pkg/analysis_server/tool/spec/from_html.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.

 /**
  * Code for reading an HTML API description.
  */
 import 'dart:io';

 import 'package:analyzer/src/codegen/html.dart';
 import 'package:html/dom.dart' as dom;
 import 'package:html/parser.dart' as parser;
 import 'package:path/path.dart';

 import 'api.dart';

 /**
  * Read the API description from the file 'plugin_spec.html'.  [pkgPath] is the
  * path to the current package.
  */
 Api readApi(String pkgPath) {
   ApiReader reader =
       new ApiReader(join(pkgPath, 'tool', 'spec', 'spec_input.html'));
   return reader.readApi();
 }

 typedef void ElementProcessor(dom.Element element);

 typedef void TextProcessor(dom.Text text);

 class ApiReader {
   static const List<String> specialElements = const [
     'domain',
     'feedback',
     'object',
     'refactorings',
     'refactoring',
     'type',
     'types',
     'request',
     'notification',
     'params',
     'result',
     'field',
     'list',
     'map',
     'enum',
     'key',
     'value',
     'options',
     'ref',
     'code',
     'version',
     'union',
     'index',
     'include'
   ];

   /**
    * The absolute and normalized path to the file being read.
    */
   final String filePath;

   /**
    * Initialize a newly created API reader to read from the file with the given
    * [filePath].
    */
   ApiReader(this.filePath);

   /**
    * Create an [Api] object from an HTML representation such as:
    *
    * <html>
    *   ...
    *   <body>
    *     ... <version>1.0</version> ...
    *     <domain name="...">...</domain> <!-- zero or more -->
    *     <types>...</types>
    *     <refactorings>...</refactorings>
    *   </body>
    * </html>
    *
    * Child elements of <api> can occur in any order.
    */
   Api apiFromHtml(dom.Element html) {
     Api api;
     List<String> versions = <String>[];
     List<Domain> domains = <Domain>[];
     Types types = null;
     Refactorings refactorings = null;
     recurse(html, 'api', {
       'domain': (dom.Element element) {
         domains.add(domainFromHtml(element));
       },
       'refactorings': (dom.Element element) {
         refactorings = refactoringsFromHtml(element);
       },
       'types': (dom.Element element) {
         types = typesFromHtml(element);
       },
       'version': (dom.Element element) {
         versions.add(innerText(element));
       },
       'index': (dom.Element element) {
         /* Ignore; generated dynamically. */
       }
     });
     if (versions.length != 1) {
       throw new Exception('The API must contain exactly one <version> element');
     }
     api = new Api(versions[0], domains, types, refactorings, html);
     return api;
   }

   /**
    * Check that the given [element] has all of the attributes in
    * [requiredAttributes], possibly some of the attributes in
    * [optionalAttributes], and no others.
    */
   void checkAttributes(
       dom.Element element, List<String> requiredAttributes, String context,
       {List<String> optionalAttributes: const []}) {
     Set<String> attributesFound = new Set<String>();
     element.attributes.forEach((name, value) {
       if (!requiredAttributes.contains(name) &&
           !optionalAttributes.contains(name)) {
         throw new Exception(
             '$context: Unexpected attribute in ${element.localName}: $name');
       }
       attributesFound.add(name);
     });
     for (String expectedAttribute in requiredAttributes) {
       if (!attributesFound.contains(expectedAttribute)) {
         throw new Exception('$context: ${element
             .localName} must contain attribute $expectedAttribute');
       }
     }
   }

   /**
    * Check that the given [element] has the given [expectedName].
    */
   void checkName(dom.Element element, String expectedName, [String context]) {
     if (element.localName != expectedName) {
       if (context == null) {
         context = element.localName;
       }
       throw new Exception(
           '$context: Expected $expectedName, found ${element.localName}');
     }
   }

   /**
    * Create a [Domain] object from an HTML representation such as:
    *
    * <domain name="domainName">
    *   <request method="...">...</request> <!-- zero or more -->
    *   <notification event="...">...</notification> <!-- zero or more -->
    * </domain>
    *
    * Child elements can occur in any order.
    */
   Domain domainFromHtml(dom.Element html) {
     checkName(html, 'domain');
     String name = html.attributes['name'];
     String context = name ?? 'domain';
     bool experimental = html.attributes['experimental'] == 'true';
     checkAttributes(html, ['name'], context,
         optionalAttributes: ['experimental']);
     List<Request> requests = <Request>[];
     List<Notification> notifications = <Notification>[];
     recurse(html, context, {
       'request': (dom.Element child) {
         requests.add(requestFromHtml(child, context));
       },
       'notification': (dom.Element child) {
         notifications.add(notificationFromHtml(child, context));
       }
     });
     return new Domain(name, requests, notifications, html,
         experimental: experimental);
   }

   dom.Element getAncestor(dom.Element html, String name, String context) {
     dom.Element ancestor = html.parent;
     while (ancestor != null) {
       if (ancestor.localName == name) {
         return ancestor;
       }
       ancestor = ancestor.parent;
     }
     throw new Exception(
         '$context: <${html.localName}> must be nested within <$name>');
   }

   /**
    * Create a [Notification] object from an HTML representation such as:
    *
    * <notification event="methodName">
    *   <params>...</params> <!-- optional -->
    * </notification>
    *
    * Note that the event name should not include the domain name.
    *
    * <params> has the same form as <object>, as described in [typeDeclFromHtml].
    *
    * Child elements can occur in any order.
    */
   Notification notificationFromHtml(dom.Element html, String context) {
     String domainName = getAncestor(html, 'domain', context).attributes['name'];
     checkName(html, 'notification', context);
     String event = html.attributes['event'];
     context = '$context.${event != null ? event : 'event'}';
     checkAttributes(html, ['event'], context,
         optionalAttributes: ['experimental']);
     bool experimental = html.attributes['experimental'] == 'true';
     TypeDecl params;
     recurse(html, context, {
       'params': (dom.Element child) {
         params = typeObjectFromHtml(child, '$context.params');
       }
     });
     return new Notification(domainName, event, params, html,
         experimental: experimental);
   }

   /**
    * Create a single of [TypeDecl] corresponding to the type defined inside the
    * given HTML element.
    */
   TypeDecl processContentsAsType(dom.Element html, String context) {
     List<TypeDecl> types = processContentsAsTypes(html, context);
     if (types.length != 1) {
       throw new Exception('$context: Exactly one type must be specified');
     }
     return types[0];
   }

   /**
    * Create a list of [TypeDecl]s corresponding to the types defined inside the
    * given HTML element.  The following forms are supported.
    *
    * To refer to a type declared elsewhere (or a built-in type):
    *
    *   <ref>typeName</ref>
    *
    * For a list: <list>ItemType</list>
    *
    * For a map: <map><key>KeyType</key><value>ValueType</value></map>
    *
    * For a JSON object:
    *
    *   <object>
    *     <field name="...">...</field> <!-- zero or more -->
    *   </object>
    *
    * For an enum:
    *
    *   <enum>
    *     <value>...</value> <!-- zero or more -->
    *   </enum>
    *
    * For a union type:
    *   <union>
    *     TYPE <!-- zero or more -->
    *   </union>
    */
   List<TypeDecl> processContentsAsTypes(dom.Element html, String context) {
     List<TypeDecl> types = <TypeDecl>[];
     recurse(html, context, {
       'object': (dom.Element child) {
         types.add(typeObjectFromHtml(child, context));
       },
       'list': (dom.Element child) {
         checkAttributes(child, [], context);
         types.add(new TypeList(processContentsAsType(child, context), child));
       },
       'map': (dom.Element child) {
         checkAttributes(child, [], context);
         TypeDecl keyType;
         TypeDecl valueType;
         recurse(child, context, {
           'key': (dom.Element child) {
             if (keyType != null) {
               throw new Exception('$context: Key type already specified');
             }
             keyType = processContentsAsType(child, '$context.key');
           },
           'value': (dom.Element child) {
             if (valueType != null) {
               throw new Exception('$context: Value type already specified');
             }
             valueType = processContentsAsType(child, '$context.value');
           }
         });
         if (keyType == null) {
           throw new Exception('$context: Key type not specified');
         }
         if (valueType == null) {
           throw new Exception('$context: Value type not specified');
         }
         types.add(new TypeMap(keyType, valueType, child));
       },
       'enum': (dom.Element child) {
         types.add(typeEnumFromHtml(child, context));
       },
       'ref': (dom.Element child) {
         checkAttributes(child, [], context);
         types.add(new TypeReference(innerText(child), child));
       },
       'union': (dom.Element child) {
         checkAttributes(child, ['field'], context);
         String field = child.attributes['field'];
         types.add(new TypeUnion(
             processContentsAsTypes(child, context), field, child));
       }
     });
     return types;
   }

   /**
    * Read the API description from file with the given [filePath].
    */
   Api readApi() {
     String htmlContents = new File(filePath).readAsStringSync();
     dom.Document document = parser.parse(htmlContents);
     dom.Element htmlElement = document.children
         .singleWhere((element) => element.localName.toLowerCase() == 'html');
     return apiFromHtml(htmlElement);
   }

   void recurse(dom.Element parent, String context,
       Map<String, ElementProcessor> elementProcessors) {
     for (String key in elementProcessors.keys) {
       if (!specialElements.contains(key)) {
         throw new Exception('$context: $key is not a special element');
       }
     }
     for (dom.Node node in parent.nodes) {
       if (node is dom.Element) {
         if (elementProcessors.containsKey(node.localName)) {
           elementProcessors[node.localName](node);
         } else if (specialElements.contains(node.localName)) {
           throw new Exception(
               '$context: Unexpected use of <${node.localName}>');
         } else {
           recurse(node, context, elementProcessors);
         }
       }
     }
   }

   /**
    * Create a [Refactoring] object from an HTML representation such as:
    *
    * <refactoring kind="refactoringKind">
    *   <feedback>...</feedback> <!-- optional -->
    *   <options>...</options> <!-- optional -->
    * </refactoring>
    *
    * <feedback> and <options> have the same form as <object>, as described in
    * [typeDeclFromHtml].
    *
    * Child elements can occur in any order.
    */
   Refactoring refactoringFromHtml(dom.Element html) {
     checkName(html, 'refactoring');
     String kind = html.attributes['kind'];
     String context = kind != null ? kind : 'refactoring';
     checkAttributes(html, ['kind'], context);
     TypeDecl feedback;
     TypeDecl options;
     recurse(html, context, {
       'feedback': (dom.Element child) {
         feedback = typeObjectFromHtml(child, '$context.feedback');
       },
       'options': (dom.Element child) {
         options = typeObjectFromHtml(child, '$context.options');
       }
     });
     return new Refactoring(kind, feedback, options, html);
   }

   /**
    * Create a [Refactorings] object from an HTML representation such as:
    *
    * <refactorings>
    *   <refactoring kind="...">...</refactoring> <!-- zero or more -->
    * </refactorings>
    */
   Refactorings refactoringsFromHtml(dom.Element html) {
     checkName(html, 'refactorings');
     String context = 'refactorings';
     checkAttributes(html, [], context);
     List<Refactoring> refactorings = <Refactoring>[];
     recurse(html, context, {
       'refactoring': (dom.Element child) {
         refactorings.add(refactoringFromHtml(child));
       }
     });
     return new Refactorings(refactorings, html);
   }

   /**
    * Create a [Request] object from an HTML representation such as:
    *
    * <request method="methodName">
    *   <params>...</params> <!-- optional -->
    *   <result>...</result> <!-- optional -->
    * </request>
    *
    * Note that the method name should not include the domain name.
    *
    * <params> and <result> have the same form as <object>, as described in
    * [typeDeclFromHtml].
    *
    * Child elements can occur in any order.
    */
   Request requestFromHtml(dom.Element html, String context) {
     String domainName = getAncestor(html, 'domain', context).attributes['name'];
     checkName(html, 'request', context);
     String method = html.attributes['method'];
     context = '$context.${method != null ? method : 'method'}';
     checkAttributes(html, ['method'], context,
         optionalAttributes: ['experimental', 'deprecated']);
     bool experimental = html.attributes['experimental'] == 'true';
     bool deprecated = html.attributes['deprecated'] == 'true';
     TypeDecl params;
     TypeDecl result;
     recurse(html, context, {
       'params': (dom.Element child) {
         params = typeObjectFromHtml(child, '$context.params');
       },
       'result': (dom.Element child) {
         result = typeObjectFromHtml(child, '$context.result');
       }
     });
     return new Request(domainName, method, params, result, html,
         experimental: experimental, deprecated: deprecated);
   }

   /**
    * Create a [TypeDefinition] object from an HTML representation such as:
    *
    * <type name="typeName">
    *   TYPE
    * </type>
    *
    * Where TYPE is any HTML that can be parsed by [typeDeclFromHtml].
    *
    * Child elements can occur in any order.
    */
   TypeDefinition typeDefinitionFromHtml(dom.Element html) {
     checkName(html, 'type');
     String name = html.attributes['name'];
     String context = name != null ? name : 'type';
     checkAttributes(html, ['name'], context,
         optionalAttributes: ['experimental', 'deprecated']);
     TypeDecl type = processContentsAsType(html, context);
     bool experimental = html.attributes['experimental'] == 'true';
     bool deprecated = html.attributes['deprecated'] == 'true';
     return new TypeDefinition(name, type, html,
         experimental: experimental, deprecated: deprecated);
   }

   /**
    * Create a [TypeEnum] from an HTML description.
    */
   TypeEnum typeEnumFromHtml(dom.Element html, String context) {
     checkName(html, 'enum', context);
     checkAttributes(html, [], context);
     List<TypeEnumValue> values = <TypeEnumValue>[];
     recurse(html, context, {
       'value': (dom.Element child) {
         values.add(typeEnumValueFromHtml(child, context));
       }
     });
     return new TypeEnum(values, html);
   }

   /**
    * Create a [TypeEnumValue] from an HTML description such as:
    *
    * <enum>
    *   <code>VALUE</code>
    * </enum>
    *
    * Where VALUE is the text of the enumerated value.
    *
    * Child elements can occur in any order.
    */
   TypeEnumValue typeEnumValueFromHtml(dom.Element html, String context) {
     checkName(html, 'value', context);
     checkAttributes(html, [], context, optionalAttributes: ['deprecated']);
     bool deprecated = html.attributes['deprecated'] == 'true';
     List<String> values = <String>[];
     recurse(html, context, {
       'code': (dom.Element child) {
         String text = innerText(child).trim();
         values.add(text);
       }
     });
     if (values.length != 1) {
       throw new Exception('$context: Exactly one value must be specified');
     }
     return new TypeEnumValue(values[0], html, deprecated: deprecated);
   }

   /**
    * Create a [TypeObjectField] from an HTML description such as:
    *
    * <field name="fieldName">
    *   TYPE
    * </field>
    *
    * Where TYPE is any HTML that can be parsed by [typeDeclFromHtml].
    *
    * In addition, the attribute optional="true" may be used to specify that the
    * field is optional, and the attribute value="..." may be used to specify that
    * the field is required to have a certain value.
    *
    * Child elements can occur in any order.
    */
   TypeObjectField typeObjectFieldFromHtml(dom.Element html, String context) {
     checkName(html, 'field', context);
     String name = html.attributes['name'];
     context = '$context.${name != null ? name : 'field'}';
     checkAttributes(html, ['name'], context,
         optionalAttributes: ['optional', 'value', 'deprecated']);
     bool deprecated = html.attributes['deprecated'] == 'true';
     bool optional = false;
     String optionalString = html.attributes['optional'];
     if (optionalString != null) {
       switch (optionalString) {
         case 'true':
           optional = true;
           break;
         case 'false':
           optional = false;
           break;
         default:
           throw new Exception(
               '$context: field contains invalid "optional" attribute: "$optionalString"');
       }
     }
     String value = html.attributes['value'];
     TypeDecl type = processContentsAsType(html, context);
     return new TypeObjectField(name, type, html,
         optional: optional, value: value, deprecated: deprecated);
   }

   /**
    * Create a [TypeObject] from an HTML description.
    */
   TypeObject typeObjectFromHtml(dom.Element html, String context) {
     checkAttributes(html, [], context, optionalAttributes: ['experimental']);
     List<TypeObjectField> fields = <TypeObjectField>[];
     recurse(html, context, {
       'field': (dom.Element child) {
         fields.add(typeObjectFieldFromHtml(child, context));
       }
     });
     bool experimental = html.attributes['experimental'] == 'true';
     return new TypeObject(fields, html, experimental: experimental);
   }

   /**
    * Create a [Types] object from an HTML representation such as:
    *
    * <types>
    *   <type name="...">...</type> <!-- zero or more -->
    * </types>
    */
   Types typesFromHtml(dom.Element html) {
     checkName(html, 'types');
     String context = 'types';
     checkAttributes(html, [], context);
     List<String> importUris = <String>[];
     Map<String, TypeDefinition> typeMap = <String, TypeDefinition>{};
     List<dom.Element> childElements = <dom.Element>[];
     recurse(html, context, {
       'include': (dom.Element child) {
         String importUri = child.attributes['import'];
         if (importUri != null) {
           importUris.add(importUri);
         }
         String relativePath = child.attributes['path'];
         String path = normalize(join(dirname(filePath), relativePath));
         ApiReader reader = new ApiReader(path);
         Api api = reader.readApi();
         for (TypeDefinition typeDefinition in api.types) {
           typeDefinition.isExternal = true;
           childElements.add(typeDefinition.html);
           typeMap[typeDefinition.name] = typeDefinition;
         }
       },
       'type': (dom.Element child) {
         TypeDefinition typeDefinition = typeDefinitionFromHtml(child);
         typeMap[typeDefinition.name] = typeDefinition;
       }
     });
     for (dom.Element element in childElements) {
       html.append(element);
     }
     Types types = new Types(typeMap, html);
     types.importUris.addAll(importUris);
     return types;
   }
 }
	// 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.

	/**
	* Code for reading an HTML API description.
	*/
	import 'dart:io';

	import 'package:analyzer/src/codegen/html.dart';
	import 'package:html/dom.dart' as dom;
	import 'package:html/parser.dart' as parser;
	import 'package:path/path.dart';

	import 'api.dart';

	/**
	* Read the API description from the file 'plugin_spec.html'. [pkgPath] is the
	* path to the current package.
	*/
	Api readApi(String pkgPath) {
	ApiReader reader =
	new ApiReader(join(pkgPath, 'tool', 'spec', 'spec_input.html'));
	return reader.readApi();
	}

	typedef void ElementProcessor(dom.Element element);

	typedef void TextProcessor(dom.Text text);

	class ApiReader {
	static const List<String> specialElements = const [
	'domain',
	'feedback',
	'object',
	'refactorings',
	'refactoring',
	'type',
	'types',
	'request',
	'notification',
	'params',
	'result',
	'field',
	'list',
	'map',
	'enum',
	'key',
	'value',
	'options',
	'ref',
	'code',
	'version',
	'union',
	'index',
	'include'
	];

	/**
	* The absolute and normalized path to the file being read.
	*/
	final String filePath;

	/**
	* Initialize a newly created API reader to read from the file with the given
	* [filePath].
	*/
	ApiReader(this.filePath);

	/**
	* Create an [Api] object from an HTML representation such as:
	*
	* <html>
	* ...
	* <body>
	* ... <version>1.0</version> ...
	* <domain name="...">...</domain> <!-- zero or more -->
	* <types>...</types>
	* <refactorings>...</refactorings>
	* </body>
	* </html>
	*
	* Child elements of <api> can occur in any order.
	*/
	Api apiFromHtml(dom.Element html) {
	Api api;
	List<String> versions = <String>[];
	List<Domain> domains = <Domain>[];
	Types types = null;
	Refactorings refactorings = null;
	recurse(html, 'api', {
	'domain': (dom.Element element) {
	domains.add(domainFromHtml(element));
	},
	'refactorings': (dom.Element element) {
	refactorings = refactoringsFromHtml(element);
	},
	'types': (dom.Element element) {
	types = typesFromHtml(element);
	},
	'version': (dom.Element element) {
	versions.add(innerText(element));
	},
	'index': (dom.Element element) {
	/* Ignore; generated dynamically. */
	}
	});
	if (versions.length != 1) {
	throw new Exception('The API must contain exactly one <version> element');
	}
	api = new Api(versions[0], domains, types, refactorings, html);
	return api;
	}

	/**
	* Check that the given [element] has all of the attributes in
	* [requiredAttributes], possibly some of the attributes in
	* [optionalAttributes], and no others.
	*/
	void checkAttributes(
	dom.Element element, List<String> requiredAttributes, String context,
	{List<String> optionalAttributes: const []}) {
	Set<String> attributesFound = new Set<String>();
	element.attributes.forEach((name, value) {
	if (!requiredAttributes.contains(name) &&
	!optionalAttributes.contains(name)) {
	throw new Exception(
	'$context: Unexpected attribute in ${element.localName}: $name');
	}
	attributesFound.add(name);
	});
	for (String expectedAttribute in requiredAttributes) {
	if (!attributesFound.contains(expectedAttribute)) {
	throw new Exception('$context: ${element
	.localName} must contain attribute $expectedAttribute');
	}
	}
	}

	/**
	* Check that the given [element] has the given [expectedName].
	*/
	void checkName(dom.Element element, String expectedName, [String context]) {
	if (element.localName != expectedName) {
	if (context == null) {
	context = element.localName;
	}
	throw new Exception(
	'$context: Expected $expectedName, found ${element.localName}');
	}
	}

	/**
	* Create a [Domain] object from an HTML representation such as:
	*
	* <domain name="domainName">
	* <request method="...">...</request> <!-- zero or more -->
	* <notification event="...">...</notification> <!-- zero or more -->
	* </domain>
	*
	* Child elements can occur in any order.
	*/
	Domain domainFromHtml(dom.Element html) {
	checkName(html, 'domain');
	String name = html.attributes['name'];
	String context = name ?? 'domain';
	bool experimental = html.attributes['experimental'] == 'true';
	checkAttributes(html, ['name'], context,
	optionalAttributes: ['experimental']);
	List<Request> requests = <Request>[];
	List<Notification> notifications = <Notification>[];
	recurse(html, context, {
	'request': (dom.Element child) {
	requests.add(requestFromHtml(child, context));
	},
	'notification': (dom.Element child) {
	notifications.add(notificationFromHtml(child, context));
	}
	});
	return new Domain(name, requests, notifications, html,
	experimental: experimental);
	}

	dom.Element getAncestor(dom.Element html, String name, String context) {
	dom.Element ancestor = html.parent;
	while (ancestor != null) {
	if (ancestor.localName == name) {
	return ancestor;
	}
	ancestor = ancestor.parent;
	}
	throw new Exception(
	'$context: <${html.localName}> must be nested within <$name>');
	}

	/**
	* Create a [Notification] object from an HTML representation such as:
	*
	* <notification event="methodName">
	* <params>...</params> <!-- optional -->
	* </notification>
	*
	* Note that the event name should not include the domain name.
	*
	* <params> has the same form as <object>, as described in [typeDeclFromHtml].
	*
	* Child elements can occur in any order.
	*/
	Notification notificationFromHtml(dom.Element html, String context) {
	String domainName = getAncestor(html, 'domain', context).attributes['name'];
	checkName(html, 'notification', context);
	String event = html.attributes['event'];
	context = '$context.${event != null ? event : 'event'}';
	checkAttributes(html, ['event'], context,
	optionalAttributes: ['experimental']);
	bool experimental = html.attributes['experimental'] == 'true';
	TypeDecl params;
	recurse(html, context, {
	'params': (dom.Element child) {
	params = typeObjectFromHtml(child, '$context.params');
	}
	});
	return new Notification(domainName, event, params, html,
	experimental: experimental);
	}

	/**
	* Create a single of [TypeDecl] corresponding to the type defined inside the
	* given HTML element.
	*/
	TypeDecl processContentsAsType(dom.Element html, String context) {
	List<TypeDecl> types = processContentsAsTypes(html, context);
	if (types.length != 1) {
	throw new Exception('$context: Exactly one type must be specified');
	}
	return types[0];
	}

	/**
	* Create a list of [TypeDecl]s corresponding to the types defined inside the
	* given HTML element. The following forms are supported.
	*
	* To refer to a type declared elsewhere (or a built-in type):
	*
	* <ref>typeName</ref>
	*
	* For a list: <list>ItemType</list>
	*
	* For a map: <map><key>KeyType</key><value>ValueType</value></map>
	*
	* For a JSON object:
	*
	* <object>
	* <field name="...">...</field> <!-- zero or more -->
	* </object>
	*
	* For an enum:
	*
	* <enum>
	* <value>...</value> <!-- zero or more -->
	* </enum>
	*
	* For a union type:
	* <union>
	* TYPE <!-- zero or more -->
	* </union>
	*/
	List<TypeDecl> processContentsAsTypes(dom.Element html, String context) {
	List<TypeDecl> types = <TypeDecl>[];
	recurse(html, context, {
	'object': (dom.Element child) {
	types.add(typeObjectFromHtml(child, context));
	},
	'list': (dom.Element child) {
	checkAttributes(child, [], context);
	types.add(new TypeList(processContentsAsType(child, context), child));
	},
	'map': (dom.Element child) {
	checkAttributes(child, [], context);
	TypeDecl keyType;
	TypeDecl valueType;
	recurse(child, context, {
	'key': (dom.Element child) {
	if (keyType != null) {
	throw new Exception('$context: Key type already specified');
	}
	keyType = processContentsAsType(child, '$context.key');
	},
	'value': (dom.Element child) {
	if (valueType != null) {
	throw new Exception('$context: Value type already specified');
	}
	valueType = processContentsAsType(child, '$context.value');
	}
	});
	if (keyType == null) {
	throw new Exception('$context: Key type not specified');
	}
	if (valueType == null) {
	throw new Exception('$context: Value type not specified');
	}
	types.add(new TypeMap(keyType, valueType, child));
	},
	'enum': (dom.Element child) {
	types.add(typeEnumFromHtml(child, context));
	},
	'ref': (dom.Element child) {
	checkAttributes(child, [], context);
	types.add(new TypeReference(innerText(child), child));
	},
	'union': (dom.Element child) {
	checkAttributes(child, ['field'], context);
	String field = child.attributes['field'];
	types.add(new TypeUnion(
	processContentsAsTypes(child, context), field, child));
	}
	});
	return types;
	}

	/**
	* Read the API description from file with the given [filePath].
	*/
	Api readApi() {
	String htmlContents = new File(filePath).readAsStringSync();
	dom.Document document = parser.parse(htmlContents);
	dom.Element htmlElement = document.children
	.singleWhere((element) => element.localName.toLowerCase() == 'html');
	return apiFromHtml(htmlElement);
	}

	void recurse(dom.Element parent, String context,
	Map<String, ElementProcessor> elementProcessors) {
	for (String key in elementProcessors.keys) {
	if (!specialElements.contains(key)) {
	throw new Exception('$context: $key is not a special element');
	}
	}
	for (dom.Node node in parent.nodes) {
	if (node is dom.Element) {
	if (elementProcessors.containsKey(node.localName)) {
	elementProcessors[node.localName](node);
	} else if (specialElements.contains(node.localName)) {
	throw new Exception(
	'$context: Unexpected use of <${node.localName}>');
	} else {
	recurse(node, context, elementProcessors);
	}
	}
	}
	}

	/**
	* Create a [Refactoring] object from an HTML representation such as:
	*
	* <refactoring kind="refactoringKind">
	* <feedback>...</feedback> <!-- optional -->
	* <options>...</options> <!-- optional -->
	* </refactoring>
	*
	* <feedback> and <options> have the same form as <object>, as described in
	* [typeDeclFromHtml].
	*
	* Child elements can occur in any order.
	*/
	Refactoring refactoringFromHtml(dom.Element html) {
	checkName(html, 'refactoring');
	String kind = html.attributes['kind'];
	String context = kind != null ? kind : 'refactoring';
	checkAttributes(html, ['kind'], context);
	TypeDecl feedback;
	TypeDecl options;
	recurse(html, context, {
	'feedback': (dom.Element child) {
	feedback = typeObjectFromHtml(child, '$context.feedback');
	},
	'options': (dom.Element child) {
	options = typeObjectFromHtml(child, '$context.options');
	}
	});
	return new Refactoring(kind, feedback, options, html);
	}

	/**
	* Create a [Refactorings] object from an HTML representation such as:
	*
	* <refactorings>
	* <refactoring kind="...">...</refactoring> <!-- zero or more -->
	* </refactorings>
	*/
	Refactorings refactoringsFromHtml(dom.Element html) {
	checkName(html, 'refactorings');
	String context = 'refactorings';
	checkAttributes(html, [], context);
	List<Refactoring> refactorings = <Refactoring>[];
	recurse(html, context, {
	'refactoring': (dom.Element child) {
	refactorings.add(refactoringFromHtml(child));
	}
	});
	return new Refactorings(refactorings, html);
	}

	/**
	* Create a [Request] object from an HTML representation such as:
	*
	* <request method="methodName">
	* <params>...</params> <!-- optional -->
	* <result>...</result> <!-- optional -->
	* </request>
	*
	* Note that the method name should not include the domain name.
	*
	* <params> and <result> have the same form as <object>, as described in
	* [typeDeclFromHtml].
	*
	* Child elements can occur in any order.
	*/
	Request requestFromHtml(dom.Element html, String context) {
	String domainName = getAncestor(html, 'domain', context).attributes['name'];
	checkName(html, 'request', context);
	String method = html.attributes['method'];
	context = '$context.${method != null ? method : 'method'}';
	checkAttributes(html, ['method'], context,
	optionalAttributes: ['experimental', 'deprecated']);
	bool experimental = html.attributes['experimental'] == 'true';
	bool deprecated = html.attributes['deprecated'] == 'true';
	TypeDecl params;
	TypeDecl result;
	recurse(html, context, {
	'params': (dom.Element child) {
	params = typeObjectFromHtml(child, '$context.params');
	},
	'result': (dom.Element child) {
	result = typeObjectFromHtml(child, '$context.result');
	}
	});
	return new Request(domainName, method, params, result, html,
	experimental: experimental, deprecated: deprecated);
	}

	/**
	* Create a [TypeDefinition] object from an HTML representation such as:
	*
	* <type name="typeName">
	* TYPE
	* </type>
	*
	* Where TYPE is any HTML that can be parsed by [typeDeclFromHtml].
	*
	* Child elements can occur in any order.
	*/
	TypeDefinition typeDefinitionFromHtml(dom.Element html) {
	checkName(html, 'type');
	String name = html.attributes['name'];
	String context = name != null ? name : 'type';
	checkAttributes(html, ['name'], context,
	optionalAttributes: ['experimental', 'deprecated']);
	TypeDecl type = processContentsAsType(html, context);
	bool experimental = html.attributes['experimental'] == 'true';
	bool deprecated = html.attributes['deprecated'] == 'true';
	return new TypeDefinition(name, type, html,
	experimental: experimental, deprecated: deprecated);
	}

	/**
	* Create a [TypeEnum] from an HTML description.
	*/
	TypeEnum typeEnumFromHtml(dom.Element html, String context) {
	checkName(html, 'enum', context);
	checkAttributes(html, [], context);
	List<TypeEnumValue> values = <TypeEnumValue>[];
	recurse(html, context, {
	'value': (dom.Element child) {
	values.add(typeEnumValueFromHtml(child, context));
	}
	});
	return new TypeEnum(values, html);
	}

	/**
	* Create a [TypeEnumValue] from an HTML description such as:
	*
	* <enum>
	* <code>VALUE</code>
	* </enum>
	*
	* Where VALUE is the text of the enumerated value.
	*
	* Child elements can occur in any order.
	*/
	TypeEnumValue typeEnumValueFromHtml(dom.Element html, String context) {
	checkName(html, 'value', context);
	checkAttributes(html, [], context, optionalAttributes: ['deprecated']);
	bool deprecated = html.attributes['deprecated'] == 'true';
	List<String> values = <String>[];
	recurse(html, context, {
	'code': (dom.Element child) {
	String text = innerText(child).trim();
	values.add(text);
	}
	});
	if (values.length != 1) {
	throw new Exception('$context: Exactly one value must be specified');
	}
	return new TypeEnumValue(values[0], html, deprecated: deprecated);
	}

	/**
	* Create a [TypeObjectField] from an HTML description such as:
	*
	* <field name="fieldName">
	* TYPE
	* </field>
	*
	* Where TYPE is any HTML that can be parsed by [typeDeclFromHtml].
	*
	* In addition, the attribute optional="true" may be used to specify that the
	* field is optional, and the attribute value="..." may be used to specify that
	* the field is required to have a certain value.
	*
	* Child elements can occur in any order.
	*/
	TypeObjectField typeObjectFieldFromHtml(dom.Element html, String context) {
	checkName(html, 'field', context);
	String name = html.attributes['name'];
	context = '$context.${name != null ? name : 'field'}';
	checkAttributes(html, ['name'], context,
	optionalAttributes: ['optional', 'value', 'deprecated']);
	bool deprecated = html.attributes['deprecated'] == 'true';
	bool optional = false;
	String optionalString = html.attributes['optional'];
	if (optionalString != null) {
	switch (optionalString) {
	case 'true':
	optional = true;
	break;
	case 'false':
	optional = false;
	break;
	default:
	throw new Exception(
	'$context: field contains invalid "optional" attribute: "$optionalString"');
	}
	}
	String value = html.attributes['value'];
	TypeDecl type = processContentsAsType(html, context);
	return new TypeObjectField(name, type, html,
	optional: optional, value: value, deprecated: deprecated);
	}

	/**
	* Create a [TypeObject] from an HTML description.
	*/
	TypeObject typeObjectFromHtml(dom.Element html, String context) {
	checkAttributes(html, [], context, optionalAttributes: ['experimental']);
	List<TypeObjectField> fields = <TypeObjectField>[];
	recurse(html, context, {
	'field': (dom.Element child) {
	fields.add(typeObjectFieldFromHtml(child, context));
	}
	});
	bool experimental = html.attributes['experimental'] == 'true';
	return new TypeObject(fields, html, experimental: experimental);
	}

	/**
	* Create a [Types] object from an HTML representation such as:
	*
	* <types>
	* <type name="...">...</type> <!-- zero or more -->
	* </types>
	*/
	Types typesFromHtml(dom.Element html) {
	checkName(html, 'types');
	String context = 'types';
	checkAttributes(html, [], context);
	List<String> importUris = <String>[];
	Map<String, TypeDefinition> typeMap = <String, TypeDefinition>{};
	List<dom.Element> childElements = <dom.Element>[];
	recurse(html, context, {
	'include': (dom.Element child) {
	String importUri = child.attributes['import'];
	if (importUri != null) {
	importUris.add(importUri);
	}
	String relativePath = child.attributes['path'];
	String path = normalize(join(dirname(filePath), relativePath));
	ApiReader reader = new ApiReader(path);
	Api api = reader.readApi();
	for (TypeDefinition typeDefinition in api.types) {
	typeDefinition.isExternal = true;
	childElements.add(typeDefinition.html);
	typeMap[typeDefinition.name] = typeDefinition;
	}
	},
	'type': (dom.Element child) {
	TypeDefinition typeDefinition = typeDefinitionFromHtml(child);
	typeMap[typeDefinition.name] = typeDefinition;
	}
	});
	for (dom.Element element in childElements) {
	html.append(element);
	}
	Types types = new Types(typeMap, html);
	types.importUris.addAll(importUris);
	return types;
	}
	}