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Initial Schema implementation.

Piotrek Koszuliński 8 年之前
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共有 2 个文件被更改,包括 1334 次插入0 次删除
  1. 278 0
      packages/ckeditor5-engine/src/model/schema2.js
  2. 1056 0
      packages/ckeditor5-engine/tests/model/schema/schema2.js

+ 278 - 0
packages/ckeditor5-engine/src/model/schema2.js

@@ -0,0 +1,278 @@
+/**
+ * @license Copyright (c) 2003-2017, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
+import ObservableMixin from '@ckeditor/ckeditor5-utils/src/observablemixin';
+import mix from '@ckeditor/ckeditor5-utils/src/mix';
+
+/**
+ * @module engine/model/schema
+ */
+
+/**
+ * @mixes module:utils/emittermixin~ObservableMixin
+ */
+export default class Schema {
+	constructor() {
+		this._sourceRules = {};
+
+		// TODO events
+		this.decorate( 'checkChild' );
+		this.decorate( 'checkAttribute' );
+
+		this.on( 'checkAttribute', ( evt, args ) => {
+			args[ 0 ] = getContext( args[ 0 ] );
+		}, { priority: 'highest' } );
+
+		this.on( 'checkChild', ( evt, args ) => {
+			args[ 0 ] = getContext( args[ 0 ] );
+		}, { priority: 'highest' } );
+	}
+
+	register( itemName, rules ) {
+		if ( this._sourceRules[ itemName ] ) {
+			// TODO docs
+			throw new CKEditorError( 'schema-cannot-register-item-twice: A single item cannot be registered twice in the schema.' );
+		}
+
+		this._sourceRules[ itemName ] = [
+			Object.assign( {}, rules )
+		];
+
+		this._clearCache();
+	}
+
+	extend( itemName, rules ) {
+		// TODO it should not throw if we want to allow e.g. adding attrs before element is registered
+		// (which may be done by another feature).
+		if ( !this._sourceRules[ itemName ] ) {
+			// TODO docs
+			throw new CKEditorError( 'schema-cannot-extend-missing-item: Cannot extend an item which was not registered yet.' );
+		}
+
+		this._sourceRules[ itemName ].push( Object.assign( {}, rules ) );
+
+		this._clearCache();
+	}
+
+	getRules() {
+		if ( !this._compiledRules ) {
+			this._compile();
+		}
+
+		return this._compiledRules;
+	}
+
+	getRule( item ) {
+		let itemName;
+
+		if ( typeof item == 'string' ) {
+			itemName = item;
+		} else if ( item.is && item.is( 'text' ) ) {
+			itemName = '$text';
+		}
+		// Element or context item.
+		else {
+			itemName = item.name;
+		}
+
+		return this.getRules()[ itemName ];
+	}
+
+	checkChild( context, child ) {
+		const rule = this.getRule( child );
+
+		if ( !rule ) {
+			return false;
+		}
+
+		return this._checkContextMatch( rule, context );
+	}
+
+	checkAttribute( context, attributeName ) {
+		const rule = this.getRule( context[ context.length - 1 ] );
+
+		if ( !rule ) {
+			return false;
+		}
+
+		return rule.allowAttributes.includes( attributeName );
+	}
+
+	_clearCache() {
+		this._compiledRules = null;
+	}
+
+	_compile() {
+		const compiledRules = {};
+		const sourceRules = this._sourceRules;
+		const itemNames = Object.keys( sourceRules );
+
+		for ( const itemName of itemNames ) {
+			compiledRules[ itemName ] = compileBaseItemRule( sourceRules[ itemName ], itemName );
+		}
+
+		for ( const itemName of itemNames ) {
+			compileAllowContentOf( compiledRules, itemName );
+		}
+
+		for ( const itemName of itemNames ) {
+			compileAllowWhere( compiledRules, itemName );
+		}
+
+		for ( const itemName of itemNames ) {
+			compileAllowAttributesOf( compiledRules, itemName );
+		}
+
+		for ( const itemName of itemNames ) {
+			cleanUpAllowIn( compiledRules, itemName );
+			cleanUpAllowAttributes( compiledRules, itemName );
+		}
+
+		this._compiledRules = compiledRules;
+	}
+
+	_checkContextMatch( rule, context, contextItemIndex = context.length - 1 ) {
+		const contextItem = context[ contextItemIndex ];
+
+		if ( rule.allowIn.includes( contextItem.name ) ) {
+			if ( contextItemIndex == 0 ) {
+				return true;
+			} else {
+				const parentRule = this.getRule( contextItem );
+
+				return this._checkContextMatch( parentRule, context, contextItemIndex - 1 );
+			}
+		} else {
+			return false;
+		}
+	}
+}
+
+mix( Schema, ObservableMixin );
+
+function compileBaseItemRule( sourceItemRules, itemName ) {
+	const itemRule = {
+		name: itemName,
+
+		allowIn: [],
+		allowContentOf: [],
+		allowWhere: [],
+
+		allowAttributes: [],
+		allowAttributesOf: []
+	};
+
+	copyTypes( sourceItemRules, itemRule );
+
+	copyProperty( sourceItemRules, itemRule, 'allowIn' );
+	copyProperty( sourceItemRules, itemRule, 'allowContentOf' );
+	copyProperty( sourceItemRules, itemRule, 'allowWhere' );
+
+	copyProperty( sourceItemRules, itemRule, 'allowAttributes' );
+	copyProperty( sourceItemRules, itemRule, 'allowAttributesOf' );
+
+	return itemRule;
+}
+
+function compileAllowContentOf( compiledRules, itemName ) {
+	for ( const allowContentOfItemName of compiledRules[ itemName ].allowContentOf ) {
+		// The allowContentOf property may point to an unregistered element.
+		if ( compiledRules[ allowContentOfItemName ] ) {
+			const allowedChildren = getAllowedChildren( compiledRules, allowContentOfItemName );
+
+			allowedChildren.forEach( allowedItem => {
+				allowedItem.allowIn.push( itemName );
+			} );
+		}
+	}
+
+	delete compiledRules[ itemName ].allowContentOf;
+}
+
+function compileAllowWhere( compiledRules, itemName ) {
+	for ( const allowWhereItemName of compiledRules[ itemName ].allowWhere ) {
+		const inheritFrom = compiledRules[ allowWhereItemName ];
+
+		// The allowWhere property may point to an unregistered element.
+		if ( inheritFrom ) {
+			const allowedIn = inheritFrom.allowIn;
+
+			compiledRules[ itemName ].allowIn.push( ...allowedIn );
+		}
+	}
+
+	delete compiledRules[ itemName ].allowWhere;
+}
+
+function compileAllowAttributesOf( compiledRules, itemName ) {
+	for ( const allowAttributeOfItem of compiledRules[ itemName ].allowAttributesOf ) {
+		const inheritFrom = compiledRules[ allowAttributeOfItem ];
+
+		if ( inheritFrom ) {
+			const inheritAttributes = inheritFrom.allowAttributes;
+
+			compiledRules[ itemName ].allowAttributes.push( ...inheritAttributes );
+		}
+	}
+
+	delete compiledRules[ itemName ].allowAttributesOf;
+}
+
+// Remove items which weren't registered (because it may break some checks or we'd need to complicate them).
+// Make sure allowIn doesn't contain repeated values.
+function cleanUpAllowIn( compiledRules, itemName ) {
+	const itemRule = compiledRules[ itemName ];
+	const existingItems = itemRule.allowIn.filter( itemToCheck => compiledRules[ itemToCheck ] );
+
+	itemRule.allowIn = Array.from( new Set( existingItems ) );
+}
+
+function cleanUpAllowAttributes( compiledRules, itemName ) {
+	const itemRule = compiledRules[ itemName ];
+
+	itemRule.allowAttributes = Array.from( new Set( itemRule.allowAttributes ) );
+}
+
+function copyTypes( sourceItemRules, itemRule ) {
+	for ( const sourceItemRule of sourceItemRules ) {
+		const typeNames = Object.keys( sourceItemRule ).filter( name => name.startsWith( 'is' ) );
+
+		for ( const name of typeNames ) {
+			itemRule[ name ] = sourceItemRule[ name ];
+		}
+	}
+}
+
+function copyProperty( sourceItemRules, itemRule, propertyName ) {
+	for ( const sourceItemRule of sourceItemRules ) {
+		if ( typeof sourceItemRule[ propertyName ] == 'string' ) {
+			itemRule[ propertyName ].push( sourceItemRule[ propertyName ] );
+		} else if ( Array.isArray( sourceItemRule[ propertyName ] ) ) {
+			itemRule[ propertyName ].push( ...sourceItemRule[ propertyName ] );
+		}
+	}
+}
+
+function getAllowedChildren( compiledRules, itemName ) {
+	const itemRule = compiledRules[ itemName ];
+
+	return getValues( compiledRules ).filter( rule => rule.allowIn.includes( itemRule.name ) );
+}
+
+function getContext( node ) {
+	return node.getAncestors( { includeSelf: true } ).map( node => {
+		return {
+			name: node.is( 'text' ) ? '$text' : node.name,
+			* getAttributes() {
+				yield* node.getAttributes();
+			}
+		};
+	} );
+}
+
+function getValues( obj ) {
+	return Object.keys( obj ).map( key => obj[ key ] );
+}

+ 1056 - 0
packages/ckeditor5-engine/tests/model/schema/schema2.js

@@ -0,0 +1,1056 @@
+/**
+ * @license Copyright (c) 2003-2017, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+import Schema from '../../../src/model/schema2';
+
+import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
+import Element from '../../../src/model/element';
+
+describe( 'Schema', () => {
+	let schema, root1, r1p1, r1p2, r1bQ, r1bQp, root2;
+
+	beforeEach( () => {
+		schema = new Schema();
+
+		root1 = new Element( '$root', null, [
+			new Element( 'paragraph', null, 'foo' ),
+			new Element( 'paragraph', { align: 'right' }, 'bar' ),
+			new Element( 'blockQuote', null, [
+				new Element( 'paragraph', null, 'foo' )
+			] )
+		] );
+		r1p1 = root1.getChild( 0 );
+		r1p2 = root1.getChild( 1 );
+		r1bQ = root1.getChild( 2 );
+		r1bQp = r1bQ.getChild( 0 );
+
+		root2 = new Element( '$root2' );
+	} );
+
+	describe( 'register()', () => {
+		it( 'allows registering an item', () => {
+			schema.register( 'foo' );
+
+			expect( schema.getRule( 'foo' ) ).to.be.an( 'object' );
+		} );
+
+		it( 'copies rules', () => {
+			const rules = {};
+
+			schema.register( 'foo', rules );
+
+			rules.isBlock = true;
+
+			expect( schema.getRules().foo ).to.not.have.property( 'isBlock' );
+		} );
+
+		it( 'throws when trying to register for a single item twice', () => {
+			schema.register( 'foo' );
+
+			expect( () => {
+				schema.register( 'foo' );
+			} ).to.throw( CKEditorError, /^schema-cannot-register-item-twice:/ );
+		} );
+	} );
+
+	describe( 'extend()', () => {
+		it( 'allows extending item\'s rules', () => {
+			schema.register( 'foo' );
+
+			schema.extend( 'foo', {
+				isBlock: true
+			} );
+
+			expect( schema.getRule( 'foo' ) ).to.have.property( 'isBlock', true );
+		} );
+
+		it( 'copies rules', () => {
+			schema.register( 'foo', {} );
+
+			const rules = {};
+			schema.extend( 'foo', rules );
+
+			rules.isBlock = true;
+
+			expect( schema.getRules().foo ).to.not.have.property( 'isBlock' );
+		} );
+
+		it( 'throws when trying to extend a not yet registered item', () => {
+			expect( () => {
+				schema.extend( 'foo' );
+			} ).to.throw( CKEditorError, /^schema-cannot-extend-missing-item:/ );
+		} );
+	} );
+
+	describe( 'getRules()', () => {
+		it( 'returns compiled rules', () => {
+			schema.register( '$root' );
+
+			schema.register( 'foo', {
+				allowIn: '$root'
+			} );
+
+			schema.extend( 'foo', {
+				isBlock: true
+			} );
+
+			const rules = schema.getRules();
+
+			expect( rules.foo ).to.deep.equal( {
+				name: 'foo',
+				allowIn: [ '$root' ],
+				allowAttributes: [],
+				isBlock: true
+			} );
+		} );
+
+		it( 'copies all is* types', () => {
+			schema.register( 'foo', {
+				isBlock: true,
+				isFoo: true
+			} );
+
+			schema.extend( 'foo', {
+				isBar: true,
+				isFoo: false // Just to check that the last one wins.
+			} );
+
+			const rules = schema.getRules();
+
+			expect( rules.foo ).to.have.property( 'isBlock', true );
+			expect( rules.foo ).to.have.property( 'isFoo', false );
+			expect( rules.foo ).to.have.property( 'isBar', true );
+		} );
+
+		it( 'does not recompile rules if not needed', () => {
+			schema.register( 'foo' );
+
+			expect( schema.getRules() ).to.equal( schema.getRules() );
+		} );
+
+		it( 'ensures no duplicates in allowIn', () => {
+			schema.register( '$root' );
+			schema.register( 'foo', {
+				allowIn: '$root'
+			} );
+			schema.extend( 'foo', {
+				allowIn: '$root'
+			} );
+
+			const rules = schema.getRules();
+
+			expect( rules.foo ).to.deep.equal( {
+				name: 'foo',
+				allowIn: [ '$root' ],
+				allowAttributes: []
+			} );
+		} );
+
+		it( 'ensures no unregistered items in allowIn', () => {
+			schema.register( 'foo', {
+				allowIn: '$root'
+			} );
+
+			const rules = schema.getRules();
+
+			expect( rules.foo ).to.deep.equal( {
+				name: 'foo',
+				allowIn: [],
+				allowAttributes: []
+			} );
+		} );
+
+		it( 'ensures no duplicates in allowAttributes', () => {
+			schema.register( 'paragraph', {
+				allowAttributes: 'foo'
+			} );
+			schema.extend( 'paragraph', {
+				allowAttributes: 'foo'
+			} );
+
+			const rules = schema.getRules();
+
+			expect( rules.paragraph ).to.deep.equal( {
+				name: 'paragraph',
+				allowIn: [],
+				allowAttributes: [ 'foo' ]
+			} );
+		} );
+
+		it( 'ensures no duplicates in allowAttributes duplicated by allowAttributesOf', () => {
+			schema.register( 'paragraph', {
+				allowAttributes: 'foo',
+				allowAttributesOf: '$block'
+			} );
+			schema.register( '$block', {
+				allowAttributes: 'foo'
+			} );
+
+			const rules = schema.getRules();
+
+			expect( rules.paragraph ).to.deep.equal( {
+				name: 'paragraph',
+				allowIn: [],
+				allowAttributes: [ 'foo' ]
+			} );
+		} );
+	} );
+
+	describe( 'getRule()', () => {
+		// TODO
+	} );
+
+	describe( 'checkChild()', () => {
+		describe( 'allowIn cases', () => {
+			it( 'passes $root>paragraph', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'passes $root>paragraph and $root2>paragraph – support for array values', () => {
+				schema.register( '$root' );
+				schema.register( '$root2' );
+				schema.register( 'paragraph', {
+					allowIn: [ '$root', '$root2' ]
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.true;
+				expect( schema.checkChild( root2, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'passes $root>paragraph[align] – attributes does not matter', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( root1, r1p2 ) ).to.be.true;
+			} );
+
+			it( 'passes $root>div>div – in case of circular refs', () => {
+				schema.register( '$root' );
+				schema.register( 'div', {
+					allowIn: [ '$root', 'div' ]
+				} );
+
+				const div = new Element( 'div' );
+				root1.appendChildren( div );
+
+				const div2 = new Element( 'div' );
+
+				expect( schema.checkChild( div, div2 ) ).to.be.true;
+			} );
+
+			it( 'passes $root>div>div – in case of circular refs, when div1==div2', () => {
+				schema.register( '$root' );
+				schema.register( 'div', {
+					allowIn: [ '$root', 'div' ]
+				} );
+
+				const div = new Element( 'div' );
+				root1.appendChildren( div );
+
+				expect( schema.checkChild( div, div ) ).to.be.true;
+			} );
+
+			it( 'rejects $root>paragraph – unregistered paragraph', () => {
+				schema.register( '$root' );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>paragraph – registered different item', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph' );
+				schema.register( 'listItem', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>paragraph – paragraph allowed in different context', () => {
+				schema.register( '$root' );
+				schema.register( '$fancyRoot' );
+				schema.register( 'paragraph', {
+					allowIn: '$fancyRoot'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>blockQuote>paragraph – since paragraph is only allowed in $root', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( r1bQ, r1bQp ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>blockQuote>paragraph – since paragraph is only allowed in $root v2', () => {
+				schema.register( '$root' );
+				schema.register( 'blockQuote', {
+					allowIn: '$root'
+				} );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( r1bQ, r1bQp ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>blockQuote>paragraph>$text - since paragraph is not allowed in blockQuote', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+				schema.register( '$text', {
+					allowIn: 'paragraph'
+				} );
+
+				expect( schema.checkChild( root1, r1bQp.getChild( 0 ) ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>blockQuote>paragraph>$text - since blockQuote is not allowed in $root', () => {
+				schema.register( '$root' );
+				schema.register( 'blockQuote' );
+				schema.register( 'paragraph', {
+					allowIn: [ 'blockQuote', '$root' ]
+				} );
+				schema.register( '$text', {
+					allowIn: 'paragraph'
+				} );
+
+				expect( schema.checkChild( root1, r1bQp.getChild( 0 ) ) ).to.be.false;
+			} );
+		} );
+
+		describe( 'allowWhere cases', () => {
+			it( 'passes $root>paragraph – paragraph inherits from $block', () => {
+				schema.register( '$root' );
+				schema.register( '$block', {
+					allowIn: '$root'
+				} );
+				schema.register( 'paragraph', {
+					allowWhere: '$block'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'supports the array syntax', () => {
+				schema.register( '$root' );
+				schema.register( '$root2' );
+				schema.register( '$block', {
+					allowIn: '$root'
+				} );
+				schema.register( '$block2', {
+					allowIn: '$root2'
+				} );
+				schema.register( 'paragraph', {
+					allowWhere: [ '$block', '$block2' ]
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ), '$root' ).to.be.true;
+				expect( schema.checkChild( root2, r1p1 ), '$root2' ).to.be.true;
+			} );
+
+			// This checks if some inapropriate caching or preprocessing isn't applied by register().
+			it( 'passes $root>paragraph – paragraph inherits from $block, order of rules does not matter', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph', {
+					allowWhere: '$block'
+				} );
+				schema.register( '$block', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'passes $root>paragraph – paragraph inherits from $specialBlock which inherits from $block', () => {
+				schema.register( '$root' );
+				schema.register( '$block', {
+					allowIn: '$root'
+				} );
+				schema.register( '$specialBlock', {
+					allowWhere: '$block'
+				} );
+				schema.register( 'paragraph', {
+					allowWhere: '$specialBlock'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'rejects $root>paragraph – paragraph inherits from $block but $block is not allowed in $root', () => {
+				schema.register( '$root' );
+				schema.register( '$block' );
+				schema.register( 'paragraph', {
+					allowWhere: '$block'
+				} );
+
+				expect( schema.checkChild( root1, r1p1 ) ).to.be.false;
+			} );
+
+			it( 'rejects $root>paragraph>$text – paragraph inherits from $block but $block is not allowed in $root', () => {
+				schema.register( '$root' );
+				schema.register( '$block' );
+				schema.register( 'paragraph', {
+					allowWhere: '$block'
+				} );
+				schema.register( '$text', {
+					allowIn: 'paragraph'
+				} );
+
+				expect( schema.checkChild( root1, r1p1.getChild( 0 ) ) ).to.be.false;
+			} );
+		} );
+
+		describe( 'allowContentOf cases', () => {
+			it( 'passes $root2>paragraph – $root2 inherits from $root', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+				schema.register( '$root2', {
+					allowContentOf: '$root'
+				} );
+
+				expect( schema.checkChild( root2, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'supports the array syntax', () => {
+				schema.register( '$root' );
+				schema.register( '$root2' );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+				schema.register( 'heading1', {
+					allowIn: '$root2'
+				} );
+				schema.register( '$root3', {
+					allowContentOf: [ '$root', '$root2' ]
+				} );
+
+				const root3 = new Element( '$root3' );
+				const heading1 = new Element( 'heading1' );
+
+				expect( schema.checkChild( root3, r1p1 ), 'paragraph' ).to.be.true;
+				expect( schema.checkChild( root3, heading1 ), 'heading1' ).to.be.true;
+			} );
+
+			it( 'passes $root2>paragraph – $root2 inherits from $root, order of rules does not matter', () => {
+				schema.register( '$root' );
+				schema.register( '$root2', {
+					allowContentOf: '$root'
+				} );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( root2, r1p1 ) ).to.be.true;
+			} );
+
+			it( 'passes $root>paragraph>$text – paragraph inherits content of $block', () => {
+				schema.register( '$root' );
+				schema.register( '$block' );
+				schema.register( 'paragraph', {
+					allowIn: '$root',
+					allowContentOf: '$block'
+				} );
+				schema.register( '$text', {
+					allowIn: '$block'
+				} );
+
+				expect( schema.checkChild( r1p1, r1p1.getChild( 0 ) ) ).to.be.true;
+			} );
+
+			// TODO we need to make it possible to disallow bQ in bQ.
+			it( 'passes $root>blockQuote>paragraph – blockQuote inherits content of $root', () => {
+				schema.register( '$root' );
+				schema.register( 'blockQuote', {
+					allowIn: '$root',
+					allowContentOf: '$root'
+				} );
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( r1bQ, r1bQp ) ).to.be.true;
+			} );
+
+			it( 'rejects $root2>paragraph – $root2 inherits from $root, but paragraph is not allowed there anyway', () => {
+				schema.register( '$root' );
+				schema.register( 'paragraph' );
+				schema.register( '$root2', {
+					allowContentOf: '$root'
+				} );
+
+				expect( schema.checkChild( root2, r1p1 ) ).to.be.false;
+			} );
+		} );
+
+		describe( 'mix of allowContentOf and allowWhere', () => {
+			it( 'passes $root>paragraph>$text – paragraph inherits all from $block', () => {
+				schema.register( '$root' );
+				schema.register( '$block', {
+					allowIn: '$root'
+				} );
+				schema.register( 'paragraph', {
+					allowContentOf: '$block',
+					allowWhere: '$block'
+				} );
+				schema.register( '$text', {
+					allowIn: '$block'
+				} );
+
+				expect( schema.checkChild( r1p1, r1p1.getChild( 0 ) ) ).to.be.true;
+			} );
+
+			it( 'passes $root>paragraph and $root2>paragraph – where $root2 inherits content of $root' +
+				'and paragraph inherits allowWhere from $block', () => {
+				schema.register( '$root' );
+				schema.register( '$root2', {
+					allowContentOf: '$root'
+				} );
+				schema.register( '$block', {
+					allowIn: '$root'
+				} );
+				schema.register( 'paragraph', {
+					allowWhere: '$block'
+				} );
+
+				expect( schema.checkChild( root1, 'paragraph' ), 'root1' ).to.be.true;
+				expect( schema.checkChild( root2, 'paragraph' ), 'root2' ).to.be.true;
+			} );
+
+			it( 'passes d>a where d inherits content of c which inherits content of b', () => {
+				schema.register( 'b' );
+				schema.register( 'a', { allowIn: 'b' } );
+				schema.register( 'c', { allowContentOf: 'b' } );
+				schema.register( 'd', { allowContentOf: 'c' } );
+
+				const d = new Element( 'd' );
+
+				expect( schema.checkChild( d, 'a' ) ).to.be.true;
+			} );
+
+			// This case won't pass becuase we compile the rules in a pretty naive way.
+			// To make chains like this work we'd need to repeat compilation of allowContentOf rules
+			// as long as the previous iteration found something to compile.
+			// This way, even though we'd not compile d<-c in the first run, we'd still find b<-c
+			// and since we've found something, we'd now try d<-c which would work.
+			//
+			// We ignore those situations for now as they are very unlikely to happen and would
+			// significantly raised the complexity of rule compilation.
+			//
+			// it( 'passes d>a where d inherits content of c which inherits content of b', () => {
+			// 	schema.register( 'b' );
+			// 	schema.register( 'a', { allowIn: 'b' } );
+			// 	schema.register( 'd', { allowContentOf: 'c' } );
+			// 	schema.register( 'c', { allowContentOf: 'b' } );
+			//
+			// 	const d = new Element( 'd' );
+			//
+			// 	expect( schema.checkChild( d, 'a' ) ).to.be.true;
+			// } );
+		} );
+
+		// We need to handle cases where some independent features registered rules which might use
+		// optional elements (elements which might not have been registered).
+		describe( 'missing rules', () => {
+			it( 'does not break when trying to check a child which is not registered', () => {
+				schema.register( '$root' );
+
+				expect( schema.checkChild( root1, 'foo404' ) ).to.be.false;
+			} );
+
+			it( 'does not break when trying to check registered child in a context which contains unregistered elements', () => {
+				const foo404 = new Element( 'foo404' );
+
+				root1.appendChildren( foo404 );
+
+				schema.register( '$root' );
+				schema.register( '$text', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( foo404, '$text' ) ).to.be.false;
+			} );
+
+			it( 'does not break when used allowedIn pointing to an unregistered element', () => {
+				schema.register( '$root' );
+				schema.register( '$text', {
+					allowIn: 'foo404'
+				} );
+
+				expect( schema.checkChild( root1, '$text' ) ).to.be.false;
+			} );
+
+			it( 'does not break when used allowWhere pointing to an unregistered element', () => {
+				schema.register( '$root' );
+				schema.register( '$text', {
+					allowWhere: 'foo404'
+				} );
+
+				expect( schema.checkChild( root1, '$text' ) ).to.be.false;
+			} );
+
+			it( 'does not break when used allowContentOf pointing to an unregistered element', () => {
+				schema.register( '$root', {
+					allowContentOf: 'foo404'
+				} );
+				schema.register( '$text', {
+					allowIn: '$root'
+				} );
+
+				expect( schema.checkChild( root1, '$text' ) ).to.be.true;
+			} );
+
+			it( 'checks whether allowIn uses a registered element', () => {
+				schema.register( 'paragraph', {
+					allowIn: '$root'
+				} );
+				// $root isn't registered!
+
+				expect( schema.checkChild( root1, 'paragraph' ) ).to.be.false;
+			} );
+		} );
+	} );
+
+	describe( 'checkAttribute()', () => {
+		describe( 'allowAttributes', () => {
+			it( 'passes paragraph[align]', () => {
+				schema.register( 'paragraph', {
+					allowAttributes: 'align'
+				} );
+
+				expect( schema.checkAttribute( r1p1, 'align' ) ).to.be.true;
+			} );
+
+			it( 'passes paragraph[align] and paragraph[dir] – support for array values', () => {
+				schema.register( 'paragraph', {
+					allowAttributes: [ 'align', 'dir' ]
+				} );
+
+				expect( schema.checkAttribute( r1p1, 'align' ), 'align' ).to.be.true;
+				expect( schema.checkAttribute( r1p1, 'dir' ), 'dir' ).to.be.true;
+			} );
+
+			it( 'passes paragraph>$text[bold]', () => {
+				schema.register( 'paragraph' );
+				schema.register( '$text', {
+					allowIn: 'paragraph',
+					allowAttributes: 'bold'
+				} );
+
+				expect( schema.checkAttribute( r1p1.getChild( 0 ), 'bold' ) ).to.be.true;
+			} );
+		} );
+
+		describe( 'allowAttributesOf', () => {
+			it( 'passes paragraph[align] – paragraph inherits from $block', () => {
+				schema.register( '$block', {
+					allowAttributes: 'align'
+				} );
+				schema.register( 'paragraph', {
+					allowAttributesOf: '$block'
+				} );
+
+				expect( schema.checkAttribute( r1p1, 'align' ) ).to.be.true;
+			} );
+
+			it( 'passes paragraph[align] and paragraph[dir] – support for array values', () => {
+				schema.register( '$block', {
+					allowAttributes: 'align'
+				} );
+				schema.register( '$block2', {
+					allowAttributes: 'dir'
+				} );
+				schema.register( 'paragraph', {
+					allowAttributesOf: [ '$block', '$block2' ]
+				} );
+
+				expect( schema.checkAttribute( r1p1, 'align' ), 'align' ).to.be.true;
+				expect( schema.checkAttribute( r1p1, 'dir' ), 'dir' ).to.be.true;
+			} );
+
+			it( 'passes paragraph[align] and paragraph[dir] – support for combined allowAttributes and allowAttributesOf', () => {
+				schema.register( '$block', {
+					allowAttributes: 'align'
+				} );
+				schema.register( 'paragraph', {
+					allowAttributes: 'dir',
+					allowAttributesOf: '$block'
+				} );
+
+				expect( schema.checkAttribute( r1p1, 'align' ), 'align' ).to.be.true;
+				expect( schema.checkAttribute( r1p1, 'dir' ), 'dir' ).to.be.true;
+			} );
+
+			// The support for allowAttributesOf is broken in the similar way as for allowContentOf (see the comment above).
+			// However, those situations are rather theoretical, so we're not going to waste time on them now.
+		} );
+
+		describe( 'missing rules', () => {
+			it( 'does not crash when checking an attribute of a unregistered element', () => {
+				expect( schema.checkAttribute( r1p1, 'align' ) ).to.be.false;
+			} );
+
+			it( 'does not crash when checking when inheriting attributes of a unregistered element', () => {
+				schema.register( 'paragraph', {
+					allowAttributesOf: '$block'
+				} );
+
+				expect( schema.checkAttribute( r1p1, 'whatever' ) ).to.be.false;
+			} );
+		} );
+	} );
+
+	describe( 'real scenarios', () => {
+		let r1bQi, r1i, r1lI, r1h, r1bQlI;
+
+		const rules = [
+			() => {
+				schema.register( 'paragraph', {
+					allowWhere: '$block',
+					allowContentOf: '$block',
+					allowAttributesOf: '$block'
+				} );
+			},
+			() => {
+				schema.register( 'heading1', {
+					allowWhere: '$block',
+					allowContentOf: '$block',
+					allowAttributesOf: '$block'
+				} );
+			},
+			() => {
+				schema.register( 'listItem', {
+					allowWhere: '$block',
+					allowContentOf: '$block',
+					allowAttributes: [ 'indent', 'type' ],
+					allowAttributesOf: '$block'
+				} );
+			},
+			() => {
+				schema.register( 'blockQuote', {
+					allowWhere: '$block',
+					allowContentOf: '$root'
+				} );
+
+				// Disallow blockQuote in blockQuote.
+				schema.on( 'checkChild', ( evt, args ) => {
+					const context = args[ 0 ];
+					const child = args[ 1 ];
+					const childRule = schema.getRule( child );
+
+					if ( childRule.name == 'blockQuote' && context[ context.length - 1 ].name == 'blockQuote' ) {
+						evt.stop();
+						evt.return = false;
+					}
+				}, { priority: 'high' } );
+			},
+			() => {
+				schema.register( 'image', {
+					allowWhere: '$block',
+					allowAttributes: [ 'src', 'alt' ]
+				} );
+			},
+			() => {
+				schema.register( 'caption', {
+					allowIn: 'image',
+					allowContentOf: '$block'
+				} );
+			},
+			() => {
+				schema.extend( '$text', {
+					allowAttributes: [ 'bold', 'italic' ]
+				} );
+
+				// Disallow bold in heading1.
+				schema.on( 'checkAttribute', ( evt, args ) => {
+					const context = args[ 0 ];
+					const contextLast = context[ context.length - 1 ];
+					const contextSecondToLast = context[ context.length - 2 ];
+					const attributeName = args[ 1 ];
+
+					if ( contextLast.name == '$text' && contextSecondToLast.name == 'heading1' && attributeName == 'bold' ) {
+						evt.stop();
+						evt.return = false;
+					}
+				}, { priority: 'high' } );
+			},
+			() => {
+				schema.extend( '$block', {
+					allowAttributes: 'alignment'
+				} );
+			}
+		];
+
+		beforeEach( () => {
+			schema.register( '$root' );
+			schema.register( '$block', {
+				allowIn: '$root'
+			} );
+			schema.register( '$text', {
+				allowIn: '$block'
+			} );
+
+			for ( const rule of rules ) {
+				rule();
+			}
+
+			// or...
+			//
+			// Use the below code to shuffle the rules.
+			// Don't look here, Szymon!
+			//
+			// const rulesCopy = rules.slice();
+			//
+			// while ( rulesCopy.length ) {
+			// 	const r = Math.floor( Math.random() * rulesCopy.length );
+			// 	rulesCopy.splice( r, 1 )[ 0 ]();
+			// }
+
+			root1 = new Element( '$root', null, [
+				new Element( 'paragraph', null, 'foo' ),
+				new Element( 'paragraph', { alignment: 'right' }, 'bar' ),
+				new Element( 'listItem', { type: 'x', indent: 0 }, 'foo' ),
+				new Element( 'heading1', null, 'foo' ),
+				new Element( 'blockQuote', null, [
+					new Element( 'paragraph', null, 'foo' ),
+					new Element( 'listItem', { type: 'x', indent: 0 }, 'foo' ),
+					new Element( 'image', null, [
+						new Element( 'caption', null, 'foo' )
+					] )
+				] ),
+				new Element( 'image', null, [
+					new Element( 'caption', null, 'foo' )
+				] )
+			] );
+			r1p1 = root1.getChild( 0 );
+			r1p2 = root1.getChild( 1 );
+			r1lI = root1.getChild( 2 );
+			r1h = root1.getChild( 3 );
+			r1bQ = root1.getChild( 4 );
+			r1i = root1.getChild( 5 );
+			r1bQp = r1bQ.getChild( 0 );
+			r1bQlI = r1bQ.getChild( 1 );
+			r1bQi = r1bQ.getChild( 2 );
+		} );
+
+		it( 'passes $root>paragraph', () => {
+			expect( schema.checkChild( root1, 'paragraph' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>paragraph>$text', () => {
+			expect( schema.checkChild( r1p1, '$text' ), 'paragraph' ).to.be.true;
+			expect( schema.checkChild( r1p2, '$text' ), 'paragraph[alignment]' ).to.be.true;
+		} );
+
+		it( 'passes $root>listItem', () => {
+			expect( schema.checkChild( root1, 'listItem' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>listItem>$text', () => {
+			expect( schema.checkChild( r1lI, '$text' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>paragraph', () => {
+			expect( schema.checkChild( r1bQ, 'paragraph' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>paragraph>$text', () => {
+			expect( schema.checkChild( r1bQp, '$text' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>listItem', () => {
+			expect( schema.checkChild( r1bQ, 'listItem' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>listItem>$text', () => {
+			expect( schema.checkChild( r1bQlI, '$text' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>image', () => {
+			expect( schema.checkChild( r1bQ, 'image' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>image>caption', () => {
+			expect( schema.checkChild( r1bQi, 'caption' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>blockQuote>image>caption>$text', () => {
+			expect( schema.checkChild( r1bQi.getChild( 0 ), '$text' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>image', () => {
+			expect( schema.checkChild( root1, 'image' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>image>caption', () => {
+			expect( schema.checkChild( r1i, 'caption' ) ).to.be.true;
+		} );
+
+		it( 'passes $root>image>caption>$text', () => {
+			expect( schema.checkChild( r1i.getChild( 0 ), '$text' ) ).to.be.true;
+		} );
+
+		it( 'rejects $root>$root', () => {
+			expect( schema.checkChild( root1, '$root' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>$text', () => {
+			expect( schema.checkChild( root1, '$text' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>caption', () => {
+			expect( schema.checkChild( root1, 'caption' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>paragraph>paragraph', () => {
+			expect( schema.checkChild( r1p1, 'paragraph' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>paragraph>paragraph>$text', () => {
+			// Edge case because p>p should not exist in the first place.
+			// But it's good to know that it blocks also this.
+			const p = new Element( 'p' );
+			r1p1.appendChildren( p );
+
+			expect( schema.checkChild( p, '$text' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>paragraph>$block', () => {
+			expect( schema.checkChild( r1p1, '$block' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>paragraph>blockQuote', () => {
+			expect( schema.checkChild( r1p1, 'blockQuote' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>paragraph>image', () => {
+			expect( schema.checkChild( r1p1, 'image' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>paragraph>caption', () => {
+			expect( schema.checkChild( r1p1, 'caption' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>blockQuote>blockQuote', () => {
+			expect( schema.checkChild( r1bQ, 'blockQuote' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>blockQuote>caption', () => {
+			expect( schema.checkChild( r1p1, 'image' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>blockQuote>$text', () => {
+			expect( schema.checkChild( r1bQ, '$text' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>image>$text', () => {
+			expect( schema.checkChild( r1i, '$text' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>image>paragraph', () => {
+			expect( schema.checkChild( r1i, 'paragraph' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>image>caption>paragraph', () => {
+			expect( schema.checkChild( r1i.getChild( 0 ), 'paragraph' ) ).to.be.false;
+		} );
+
+		it( 'rejects $root>image>caption>blockQuote', () => {
+			expect( schema.checkChild( r1i.getChild( 0 ), 'blockQuote' ) ).to.be.false;
+		} );
+
+		it( 'accepts attribute $root>paragraph[alignment]', () => {
+			expect( schema.checkAttribute( r1p1, 'alignment' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>paragraph>$text[bold]', () => {
+			expect( schema.checkAttribute( r1p1.getChild( 0 ), 'bold' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>heading1>$text[italic]', () => {
+			expect( schema.checkAttribute( r1h.getChild( 0 ), 'italic' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>blockQuote>paragraph>$text[bold]', () => {
+			expect( schema.checkAttribute( r1bQp.getChild( 0 ), 'bold' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>listItem[alignment]', () => {
+			expect( schema.checkAttribute( r1lI, 'alignment' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>listItem[indent]', () => {
+			expect( schema.checkAttribute( r1lI, 'indent' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>listItem[type]', () => {
+			expect( schema.checkAttribute( r1lI, 'type' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>image[src]', () => {
+			expect( schema.checkAttribute( r1i, 'src' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>image[alt]', () => {
+			expect( schema.checkAttribute( r1i, 'alt' ) ).to.be.true;
+		} );
+
+		it( 'accepts attribute $root>image>caption>$text[bold]', () => {
+			expect( schema.checkAttribute( r1i.getChild( 0 ).getChild( 0 ), 'bold' ) ).to.be.true;
+		} );
+
+		it( 'rejects attribute $root[indent]', () => {
+			expect( schema.checkAttribute( root1, 'indent' ) ).to.be.false;
+		} );
+
+		it( 'rejects attribute $root>paragraph[indent]', () => {
+			expect( schema.checkAttribute( r1p1, 'indent' ) ).to.be.false;
+		} );
+
+		it( 'accepts attribute $root>heading1>$text[bold]', () => {
+			expect( schema.checkAttribute( r1h.getChild( 0 ), 'bold' ) ).to.be.false;
+		} );
+
+		it( 'rejects attribute $root>paragraph>$text[alignment]', () => {
+			expect( schema.checkAttribute( r1p1.getChild( 0 ), 'alignment' ) ).to.be.false;
+		} );
+
+		it( 'rejects attribute $root>blockQuote[indent]', () => {
+			expect( schema.checkAttribute( r1bQ, 'indent' ) ).to.be.false;
+		} );
+
+		it( 'rejects attribute $root>blockQuote[alignment]', () => {
+			expect( schema.checkAttribute( r1bQ, 'alignment' ) ).to.be.false;
+		} );
+
+		it( 'rejects attribute $root>image[indent]', () => {
+			expect( schema.checkAttribute( r1i, 'indent' ) ).to.be.false;
+		} );
+
+		it( 'rejects attribute $root>image[alignment]', () => {
+			expect( schema.checkAttribute( r1i, 'alignment' ) ).to.be.false;
+		} );
+	} );
+
+	// TODO:
+	// * getValidRanges
+	// * checkAttributeInSelection
+	// * getLimitElement
+	// * removeDisallowedAttributes
+	// * isBlock, isLimit, isObject, isRegistered
+} );