {
   570  			return false
   571  		}
   572  	}
   573  	emitter.states = append(emitter.states, yaml_EMIT_FLOW_MAPPING_KEY_STATE)
   574  	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
   575  }
   576  
   577  // Expect a block item node.
   578  func yaml_emitter_emit_block_sequence_item(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
   579  	if first {
   580  		if !yaml_emitter_increase_indent(emitter, false, emitter.mapping_context && !emitter.indention) {
   581  			return false
   582  		}
   583  	}
   584  	if event.typ == yaml_SEQUENCE_END_EVENT {
   585  		emitter.indent = emitter.indents[len(emitter.indents)-1]
   586  		emitter.indents = emitter.indents[:len(emitter.indents)-1]
   587  		emitter.state = emitter.states[len(emitter.states)-1]
   588  		emitter.states = emitter.states[:len(emitter.states)-1]
   589  		return true
   590  	}
   591  	if !yaml_emitter_write_indent(emitter) {
   592  		return false
   593  	}
   594  	if !yaml_emitter_write_indicator(emitter, []byte{'-'}, true, false, true) {
   595  		return false
   596  	}
   597  	emitter.states = append(emitter.states, yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE)
   598  	return yaml_emitter_emit_node(emitter, event, false, true, false, false)
   599  }
   600  
   601  // Expect a block key node.
   602  func yaml_emitter_emit_block_mapping_key(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
   603  	if first {
   604  		if !yaml_emitter_increase_indent(emitter, false, false) {
   605  			return false
   606  		}
   607  	}
   608  	if event.typ == yaml_MAPPING_END_EVENT {
   609  		emitter.indent = emitter.indents[len(emitter.indents)-1]
   610  		emitter.indents = emitter.indents[:len(emitter.indents)-1]
   611  		emitter.state = emitter.states[len(emitter.states)-1]
   612  		emitter.states = emitter.states[:len(emitter.states)-1]
   613  		return true
   614  	}
   615  	if !yaml_emitter_write_indent(emitter) {
   616  		return false
   617  	}
   618  	if yaml_emitter_check_simple_key(emitter) {
   619  		emitter.states = append(emitter.states, yaml_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE)
   620  		return yaml_emitter_emit_node(emitter, event, false, false, true, true)
   621  	}
   622  	if !yaml_emitter_write_indicator(emitter, []byte{'?'}, true, false, true) {
   623  		return false
   624  	}
   625  	emitter.states = append(emitter.states, yaml_EMIT_BLOCK_MAPPING_VALUE_STATE)
   626  	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
   627  }
   628  
   629  // Expect a block value node.
   630  func yaml_emitter_emit_block_mapping_value(emitter *yaml_emitter_t, event *yaml_event_t, simple bool) bool {
   631  	if simple {
   632  		if !yaml_emitter_write_indicator(emitter, []byte{':'}, false, false, false) {
   633  			return false
   634  		}
   635  	} else {
   636  		if !yaml_emitter_write_indent(emitter) {
   637  			return false
   638  		}
   639  		if !yaml_emitter_write_indicator(emitter, []byte{':'}, true, false, true) {
   640  			return false
   641  		}
   642  	}
   643  	emitter.states = append(emitter.states, yaml_EMIT_BLOCK_MAPPING_KEY_STATE)
   644  	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
   645  }
   646  
   647  // Expect a node.
   648  func yaml_emitter_emit_node(emitter *yaml_emitter_t, event *yaml_event_t,
   649  	root bool, sequence bool, mapping bool, simple_key bool) bool {
   650  
   651  	emitter.root_context = root
   652  	emitter.sequence_context = sequence
   653  	emitter.mapping_context = mapping
   654  	emitter.simple_key_context = simple_key
   655  
   656  	switch event.typ {
   657  	case yaml_ALIAS_EVENT:
   658  		return yaml_emitter_emit_alias(emitter, event)
   659  	case yaml_SCALAR_EVENT:
   660  		return yaml_emitter_emit_scalar(emitter, event)
   661  	case yaml_SEQUENCE_START_EVENT:
   662  		return yaml_emitter_emit_sequence_start(emitter, event)
   663  	case yaml_MAPPING_START_EVENT:
   664  		return yaml_emitter_emit_mapping_start(emitter, event)
   665  	default:
   666  		return yaml_emitter_set_emitter_error(emitter,
   667  			"expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS")
   668  	}
   669  	return false
   670  }
   671  
   672  // Expect ALIAS.
   673  func yaml_emitter_emit_alias(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   674  	if !yaml_emitter_process_anchor(emitter) {
   675  		return false
   676  	}
   677  	emitter.state = emitter.states[len(emitter.states)-1]
   678  	emitter.states = emitter.states[:len(emitter.states)-1]
   679  	return true
   680  }
   681  
   682  // Expect SCALAR.
   683  func yaml_emitter_emit_scalar(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   684  	if !yaml_emitter_select_scalar_style(emitter, event) {
   685  		return false
   686  	}
   687  	if !yaml_emitter_process_anchor(emitter) {
   688  		return false
   689  	}
   690  	if !yaml_emitter_process_tag(emitter) {
   691  		return false
   692  	}
   693  	if !yaml_emitter_increase_indent(emitter, true, false) {
   694  		return false
   695  	}
   696  	if !yaml_emitter_process_scalar(emitter) {
   697  		return false
   698  	}
   699  	emitter.indent = emitter.indents[len(emitter.indents)-1]
   700  	emitter.indents = emitter.indents[:len(emitter.indents)-1]
   701  	emitter.state = emitter.states[len(emitter.states)-1]
   702  	emitter.states = emitter.states[:len(emitter.states)-1]
   703  	return true
   704  }
   705  
   706  // Expect SEQUENCE-START.
   707  func yaml_emitter_emit_sequence_start(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   708  	if !yaml_emitter_process_anchor(emitter) {
   709  		return false
   710  	}
   711  	if !yaml_emitter_process_tag(emitter) {
   712  		return false
   713  	}
   714  	if emitter.flow_level > 0 || emitter.canonical || event.sequence_style() == yaml_FLOW_SEQUENCE_STYLE ||
   715  		yaml_emitter_check_empty_sequence(emitter) {
   716  		emitter.state = yaml_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE
   717  	} else {
   718  		emitter.state = yaml_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE
   719  	}
   720  	return true
   721  }
   722  
   723  // Expect MAPPING-START.
   724  func yaml_emitter_emit_mapping_start(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   725  	if !yaml_emitter_process_anchor(emitter) {
   726  		return false
   727  	}
   728  	if !yaml_emitter_process_tag(emitter) {
   729  		return false
   730  	}
   731  	if emitter.flow_level > 0 || emitter.canonical || event.mapping_style() == yaml_FLOW_MAPPING_STYLE ||
   732  		yaml_emitter_check_empty_mapping(emitter) {
   733  		emitter.state = yaml_EMIT_FLOW_MAPPING_FIRST_KEY_STATE
   734  	} else {
   735  		emitter.state = yaml_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE
   736  	}
   737  	return true
   738  }
   739  
   740  // Check if the document content is an empty scalar.
   741  func yaml_emitter_check_empty_document(emitter *yaml_emitter_t) bool {
   742  	return false // [Go] Huh?
   743  }
   744  
   745  // Check if the next events represent an empty sequence.
   746  func yaml_emitter_check_empty_sequence(emitter *yaml_emitter_t) bool {
   747  	if len(emitter.events)-emitter.events_head < 2 {
   748  		return false
   749  	}
   750  	return emitter.events[emitter.events_head].typ == yaml_SEQUENCE_START_EVENT &&
   751  		emitter.events[emitter.events_head+1].typ == yaml_SEQUENCE_END_EVENT
   752  }
   753  
   754  // Check if the next events represent an empty mapping.
   755  func yaml_emitter_check_empty_mapping(emitter *yaml_emitter_t) bool {
   756  	if len(emitter.events)-emitter.events_head < 2 {
   757  		return false
   758  	}
   759  	return emitter.events[emitter.events_head].typ == yaml_MAPPING_START_EVENT &&
   760  		emitter.events[emitter.events_head+1].typ == yaml_MAPPING_END_EVENT
   761  }
   762  
   763  // Check if the next node can be expressed as a simple key.
   764  func yaml_emitter_check_simple_key(emitter *yaml_emitter_t) bool {
   765  	length := 0
   766  	switch emitter.events[emitter.events_head].typ {
   767  	case yaml_ALIAS_EVENT:
   768  		length += len(emitter.anchor_data.anchor)
   769  	case yaml_SCALAR_EVENT:
   770  		if emitter.scalar_data.multiline {
   771  			return false
   772  		}
   773  		length += len(emitter.anchor_data.anchor) +
   774  			len(emitter.tag_data.handle) +
   775  			len(emitter.tag_data.suffix) +
   776  			len(emitter.scalar_data.value)
   777  	case yaml_SEQUENCE_START_EVENT:
   778  		if !yaml_emitter_check_empty_sequence(emitter) {
   779  			return false
   780  		}
   781  		length += len(emitter.anchor_data.anchor) +
   782  			len(emitter.tag_data.handle) +
   783  			len(emitter.tag_data.suffix)
   784  	case yaml_MAPPING_START_EVENT:
   785  		if !yaml_emitter_check_empty_mapping(emitter) {
   786  			return false
   787  		}
   788  		length += len(emitter.anchor_data.anchor) +
   789  			len(emitter.tag_data.handle) +
   790  			len(emitter.tag_data.suffix)
   791  	default:
   792  		return false
   793  	}
   794  	return length <= 128
   795  }
   796  
   797  // Determine an acceptable scalar style.
   798  func yaml_emitter_select_scalar_style(emitter *yaml_emitter_t, event *yaml_event_t) bool {
   799  
   800  	no_tag := len(emitter.tag_data.handle) == 0 && len(emitter.tag_data.suffix) == 0
   801  	if no_tag && !event.implicit && !event.quoted_implicit {
   802  		return yaml_emitter_set_emitter_error(emitter, "neither tag nor implicit flags are specified")
   803  	}
   804  
   805  	style := event.scalar_style()
   806  	if style == yaml_ANY_SCALAR_STYLE {
   807  		style = yaml_PLAIN_SCALAR_STYLE
   808  	}
   809  	if emitter.canonical {
   810  		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
   811  	}
   812  	if emitter.simple_key_context && emitter.scalar_data.multiline {
   813  		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
   814  	}
   815  
   816  	if style == yaml_PLAIN_SCALAR_STYLE {
   817  		if emitter.flow_level > 0 && !emitter.scalar_data.flow_plain_allowed ||
   818  			emitter.flow_level == 0 && !emitter.scalar_data.block_plain_allowed {
   819  			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
   820  		}
   821  		if len(emitter.scalar_data.value) == 0 && (emitter.flow_level > 0 || emitter.simple_key_context) {
   822  			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
   823  		}
   824  		if no_tag && !event.implicit {
   825  			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
   826  		}
   827  	}
   828  	if style == yaml_SINGLE_QUOTED_SCALAR_STYLE {
   829  		if !emitter.scalar_data.single_quoted_allowed {
   830  			style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
   831  		}
   832  	}
   833  	if style == yaml_LITERAL_SCALAR_STYLE || style == yaml_FOLDED_SCALAR_STYLE {
   834  		if !emitter.scalar_data.block_allowed || emitter.flow_level > 0 || emitter.simple_key_context {
   835  			style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
   836  		}
   837  	}
   838  
   839  	if no_tag && !event.quoted_implicit && style != yaml_PLAIN_SCALAR_STYLE {
   840  		emitter.tag_data.handle = []byte{'!'}
   841  	}
   842  	emitter.scalar_data.style = style
   843  	return true
   844  }
   845  
   846  // Write an achor.
   847  func yaml_emitter_process_anchor(emitter *yaml_emitter_t) bool {
   848  	if emitter.anchor_data.anchor == nil {
   849  		return true
   850  	}
   851  	c := []byte{'&'}
   852  	if emitter.anchor_data.alias {
   853  		c[0] = '*'
   854  	}
   855  	if !yaml_emitter_write_indicator(emitter, c, true, false, false) {
   856  		return false
   857  	}
   858  	return yaml_emitter_write_anchor(emitter, emitter.anchor_data.anchor)
   859  }
   860  
   861  // Write a tag.
   862  func yaml_emitter_process_tag(emitter *yaml_emitter_t) bool {
   863  	if len(emitter.tag_data.handle) == 0 && len(emitter.tag_data.suffix) == 0 {
   864  		return true
   865  	}
   866  	if len(emitter.tag_data.handle) > 0 {
   867  		if !yaml_emitter_write_tag_handle(emitter, emitter.tag_data.handle) {
   868  			return false
   869  		}
   870  		if len(emitter.tag_data.suffix) > 0 {
   871  			if !yaml_emitter_write_tag_content(emitter, emitter.tag_data.suffix, false) {
   872  				return false
   873  			}
   874  		}
   875  	} else {
   876  		// [Go] Allocate these slices elsewhere.
   877  		if !yaml_emitter_write_indicator(emitter, []byte("!<"), true, false, false) {
   878  			return false
   879  		}
   880  		if !yaml_emitter_write_tag_content(emitter, emitter.tag_data.suffix, false) {
   881  			return false
   882  		}
   883  		if !yaml_emitter_write_indicator(emitter, []byte{'>'}, false, false, false) {
   884  			return false
   885  		}
   886  	}
   887  	return true
   888  }
   889  
   890  // Write a scalar.
   891  func yaml_emitter_process_scalar(emitter *yaml_emitter_t) bool {
   892  	switch emitter.scalar_data.style {
   893  	case yaml_PLAIN_SCALAR_STYLE:
   894  		return yaml_emitter_write_plain_scalar(emitter, emitter.scalar_data.value, !emitter.simple_key_context)
   895  
   896  	case yaml_SINGLE_QUOTED_SCALAR_STYLE:
   897  		return yaml_emitter_write_single_quoted_scalar(emitter, emitter.scalar_data.value, !emitter.simple_key_context)
   898  
   899  	case yaml_DOUBLE_QUOTED_SCALAR_STYLE:
   900  		return yaml_emitter_write_double_quoted_scalar(emitter, emitter.scalar_data.value, !emitter.simple_key_context)
   901  
   902  	case yaml_LITERAL_SCALAR_STYLE:
   903  		return yaml_emitter_write_literal_scalar(emitter, emitter.scalar_data.value)
   904  
   905  	case yaml_FOLDED_SCALAR_STYLE:
   906  		return yaml_emitter_write_folded_scalar(emitter, emitter.scalar_data.value)
   907  	}
   908  	panic("unknown scalar style")
   909  }
   910  
   911  // Check if a %YAML directive is valid.
   912  func yaml_emitter_analyze_version_directive(emitter *yaml_emitter_t, version_directive *yaml_version_directive_t) bool {
   913  	if version_directive.major != 1 || version_directive.minor != 1 {
   914  		return yaml_emitter_set_emitter_error(emitter, "incompatible %YAML directive")
   915  	}
   916  	return true
   917  }
   918  
   919  // Check if a %TAG directive is valid.
   920  func yaml_emitter_analyze_tag_directive(emitter *yaml_emitter_t, tag_directive *yaml_tag_directive_t) bool {
   921  	handle := tag_directive.handle
   922  	prefix := tag_directive.prefix
   923  	if len(handle) == 0 {
   924  		return yaml_emitter_set_emitter_error(emitter, "tag handle must not be empty")
   925  	}
   926  	if handle[0] != '!' {
   927  		return yaml_emitter_set_emitter_error(emitter, "tag handle must start with '!'")
   928  	}
   929  	if handle[len(handle)-1] != '!' {
   930  		return yaml_emitter_set_emitter_error(emitter, "tag handle must end with '!'")
   931  	}
   932  	for i := 1; i < len(handle)-1; i += width(handle[i]) {
   933  		if !is_alpha(handle, i) {
   934  			return yaml_emitter_set_emitter_error(emitter, "tag handle must contain alphanumerical characters only")
   935  		}
   936  	}
   937  	if len(prefix) == 0 {
   938  		return yaml_emitter_set_emitter_error(emitter, "tag prefix must not be empty")
   939  	}
   940  	return true
   941  }
   942  
   943  // Check if an anchor is valid.
   944  func yaml_emitter_analyze_anchor(emitter *yaml_emitter_t, anchor []byte, alias bool) bool {
   945  	if len(anchor) == 0 {
   946  		problem := "anchor value must not be empty"
   947  		if alias {
   948  			problem = "alias value must not be empty"
   949  		}
   950  		return yaml_emitter_set_emitter_error(emitter, problem)
   951  	}
   952  	for i := 0; i < len(anchor); i += width(anchor[i]) {
   953  		if !is_alpha(anchor, i) {
   954  			problem := "anchor value must contain alphanumerical characters only"
   955  			if alias {
   956  				problem = "alias value must contain alphanumerical characters only"
   957  			}
   958  			return yaml_emitter_set_emitter_error(emitter, problem)
   959  		}
   960  	}
   961  	emitter.anchor_data.anchor = anchor
   962  	emitter.anchor_data.alias = alias
   963  	return true
   964  }
   965  
   966  // Check if a tag is valid.
   967  func yaml_emitter_analyze_tag(emitter *yaml_emitter_t, tag []byte) bool {
   968  	if len(tag) == 0 {
   969  		return yaml_emitter_set_emitter_error(emitter, "tag value must not be empty")
   970  	}
   971  	for i := 0; i < len(emitter.tag_directives); i++ {
   972  		tag_directive := &emitter.tag_directives[i]
   973  		if bytes.HasPrefix(tag, tag_directive.prefix) {
   974  			emitter.tag_data.handle = tag_directive.handle
   975  			emitter.tag_data.suffix = tag[len(tag_directive.prefix):]
   976  			return true
   977  		}
   978  	}
   979  	emitter.tag_data.suffix = tag
   980  	return true
   981  }
   982  
   983  // Check if a scalar is valid.
   984  func yaml_emitter_analyze_scalar(emitter *yaml_emitter_t, value []byte) bool {
   985  	var (
   986  		block_indicators   = false
   987  		flow_indicators    = false
   988  		line_breaks        = false
   989  		special_characters = false
   990  
   991  		leading_space  = false
   992  		leading_break  = false
   993  		trailing_space = false
   994  		trailing_break = false
   995  		break_space    = false
   996  		space_break    = false
   997  
   998  		preceeded_by_whitespace = false
   999  		followed_by_whitespace  = false
  1000  		previous_space          = false
  1001  		previous_break          = false
  1002  	)
  1003  
  1004  	emitter.scalar_data.value = value
  1005  
  1006  	if len(value) == 0 {
  1007  		emitter.scalar_data.multiline = false
  1008  		emitter.scalar_data.flow_plain_allowed = false
  1009  		emitter.scalar_data.block_plain_allowed = true
  1010  		emitter.scalar_data.single_quoted_allowed = true
  1011  		emitter.scalar_data.block_allowed = false
  1012  		return true
  1013  	}
  1014  
  1015  	if len(value) >= 3 && ((value[0] == '-' && value[1] == '-' && value[2] == '-') || (value[0] == '.' && value[1] == '.' && value[2] == '.')) {
  1016  		block_indicators = true
  1017  		flow_indicators = true
  1018  	}
  1019  
  1020  	preceeded_by_whitespace = true
  1021  	for i, w := 0, 0; i < len(value); i += w {
  1022  		w = width(value[i])
  1023  		followed_by_whitespace = i+w >= len(value) || is_blank(value, i+w)
  1024  
  1025  		if i == 0 {
  1026  			switch value[i] {
  1027  			case '#', ',', '[', ']', '{', '}', '&', '*', '!', '|', '>', '\'', '"', '%', '@', '`':
  1028  				flow_indicators = true
  1029  				block_indicators = true
  1030  			case '?', ':':
  1031  				flow_indicators = true
  1032  				if followed_by_whitespace {
  1033  					block_indicators = true
  1034  				}
  1035  			case '-':
  1036  				if followed_by_whitespace {
  1037  					flow_indicators = true
  1038  					block_indicators = true
  1039  				}
  1040  			}
  1041  		} else {
  1042  			switch value[i] {
  1043  			case ',', '?', '[', ']', '{', '}':
  1044  				flow_indicators = true
  1045  			case ':':
  1046  				flow_indicators = true
  1047  				if followed_by_whitespace {
  1048  					block_indicators = true
  1049  				}
  1050  			case '#':
  1051  				if preceeded_by_whitespace {
  1052  					flow_indicators = true
  1053  					block_indicators = true
  1054  				}
  1055  			}
  1056  		}
  1057  
  1058  		if !is_printable(value, i) || !is_ascii(value, i) && !emitter.unicode {
  1059  			special_characters = true
  1060  		}
  1061  		if is_space(value, i) {
  1062  			if i == 0 {
  1063  				leading_space = true
  1064  			}
  1065  			if i+width(value[i]) == len(value) {
  1066  				trailing_space = true
  1067  			}
  1068  			if previous_break {
  1069  				break_space = true
  1070  			}
  1071  			previous_space = true
  1072  			previous_break = false
  1073  		} else if is_break(value, i) {
  1074  			line_breaks = true
  1075  			if i == 0 {
  1076  				leading_break = true
  1077  			}
  1078  			if i+width(value[i]) == len(value) {
  1079  				trailing_break = true
  1080  			}
  1081  			if previous_space {
  1082  				space_break = true
  1083  			}
  1084  			previous_space = false
  1085  			previous_break = true
  1086  		} else {
  1087  			previous_space = false
  1088  			previous_break = false
  1089  		}
  1090  
  1091  		// [Go]: Why 'z'? Couldn't be the end of the string as that's the loop condition.
  1092  		preceeded_by_whitespace = is_blankz(value, i)
  1093  	}
  1094  
  1095  	emitter.scalar_data.multiline = line_breaks
  1096  	emitter.scalar_data.flow_plain_allowed = true
  1097  	emitter.scalar_data.block_plain_allowed = true
  1098  	emitter.scalar_data.single_quoted_allowed = true
  1099  	emitter.scalar_data.block_allowed = true
  1100  
  1101  	if leading_space || leading_break || trailing_space || trailing_break {
  1102  		emitter.scalar_data.flow_plain_allowed = false
  1103  		emitter.scalar_data.block_plain_allowed = false
  1104  	}
  1105  	if trailing_space {
  1106  		emitter.scalar_data.block_allowed = false
  1107  	}
  1108  	if break_space {
  1109  		emitter.scalar_data.flow_plain_allowed = false
  1110  		emitter.scalar_data.block_plain_allowed = false
  1111  		emitter.scalar_data.single_quoted_allowed = false
  1112  	}
  1113  	if space_break || special_characters {
  1114  		emitter.scalar_data.flow_plain_allowed = false
  1115  		emitter.scalar_data.block_plain_allowed = false
  1116  		emitter.scalar_data.single_quoted_allowed = false
  1117  		emitter.scalar_data.block_allowed = false
  1118  	}
  1119  	if line_breaks {
  1120  		emitter.scalar_data.flow_plain_allowed = false
  1121  		emitter.scalar_data.block_plain_allowed = false
  1122  	}
  1123  	if flow_indicators {
  1124  		emitter.scalar_data.flow_plain_allowed = false
  1125  	}
  1126  	if block_indicators {
  1127  		emitter.scalar_data.block_plain_allowed = false
  1128  	}
  1129  	return true
  1130  }
  1131  
  1132  // Check if the event data is valid.
  1133  func yaml_emitter_analyze_event(emitter *yaml_emitter_t, event *yaml_event_t) bool {
  1134  
  1135  	emitter.anchor_data.anchor = nil
  1136  	emitter.tag_data.handle = nil
  1137  	emitter.tag_data.suffix = nil
  1138  	emitter.scalar_data.value = nil
  1139  
  1140  	switch event.typ {
  1141  	case yaml_ALIAS_EVENT:
  1142  		if !yaml_emitter_analyze_anchor(emitter, event.anchor, true) {
  1143  			return false
  1144  		}
  1145  
  1146  	case yaml_SCALAR_EVENT:
  1147  		if len(event.anchor) > 0 {
  1148  			if !yaml_emitter_analyze_anchor(emitter, event.anchor, false) {
  1149  				return false
  1150  			}
  1151  		}
  1152  		if len(event.tag) > 0 && (emitter.canonical || (!event.implicit && !event.quoted_implicit)) {
  1153  			if !yaml_emitter_analyze_tag(emitter, event.tag) {
  1154  				return false
  1155  			}
  1156  		}
  1157  		if !yaml_emitter_analyze_scalar(emitter, event.value) {
  1158  			return false
  1159  		}
  1160  
  1161  	case yaml_SEQUENCE_START_EVENT:
  1162  		if len(event.anchor) > 0 {
  1163  			if !yaml_emitter_analyze_anchor(emitter, event.anchor, false) {
  1164  				return false
  1165  			}
  1166  		}
  1167  		if len(event.tag) > 0 && (emitter.canonical || !event.implicit) {
  1168  			if !yaml_emitter_analyze_tag(emitter, event.tag) {
  1169  				return false
  1170  			}
  1171  		}
  1172  
  1173  	case yaml_MAPPING_START_EVENT:
  1174  		if len(event.anchor) > 0 {
  1175  			if !yaml_emitter_analyze_anchor(emitter, event.anchor, false) {
  1176  				return false
  1177  			}
  1178  		}
  1179  		if len(event.tag) > 0 && (emitter.canonical || !event.implicit) {
  1180  			if !yaml_emitter_analyze_tag(emitter, event.tag) {
  1181  				return false
  1182  			}
  1183  		}
  1184  	}
  1185  	return true
  1186  }
  1187  
  1188  // Write the BOM character.
  1189  func yaml_emitter_write_bom(emitter *yaml_emitter_t) bool {
  1190  	if !flush(emitter) {
  1191  		return false
  1192  	}
  1193  	pos := emitter.buffer_pos
  1194  	emitter.buffer[pos+0] = '\xEF'
  1195  	emitter.buffer[pos+1] = '\xBB'
  1196  	emitter.buffer[pos+2] = '\xBF'
  1197  	emitter.buffer_pos += 3
  1198  	return true
  1199  }
  1200  
  1201  func yaml_emitter_write_indent(emitter *yaml_emitter_t) bool {
  1202  	indent := emitter.indent
  1203  	if indent < 0 {
  1204  		indent = 0
  1205  	}
  1206  	if !emitter.indention || emitter.column > indent || (emitter.column == indent && !emitter.whitespace) {
  1207  		if !put_break(emitter) {
  1208  			return false
  1209  		}
  1210  	}
  1211  	for emitter.column < indent {
  1212  		if !put(emitter, ' ') {
  1213  			return false
  1214  		}
  1215  	}
  1216  	emitter.whitespace = true
  1217  	emitter.indention = true
  1218  	return true
  1219  }
  1220  
  1221  func yaml_emitter_write_indicator(emitter *yaml_emitter_t, indicator []byte, need_whitespace, is_whitespace, is_indention bool) bool {
  1222  	if need_whitespace && !emitter.whitespace {
  1223  		if !put(emitter, ' ') {
  1224  			return false
  1225  		}
  1226  	}
  1227  	if !write_all(emitter, indicator) {
  1228  		return false
  1229  	}
  1230  	emitter.whitespace = is_whitespace
  1231  	emitter.indention = (emitter.indention && is_indention)
  1232  	emitter.open_ended = false
  1233  	return true
  1234  }
  1235  
  1236  func yaml_emitter_write_anchor(emitter *yaml_emitter_t, value []byte) bool {
  1237  	if !write_all(emitter, value) {
  1238  		return false
  1239  	}
  1240  	emitter.whitespace = false
  1241  	emitter.indention = false
  1242  	return true
  1243  }
  1244  
  1245  func yaml_emitter_write_tag_handle(emitter *yaml_emitter_t, value []byte) bool {
  1246  	if !emitter.whitespace {
  1247  		if !put(emitter, ' ') {
  1248  			return false
  1249  		}
  1250  	}
  1251  	if !write_all(emitter, value) {
  1252  		return false
  1253  	}
  1254  	emitter.whitespace = false
  1255  	emitter.indention = false
  1256  	return true
  1257  }
  1258  
  1259  func yaml_emitter_write_tag_content(emitter *yaml_emitter_t, value []byte, need_whitespace bool) bool {
  1260  	if need_whitespace && !emitter.whitespace {
  1261  		if !put(emitter, ' ') {
  1262  			return false
  1263  		}
  1264  	}
  1265  	for i := 0; i < len(value); {
  1266  		var must_write bool
  1267  		switch value[i] {
  1268  		case ';', '/', '?', ':', '@', '&', '=', '+', '$', ',', '_', '.', '~', '*', '\'', '(', ')', '[', ']':
  1269  			must_write = true
  1270  		default:
  1271  			must_write = is_alpha(value, i)
  1272  		}
  1273  		if must_write {
  1274  			if !write(emitter, value, &i) {
  1275  				return false
  1276  			}
  1277  		} else {
  1278  			w := width(value[i])
  1279  			for k := 0; k < w; k++ {
  1280  				octet := value[i]
  1281  				i++
  1282  				if !put(emitter, '%') {
  1283  					return false
  1284  				}
  1285  
  1286  				c := octet >> 4
  1287  				if c < 10 {
  1288  					c += '0'
  1289  				} else {
  1290  					c += 'A' - 10
  1291  				}
  1292  				if !put(emitter, c) {
  1293  					return false
  1294  				}
  1295  
  1296  				c = octet & 0x0f
  1297  				if c < 10 {
  1298  					c += '0'
  1299  				} else {
  1300  					c += 'A' - 10
  1301  				}
  1302  				if !put(emitter, c) {
  1303  					return false
  1304  				}
  1305  			}
  1306  		}
  1307  	}
  1308  	emitter.whitespace = false
  1309  	emitter.indention = false
  1310  	return true
  1311  }
  1312  
  1313  func yaml_emitter_write_plain_scalar(emitter *yaml_emitter_t, value []byte, allow_breaks bool) bool {
  1314  	if !emitter.whitespace {
  1315  		if !put(emitter, ' ') {
  1316  			return false
  1317  		}
  1318  	}
  1319  
  1320  	spaces := false
  1321  	breaks := false
  1322  	for i := 0; i < len(value); {
  1323  		if is_space(value, i) {
  1324  			if allow_breaks && !spaces && emitter.column > emitter.best_width && !is_space(value, i+1) {
  1325  				if !yaml_emitter_write_indent(emitter) {
  1326  					return false
  1327  				}
  1328  				i += width(value[i])
  1329  			} else {
  1330  				if !write(emitter, value, &i) {
  1331  					return false
  1332  				}
  1333  			}
  1334  			spaces = true
  1335  		} else if is_break(value, i) {
  1336  			if !breaks && value[i] == '\n' {
  1337  				if !put_break(emitter) {
  1338  					return false
  1339  				}
  1340  			}
  1341  			if !write_break(emitter, value, &i) {
  1342  				return false
  1343  			}
  1344  			emitter.indention = true
  1345  			breaks = true
  1346  		} else {
  1347  			if breaks {
  1348  				if !yaml_emitter_write_indent(emitter) {
  1349  					return false
  1350  				}
  1351  			}
  1352  			if !write(emitter, value, &i) {
  1353  				return false
  1354  			}
  1355  			emitter.indention = false
  1356  			spaces = false
  1357  			breaks = false
  1358  		}
  1359  	}
  1360  
  1361  	emitter.whitespace = false
  1362  	emitter.indention = false
  1363  	if emitter.root_context {
  1364  		emitter.open_ended = true
  1365  	}
  1366  
  1367  	return true
  1368  }
  1369  
  1370  func yaml_emitter_write_single_quoted_scalar(emitter *yaml_emitter_t, value []byte, allow_breaks bool) bool {
  1371  
  1372  	if !yaml_emitter_write_indicator(emitter, []byte{'\''}, true, false, false) {
  1373  		return false
  1374  	}
  1375  
  1376  	spaces := false
  1377  	breaks := false
  1378  	for i := 0; i < len(value); {
  1379  		if is_space(value, i) {
  1380  			if allow_breaks && !spaces && emitter.column > emitter.best_width && i > 0 && i < len(value)-1 && !is_space(value, i+1) {
  1381  				if !yaml_emitter_write_indent(emitter) {
  1382  					return false
  1383  				}
  1384  				i += width(value[i])
  1385  			} else {
  1386  				if !write(emitter, value, &i) {
  1387  					return false
  1388  				}
  1389  			}
  1390  			spaces = true
  1391  		} else if is_break(value, i) {
  1392  			if !breaks && value[i] == '\n' {
  1393  				if !put_break(emitter) {
  1394  					return false
  1395  				}
  1396  			}
  1397  			if !write_break(emitter, value, &i) {
  1398  				return false
  1399  			}
  1400  			emitter.indention = true
  1401  			breaks = true
  1402  		} else {
  1403  			if breaks {
  1404  				if !yaml_emitter_write_indent(emitter) {
  1405  					return false
  1406  				}
  1407  			}
  1408  			if value[i] == '\'' {
  1409  				if !put(emitter, '\'') {
  1410  					return false
  1411  				}
  1412  			}
  1413  			if !write(emitter, value, &i) {
  1414  				return false
  1415  			}
  1416  			emitter.indention = false
  1417  			spaces = false
  1418  			breaks = false
  1419  		}
  1420  	}
  1421  	if !yaml_emitter_write_indicator(emitter, []byte{'\''}, false, false, false) {
  1422  		return false
  1423  	}
  1424  	emitter.whitespace = false
  1425  	emitter.indention = false
  1426  	return true
  1427  }
  1428  
  1429  func yaml_emitter_write_double_quoted_scalar(emitter *yaml_emitter_t, value []byte, allow_breaks bool) bool {
  1430  	spaces := false
  1431  	if !yaml_emitter_write_indicator(emitter, []byte{'"'}, true, false, false) {
  1432  		return false
  1433  	}
  1434  
  1435  	for i := 0; i < len(value); {
  1436  		if !is_printable(value, i) || (!emitter.unicode && !is_ascii(value, i)) ||
  1437  			is_bom(value, i) || is_break(value, i) ||
  1438  			value[i] == '"' || value[i] == '\\' {
  1439  
  1440  			octet := value[i]
  1441  
  1442  			var w int
  1443  			var v rune
  1444  			switch {
  1445  			case octet&0x80 == 0x00:
  1446  				w, v = 1, rune(octet&0x7F)
  1447  			case octet&0xE0 == 0xC0:
  1448  				w, v = 2, rune(octet&0x1F)
  1449  			case octet&0xF0 == 0xE0:
  1450  				w, v = 3, rune(octet&0x0F)
  1451  			case octet&0xF8 == 0xF0:
  1452  				w, v = 4, rune(octet&0x07)
  1453  			}
  1454  			for k := 1; k < w; k++ {
  1455  				octet = value[i+k]
  1456  				v = (v << 6) + (rune(octet) & 0x3F)
  1457  			}
  1458  			i += w
  1459  
  1460  			if !put(emitter, '\\') {
  1461  				return false
  1462  			}
  1463  
  1464  			var ok bool
  1465  			switch v {
  1466  			case 0x00:
  1467  				ok = put(emitter, '0')
  1468  			case 0x07:
  1469  				ok = put(emitter, 'a')
  1470  			case 0x08:
  1471  				ok = put(emitter, 'b')
  1472  			case 0x09:
  1473  				ok = put(emitter, 't')
  1474  			case 0x0A:
  1475  				ok = put(emitter, 'n')
  1476  			case 0x0b:
  1477  				ok = put(emitter, 'v')
  1478  			case 0x0c:
  1479  				ok = put(emitter, 'f')
  1480  			case 0x0d:
  1481  				ok = put(emitter, 'r')
  1482  			case 0x1b:
  1483  				ok = put(emitter, 'e')
  1484  			case 0x22:
  1485  				ok = put(emitter, '"')
  1486  			case 0x5c:
  1487  				ok = put(emitter, '\\')
  1488  			case 0x85:
  1489  				ok = put(emitter, 'N')
  1490  			case 0xA0:
  1491  				ok = put(emitter, '_')
  1492  			case 0x2028:
  1493  				ok = put(emitter, 'L')
  1494  			case 0x2029:
  1495  				ok = put(emitter, 'P')
  1496  			default:
  1497  				if v <= 0xFF {
  1498  					ok = put(emitter, 'x')
  1499  					w = 2
  1500  				} else if v <= 0xFFFF {
  1501  					ok = put(emitter, 'u')
  1502  					w = 4
  1503  				} else {
  1504  					ok = put(emitter, 'U')
  1505  					w = 8
  1506  				}
  1507  				for k := (w - 1) * 4; ok && k >= 0; k -= 4 {
  1508  					digit := byte((v >> uint(k)) & 0x0F)
  1509  					if digit < 10 {
  1510  						ok = put(emitter, digit+'0')
  1511  					} else {
  1512  						ok = put(emitter, digit+'A'-10)
  1513  					}
  1514  				}
  1515  			}
  1516  			if !ok {
  1517  				return false
  1518  			}
  1519  			spaces = false
  1520  		} else if is_space(value, i) {
  1521  			if allow_breaks && !spaces && emitter.column > emitter.best_width && i > 0 && i < len(value)-1 {
  1522  				if !yaml_emitter_write_indent(emitter) {
  1523  					return false
  1524  				}
  1525  				if is_space(value, i+1) {
  1526  					if !put(emitter, '\\') {
  1527  						return false
  1528  					}
  1529  				}
  1530  				i += width(value[i])
  1531  			} else if !write(emitter, value, &i) {
  1532  				return false
  1533  			}
  1534  			spaces = true
  1535  		} else {
  1536  			if !write(emitter, value, &i) {
  1537  				return false
  1538  			}
  1539  			spaces = false
  1540  		}
  1541  	}
  1542  	if !yaml_emitter_write_indicator(emitter, []byte{'"'}, false, false, false) {
  1543  		return false
  1544  	}
  1545  	emitter.whitespace = false
  1546  	emitter.indention = false
  1547  	return true
  1548  }
  1549  
  1550  func yaml_emitter_write_block_scalar_hints(emitter *yaml_emitter_t, value []byte) bool {
  1551  	if is_space(value, 0) || is_break(value, 0) {
  1552  		indent_hint := []byte{'0' + byte(emitter.best_indent)}
  1553  		if !yaml_emitter_write_indicator(emitter, indent_hint, false, false, false) {
  1554  			return false
  1555  		}
  1556  	}
  1557  
  1558  	emitter.open_ended = false
  1559  
  1560  	var chomp_hint [1]byte
  1561  	if len(value) == 0 {
  1562  		chomp_hint[0] = '-'
  1563  	} else {
  1564  		i := len(value) - 1
  1565  		for value[i]&0xC0 == 0x80 {
  1566  			i--
  1567  		}
  1568  		if !is_break(value, i) {
  1569  			chomp_hint[0] = '-'
  1570  		} else if i == 0 {
  1571  			chomp_hint[0] = '+'
  1572  			emitter.open_ended = true
  1573  		} else {
  1574  			i--
  1575  			for value[i]&0xC0 == 0x80 {
  1576  				i--
  1577  			}
  1578  			if is_break(value, i) {
  1579  				chomp_hint[0] = '+'
  1580  				emitter.open_ended = true
  1581  			}
  1582  		}
  1583  	}
  1584  	if chomp_hint[0] != 0 {
  1585  		if !yaml_emitter_write_indicator(emitter, chomp_hint[:], false, false, false) {
  1586  			return false
  1587  		}
  1588  	}
  1589  	return true
  1590  }
  1591  
  1592  func yaml_emitter_write_literal_scalar(emitter *yaml_emitter_t, value []byte) bool {
  1593  	if !yaml_emitter_write_indicator(emitter, []byte{'|'}, true, false, false) {
  1594  		return false
  1595  	}
  1596  	if !yaml_emitter_write_block_scalar_hints(emitter, value) {
  1597  		return false
  1598  	}
  1599  	if !put_break(emitter) {
  1600  		return false
  1601  	}
  1602  	emitter.indention = true
  1603  	emitter.whitespace = true
  1604  	breaks := true
  1605  	for i := 0; i < len(value); {
  1606  		if is_break(value, i) {
  1607  			if !write_break(emitter, value, &i) {
  1608  				return false
  1609  			}
  1610  			emitter.indention = true
  1611  			breaks = true
  1612  		} else {
  1613  			if breaks {
  1614  				if !yaml_emitter_write_indent(emitter) {
  1615  					return false
  1616  				}
  1617  			}
  1618  			if !write(emitter, value, &i) {
  1619  				return false
  1620  			}
  1621  			emitter.indention = false
  1622  			breaks = false
  1623  		}
  1624  	}
  1625  
  1626  	return true
  1627  }
  1628  
  1629  func yaml_emitter_write_folded_scalar(emitter *yaml_emitter_t, value []byte) bool {
  1630  	if !yaml_emitter_write_indicator(emitter, []byte{'>'}, true, false, false) {
  1631  		return false
  1632  	}
  1633  	if !yaml_emitter_write_block_scalar_hints(emitter, value) {
  1634  		return false
  1635  	}
  1636  
  1637  	if !put_break(emitter) {
  1638  		return false
  1639  	}
  1640  	emitter.indention = true
  1641  	emitter.whitespace = true
  1642  
  1643  	breaks := true
  1644  	leading_spaces := true
  1645  	for i := 0; i < len(value); {
  1646  		if is_break(value, i) {
  1647  			if !breaks && !leading_spaces && value[i] == '\n' {
  1648  				k := 0
  1649  				for is_break(value, k) {
  1650  					k += width(value[k])
  1651  				}
  1652  				if !is_blankz(value, k) {
  1653  					if !put_break(emitter) {
  1654  						return false
  1655  					}
  1656  				}
  1657  			}
  1658  			if !write_break(emitter, value, &i) {
  1659  				return false
  1660  			}
  1661  			emitter.indention = true
  1662  			breaks = true
  1663  		} else {
  1664  			if breaks {
  1665  				if !yaml_emitter_write_indent(emitter) {
  1666  					return false
  1667  				}
  1668  				leading_spaces = is_blank(value, i)
  1669  			}
  1670  			if !breaks && is_space(value, i) && !is_space(value, i+1) && emitter.column > emitter.best_width {
  1671  				if !yaml_emitter_write_indent(emitter) {
  1672  					return false
  1673  				}
  1674  				i += width(value[i])
  1675  			} else {
  1676  				if !write(emitter, value, &i) {
  1677  					return false
  1678  				}
  1679  			}
  1680  			emitter.indention = false
  1681  			breaks = false
  1682  		}
  1683  	}
  1684  	return true
  1685  }