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Code Issues Projects Releases Wiki Activity

hoist variables where appropriate (#504)

Browse Source
pull/506/head
Rich-Harris 9 years ago
parent cf86d8cff6
commit f82d04913f
8 changed files with 49 additions and 25 deletions
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21
src/generators/dom/Block.js
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@ -30,6 +30,7 @@ export default class Block {
};
this.aliases = new Map();
this.variables = new Map();
this.getUniqueName = this.generator.getUniqueNameMaker( options.params );
// unique names
@ -62,6 +63,14 @@ export default class Block {
}
}
addVariable ( name, init ) {
if ( this.variables.has( name ) && this.variables.get( name ) !== init ) {
throw new Error( `Variable '${name}' already initialised with a different value` );
}
this.variables.set( name, init );
}
alias ( name ) {
if ( !this.aliases.has( name ) ) {
this.aliases.set( name, this.getUniqueName( name ) );
@ -96,6 +105,17 @@ export default class Block {
}
render () {
if ( this.variables.size ) {
const variables = Array.from( this.variables.keys() )
.map( key => {
const init = this.variables.get( key );
return init !== undefined ? `${key} = ${init}` : key;
})
.join( ', ' );
this.builders.create.addBlockAtStart( `var ${variables};` );
}
if ( this.autofocus ) {
this.builders.create.addLine( `${this.autofocus}.focus();` );
}
@ -134,7 +154,6 @@ export default class Block {
if ( this.builders.update.isEmpty() ) {
properties.addBlock( `update: ${this.generator.helper( 'noop' )},` );
} else {
if ( this._tmp ) this.builders.update.addBlockAtStart( `var ${this._tmp};` );
properties.addBlock( deindent`
update: function ( changed, ${this.params.join( ', ' )} ) {
${this.builders.update}

3
src/generators/dom/visitors/Component/Binding.js
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@ -40,10 +40,9 @@ export default function visitBinding ( generator, block, state, node, attribute,
generator.hasComplexBindings = true;
const updating = block.getUniqueName( `${local.name}_updating` );
block.addVariable( updating, 'false' );
local.create.addBlock( deindent`
var ${updating} = false;
${block.component}._bindings.push( function () {
if ( ${local.name}._torndown ) return;
${local.name}.observe( '${attribute.name}', function ( value ) {

11
src/generators/dom/visitors/Element/Attribute.js
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@ -44,7 +44,7 @@ export default function visitAttribute ( generator, block, state, node, attribut
}
const last = block.getUniqueName( `${state.parentNode}_${name.replace( /[^a-zA-Z_$]/g, '_')}_value` );
block.builders.create.addLine( `var ${last} = ${value};` );
block.addVariable( last );
const isSelectValueAttribute = name === 'value' && state.parentNodeName === 'select';
@ -66,20 +66,25 @@ export default function visitAttribute ( generator, block, state, node, attribut
}`;
updater = deindent`
var ${last} = ${last};
for ( var ${i} = 0; ${i} < ${state.parentNode}.options.length; ${i} += 1 ) {
var ${option} = ${state.parentNode}.options[${i}];
${ifStatement}
}
`;
block.builders.create.addLine( deindent`
${last} = ${value}
${updater}
` );
} else if ( propertyName ) {
block.builders.create.addLine( `${state.parentNode}.${propertyName} = ${last} = ${value};` );
updater = `${state.parentNode}.${propertyName} = ${last};`;
} else {
block.builders.create.addLine( `${generator.helper( method )}( ${state.parentNode}, '${name}', ${last} = ${value} );` );
updater = `${generator.helper( method )}( ${state.parentNode}, '${name}', ${last} );`;
}
block.builders.create.addLine( updater );
block.builders.update.addBlock( deindent`
if ( ${last} !== ( ${last} = ${value} ) ) {
${updater}

12
src/generators/dom/visitors/Element/Binding.js
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@ -4,7 +4,7 @@ import getSetter from '../shared/binding/getSetter.js';
import getStaticAttributeValue from './getStaticAttributeValue.js';
export default function visitBinding ( generator, block, state, node, attribute ) {
const { name, keypath, parts } = flattenReference( attribute.value );
const { name, parts } = flattenReference( attribute.value );
const { snippet, contexts, dependencies } = block.contextualise( attribute.value );
if ( dependencies.length > 1 ) throw new Error( 'An unexpected situation arose. Please raise an issue at https://github.com/sveltejs/svelte/issues — thanks!' );
@ -25,6 +25,8 @@ export default function visitBinding ( generator, block, state, node, attribute
const lock = block.alias( `${state.parentNode}_updating` );
let updateCondition = `!${lock}`;
block.addVariable( lock, 'false' );
// <select> special case
if ( node.name === 'select' ) {
if ( !isMultipleSelect ) {
@ -32,7 +34,7 @@ export default function visitBinding ( generator, block, state, node, attribute
}
const value = block.getUniqueName( 'value' );
const i = block.getUniqueName( 'i' );
const i = block.alias( 'i' );
const option = block.getUniqueName( 'option' );
const ifStatement = isMultipleSelect ?
@ -84,7 +86,7 @@ export default function visitBinding ( generator, block, state, node, attribute
if ( attribute.name === 'currentTime' ) {
const frame = block.getUniqueName( `${state.parentNode}_animationframe` );
block.builders.create.addLine( `var ${frame};` );
block.addVariable( frame );
setter = deindent`
cancelAnimationFrame( ${frame} );
if ( !${state.parentNode}.paused ) ${frame} = requestAnimationFrame( ${handler} );
@ -101,7 +103,7 @@ export default function visitBinding ( generator, block, state, node, attribute
else if ( attribute.name === 'paused' ) {
// this is necessary to prevent the audio restarting by itself
const last = block.getUniqueName( `${state.parentNode}_paused_value` );
block.builders.create.addLine( `var ${last} = true;` );
block.addVariable( last, 'true' );
updateCondition = `${last} !== ( ${last} = ${snippet} )`;
updateElement = `${state.parentNode}[ ${last} ? 'pause' : 'play' ]();`;
@ -109,8 +111,6 @@ export default function visitBinding ( generator, block, state, node, attribute
}
block.builders.create.addBlock( deindent`
var ${lock} = false;
function ${handler} () {
${lock} = true;
${setter}

2
src/generators/dom/visitors/Element/meta/Window.js
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@ -98,7 +98,7 @@ export default function visitWindow ( generator, block, node ) {
const handlerBody = new CodeBuilder();
if ( event === 'scroll' ) { // TODO other bidirectional bindings...
block.builders.create.addLine( `var ${lock} = false;` );
block.addVariable( lock, 'false' );
handlerBody.addLine( `${lock} = true;` );
}

4
src/generators/dom/visitors/MustacheTag.js
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@ -6,8 +6,8 @@ export default function visitMustacheTag ( generator, block, state, node ) {
const { snippet } = block.contextualise( node.expression );
block.builders.create.addLine( `var ${value} = ${snippet};` );
block.addElement( name, `${generator.helper( 'createText' )}( ${value} )`, state.parentNode, true );
block.addVariable( value );
block.addElement( name, `${generator.helper( 'createText' )}( ${value} = ${snippet} )`, state.parentNode, true );
block.builders.update.addBlock( deindent`
if ( ${value} !== ( ${value} = ${snippet} ) ) {

5
test/js/samples/collapses-text-around-comments/expected.js
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@ -18,10 +18,11 @@ function add_css () {
}
function create_main_fragment ( root, component ) {
var text_value;
var p = createElement( 'p' );
setAttribute( p, 'svelte-3842350206', '' );
var text_value = root.foo;
var text = createText( text_value );
var text = createText( text_value = root.foo );
appendNode( text, p );
return {

16
test/js/samples/each-block-changed-check/expected.js
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@ -1,6 +1,8 @@
import { appendNode, assign, createComment, createElement, createText, destroyEach, detachBetween, detachNode, dispatchObservers, insertNode, proto } from "svelte/shared.js";
function create_main_fragment ( root, component ) {
var text_1_value;
var each_block_anchor = createComment();
var each_block_value = root.comments;
var each_block_iterations = [];
@ -11,8 +13,7 @@ function create_main_fragment ( root, component ) {
var text = createText( "\n\n" );
var p = createElement( 'p' );
var text_1_value = root.foo;
var text_1 = createText( text_1_value );
var text_1 = createText( text_1_value = root.foo );
appendNode( text_1, p );
return {
@ -63,23 +64,22 @@ function create_main_fragment ( root, component ) {
}
function create_each_block ( root, each_block_value, comment, i, component ) {
var text_value, text_2_value, text_4_value;
var div = createElement( 'div' );
div.className = "comment";
var strong = createElement( 'strong' );
appendNode( strong, div );
var text_value = i;
var text = createText( text_value );
var text = createText( text_value = i );
appendNode( text, strong );
appendNode( createText( "\n\n\t\t" ), div );
var span = createElement( 'span' );
appendNode( span, div );
span.className = "meta";
var text_2_value = comment.author;
var text_2 = createText( text_2_value );
var text_2 = createText( text_2_value = comment.author );
appendNode( text_2, span );
appendNode( createText( " wrote " ), span );
var text_4_value = root.elapsed(comment.time, root.time);
var text_4 = createText( text_4_value );
var text_4 = createText( text_4_value = root.elapsed(comment.time, root.time) );
appendNode( text_4, span );
appendNode( createText( " ago:" ), span );
appendNode( createText( "\n\n\t\t" ), div );

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