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Bundle.js
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Bundle.js
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import { basename, dirname, extname, relative, resolve } from 'path';
import { readFile, Promise } from 'sander';
import MagicString from 'magic-string';
import { keys, has } from './utils/object';
import Module from './Module';
import ExternalModule from './ExternalModule';
import finalisers from './finalisers/index';
import makeLegalIdentifier from './utils/makeLegalIdentifier';
import { defaultResolver } from './utils/resolvePath';
function badExports ( option, keys ) {
throw new Error( `'${option}' was specified for options.exports, but entry module has following exports: ${keys.join(', ')}` );
}
export default class Bundle {
constructor ( options ) {
this.entryPath = resolve( options.entry ).replace( /\.js$/, '' ) + '.js';
this.base = dirname( this.entryPath );
this.resolvePath = options.resolvePath || defaultResolver;
this.entryModule = null;
this.modulePromises = {};
this.statements = [];
this.externalModules = [];
this.internalNamespaceModules = [];
}
fetchModule ( importee, importer ) {
return Promise.resolve( importer === null ? importee : this.resolvePath( importee, importer ) )
.then( path => {
if ( !path ) {
// external module
if ( !has( this.modulePromises, importee ) ) {
const module = new ExternalModule( importee );
this.externalModules.push( module );
this.modulePromises[ importee ] = Promise.resolve( module );
}
return this.modulePromises[ importee ];
}
if ( !has( this.modulePromises, path ) ) {
this.modulePromises[ path ] = readFile( path, { encoding: 'utf-8' })
.then( source => {
const module = new Module({
path,
source,
bundle: this
});
return module;
});
}
return this.modulePromises[ path ];
});
}
build () {
// bring in top-level AST nodes from the entry module
return this.fetchModule( this.entryPath, null )
.then( entryModule => {
this.entryModule = entryModule;
if ( entryModule.exports.default ) {
let defaultExportName = makeLegalIdentifier( basename( this.entryPath ).slice( 0, -extname( this.entryPath ).length ) );
let topLevelNames = [];
entryModule.statements.forEach( statement => {
keys( statement.defines ).forEach( name => topLevelNames.push( name ) );
});
while ( ~topLevelNames.indexOf( defaultExportName ) ) {
defaultExportName = `_${defaultExportName}`;
}
entryModule.suggestName( 'default', defaultExportName );
}
return entryModule.expandAllStatements( true );
})
.then( statements => {
this.statements = statements;
this.deconflict();
});
}
deconflict () {
let definers = {};
let conflicts = {};
// Discover conflicts (i.e. two statements in separate modules both define `foo`)
this.statements.forEach( statement => {
const module = statement.module;
const names = keys( statement.defines );
// with default exports that are expressions (`export default 42`),
// we need to ensure that the name chosen for the expression does
// not conflict
if ( statement.node.type === 'ExportDefaultDeclaration' ) {
const name = module.getCanonicalName( 'default' );
const isProxy = statement.node.declaration && statement.node.declaration.type === 'Identifier';
const shouldDeconflict = !isProxy || ( module.getCanonicalName( statement.node.declaration.name ) !== name );
if ( shouldDeconflict && !~names.indexOf( name ) ) {
names.push( name );
}
}
names.forEach( name => {
if ( has( definers, name ) ) {
conflicts[ name ] = true;
} else {
definers[ name ] = [];
}
// TODO in good js, there shouldn't be duplicate definitions
// per module... but some people write bad js
definers[ name ].push( module );
});
});
// Assign names to external modules
this.externalModules.forEach( module => {
// TODO is this right?
let name = makeLegalIdentifier( module.suggestedNames['*'] || module.suggestedNames.default || module.id );
if ( has( definers, name ) ) {
conflicts[ name ] = true;
} else {
definers[ name ] = [];
}
definers[ name ].push( module );
module.name = name;
});
// Rename conflicting identifiers so they can live in the same scope
keys( conflicts ).forEach( name => {
const modules = definers[ name ];
modules.pop(); // the module closest to the entryModule gets away with keeping things as they are
modules.forEach( module => {
const replacement = getSafeName( name );
module.rename( name, replacement );
});
});
function getSafeName ( name ) {
while ( has( conflicts, name ) ) {
name = `_${name}`;
}
conflicts[ name ] = true;
return name;
}
}
generate ( options = {} ) {
let magicString = new MagicString.Bundle({ separator: '' });
// Determine export mode - 'default', 'named', 'none'
let exportMode = this.getExportMode( options.exports );
let previousMargin = 0;
// Apply new names and add to the output bundle
this.statements.forEach( statement => {
let replacements = {};
keys( statement.dependsOn )
.concat( keys( statement.defines ) )
.forEach( name => {
const canonicalName = statement.module.getCanonicalName( name );
if ( name !== canonicalName ) {
replacements[ name ] = canonicalName;
}
});
const source = statement.replaceIdentifiers( replacements );
// modify exports as necessary
if ( statement.isExportDeclaration ) {
// skip `export { foo, bar, baz }`
if ( statement.node.type === 'ExportNamedDeclaration' && statement.node.specifiers.length ) {
return;
}
// remove `export` from `export var foo = 42`
if ( statement.node.type === 'ExportNamedDeclaration' && statement.node.declaration.type === 'VariableDeclaration' ) {
source.remove( statement.node.start, statement.node.declaration.start );
}
// remove `export` from `export class Foo {...}` or `export default Foo`
// TODO default exports need different treatment
else if ( statement.node.declaration.id ) {
source.remove( statement.node.start, statement.node.declaration.start );
}
else if ( statement.node.type === 'ExportDefaultDeclaration' ) {
const module = statement.module;
const canonicalName = module.getCanonicalName( 'default' );
if ( statement.node.declaration.type === 'Identifier' && canonicalName === module.getCanonicalName( statement.node.declaration.name ) ) {
return;
}
source.overwrite( statement.node.start, statement.node.declaration.start, `var ${canonicalName} = ` );
}
else {
throw new Error( 'Unhandled export' );
}
}
// add leading comments
if ( statement.leadingComments.length ) {
const commentBlock = statement.leadingComments.map( comment => {
return comment.block ?
`/*${comment.text}*/` :
`//${comment.text}`;
}).join( '\n' );
magicString.addSource( new MagicString( commentBlock ) );
}
// add margin
const margin = Math.max( statement.margin[0], previousMargin );
const newLines = new Array( margin ).join( '\n' );
// add the statement itself
magicString.addSource({
content: source,
separator: newLines
});
// add trailing comments
const comment = statement.trailingComment;
if ( comment ) {
const commentBlock = comment.block ?
` /*${comment.text}*/` :
` //${comment.text}`;
magicString.append( commentBlock );
}
previousMargin = statement.margin[1];
});
// prepend bundle with internal namespaces
const indentString = magicString.getIndentString();
const namespaceBlock = this.internalNamespaceModules.map( module => {
const exportKeys = keys( module.exports );
return `var ${module.getCanonicalName('*')} = {\n` +
exportKeys.map( key => `${indentString}get ${key} () { return ${module.getCanonicalName(key)}; }` ).join( ',\n' ) +
`\n};\n\n`;
}).join( '' );
magicString.prepend( namespaceBlock );
const finalise = finalisers[ options.format || 'es6' ];
if ( !finalise ) {
throw new Error( `You must specify an output type - valid options are ${keys( finalisers ).join( ', ' )}` );
}
magicString = finalise( this, magicString.trim(), exportMode, options );
const code = magicString.toString();
let map = null;
if ( options.sourceMap ) {
map = magicString.generateMap({
includeContent: true,
file: options.sourceMapFile || options.dest
// TODO
});
// make sources relative. TODO fix this upstream?
const dir = dirname( map.file );
map.sources = map.sources.map( source => {
return source ? relative( dir, source ) : null
});
}
return { code, map };
}
getExportMode ( exportMode ) {
const exportKeys = keys( this.entryModule.exports );
if ( exportMode === 'default' ) {
if ( exportKeys.length !== 1 || exportKeys[0] !== 'default' ) {
badExports( 'default', exportKeys );
}
} else if ( exportMode === 'none' && exportKeys.length ) {
badExports( 'none', exportKeys );
}
if ( !exportMode || exportMode === 'auto' ) {
if ( exportKeys.length === 0 ) {
exportMode = 'none';
} else if ( exportKeys.length === 1 && exportKeys[0] === 'default' ) {
exportMode = 'default';
} else {
exportMode = 'named';
}
}
if ( !/(?:default|named|none)/.test( exportMode ) ) {
throw new Error( `options.exports must be 'default', 'named', 'none', 'auto', or left unspecified (defaults to 'auto')` );
}
return exportMode;
}
}