Remove lodash and add ability to have user customizations

Author: Dan White

packages/patternengine-node-nunjucks/README.md

@@ -5,3 +5,33 @@
 To install the Nunjucks engine in your edition, `npm install patternengine-node-nunjucks` should do the trick.
 
 Level of Support is more or less full. Partial calls and lineage hunting are supported. Nunjucks does not support the mustache-specific syntax extensions, style modifiers and pattern parameters, because their use cases are addressed by the core Nunjucks feature set.
+
+## Extending the Nunjucks
+
+To add custom filters or make customizations the nunjucks instance, create a file named `patternlab-nunjucks-config.js` in the root fo your Pattern Lab project. It should export a function that takes two paramerters. The first parameter being the nunjucks instance and the second the nunjucks instance environment.
+
+```
+module.exports = function (nunjucks, env) {
+  [YOUR CUSTOM CODE HERE]
+};
+```
+
+EXAMPLE: patternlab-nunjucks-config.js file that uses lodash and adds three custom filters.
+```
+var _shuffle = require('lodash/shuffle'),
+  _take = require('lodash/take');
+
+exports = module.exports = function (nunjucks, env) {
+  env.addFilter('shorten', function (str, count) {
+    return str.slice(0, count || 5);
+  });
+
+  env.addFilter('shuffle', (arr) => {
+    return _shuffle(arr);
+  });
+
+  env.addFilter('take', (arr, number) => {
+    return _take(arr, number);
+  });
+};
+```

packages/patternengine-node-nunjucks/lib/engine_nunjucks.js

@@ -4,8 +4,6 @@
   - Look into if we need to handle partials in the render method
   - Add try catch blocks to prevent Pl from crashing
   - Test methods of including files
-  - Add a way to extend the Nunjucks instance from the PL instance
-    - This could be used to add our lodash filters. That way we're seperating concerns properly and making the engine more flexible.
   - Compare features and syntax with the mustache version so we can document
   - Document and submit to PatternLab
 */
@@ -15,21 +13,23 @@
 var path = require('path'),
   plPath = process.cwd(),
   plConfig = require(path.join(plPath, 'patternlab-config.json')),
-  _shuffle = require('lodash/shuffle'),
-  _take = require('lodash/take'),
   nunjucks = require('nunjucks'),
   env = nunjucks.configure(plConfig.paths.source.patterns),
   partialRegistry = [];
 
 
 ////////////////////////////
-// NUNJUCKS CUSTOMIZATIONS
+// LOAD ANY USER NUNJUCKS CONFIGURATIONS
 ////////////////////////////
-env.addFilter('shorten', function (str, count) {
-  return str.slice(0, count || 5);
-});
-env.addFilter('shuffle', (arr) => _shuffle(arr));
-env.addFilter('take', (arr, number) => _take(arr, number));
+try {
+  var nunjucksConfig = require(path.join(plPath, 'patternlab-nunjucks-config.js'));
+  if (typeof nunjucksConfig == 'function') {
+    nunjucksConfig(nunjucks, env);
+  }
+}
+catch (err) {
+  console.log('Cannot find module \'patternlab-nunjucks-config.js\'');
+}
 
 
 ////////////////////////////

packages/patternengine-node-nunjucks/package-lock.json

@@ -26,7 +26,6 @@
   "deprecated": false,
   "description": "The nunjucks engine for Pattern Lab / Node",
   "dependencies": {
-    "lodash": "^4.17.4",
     "nunjucks": "^3.0.1"
   },
   "devDependencies": {},