pkg/yaml/lib/src/loader.dart - sdk.git - Git at Google

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 library yaml.loader;

 import 'package:source_span/source_span.dart';

 import 'equality.dart';
 import 'event.dart';
 import 'parser.dart';
 import 'yaml_document.dart';
 import 'yaml_exception.dart';
 import 'yaml_node.dart';

 /// A loader that reads [Event]s emitted by a [Parser] and emits
 /// [YamlDocument]s.
 ///
 /// This is based on the libyaml loader, available at
 /// https://github.com/yaml/libyaml/blob/master/src/loader.c. The license for
 /// that is available in ../../libyaml-license.txt.
 class Loader {
   /// The underlying [Parser] that generates [Event]s.
   final Parser _parser;

   /// Aliases by the alias name.
   final _aliases = new Map<String, YamlNode>();

   /// The span of the entire stream emitted so far.
   FileSpan get span => _span;
   FileSpan _span;

   /// Creates a loader that loads [source].
   ///
   /// [sourceUrl] can be a String or a [Uri].
   Loader(String source, {sourceUrl})
       : _parser = new Parser(source, sourceUrl: sourceUrl) {
     var event = _parser.parse();
     _span = event.span;
     assert(event.type == EventType.STREAM_START);
   }

   /// Loads the next document from the stream.
   ///
   /// If there are no more documents, returns `null`.
   YamlDocument load() {
     if (_parser.isDone) return null;

     var event = _parser.parse();
     if (event.type == EventType.STREAM_END) {
       _span = _span.expand(event.span);
       return null;
     }

     var document = _loadDocument(event);
     _span = _span.expand(document.span);
     _aliases.clear();
     return document;
   }

   /// Composes a document object.
   YamlDocument _loadDocument(DocumentStartEvent firstEvent) {
     var contents = _loadNode(_parser.parse());

     var lastEvent = _parser.parse();
     assert(lastEvent.type == EventType.DOCUMENT_END);

     return new YamlDocument.internal(
         contents,
         firstEvent.span.expand(lastEvent.span),
         firstEvent.versionDirective,
         firstEvent.tagDirectives,
         startImplicit: firstEvent.isImplicit,
         endImplicit: lastEvent.isImplicit);
   }

   /// Composes a node.
   YamlNode _loadNode(Event firstEvent) {
     switch (firstEvent.type) {
       case EventType.ALIAS: return _loadAlias(firstEvent);
       case EventType.SCALAR: return _loadScalar(firstEvent);
       case EventType.SEQUENCE_START: return _loadSequence(firstEvent);
       case EventType.MAPPING_START: return _loadMapping(firstEvent);
       default: throw "Unreachable";
     }
   }

   /// Registers an anchor.
   void _registerAnchor(String anchor, YamlNode node) {
     if (anchor == null) return;

     // libyaml throws an error for duplicate anchors, but example 7.1 makes it
     // clear that they should be overridden:
     // http://yaml.org/spec/1.2/spec.html#id2786448.

     _aliases[anchor] = node;
   }

   /// Composes a node corresponding to an alias.
   YamlNode _loadAlias(AliasEvent event) {
     var alias = _aliases[event.name];
     if (alias != null) return alias;

     throw new YamlException("Undefined alias.", event.span);
   }

   /// Composes a scalar node.
   YamlNode _loadScalar(ScalarEvent scalar) {
     var node;
     if (scalar.tag == "!") {
       node = _parseString(scalar);
     } else if (scalar.tag != null) {
       node = _parseByTag(scalar);
     } else {
       node = _parseNull(scalar);
       if (node == null) node = _parseBool(scalar);
       if (node == null) node = _parseInt(scalar);
       if (node == null) node = _parseFloat(scalar);
       if (node == null) node = _parseString(scalar);
     }

     _registerAnchor(scalar.anchor, node);
     return node;
   }

   /// Composes a sequence node.
   YamlNode _loadSequence(SequenceStartEvent firstEvent) {
     if (firstEvent.tag != "!" && firstEvent.tag != null &&
         firstEvent.tag != "tag:yaml.org,2002:seq") {
       throw new YamlException("Invalid tag for sequence.", firstEvent.span);
     }

     var children = [];
     var node = new YamlList.internal(
         children, firstEvent.span, firstEvent.style);
     _registerAnchor(firstEvent.anchor, node);

     var event = _parser.parse();
     while (event.type != EventType.SEQUENCE_END) {
       children.add(_loadNode(event));
       event = _parser.parse();
     }

     setSpan(node, firstEvent.span.expand(event.span));
     return node;
   }

   /// Composes a mapping node.
   YamlNode _loadMapping(MappingStartEvent firstEvent) {
     if (firstEvent.tag != "!" && firstEvent.tag != null &&
         firstEvent.tag != "tag:yaml.org,2002:map") {
       throw new YamlException("Invalid tag for mapping.", firstEvent.span);
     }

     var children = deepEqualsMap();
     var node = new YamlMap.internal(
         children, firstEvent.span, firstEvent.style);
     _registerAnchor(firstEvent.anchor, node);

     var event = _parser.parse();
     while (event.type != EventType.MAPPING_END) {
       var key = _loadNode(event);
       var value = _loadNode(_parser.parse());
       children[key] = value;
       event = _parser.parse();
     }

     setSpan(node, firstEvent.span.expand(event.span));
     return node;
   }

   /// Parses a scalar according to its tag name.
   YamlScalar _parseByTag(ScalarEvent scalar) {
     switch (scalar.tag) {
       case "tag:yaml.org,2002:null": return _parseNull(scalar);
       case "tag:yaml.org,2002:bool": return _parseBool(scalar);
       case "tag:yaml.org,2002:int": return _parseInt(scalar);
       case "tag:yaml.org,2002:float": return _parseFloat(scalar);
       case "tag:yaml.org,2002:str": return _parseString(scalar);
     }
     throw new YamlException('Undefined tag: ${scalar.tag}.', scalar.span);
   }

   /// Parses a null scalar.
   YamlScalar _parseNull(ScalarEvent scalar) {
     // TODO(nweiz): stop using regexps.
     // TODO(nweiz): add ScalarStyle and implicit metadata to the scalars.
     if (new RegExp(r"^(null|Null|NULL|~|)$").hasMatch(scalar.value)) {
       return new YamlScalar.internal(null, scalar.span, scalar.style);
     } else {
       return null;
     }
   }

   /// Parses a boolean scalar.
   YamlScalar _parseBool(ScalarEvent scalar) {
     var match = new RegExp(r"^(?:(true|True|TRUE)|(false|False|FALSE))$").
         firstMatch(scalar.value);
     if (match == null) return null;
     return new YamlScalar.internal(
         match.group(1) != null, scalar.span, scalar.style);
   }

   /// Parses an integer scalar.
   YamlScalar _parseInt(ScalarEvent scalar) {
     var match = new RegExp(r"^[-+]?[0-9]+$").firstMatch(scalar.value);
     if (match != null) {
       return new YamlScalar.internal(
           int.parse(match.group(0)), scalar.span, scalar.style);
     }

     match = new RegExp(r"^0o([0-7]+)$").firstMatch(scalar.value);
     if (match != null) {
       var n = int.parse(match.group(1), radix: 8);
       return new YamlScalar.internal(n, scalar.span, scalar.style);
     }

     match = new RegExp(r"^0x[0-9a-fA-F]+$").firstMatch(scalar.value);
     if (match != null) {
       return new YamlScalar.internal(
           int.parse(match.group(0)), scalar.span, scalar.style);
     }

     return null;
   }

   /// Parses a floating-point scalar.
   YamlScalar _parseFloat(ScalarEvent scalar) {
     var match = new RegExp(
           r"^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$").
         firstMatch(scalar.value);
     if (match != null) {
       // YAML allows floats of the form "0.", but Dart does not. Fix up those
       // floats by removing the trailing dot.
       var matchStr = match.group(0).replaceAll(new RegExp(r"\.$"), "");
       return new YamlScalar.internal(
           double.parse(matchStr), scalar.span, scalar.style);
     }

     match = new RegExp(r"^([+-]?)\.(inf|Inf|INF)$").firstMatch(scalar.value);
     if (match != null) {
       var value = match.group(1) == "-" ? -double.INFINITY : double.INFINITY;
       return new YamlScalar.internal(value, scalar.span, scalar.style);
     }

     match = new RegExp(r"^\.(nan|NaN|NAN)$").firstMatch(scalar.value);
     if (match != null) {
       return new YamlScalar.internal(double.NAN, scalar.span, scalar.style);
     }

     return null;
   }

   /// Parses a string scalar.
   YamlScalar _parseString(ScalarEvent scalar) =>
       new YamlScalar.internal(scalar.value, scalar.span, scalar.style);
 }
	// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	library yaml.loader;

	import 'package:source_span/source_span.dart';

	import 'equality.dart';
	import 'event.dart';
	import 'parser.dart';
	import 'yaml_document.dart';
	import 'yaml_exception.dart';
	import 'yaml_node.dart';

	/// A loader that reads [Event]s emitted by a [Parser] and emits
	/// [YamlDocument]s.
	///
	/// This is based on the libyaml loader, available at
	/// https://github.com/yaml/libyaml/blob/master/src/loader.c. The license for
	/// that is available in ../../libyaml-license.txt.
	class Loader {
	/// The underlying [Parser] that generates [Event]s.
	final Parser _parser;

	/// Aliases by the alias name.
	final _aliases = new Map<String, YamlNode>();

	/// The span of the entire stream emitted so far.
	FileSpan get span => _span;
	FileSpan _span;

	/// Creates a loader that loads [source].
	///
	/// [sourceUrl] can be a String or a [Uri].
	Loader(String source, {sourceUrl})
	: _parser = new Parser(source, sourceUrl: sourceUrl) {
	var event = _parser.parse();
	_span = event.span;
	assert(event.type == EventType.STREAM_START);
	}

	/// Loads the next document from the stream.
	///
	/// If there are no more documents, returns `null`.
	YamlDocument load() {
	if (_parser.isDone) return null;

	var event = _parser.parse();
	if (event.type == EventType.STREAM_END) {
	_span = _span.expand(event.span);
	return null;
	}

	var document = _loadDocument(event);
	_span = _span.expand(document.span);
	_aliases.clear();
	return document;
	}

	/// Composes a document object.
	YamlDocument _loadDocument(DocumentStartEvent firstEvent) {
	var contents = _loadNode(_parser.parse());

	var lastEvent = _parser.parse();
	assert(lastEvent.type == EventType.DOCUMENT_END);

	return new YamlDocument.internal(
	contents,
	firstEvent.span.expand(lastEvent.span),
	firstEvent.versionDirective,
	firstEvent.tagDirectives,
	startImplicit: firstEvent.isImplicit,
	endImplicit: lastEvent.isImplicit);
	}

	/// Composes a node.
	YamlNode _loadNode(Event firstEvent) {
	switch (firstEvent.type) {
	case EventType.ALIAS: return _loadAlias(firstEvent);
	case EventType.SCALAR: return _loadScalar(firstEvent);
	case EventType.SEQUENCE_START: return _loadSequence(firstEvent);
	case EventType.MAPPING_START: return _loadMapping(firstEvent);
	default: throw "Unreachable";
	}
	}

	/// Registers an anchor.
	void _registerAnchor(String anchor, YamlNode node) {
	if (anchor == null) return;

	// libyaml throws an error for duplicate anchors, but example 7.1 makes it
	// clear that they should be overridden:
	// http://yaml.org/spec/1.2/spec.html#id2786448.

	_aliases[anchor] = node;
	}

	/// Composes a node corresponding to an alias.
	YamlNode _loadAlias(AliasEvent event) {
	var alias = _aliases[event.name];
	if (alias != null) return alias;

	throw new YamlException("Undefined alias.", event.span);
	}

	/// Composes a scalar node.
	YamlNode _loadScalar(ScalarEvent scalar) {
	var node;
	if (scalar.tag == "!") {
	node = _parseString(scalar);
	} else if (scalar.tag != null) {
	node = _parseByTag(scalar);
	} else {
	node = _parseNull(scalar);
	if (node == null) node = _parseBool(scalar);
	if (node == null) node = _parseInt(scalar);
	if (node == null) node = _parseFloat(scalar);
	if (node == null) node = _parseString(scalar);
	}

	_registerAnchor(scalar.anchor, node);
	return node;
	}

	/// Composes a sequence node.
	YamlNode _loadSequence(SequenceStartEvent firstEvent) {
	if (firstEvent.tag != "!" && firstEvent.tag != null &&
	firstEvent.tag != "tag:yaml.org,2002:seq") {
	throw new YamlException("Invalid tag for sequence.", firstEvent.span);
	}

	var children = [];
	var node = new YamlList.internal(
	children, firstEvent.span, firstEvent.style);
	_registerAnchor(firstEvent.anchor, node);

	var event = _parser.parse();
	while (event.type != EventType.SEQUENCE_END) {
	children.add(_loadNode(event));
	event = _parser.parse();
	}

	setSpan(node, firstEvent.span.expand(event.span));
	return node;
	}

	/// Composes a mapping node.
	YamlNode _loadMapping(MappingStartEvent firstEvent) {
	if (firstEvent.tag != "!" && firstEvent.tag != null &&
	firstEvent.tag != "tag:yaml.org,2002:map") {
	throw new YamlException("Invalid tag for mapping.", firstEvent.span);
	}

	var children = deepEqualsMap();
	var node = new YamlMap.internal(
	children, firstEvent.span, firstEvent.style);
	_registerAnchor(firstEvent.anchor, node);

	var event = _parser.parse();
	while (event.type != EventType.MAPPING_END) {
	var key = _loadNode(event);
	var value = _loadNode(_parser.parse());
	children[key] = value;
	event = _parser.parse();
	}

	setSpan(node, firstEvent.span.expand(event.span));
	return node;
	}

	/// Parses a scalar according to its tag name.
	YamlScalar _parseByTag(ScalarEvent scalar) {
	switch (scalar.tag) {
	case "tag:yaml.org,2002:null": return _parseNull(scalar);
	case "tag:yaml.org,2002:bool": return _parseBool(scalar);
	case "tag:yaml.org,2002:int": return _parseInt(scalar);
	case "tag:yaml.org,2002:float": return _parseFloat(scalar);
	case "tag:yaml.org,2002:str": return _parseString(scalar);
	}
	throw new YamlException('Undefined tag: ${scalar.tag}.', scalar.span);
	}

	/// Parses a null scalar.
	YamlScalar _parseNull(ScalarEvent scalar) {
	// TODO(nweiz): stop using regexps.
	// TODO(nweiz): add ScalarStyle and implicit metadata to the scalars.
	if (new RegExp(r"^(null\|Null\|NULL\|~\|)$").hasMatch(scalar.value)) {
	return new YamlScalar.internal(null, scalar.span, scalar.style);
	} else {
	return null;
	}
	}

	/// Parses a boolean scalar.
	YamlScalar _parseBool(ScalarEvent scalar) {
	var match = new RegExp(r"^(?:(true\|True\|TRUE)\|(false\|False\|FALSE))$").
	firstMatch(scalar.value);
	if (match == null) return null;
	return new YamlScalar.internal(
	match.group(1) != null, scalar.span, scalar.style);
	}

	/// Parses an integer scalar.
	YamlScalar _parseInt(ScalarEvent scalar) {
	var match = new RegExp(r"^[-+]?[0-9]+$").firstMatch(scalar.value);
	if (match != null) {
	return new YamlScalar.internal(
	int.parse(match.group(0)), scalar.span, scalar.style);
	}

	match = new RegExp(r"^0o([0-7]+)$").firstMatch(scalar.value);
	if (match != null) {
	var n = int.parse(match.group(1), radix: 8);
	return new YamlScalar.internal(n, scalar.span, scalar.style);
	}

	match = new RegExp(r"^0x[0-9a-fA-F]+$").firstMatch(scalar.value);
	if (match != null) {
	return new YamlScalar.internal(
	int.parse(match.group(0)), scalar.span, scalar.style);
	}

	return null;
	}

	/// Parses a floating-point scalar.
	YamlScalar _parseFloat(ScalarEvent scalar) {
	var match = new RegExp(
	r"^[-+]?(\.[0-9]+\|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$").
	firstMatch(scalar.value);
	if (match != null) {
	// YAML allows floats of the form "0.", but Dart does not. Fix up those
	// floats by removing the trailing dot.
	var matchStr = match.group(0).replaceAll(new RegExp(r"\.$"), "");
	return new YamlScalar.internal(
	double.parse(matchStr), scalar.span, scalar.style);
	}

	match = new RegExp(r"^([+-]?)\.(inf\|Inf\|INF)$").firstMatch(scalar.value);
	if (match != null) {
	var value = match.group(1) == "-" ? -double.INFINITY : double.INFINITY;
	return new YamlScalar.internal(value, scalar.span, scalar.style);
	}

	match = new RegExp(r"^\.(nan\|NaN\|NAN)$").firstMatch(scalar.value);
	if (match != null) {
	return new YamlScalar.internal(double.NAN, scalar.span, scalar.style);
	}

	return null;
	}

	/// Parses a string scalar.
	YamlScalar _parseString(ScalarEvent scalar) =>
	new YamlScalar.internal(scalar.value, scalar.span, scalar.style);
	}