rax-hot-module-replacement-webpack-plugin/src/Template.js

/*
  MIT License http://www.opensource.org/licenses/mit-license.php
  Author Tobias Koppers @sokra
*/
'use strict';

const Tapable = require('tapable');
const ConcatSource = require('webpack-sources').ConcatSource;

const START_LOWERCASE_ALPHABET_CODE = 'a'.charCodeAt(0);
const START_UPPERCASE_ALPHABET_CODE = 'A'.charCodeAt(0);
const DELTA_A_TO_Z = 'z'.charCodeAt(0) - START_LOWERCASE_ALPHABET_CODE + 1;

module.exports = class Template extends Tapable {
  constructor(outputOptions) {
    super();
    this.outputOptions = outputOptions || {};
  }

  static getFunctionContent(fn) {
    return fn.toString().replace(/^function\s?\(\)\s?\{\n?|\n?\}$/g, '').replace(/^\t/mg, '');
  }

  static toIdentifier(str) {
    if (typeof str !== 'string') return '';
    return str.replace(/^[^a-zA-Z$_]/, '_').replace(/[^a-zA-Z0-9$_]/g, '_');
  }

  static toPath(str) {
    if (typeof str !== 'string') return '';
    return str.replace(/[^a-zA-Z0-9_!§$()=\-\^°]+/g, '-').replace(/^-|-$/, '');
  }

  // map number to a single character a-z, A-Z or <_ + number> if number is too big
  static numberToIdentifer(n) {
    // lower case
    if (n < DELTA_A_TO_Z) return String.fromCharCode(START_LOWERCASE_ALPHABET_CODE + n);

    // upper case
    n -= DELTA_A_TO_Z;
    if (n < DELTA_A_TO_Z) return String.fromCharCode(START_UPPERCASE_ALPHABET_CODE + n);

    // fall back to _ + number
    n -= DELTA_A_TO_Z;
    return '_' + n;
  }

  indent(str) {
    if (Array.isArray(str)) {
      return str.map(this.indent.bind(this)).join('\n');
    } else {
      str = str.trimRight();
      if (!str) return '';
      var ind = str[0] === '\n' ? '' : '\t';
      return ind + str.replace(/\n([^\n])/g, '\n\t$1');
    }
  }

  prefix(str, prefix) {
    if (Array.isArray(str)) {
      str = str.join('\n');
    }
    str = str.trim();
    if (!str) return '';
    const ind = str[0] === '\n' ? '' : prefix;
    return ind + str.replace(/\n([^\n])/g, '\n' + prefix + '$1');
  }

  asString(str) {
    if (Array.isArray(str)) {
      return str.join('\n');
    }
    return str;
  }

  getModulesArrayBounds(modules) {
    if (!modules.every(moduleIdIsNumber))
      return false;
    var maxId = -Infinity;
    var minId = Infinity;
    modules.forEach(function(module) {
      if (maxId < module.id) maxId = module.id;
      if (minId > module.id) minId = module.id;
    });
    if (minId < 16 + ('' + minId).length) {
      // add minId x ',' instead of 'Array(minId).concat(...)'
      minId = 0;
    }
    var objectOverhead = modules.map(function(module) {
      var idLength = (module.id + '').length;
      return idLength + 2;
    }).reduce(function(a, b) {
      return a + b;
    }, -1);
    var arrayOverhead = minId === 0 ? maxId : 16 + ('' + minId).length + maxId;
    return arrayOverhead < objectOverhead ? [minId, maxId] : false;
  }

  renderChunkModules(chunk, moduleTemplate, dependencyTemplates, prefix) {
    if (!prefix) prefix = '';
    var source = new ConcatSource();
    if (chunk.modules.length === 0) {
      source.add('[]');
      return source;
    }
    var removedModules = chunk.removedModules;
    var allModules = chunk.modules.map(function(module) {
      return {
        id: module.id,
        source: moduleTemplate.render(module, dependencyTemplates, chunk)
      };
    });
    if (removedModules && removedModules.length > 0) {
      removedModules.forEach(function(id) {
        allModules.push({
          id: id,
          source: 'false'
        });
      });
    }
    var bounds = this.getModulesArrayBounds(chunk.modules);

    if (bounds) {
      // Render a spare array
      var minId = bounds[0];
      var maxId = bounds[1];
      if (minId !== 0) source.add('Array(' + minId + ').concat(');
      source.add('[\n');
      var modules = {};
      allModules.forEach(function(module) {
        modules[module.id] = module;
      });
      for (var idx = minId; idx <= maxId; idx++) {
        var module = modules[idx];
        if (idx !== minId) source.add(',\n');
        source.add('/* ' + idx + ' */');
        if (module) {
          source.add('\n');
          source.add(module.source);
        }
      }
      source.add('\n' + prefix + ']');
      if (minId !== 0) source.add(')');
    } else {
      // Render an object
      source.add('{\n');
      allModules.sort(function(a, b) {
        var aId = a.id + '';
        var bId = b.id + '';
        if (aId < bId) return -1;
        if (aId > bId) return 1;
        return 0;
      }).forEach(function(module, idx) {
        if (idx !== 0) source.add(',\n');
        source.add('\n/***/ ' + JSON.stringify(module.id) + ':\n');
        source.add(module.source);
      });
      source.add('\n\n' + prefix + '}');
    }
    return source;
  }
};

function moduleIdIsNumber(module) {
  return typeof module.id === 'number';
}