Handlebars (and possibly other engines) need to be excluded from

"partial expansion", the process of recursively "manually" rendering
partials into the extendedTemplate property of the oPattern, in order to
have access to the calling pattern's correct JSON environment. Each
engine must indicate if it supports partial expansion (probably no by
default). Also, factor out the partial expansion process from the main
processPatternRecursively function for clarity and easy
conditionalizing, and add a unit test to verify that this works okay.

Author: geoffp

builder/pattern_assembler.js

@@ -139,22 +139,61 @@
 
 
 
+    function expandPartials(foundPatternPartials, list_item_hunter, patternlab, currentPattern) {
+      var smh = require('./style_modifier_hunter'),
+          ph = require('./parameter_hunter');
+
+      var style_modifier_hunter = new smh(),
+          parameter_hunter = new ph();
+
+      if(patternlab.config.debug){
+        console.log('found partials for ' + currentPattern.key);
+      }
+
+      // determine if the template contains any pattern parameters. if so they
+      // must be immediately consumed
+      parameter_hunter.find_parameters(currentPattern, patternlab);
+
+      //do something with the regular old partials
+      for(var i = 0; i < foundPatternPartials.length; i++){
+        var partialKey = currentPattern.getPartialKey(foundPatternPartials[i]);
+        var partialPath;
+
+        //identify which pattern this partial corresponds to
+        for(var j = 0; j < patternlab.patterns.length; j++){
+          if(patternlab.patterns[j].key === partialKey ||
+             patternlab.patterns[j].abspath.indexOf(partialKey) > -1)
+          {
+            partialPath = patternlab.patterns[j].abspath;
+          }
+        }
+
+        //recurse through nested partials to fill out this extended template.
+        processPatternRecursive(partialPath, patternlab);
+
+        //complete assembly of extended template
+        var partialPattern = getpatternbykey(partialKey, patternlab);
+
+        //if partial has style modifier data, replace the styleModifier value
+        if(currentPattern.stylePartials && currentPattern.stylePartials.length > 0){
+          style_modifier_hunter.consume_style_modifier(partialPattern, foundPatternPartials[i], patternlab);
+        }
+
+        currentPattern.extendedTemplate = currentPattern.extendedTemplate.replace(foundPatternPartials[i], partialPattern.extendedTemplate);
+      }
+    }
+
     function processPatternRecursive(file, patternlab, additionalData){
       var lh = require('./lineage_hunter'),
-          ph = require('./parameter_hunter'),
           pph = require('./pseudopattern_hunter'),
-          lih = require('./list_item_hunter'),
-          smh = require('./style_modifier_hunter');
+          lih = require('./list_item_hunter');
 
-      var parameter_hunter = new ph(),
-      lineage_hunter = new lh(),
-      list_item_hunter = new lih(),
-      style_modifier_hunter = new smh(),
-      pseudopattern_hunter = new pph();
+      var lineage_hunter = new lh(),
+          list_item_hunter = new lih(),
+          pseudopattern_hunter = new pph();
 
       //find current pattern in patternlab object using var file as a key
-      var currentPattern,
-      i;
+      var currentPattern, i;
 
       for(i = 0; i < patternlab.patterns.length; i++){
         if(patternlab.patterns[i].abspath === file){
@@ -163,60 +202,19 @@
       }
 
       //return if processing an ignored file
-      if(typeof currentPattern === 'undefined'){
-        return;
-      }
+      if (typeof currentPattern === 'undefined') { return; }
 
       currentPattern.extendedTemplate = currentPattern.template;
 
       //find how many partials there may be for the given pattern
       var foundPatternPartials = currentPattern.findPartials(currentPattern);
 
-      if(foundPatternPartials !== null && foundPatternPartials.length > 0){
-
-        if(patternlab.config.debug){
-          console.log('found partials for ' + currentPattern.key);
-        }
-
-        //find any listItem blocks
-        list_item_hunter.process_list_item_partials(currentPattern, patternlab);
-
-        //determine if the template contains any pattern parameters. if so they must be immediately consumed
-        parameter_hunter.find_parameters(currentPattern, patternlab);
-
-        //do something with the regular old partials
-        for(i = 0; i < foundPatternPartials.length; i++){
-          var partialKey = currentPattern.getPartialKey(foundPatternPartials[i]);
-
-          var partialPath;
-
-          //identify which pattern this partial corresponds to
-          for(var j = 0; j < patternlab.patterns.length; j++){
-            if(patternlab.patterns[j].key === partialKey ||
-              patternlab.patterns[j].abspath.indexOf(partialKey) > -1)
-            {
-              partialPath = patternlab.patterns[j].abspath;
-            }
-          }
+      //find any listItem blocks that within the pattern, even if there are no partials
+      list_item_hunter.process_list_item_partials(currentPattern, patternlab);
 
-          //recurse through nested partials to fill out this extended template.
-          processPatternRecursive(partialPath, patternlab);
-
-          //complete assembly of extended template
-          var partialPattern = getpatternbykey(partialKey, patternlab);
-
-          //if partial has style modifier data, replace the styleModifier value
-          if(currentPattern.stylePartials && currentPattern.stylePartials.length > 0){
-            style_modifier_hunter.consume_style_modifier(partialPattern, foundPatternPartials[i], patternlab);
-          }
-
-          currentPattern.extendedTemplate = currentPattern.extendedTemplate.replace(foundPatternPartials[i], partialPattern.extendedTemplate);
-
-        }
-
-      } else{
-        //find any listItem blocks that within the pattern, even if there are no partials
-        list_item_hunter.process_list_item_partials(currentPattern, patternlab);
+      // expand any partials present in this pattern; that is, drill down into the template and replace their calls in this template with rendered results
+      if (currentPattern.engine.expandPartials && (foundPatternPartials !== null && foundPatternPartials.length > 0)) {
+        expandPartials(foundPatternPartials, list_item_hunter, patternlab, currentPattern);
       }
 
       //find pattern lineage

builder/pattern_engines/engine_handlebars.js

@@ -18,6 +18,10 @@
     engineName: 'handlebars',
     engineFileExtension: '.hbs',
 
+    // partial expansion is only necessary for Mustache templates that have
+    // style modifiers or pattern parameters (I think)
+    expandPartials: false,
+
     // regexes, stored here so they're only compiled once
     // GTP warning: unchanged copypasta from mustache engine
     // findPartialsRE: /{{>\s*((?:\d+-[\w-]+\/)+(\d+-[\w-]+(\.\w+)?)|[A-Za-z0-9-]+)(\:[\w-]+)?(\(\s*\w+\s*:\s*(?:'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*")\))?\s*}}/g,

builder/pattern_engines/engine_mustache.js

@@ -18,6 +18,10 @@
     engineName: 'mustache',
     engineFileExtension: '.mustache',
 
+    // partial expansion is only necessary for Mustache templates that have
+    // style modifiers or pattern parameters (I think)
+    expandPartials: true,
+
     // regexes, stored here so they're only compiled once
     findPartialsRE: /{{>\s*((?:\d+-[\w-]+\/)+(\d+-[\w-]+(\.\w+)?)|[A-Za-z0-9-]+)(\:[\w-]+)?(\(\s*\w+\s*:\s*(?:'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*")\))?\s*}}/g,
     findPartialsWithStyleModifiersRE: /{{>([ ])?([\w\-\.\/~]+)(?!\()(\:[A-Za-z0-9-_|]+)+(?:(| )\(.*)?([ ])?}}/g,

test/engine_handlebars_tests.js

@@ -135,6 +135,37 @@
       test.equals(helloWorldWithData.render(), 'Hello world!\nYeah, we got the subtitle from the JSON.\n');
       test.done();
     },
+    'handlebars partials use the JSON environment from the calling pattern and can accept passed parameters': function (test) {
+      test.expect(1);
+
+      // pattern paths
+      var atomPath = path.resolve(
+        testPatternsPath,
+        '00-atoms',
+        '00-global',
+        '00-helloworld-withdata.hbs'
+      );
+      var molPath = path.resolve(
+        testPatternsPath,
+        '00-molecules',
+        '00-global',
+        '00-call-atom-with-molecule-data.hbs'
+      );
+
+      // set up environment
+      var patternlab = new fakePatternLab(); // environment
+      var assembler = new pa();
+
+      // do all the normal processing of the pattern
+      var atom = assembler.process_pattern_iterative(atomPath, patternlab);
+      var mol = assembler.process_pattern_iterative(molPath, patternlab);
+      assembler.process_pattern_recursive(atomPath, patternlab);
+      assembler.process_pattern_recursive(molPath, patternlab);
+
+      // test
+      test.equals(mol.render(), '<h2>Call with default JSON environment:</h2>\nThis is Hello world!\nfrom the default JSON.\n\n\n<h2>Call with passed parameter:</h2>\nHowever, this is Hello world!\nfrom a totally different blob.\n\n');
+      test.done();
+    },
     'find_pattern_partials finds partials': function(test){
       testFindPartials(test, [
         "{{> molecules-comment-header}}",