expose render function

Readme.md

@@ -85,6 +85,7 @@ You can pass options to `metalsmith-layouts` with the [Javascript API](https://g
 * [partials](#partials): directory for the partials (optional)
 * [pattern](#pattern): only files that match this pattern will be processed (optional)
 * [rename](#rename): change the file extension of processed files to `.html` (optional)
+* [renderer](#renderer): apply a custom render function (optional)
 
 ### engine
 
@@ -192,16 +193,41 @@ Change the file extension of processed files to `.html` (optional). This option
 
 Would rename the extensions of all processed files to `.html`.
 
-### exposeConsolidate
+### renderer
 
 Not available over the `metalsmith.json` file.
-Exposes Consolidate.requires as a function.
+Exposes the renderer as a function.
+You use this if you want to access consolidate.requires.
 
 ```js
 // ...
 .use(layout('swig', {
-  exposeConsolidate: function(requires) {
-    // your code here
+  renderer: function(engine) {
+    var consolidate = require('consolidate');
+    var nunjucks    = require('nunjucks');
+    var render      = consolidate[engine];
+
+    if (!consolidate[engine]) {
+      throw new Error('Unknown template engine: "' + engine + '"');
+    }
+
+    // add nunjucks to requires so filters can be
+    // added and the same instance will be used inside the render method
+    consolidate.requires.nunjucks = nunjucks.configure();
+
+    consolidate.requires.nunjucks.addFilter('foo', function () {
+      return 'bar';
+    });
+
+    return function render(layoutPath, params, done) {
+      render(layoutPath, params, function(err, result){
+        if (err) {
+          return done(err);
+        }
+
+        done(err, result);
+      });
+    }
   }
 }))
 // ...

lib/helpers/renderer.js

@@ -0,0 +1,39 @@
+/**
+ * Dependencies
+ */
+var consolidate = require('consolidate');
+
+/**
+ * Expose `renderer`
+ */
+module.exports = renderer;
+
+/**
+ * Helper for creating a render function.
+ *
+ * @param {String} engine
+ * @return {Function}
+ */
+function renderer (engine) {
+  if (!consolidate[engine]) {
+    throw new Error('Unknown template engine: "' + engine + '"');
+  }
+
+  var render = consolidate[engine];
+
+  /**
+   * A function that renders a layout
+   *
+   * @param {String} engine
+   * @return {Function}
+   */
+  return function renderFn (layoutPath, params, done) {
+    render(layoutPath, params, function(err, result) {
+      if (err) {
+        return done(err);
+      }
+
+      done(err, result);
+    });
+  }
+}

lib/index.js

@@ -1,18 +1,18 @@
 /**
  * Dependencies
  */
-var consolidate = require('consolidate');
-var debug = require('debug')('metalsmith-layouts');
-var each = require('async').each;
+var debug  = require('debug')('metalsmith-layouts');
+var each   = require('async').each;
 var extend = require('extend');
-var omit = require('lodash.omit');
-var path = require('path');
+var omit   = require('lodash.omit');
+var path   = require('path');
 
 /**
  * Helpers
  */
-var check = require('./helpers/check');
+var check        = require('./helpers/check');
 var readPartials = require('./helpers/read-partials');
+var renderer     = require('./helpers/renderer');
 
 /**
  * Expose `plugin`.
@@ -31,7 +31,7 @@ var settings = [
   'partials',
   'pattern',
   'rename',
-  'exposeConsolidate'
+  'renderer',
 ];
 
 /**
@@ -44,6 +44,7 @@ var settings = [
  *   @property {String} partials (optional)
  *   @property {String} pattern (optional)
  *   @property {Boolean} rename (optional)
+ *   @property {Function} renderer (optional)
  * @return {Function}
  */
 function plugin(opts){
@@ -62,22 +63,21 @@ function plugin(opts){
     throw new Error('"engine" option required');
   }
 
-  // Throw an error for unsupported engines or typos
-  if (!consolidate[opts.engine]) {
-    throw new Error('Unknown template engine: "' + opts.engine + '"');
-  }
-
-  if (typeof opts.exposeConsolidate === 'function') {
-    opts.exposeConsolidate(consolidate.requires)
+  // An renderer for the layout can be added
+  var render;
+  if (typeof opts.renderer === 'function') {
+    render = opts.renderer(opts.engine);
+  } else {
+    render = renderer(opts.engine);
   }
 
   // Map options to local variables
-  var def = opts.default;
-  var dir = opts.directory || 'layouts';
-  var engine = opts.engine;
+  var def      = opts.default;
+  var dir      = opts.directory || 'layouts';
+  var engine   = opts.engine;
   var partials = opts.partials;
-  var pattern = opts.pattern;
-  var rename = opts.rename;
+  var pattern  = opts.pattern;
+  var rename   = opts.rename;
 
   // Move all unrecognised options to params
   var params = omit(opts, settings);
@@ -123,30 +123,40 @@ function plugin(opts){
 
       // Deep clone params (by passing 'true')
       var clonedParams = extend(true, {}, params);
-      var clone = extend({}, clonedParams, metadata, data);
-      var str = metalsmith.path(dir, data.layout || def);
-      var render = consolidate[engine];
+      var paramsToPass = extend({}, clonedParams, metadata, data);
+      var layoutPath   = metalsmith.path(dir, data.layout || def);
 
-      // Rename file if necessary
-      var fileInfo;
-      if (rename) {
-        delete files[file];
-        fileInfo = path.parse(file);
-        file = path.join(fileInfo.dir, fileInfo.name + '.html');
-        debug('renamed file to: %s', file);
+      var renameFile = function(data){
+        // Rename file if necessary
+        var fileInfo;
+        if (rename) {
+          delete files[file];
+          fileInfo = path.parse(file);
+          file = path.join(fileInfo.dir, fileInfo.name + '.html');
+          debug('renamed file to: %s', file);
+          files[file] = data;
+        }
       }
 
-      render(str, clone, function(err, str){
+      /**
+       * is called after a layout is renderd
+       * renames file if neccessary 
+       * applys the render result to the new file
+       */
+      var handleRenderResult = function(err, result) {
         if (err) {
           return done(err);
         }
 
-        data.contents = new Buffer(str);
         debug('converted file: %s', file);
 
-        files[file] = data;
+        data.contents = new Buffer(result);
+
+        renameFile(data);
         done();
-      });
+      }
+
+      render(layoutPath, paramsToPass, handleRenderResult);
     }
 
     /**