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svelte/compiler/generate/index.js

380 lines
9.8 KiB

import MagicString from 'magic-string';
import { walk } from 'estree-walker';
import deindent from './utils/deindent.js';
import walkHtml from './utils/walkHtml.js';
import flattenReference from './utils/flattenReference.js';
import counter from './utils/counter.js';
function createRenderer ( fragment ) {
return deindent`
function ${fragment.name} ( component, target${fragment.useAnchor ? ', anchor' : ''} ) {
${fragment.initStatements.join( '\n\n' )}
return {
update: function ( ${fragment.contextChain.join( ', ' )} ) {
${fragment.updateStatements.join( '\n\n' )}
},
teardown: function () {
${fragment.teardownStatements.join( '\n\n' )}
}
};
}
`;
}
export default function generate ( parsed, template ) {
const code = new MagicString( template );
const renderers = [];
const counters = {
if: 0,
each: 0
};
// TODO add contents of <script> tag, with `export default` replaced with `var template =`
// TODO css
let current = {
useAnchor: false,
name: 'renderMainFragment',
target: 'target',
initStatements: [],
updateStatements: [],
teardownStatements: [],
contexts: {},
contextChain: [ 'context' ],
counter: counter(),
parent: null
};
function flattenExpression ( node, contexts ) {
const flattened = flattenReference( node );
if ( flattened ) {
if ( flattened.name in contexts ) return flattened.keypath;
// TODO handle globals, e.g. {{Math.round(foo)}}
return `context.${flattened.keypath}`;
}
console.log( `node, contexts`, node, contexts )
return 'TODO'
throw new Error( 'TODO expressions' );
}
parsed.html.children.forEach( child => {
walkHtml( child, {
Element: {
enter ( node ) {
const name = current.counter( node.name );
const initStatements = [
`var ${name} = document.createElement( '${node.name}' );`
];
const teardownStatements = [
`${name}.parentNode.removeChild( ${name} );`
];
node.attributes.forEach( attribute => {
if ( attribute.type === 'EventHandler' ) {
// TODO use magic-string here, so that stack traces
// go through the template
// TODO verify that it's a valid callee (i.e. built-in or declared method)
const handler = current.counter( `${attribute.name}Handler` );
const callee = `component.${attribute.expression.callee.name}`;
const args = attribute.expression.arguments
.map( arg => flattenExpression( arg, current.contexts ) )
.join( ', ' );
initStatements.push( deindent`
function ${handler} ( event ) {
${callee}(${args});
}
${name}.addEventListener( '${attribute.name}', ${handler}, false );
` );
teardownStatements.push( deindent`
${name}.removeEventListener( '${attribute.name}', ${handler}, false );
` );
}
else {
throw new Error( `Not implemented: ${attribute.type}` );
}
});
current.initStatements.push( initStatements.join( '\n' ) );
current.teardownStatements.push( teardownStatements.join( '\n' ) );
current = Object.assign( {}, current, {
target: name,
parent: current
});
},
leave () {
const name = current.target;
current = current.parent;
if ( current.useAnchor && current.target === 'target' ) {
current.initStatements.push( deindent`
target.insertBefore( ${name}, anchor );
` );
} else {
current.initStatements.push( deindent`
${current.target}.appendChild( ${name} );
` );
}
}
},
Text: {
enter ( node ) {
current.initStatements.push( deindent`
${current.target}.appendChild( document.createTextNode( ${JSON.stringify( node.data )} ) );
` );
}
},
MustacheTag: {
enter ( node ) {
const name = current.counter( 'text' );
const expression = flattenExpression( node.expression, current.contexts );
current.initStatements.push( deindent`
var ${name} = document.createTextNode( '' );
var ${name}_value = '';
${current.target}.appendChild( ${name} );
` );
current.updateStatements.push( deindent`
if ( ${expression} !== ${name}_value ) {
${name}_value = ${expression};
${name}.data = ${name}_value;
}
` );
}
},
IfBlock: {
enter ( node ) {
const i = counters.if++;
const name = `ifBlock_${i}`;
const renderer = `renderIfBlock_${i}`;
const expression = flattenExpression( node.expression, current.contexts );
current.initStatements.push( deindent`
var ${name}_anchor = document.createComment( '#if ${template.slice( node.expression.start, node.expression.end )}' );
${current.target}.appendChild( ${name}_anchor );
var ${name} = null;
` );
current.updateStatements.push( deindent`
if ( ${expression} && !${name} ) {
${name} = ${renderer}( component, ${current.target}, ${name}_anchor );
}
else if ( !${expression} && ${name} ) {
${name}.teardown();
${name} = null;
}
if ( ${name} ) {
${name}.update( context );
}
` );
current.teardownStatements.push( deindent`
if ( ${name} ) ${name}.teardown();
` );
current = {
useAnchor: true,
name: renderer,
target: 'target',
contextChain: current.contextChain,
initStatements: [],
updateStatements: [],
teardownStatements: [],
counter: counter(),
parent: current
};
},
leave () {
renderers.push( createRenderer( current ) );
current = current.parent;
}
},
EachBlock: {
enter ( node ) {
const i = counters.each++;
const name = `eachBlock_${i}`;
const renderer = `renderEachBlock_${i}`;
const expression = flattenExpression( node.expression, current.contexts );
current.initStatements.push( deindent`
var ${name}_anchor = document.createComment( '#each ${template.slice( node.expression.start, node.expression.end )}' );
${current.target}.appendChild( ${name}_anchor );
var ${name}_iterations = [];
const ${name}_fragment = document.createDocumentFragment();
` );
current.updateStatements.push( deindent`
for ( var i = 0; i < ${expression}.length; i += 1 ) {
if ( !${name}_iterations[i] ) {
${name}_iterations[i] = ${renderer}( component, ${name}_fragment );
}
const iteration = ${name}_iterations[i];
${name}_iterations[i].update( ${current.contextChain.join( ', ' )}, ${expression}[i] );
}
for ( var i = ${expression}.length; i < ${name}_iterations.length; i += 1 ) {
${name}_iterations[i].teardown();
}
${name}_anchor.parentNode.insertBefore( ${name}_fragment, ${name}_anchor );
${name}_iterations.length = ${expression}.length;
` );
current.teardownStatements.push( deindent`
for ( let i = 0; i < ${name}_iterations.length; i += 1 ) {
${name}_iterations[i].teardown();
}
` );
const contexts = Object.assign( {}, current.contexts );
contexts[ node.context ] = true;
current = {
useAnchor: false,
name: renderer,
target: 'target',
contexts,
contextChain: current.contextChain.concat( node.context ),
initStatements: [],
updateStatements: [],
teardownStatements: [],
counter: counter(),
parent: current
};
},
leave () {
renderers.push( createRenderer( current ) );
current = current.parent;
}
}
});
});
renderers.push( createRenderer( current ) );
let js = '';
let hasDefaultData = false;
// TODO wrap all this in magic-string
if ( parsed.js ) {
const defaultExport = parsed.js.content.body.find( node => node.type === 'ExportDefaultDeclaration' );
if ( defaultExport ) {
js = `${template.slice( parsed.js.content.start, defaultExport.start )}const template = ${template.slice( defaultExport.declaration.start, parsed.js.content.end)}`;
hasDefaultData = defaultExport.declaration.properties.find( prop => prop.key.name === 'data' );
} else {
js = template.slice( parsed.js.content.start, parsed.js.content.end );
}
}
const result = deindent`
${js}
${renderers.reverse().join( '\n\n' )}
export default function createComponent ( options ) {
var component = {};
var state = {};
var observers = {
immediate: Object.create( null ),
deferred: Object.create( null )
};
function dispatchObservers ( group, state, oldState ) {
for ( const key in group ) {
const newValue = state[ key ];
const oldValue = oldState[ key ];
if ( newValue === oldValue && typeof newValue !== 'object' ) continue;
const callbacks = group[ key ];
if ( !callbacks ) continue;
for ( let i = 0; i < callbacks.length; i += 1 ) {
callbacks[i].call( component, newValue, oldValue );
}
}
}
component.get = function get ( key ) {
return state[ key ];
};
component.set = function set ( newState ) {
Object.assign( state, newState );
mainFragment.update( state );
};
component.observe = function ( key, callback, options = {} ) {
const group = options.defer ? observers.deferred : observers.immediate;
( group[ key ] || ( group[ key ] = [] ) ).push( callback );
if ( options.init !== false ) callback( state[ key ] );
return {
cancel () {
const index = group[ key ].indexOf( callback );
if ( ~index ) group[ key ].splice( index, 1 );
}
};
};
component.teardown = function teardown () {
mainFragment.teardown();
mainFragment = null;
state = {};
};
let mainFragment = renderMainFragment( component, options.target );
component.set( ${hasDefaultData ? `Object.assign( template.data(), options.data )` : `options.data`} );
return component;
}
`;
return { code: result }; // TODO use magic-string
}