svelte/src/generators/dom/index.js

import deindent from '../../utils/deindent.js';
import getBuilders from './utils/getBuilders.js';
import CodeBuilder from '../../utils/CodeBuilder.js';
import namespaces from '../../utils/namespaces.js';
import removeObjectKey from '../../utils/removeObjectKey.js';
import visitors from './visitors/index.js';
import Generator from '../Generator.js';
import * as shared from '../../shared/index.js';

class DomGenerator extends Generator {
	constructor ( parsed, source, name, visitors, options ) {
		super( parsed, source, name, visitors, options );
		this.renderers = [];
		this.uses = new Set();

		// initial values for e.g. window.innerWidth, if there's a <:Window> meta tag
		this.builders = {
			metaBindings: new CodeBuilder()
		};

		this.importedComponents = new Map();
	}

	addElement ( name, renderStatement, needsIdentifier = false ) {
		const isToplevel = this.current.localElementDepth === 0;
		if ( needsIdentifier || isToplevel ) {
			this.current.builders.init.addLine(
				`var ${name} = ${renderStatement};`
			);

			this.createMountStatement( name );
		} else {
			this.current.builders.init.addLine( `${this.helper( 'appendNode' )}( ${renderStatement}, ${this.current.target} );` );
		}

		if ( isToplevel ) {
			this.current.builders.detach.addLine( `${this.helper( 'detachNode' )}( ${name} );` );
		}
	}

	addRenderer ( fragment ) {
		if ( fragment.autofocus ) {
			fragment.builders.init.addLine( `${fragment.autofocus}.focus();` );
		}

		// minor hack – we need to ensure that any {{{triples}}} are detached
		// first, so we append normal detach statements to detachRaw
		fragment.builders.detachRaw.addBlock( fragment.builders.detach );

		if ( !fragment.builders.detachRaw.isEmpty() ) {
			fragment.builders.teardown.addBlock( deindent`
				if ( detach ) {
					${fragment.builders.detachRaw}
				}
			` );
		}

		const properties = new CodeBuilder();

		let localKey;
		if ( fragment.key ) {
			localKey = fragment.getUniqueName( 'key' );
			properties.addBlock( `key: ${localKey},` );
		}

		if ( fragment.builders.mount.isEmpty() ) {
			properties.addBlock( `mount: ${this.helper( 'noop' )},` );
		} else {
			properties.addBlock( deindent`
				mount: function ( target, anchor ) {
					${fragment.builders.mount}
				},
			` );
		}

		if ( fragment.builders.update.isEmpty() ) {
			properties.addBlock( `update: ${this.helper( 'noop' )},` );
		} else {
			properties.addBlock( deindent`
				update: function ( changed, ${fragment.params.join( ', ' )} ) {
					${fragment.tmp ? `var ${fragment.tmp};` : ''}

					${fragment.builders.update}
				},
			` );
		}

		if ( fragment.builders.teardown.isEmpty() ) {
			properties.addBlock( `teardown: ${this.helper( 'noop' )},` );
		} else {
			properties.addBlock( deindent`
				teardown: function ( detach ) {
					${fragment.builders.teardown}
				}
			` );
		}

		this.renderers.push( deindent`
			function ${fragment.name} ( ${fragment.params.join( ', ' )}, ${fragment.component}${fragment.key ? `, ${localKey}` : ''} ) {
				${fragment.builders.init}

				return {
					${properties}
				};
			}
		` );
	}

	createAnchor ( name ) {
		const renderStatement = `${this.helper( 'createComment' )}()`;
		this.addElement( name, renderStatement, true );
	}

	createMountStatement ( name ) {
		if ( this.current.target === 'target' ) {
			this.current.builders.mount.addLine( `${this.helper( 'insertNode' )}( ${name}, target, anchor );` );
		} else {
			this.current.builders.init.addLine( `${this.helper( 'appendNode' )}( ${name}, ${this.current.target} );` );
		}
	}

	generateBlock ( node, name, type ) {
		this.push({
			type,
			name,
			target: 'target',
			localElementDepth: 0,
			builders: getBuilders(),
			getUniqueName: this.getUniqueNameMaker( this.current.params )
		});

		// walk the children here
		node.children.forEach( node => this.visit( node ) );
		this.addRenderer( this.current );
		this.pop();

		// unset the children, to avoid them being visited again
		node.children = [];
	}

	helper ( name ) {
		if ( this.options.dev && `${name}Dev` in shared ) {
			name = `${name}Dev`;
		}

		this.uses.add( name );

		return this.alias( name );
	}
}

export default function dom ( parsed, source, options ) {
	const format = options.format || 'es';
	const name = options.name || 'SvelteComponent';

	const generator = new DomGenerator( parsed, source, name, visitors, options );

	const { computations, defaultExport, templateProperties } = generator.parseJs();

	// Remove these after version 2
	if ( templateProperties.onrender ) {
		const { key } = templateProperties.onrender;
		generator.code.overwrite( key.start, key.end, 'oncreate', true );
		templateProperties.oncreate = templateProperties.onrender;
	}

	if ( templateProperties.onteardown ) {
		const { key } = templateProperties.onteardown;
		generator.code.overwrite( key.start, key.end, 'ondestroy', true );
		templateProperties.ondestroy = templateProperties.onteardown;
	}

	let namespace = null;
	if ( templateProperties.namespace ) {
		const ns = templateProperties.namespace.value.value;
		namespace = namespaces[ ns ] || ns;

		removeObjectKey( generator, defaultExport.declaration, 'namespace' );
	}

	if ( templateProperties.components ) {
		let hasNonImportedComponent = false;
		templateProperties.components.value.properties.forEach( property => {
			const key = property.key.name;
			const value = source.slice( property.value.start, property.value.end );
			if ( generator.importedNames.has( value ) ) {
				generator.importedComponents.set( key, value );
			} else {
				hasNonImportedComponent = true;
			}
		});
		if ( hasNonImportedComponent ) {
			// remove the specific components that were imported, as we'll refer to them directly
			Array.from( generator.importedComponents.keys() ).forEach( key => {
				removeObjectKey( generator, templateProperties.components.value, key );
			});
		} else {
			// remove the entire components portion of the export
			removeObjectKey( generator, defaultExport.declaration, 'components' );
		}
	}

	const getUniqueName = generator.getUniqueNameMaker( [ 'root' ] );
	const component = getUniqueName( 'component' );

	generator.push({
		type: 'block',
		name: generator.alias( 'render_main_fragment' ),
		namespace,
		target: 'target',
		localElementDepth: 0,
		key: null,

		component,

		contexts: new Map(),
		indexes: new Map(),

		params: [ 'root' ],
		indexNames: new Map(),
		listNames: new Map(),

		builders: getBuilders(),
		getUniqueName,
	});

	parsed.html.children.forEach( node => generator.visit( node ) );

	generator.addRenderer( generator.pop() );

	const builders = {
		main: new CodeBuilder(),
		init: new CodeBuilder(),
		_set: new CodeBuilder()
	};

	if ( options.dev ) {
		builders._set.addBlock ( deindent`
			if ( typeof newState !== 'object' ) {
				throw new Error( 'Component .set was called without an object of data key-values to update.' );
			}
		`);
	}

	builders._set.addLine( 'var oldState = this._state;' );
	builders._set.addLine( `this._state = ${generator.helper( 'assign' )}( {}, oldState, newState );` );

	if ( computations.length ) {
		const builder = new CodeBuilder();
		const differs = generator.helper( 'differs' );

		computations.forEach( ({ key, deps }) => {
			builder.addBlock( deindent`
				if ( isInitial || ${deps.map( dep => `( '${dep}' in newState && ${differs}( state.${dep}, oldState.${dep} ) )` ).join( ' || ' )} ) {
					state.${key} = newState.${key} = ${generator.alias( 'template' )}.computed.${key}( ${deps.map( dep => `state.${dep}` ).join( ', ' )} );
				}
			` );
		});

		builders.main.addBlock( deindent`
			function ${generator.alias( 'recompute' )} ( state, newState, oldState, isInitial ) {
				${builder}
			}
		` );

		builders._set.addLine( `${generator.alias( 'recompute' )}( this._state, newState, oldState, false )` );
	}

	// TODO is the `if` necessary?
	builders._set.addBlock( deindent`
		${generator.helper( 'dispatchObservers' )}( this, this._observers.pre, newState, oldState );
		if ( this._fragment ) this._fragment.update( newState, this._state );
		${generator.helper( 'dispatchObservers' )}( this, this._observers.post, newState, oldState );
	` );

	if ( parsed.js ) {
		builders.main.addBlock( `[✂${parsed.js.content.start}-${parsed.js.content.end}✂]` );
	}

	if ( generator.css && options.css !== false ) {
		builders.main.addBlock( deindent`
			var ${generator.alias( 'added_css' )} = false;
			function ${generator.alias( 'add_css' )} () {
				var style = ${generator.helper( 'createElement' )}( 'style' );
				style.textContent = ${JSON.stringify( generator.css )};
				${generator.helper( 'appendNode' )}( style, document.head );

				${generator.alias( 'added_css' )} = true;
			}
		` );
	}

	let i = generator.renderers.length;
	while ( i-- ) builders.main.addBlock( generator.renderers[i] );

	builders.init.addLine( `this._torndown = false;` );

	if ( parsed.css && options.css !== false ) {
		builders.init.addLine( `if ( !${generator.alias( 'added_css' )} ) ${generator.alias( 'add_css' )}();` );
	}

	if ( generator.hasComponents ) {
		builders.init.addLine( `this._renderHooks = [];` );
	}

	if ( generator.hasComplexBindings ) {
		builders.init.addBlock( deindent`
			this._bindings = [];
			this._fragment = ${generator.alias( 'render_main_fragment' )}( this._state, this );
			if ( options.target ) this._fragment.mount( options.target, null );
			while ( this._bindings.length ) this._bindings.pop()();
		` );

		builders._set.addLine( `while ( this._bindings.length ) this._bindings.pop()();` );
	} else {
		builders.init.addBlock( deindent`
			this._fragment = ${generator.alias( 'render_main_fragment' )}( this._state, this );
			if ( options.target ) this._fragment.mount( options.target, null );
		` );
	}

	if ( generator.hasComponents ) {
		const statement = `this._flush();`;

		builders.init.addBlock( statement );
		builders._set.addBlock( statement );
	}

	if ( templateProperties.oncreate ) {
		builders.init.addBlock( deindent`
			if ( options._root ) {
				options._root._renderHooks.push({ fn: ${generator.alias( 'template' )}.oncreate, context: this });
			} else {
				${generator.alias( 'template' )}.oncreate.call( this );
			}
		` );
	}

	const constructorBlock = new CodeBuilder();

	constructorBlock.addLine( `options = options || {};` );
	if ( generator.usesRefs ) constructorBlock.addLine( `this.refs = {};` );

	constructorBlock.addLine(
		`this._state = ${templateProperties.data ? `${generator.helper( 'assign' )}( ${generator.alias( 'template' )}.data(), options.data )` : `options.data || {}`};`
	);

	if ( !generator.builders.metaBindings.isEmpty() ) {
		constructorBlock.addBlock( generator.builders.metaBindings );
	}

	if ( templateProperties.computed ) {
		constructorBlock.addLine(
			`${generator.alias( 'recompute' )}( this._state, this._state, {}, true );`
		);
	}

	if ( options.dev ) {
		generator.expectedProperties.forEach( prop => {
			constructorBlock.addLine(
				`if ( !( '${prop}' in this._state ) ) throw new Error( "Component was created without expected data property '${prop}'" );`
			);
		});

		constructorBlock.addBlock(
			`if ( !options.target && !options._root ) throw new Error( "'target' is a required option" );`
		);
	}

	if ( generator.bindingGroups.length ) {
		constructorBlock.addLine( `this._bindingGroups = [ ${Array( generator.bindingGroups.length ).fill( '[]' ).join( ', ' )} ];` );
	}

	constructorBlock.addBlock( deindent`
		this._observers = {
			pre: Object.create( null ),
			post: Object.create( null )
		};

		this._handlers = Object.create( null );

		this._root = options._root;
		this._yield = options._yield;

		${builders.init}
	` );

	builders.main.addBlock( deindent`
		function ${name} ( options ) {
			${constructorBlock}
		}
	` );

	const sharedPath = options.shared === true ? 'svelte/shared.js' : options.shared;

	if ( sharedPath ) {
		const base = templateProperties.methods ? `{}, ${generator.alias( 'template' )}.methods` : `{}`;
		builders.main.addBlock( `${name}.prototype = ${generator.helper( 'assign' )}( ${base}, ${generator.helper( 'proto' )} );` );
	} else {
		if ( templateProperties.methods ) {
			builders.main.addBlock( `${name}.prototype = ${generator.alias( 'template' )}.methods;` );
		}

		[ 'get', 'fire', 'observe', 'on', 'set', '_flush' ].forEach( methodName => {
			builders.main.addLine( `${name}.prototype.${methodName} = ${generator.helper( methodName )};` );
		});
	}

	// TODO deprecate component.teardown()
	builders.main.addBlock( deindent`
		${name}.prototype._set = function _set ( newState ) {
			${builders._set}
		};

		${name}.prototype.teardown = ${name}.prototype.destroy = function destroy ( detach ) {
			this.fire( 'destroy' );${templateProperties.ondestroy ? `\n${generator.alias( 'template' )}.ondestroy.call( this );` : ``}

			this._fragment.teardown( detach !== false );
			this._fragment = null;

			this._state = {};
			this._torndown = true;
		};
	` );

	if ( sharedPath ) {
		if ( format !== 'es' ) {
			throw new Error( `Components with shared helpers must be compiled to ES2015 modules (format: 'es')` );
		}

		const names = Array.from( generator.uses ).map( name => {
			return name !== generator.alias( name ) ? `${name} as ${generator.alias( name )}` : name;
		});

		builders.main.addLineAtStart(
			`import { ${names.join( ', ' )} } from ${JSON.stringify( sharedPath )};`
		);
	} else {
		generator.uses.forEach( key => {
			const fn = shared[ key ]; // eslint-disable-line import/namespace
			builders.main.addBlock( fn.toString().replace( /^function [^(]*/, 'function ' + generator.alias( key ) ) );
		});
	}

	return generator.generate( builders.main.toString(), options, { name, format } );
}