'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

var _templateObject = _taggedTemplateLiteral(['', ''], ['', '']);

function _taggedTemplateLiteral(strings, raw) { return Object.freeze(Object.defineProperties(strings, { raw: { value: Object.freeze(raw) } })); }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

/**
 * @class TemplateTag
 * @classdesc Consumes a pipeline of composable transformer plugins and produces a template tag.
 */
var TemplateTag = function () {
  /**
   * constructs a template tag
   * @constructs TemplateTag
   * @param  {...Object} [...transformers] - an array or arguments list of transformers
   * @return {Function}                    - a template tag
   */
  function TemplateTag() {
    var _this = this;

    for (var _len = arguments.length, transformers = Array(_len), _key = 0; _key < _len; _key++) {
      transformers[_key] = arguments[_key];
    }

    _classCallCheck(this, TemplateTag);

    this.tag = function (strings) {
      for (var _len2 = arguments.length, expressions = Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
        expressions[_key2 - 1] = arguments[_key2];
      }

      if (typeof strings === 'function') {
        // if the first argument passed is a function, assume it is a template tag and return
        // an intermediary tag that processes the template using the aforementioned tag, passing the
        // result to our tag
        return _this.interimTag.bind(_this, strings);
      }

      if (typeof strings === 'string') {
        // if the first argument passed is a string, just transform it
        return _this.transformEndResult(strings);
      }

      // else, return a transformed end result of processing the template with our tag
      strings = strings.map(_this.transformString.bind(_this));
      return _this.transformEndResult(strings.reduce(_this.processSubstitutions.bind(_this, expressions)));
    };

    // if first argument is an array, extrude it as a list of transformers
    if (transformers.length > 0 && Array.isArray(transformers[0])) {
      transformers = transformers[0];
    }

    // if any transformers are functions, this means they are not initiated - automatically initiate them
    this.transformers = transformers.map(function (transformer) {
      return typeof transformer === 'function' ? transformer() : transformer;
    });

    // return an ES2015 template tag
    return this.tag;
  }

  /**
   * Applies all transformers to a template literal tagged with this method.
   * If a function is passed as the first argument, assumes the function is a template tag
   * and applies it to the template, returning a template tag.
   * @param  {(Function|String|Array<String>)} strings        - Either a template tag or an array containing template strings separated by identifier
   * @param  {...*}                            ...expressions - Optional list of substitution values.
   * @return {(String|Function)}                              - Either an intermediary tag function or the results of processing the template.
   */


  _createClass(TemplateTag, [{
    key: 'interimTag',


    /**
     * An intermediary template tag that receives a template tag and passes the result of calling the template with the received
     * template tag to our own template tag.
     * @param  {Function}        nextTag          - the received template tag
     * @param  {Array<String>}   template         - the template to process
     * @param  {...*}            ...substitutions - `substitutions` is an array of all substitutions in the template
     * @return {*}                                - the final processed value
     */
    value: function interimTag(previousTag, template) {
      for (var _len3 = arguments.length, substitutions = Array(_len3 > 2 ? _len3 - 2 : 0), _key3 = 2; _key3 < _len3; _key3++) {
        substitutions[_key3 - 2] = arguments[_key3];
      }

      return this.tag(_templateObject, previousTag.apply(undefined, [template].concat(substitutions)));
    }

    /**
     * Performs bulk processing on the tagged template, transforming each substitution and then
     * concatenating the resulting values into a string.
     * @param  {Array<*>} substitutions - an array of all remaining substitutions present in this template
     * @param  {String}   resultSoFar   - this iteration's result string so far
     * @param  {String}   remainingPart - the template chunk after the current substitution
     * @return {String}                 - the result of joining this iteration's processed substitution with the result
     */

  }, {
    key: 'processSubstitutions',
    value: function processSubstitutions(substitutions, resultSoFar, remainingPart) {
      var substitution = this.transformSubstitution(substitutions.shift(), resultSoFar);
      return ''.concat(resultSoFar, substitution, remainingPart);
    }

    /**
     * Iterate through each transformer, applying the transformer's `onString` method to the template
     * strings before all substitutions are processed.
     * @param {String}  str - The input string
     * @return {String}     - The final results of processing each transformer
     */

  }, {
    key: 'transformString',
    value: function transformString(str) {
      var cb = function cb(res, transform) {
        return transform.onString ? transform.onString(res) : res;
      };
      return this.transformers.reduce(cb, str);
    }

    /**
     * When a substitution is encountered, iterates through each transformer and applies the transformer's
     * `onSubstitution` method to the substitution.
     * @param  {*}      substitution - The current substitution
     * @param  {String} resultSoFar  - The result up to and excluding this substitution.
     * @return {*}                   - The final result of applying all substitution transformations.
     */

  }, {
    key: 'transformSubstitution',
    value: function transformSubstitution(substitution, resultSoFar) {
      var cb = function cb(res, transform) {
        return transform.onSubstitution ? transform.onSubstitution(res, resultSoFar) : res;
      };
      return this.transformers.reduce(cb, substitution);
    }

    /**
     * Iterates through each transformer, applying the transformer's `onEndResult` method to the
     * template literal after all substitutions have finished processing.
     * @param  {String} endResult - The processed template, just before it is returned from the tag
     * @return {String}           - The final results of processing each transformer
     */

  }, {
    key: 'transformEndResult',
    value: function transformEndResult(endResult) {
      var cb = function cb(res, transform) {
        return transform.onEndResult ? transform.onEndResult(res) : res;
      };
      return this.transformers.reduce(cb, endResult);
    }
  }]);

  return TemplateTag;
}();

exports.default = TemplateTag;
module.exports = exports['default'];
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