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node_modules/html-webpack-plugin/lib/compiler.js 4.38 KB
aaac7fed   liuqimichale   add
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  /*
   * This file uses webpack to compile a template with a child compiler.
   *
   * [TEMPLATE] -> [JAVASCRIPT]
   *
   */
  'use strict';
  var Promise = require('bluebird');
  var _ = require('lodash');
  var path = require('path');
  var NodeTemplatePlugin = require('webpack/lib/node/NodeTemplatePlugin');
  var NodeTargetPlugin = require('webpack/lib/node/NodeTargetPlugin');
  var LoaderTargetPlugin = require('webpack/lib/LoaderTargetPlugin');
  var LibraryTemplatePlugin = require('webpack/lib/LibraryTemplatePlugin');
  var SingleEntryPlugin = require('webpack/lib/SingleEntryPlugin');
  
  /**
   * Compiles the template into a nodejs factory, adds its to the compilation.assets
   * and returns a promise of the result asset object.
   *
   * @param template relative path to the template file
   * @param context path context
   * @param outputFilename the file name
   * @param compilation The webpack compilation object
   *
   * Returns an object:
   * {
   *  hash: {String} - Base64 hash of the file
   *  content: {String} - Javascript executable code of the template
   * }
   *
   */
  module.exports.compileTemplate = function compileTemplate (template, context, outputFilename, compilation) {
    // The entry file is just an empty helper as the dynamic template
    // require is added in "loader.js"
    var outputOptions = {
      filename: outputFilename,
      publicPath: compilation.outputOptions.publicPath
    };
    // Store the result of the parent compilation before we start the child compilation
    var assetsBeforeCompilation = _.assign({}, compilation.assets[outputOptions.filename]);
    // Create an additional child compiler which takes the template
    // and turns it into an Node.JS html factory.
    // This allows us to use loaders during the compilation
    var compilerName = getCompilerName(context, outputFilename);
    var childCompiler = compilation.createChildCompiler(compilerName, outputOptions);
    childCompiler.context = context;
    childCompiler.apply(
      new NodeTemplatePlugin(outputOptions),
      new NodeTargetPlugin(),
      new LibraryTemplatePlugin('HTML_WEBPACK_PLUGIN_RESULT', 'var'),
      new SingleEntryPlugin(this.context, template),
      new LoaderTargetPlugin('node')
    );
  
    // Fix for "Uncaught TypeError: __webpack_require__(...) is not a function"
    // Hot module replacement requires that every child compiler has its own
    // cache. @see https://github.com/ampedandwired/html-webpack-plugin/pull/179
    childCompiler.plugin('compilation', function (compilation) {
      if (compilation.cache) {
        if (!compilation.cache[compilerName]) {
          compilation.cache[compilerName] = {};
        }
        compilation.cache = compilation.cache[compilerName];
      }
    });
  
    // Compile and return a promise
    return new Promise(function (resolve, reject) {
      childCompiler.runAsChild(function (err, entries, childCompilation) {
        // Resolve / reject the promise
        if (childCompilation && childCompilation.errors && childCompilation.errors.length) {
          var errorDetails = childCompilation.errors.map(function (error) {
            return error.message + (error.error ? ':\n' + error.error : '');
          }).join('\n');
          reject(new Error('Child compilation failed:\n' + errorDetails));
        } else if (err) {
          reject(err);
        } else {
          // Replace [hash] placeholders in filename
          var outputName = compilation.mainTemplate.applyPluginsWaterfall('asset-path', outputOptions.filename, {
            hash: childCompilation.hash,
            chunk: entries[0]
          });
          // Restore the parent compilation to the state like it
          // was before the child compilation
          compilation.assets[outputName] = assetsBeforeCompilation[outputName];
          if (assetsBeforeCompilation[outputName] === undefined) {
            // If it wasn't there - delete it
            delete compilation.assets[outputName];
          }
          resolve({
            // Hash of the template entry point
            hash: entries[0].hash,
            // Output name
            outputName: outputName,
            // Compiled code
            content: childCompilation.assets[outputName].source()
          });
        }
      });
    });
  };
  
  /**
   * Returns the child compiler name e.g. 'html-webpack-plugin for "index.html"'
   */
  function getCompilerName (context, filename) {
    var absolutePath = path.resolve(context, filename);
    var relativePath = path.relative(context, absolutePath);
    return 'html-webpack-plugin for "' + (absolutePath.length < relativePath.length ? absolutePath : relativePath) + '"';
  }