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YAML event parser class. This class parses a YAML document and calls events on the handler that is passed to the constructor. The events can be used for things such as constructing a YAML AST or deserializing YAML documents. It can even be fed back to Psych::Emitter to emit the same document that was parsed.
See Psych::Handler for documentation on the events that Psych::Parser emits.
Here is an example that prints out ever scalar found in a YAML document:
# Handler for detecting scalar values class ScalarHandler < Psych::Handler def scalar value, anchor, tag, plain, quoted, style puts value end end parser = Psych::Parser.new(ScalarHandler.new) parser.parse(yaml_document)
Here is an example that feeds the parser back in to Psych::Emitter. The YAML document is read from STDIN and written back out to STDERR:
parser = Psych::Parser.new(Psych::Emitter.new($stderr)) parser.parse($stdin)
Psych uses Psych::Parser in combination with Psych::TreeBuilder to construct an AST of the parsed YAML document.
Creates a new Psych::Parser instance with
handler
. YAML events will be called on handler
.
See Psych::Parser for more details.
# File psych/lib/psych/parser.rb, line 46 def initialize handler = Handler.new @handler = handler @external_encoding = ANY end
Returns a Psych::Parser::Mark object that contains line, column, and index information.
static VALUE mark(VALUE self) { VALUE mark_klass; VALUE args[3]; yaml_parser_t * parser; Data_Get_Struct(self, yaml_parser_t, parser); mark_klass = rb_const_get_at(cPsychParser, rb_intern("Mark")); args[0] = INT2NUM(parser->mark.index); args[1] = INT2NUM(parser->mark.line); args[2] = INT2NUM(parser->mark.column); return rb_class_new_instance(3, args, mark_klass); }
Parse the YAML document contained in yaml
. Events will be
called on the handler set on the parser instance.
See Psych::Parser and #handler
static VALUE parse(int argc, VALUE *argv, VALUE self) { VALUE yaml, path; yaml_parser_t * parser; yaml_event_t event; int done = 0; int tainted = 0; int state = 0; int parser_encoding = YAML_ANY_ENCODING; #ifdef HAVE_RUBY_ENCODING_H int encoding = rb_utf8_encindex(); rb_encoding * internal_enc = rb_default_internal_encoding(); #endif VALUE handler = rb_iv_get(self, "@handler"); if (rb_scan_args(argc, argv, "11", &yaml, &path) == 1) { if(rb_respond_to(yaml, id_path)) path = rb_funcall(yaml, id_path, 0); else path = rb_str_new2("<unknown>"); } Data_Get_Struct(self, yaml_parser_t, parser); yaml_parser_delete(parser); yaml_parser_initialize(parser); if (OBJ_TAINTED(yaml)) tainted = 1; if (rb_respond_to(yaml, id_read)) { #ifdef HAVE_RUBY_ENCODING_H yaml = transcode_io(yaml, &parser_encoding); yaml_parser_set_encoding(parser, parser_encoding); #endif yaml_parser_set_input(parser, io_reader, (void *)yaml); if (RTEST(rb_obj_is_kind_of(yaml, rb_cIO))) tainted = 1; } else { StringValue(yaml); #ifdef HAVE_RUBY_ENCODING_H yaml = transcode_string(yaml, &parser_encoding); yaml_parser_set_encoding(parser, parser_encoding); #endif yaml_parser_set_input_string( parser, (const unsigned char *)RSTRING_PTR(yaml), (size_t)RSTRING_LEN(yaml) ); } while(!done) { if(!yaml_parser_parse(parser, &event)) { VALUE exception; exception = make_exception(parser, path); yaml_parser_delete(parser); yaml_parser_initialize(parser); rb_exc_raise(exception); } switch(event.type) { case YAML_STREAM_START_EVENT: { VALUE args[2]; args[0] = handler; args[1] = INT2NUM((long)event.data.stream_start.encoding); rb_protect(protected_start_stream, (VALUE)args, &state); } break; case YAML_DOCUMENT_START_EVENT: { VALUE args[4]; /* Get a list of tag directives (if any) */ VALUE tag_directives = rb_ary_new(); /* Grab the document version */ VALUE version = event.data.document_start.version_directive ? rb_ary_new3( (long)2, INT2NUM((long)event.data.document_start.version_directive->major), INT2NUM((long)event.data.document_start.version_directive->minor) ) : rb_ary_new(); if(event.data.document_start.tag_directives.start) { yaml_tag_directive_t *start = event.data.document_start.tag_directives.start; yaml_tag_directive_t *end = event.data.document_start.tag_directives.end; for(; start != end; start++) { VALUE handle = Qnil; VALUE prefix = Qnil; if(start->handle) { handle = rb_str_new2((const char *)start->handle); if (tainted) OBJ_TAINT(handle); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(handle, encoding, internal_enc); #endif } if(start->prefix) { prefix = rb_str_new2((const char *)start->prefix); if (tainted) OBJ_TAINT(prefix); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(prefix, encoding, internal_enc); #endif } rb_ary_push(tag_directives, rb_ary_new3((long)2, handle, prefix)); } } args[0] = handler; args[1] = version; args[2] = tag_directives; args[3] = event.data.document_start.implicit == 1 ? Qtrue : Qfalse; rb_protect(protected_start_document, (VALUE)args, &state); } break; case YAML_DOCUMENT_END_EVENT: { VALUE args[2]; args[0] = handler; args[1] = event.data.document_end.implicit == 1 ? Qtrue : Qfalse; rb_protect(protected_end_document, (VALUE)args, &state); } break; case YAML_ALIAS_EVENT: { VALUE args[2]; VALUE alias = Qnil; if(event.data.alias.anchor) { alias = rb_str_new2((const char *)event.data.alias.anchor); if (tainted) OBJ_TAINT(alias); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(alias, encoding, internal_enc); #endif } args[0] = handler; args[1] = alias; rb_protect(protected_alias, (VALUE)args, &state); } break; case YAML_SCALAR_EVENT: { VALUE args[7]; VALUE anchor = Qnil; VALUE tag = Qnil; VALUE plain_implicit, quoted_implicit, style; VALUE val = rb_str_new( (const char *)event.data.scalar.value, (long)event.data.scalar.length ); if (tainted) OBJ_TAINT(val); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(val, encoding, internal_enc); #endif if(event.data.scalar.anchor) { anchor = rb_str_new2((const char *)event.data.scalar.anchor); if (tainted) OBJ_TAINT(anchor); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(anchor, encoding, internal_enc); #endif } if(event.data.scalar.tag) { tag = rb_str_new2((const char *)event.data.scalar.tag); if (tainted) OBJ_TAINT(tag); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(tag, encoding, internal_enc); #endif } plain_implicit = event.data.scalar.plain_implicit == 0 ? Qfalse : Qtrue; quoted_implicit = event.data.scalar.quoted_implicit == 0 ? Qfalse : Qtrue; style = INT2NUM((long)event.data.scalar.style); args[0] = handler; args[1] = val; args[2] = anchor; args[3] = tag; args[4] = plain_implicit; args[5] = quoted_implicit; args[6] = style; rb_protect(protected_scalar, (VALUE)args, &state); } break; case YAML_SEQUENCE_START_EVENT: { VALUE args[5]; VALUE anchor = Qnil; VALUE tag = Qnil; VALUE implicit, style; if(event.data.sequence_start.anchor) { anchor = rb_str_new2((const char *)event.data.sequence_start.anchor); if (tainted) OBJ_TAINT(anchor); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(anchor, encoding, internal_enc); #endif } tag = Qnil; if(event.data.sequence_start.tag) { tag = rb_str_new2((const char *)event.data.sequence_start.tag); if (tainted) OBJ_TAINT(tag); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(tag, encoding, internal_enc); #endif } implicit = event.data.sequence_start.implicit == 0 ? Qfalse : Qtrue; style = INT2NUM((long)event.data.sequence_start.style); args[0] = handler; args[1] = anchor; args[2] = tag; args[3] = implicit; args[4] = style; rb_protect(protected_start_sequence, (VALUE)args, &state); } break; case YAML_SEQUENCE_END_EVENT: rb_protect(protected_end_sequence, handler, &state); break; case YAML_MAPPING_START_EVENT: { VALUE args[5]; VALUE anchor = Qnil; VALUE tag = Qnil; VALUE implicit, style; if(event.data.mapping_start.anchor) { anchor = rb_str_new2((const char *)event.data.mapping_start.anchor); if (tainted) OBJ_TAINT(anchor); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(anchor, encoding, internal_enc); #endif } if(event.data.mapping_start.tag) { tag = rb_str_new2((const char *)event.data.mapping_start.tag); if (tainted) OBJ_TAINT(tag); #ifdef HAVE_RUBY_ENCODING_H PSYCH_TRANSCODE(tag, encoding, internal_enc); #endif } implicit = event.data.mapping_start.implicit == 0 ? Qfalse : Qtrue; style = INT2NUM((long)event.data.mapping_start.style); args[0] = handler; args[1] = anchor; args[2] = tag; args[3] = implicit; args[4] = style; rb_protect(protected_start_mapping, (VALUE)args, &state); } break; case YAML_MAPPING_END_EVENT: rb_protect(protected_end_mapping, handler, &state); break; case YAML_NO_EVENT: rb_protect(protected_empty, handler, &state); break; case YAML_STREAM_END_EVENT: rb_protect(protected_end_stream, handler, &state); done = 1; break; } yaml_event_delete(&event); if (state) rb_jump_tag(state); } return self; }
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