fix(engine_twig_php): Twig incremental rebuilds

Fixes issue where edits to twig files included in parent do not appear
until the parent file is updated.

Closes issue #1015

Author: ZackHawkinsMC

packages/engine-twig-php/lib/engine_twig_php.js

@@ -26,10 +26,9 @@ const engine_twig_php = {
   engineName: 'twig-php',
   engineFileExtension: '.twig',
   expandPartials: false,
-
-  // @todo Evaluate RegExs
-  // findPartialsRE: /{%\s*(?:extends|include|embed)\s+('[^']+'|"[^"]+").*?%}/g,
-  // findPartialKeyRE: /"((?:\\.|[^"\\])*)"/,
+  findPartialsRE: /{%\s*(?:extends|include|embed)\s+('[^']+'|"[^"]+").*?(with|%}|\s*%})/g,
+  findPartialKeyRE: /"((?:\\.|[^"\\])*)"|'((?:\\.|[^"\\])*)'/,
+  namespaces: [],
 
   /**
    * Accept a Pattern Lab config object from the core and put it in
@@ -47,6 +46,10 @@ const engine_twig_php = {
 
     const { namespaces, alterTwigEnv, relativeFrom } = config.engines.twig;
 
+    // Preserve the namespaces from the config so we can use them later to
+    // evaluate partials.
+    this.namespaces = namespaces;
+
     // Schema on config object being passed in:
     // https://github.com/basaltinc/twig-renderer/blob/master/config.schema.json
     twigRenderer = new TwigRenderer({
@@ -64,7 +67,6 @@ const engine_twig_php = {
       const patternPath = path.isAbsolute(pattern.relPath)
         ? path.relative(patternLabConfig.paths.source.root, pattern.relPath)
         : pattern.relPath;
-      // console.log(patternPath);
 
       let details = '';
       if (patternLabConfig.logLevel === 'debug') {
@@ -118,8 +120,22 @@ const engine_twig_php = {
   // @todo Add all functions that get called even if disabled to ease implementing engine further
   // Currently all of them return `null` as I'm not totally sure there absence will be ok. Additionally, future improvements may be implemented in this functions.
 
-  findPartials(pattern) {
-    return null;
+  // Find and return any {% extends|include|embed 'template-name' %} within pattern.
+  // The regex should match the following examples:
+  // {%
+  //   include '@molecules/teaser-card/teaser-card.twig' with {
+  //     teaser_card: card
+  //   } only
+  // %}
+  // OR
+  // {% include '@molecules/teaser-card/teaser-card.twig' %}
+  // OR
+  // {%
+  //   include '@molecules/teaser-card/teaser-card.twig'
+  // %}
+  findPartials: function(pattern) {
+    const matches = pattern.template.match(this.findPartialsRE);
+    return matches;
   },
 
   findPartialsWithStyleModifiers(pattern) {
@@ -138,8 +154,65 @@ const engine_twig_php = {
     return null;
   },
 
-  findPartial(partialString) {
-    return null;
+  // Given a pattern, and a partial string, tease out the "pattern key" and
+  // return it.
+  findPartial: function(partialString) {
+    try {
+      let partial = partialString.match(this.findPartialKeyRE)[0];
+      partial = partial.replace(/"/g, '');
+      partial = partial.replace(/'/g, '');
+
+      // Check if namespaces is not empty.
+      const selectedNamespace = this.namespaces.filter(namespace => {
+        // Check to see if this partial contains within the namespace id.
+        return partial.indexOf(`@${namespace.id}`) !== -1;
+      });
+
+      let namespaceResolvedPartial = '';
+
+      if (selectedNamespace.length > 0) {
+        // Loop through all namespaces and try to resolve the namespace to a file path.
+        for (
+          let index = 0;
+          index < selectedNamespace[0].paths.length;
+          index++
+        ) {
+          const path = selectedNamespace[0].paths[index];
+          // Replace the name space with the actual path.
+          // i.e. @atoms -> source/_patterns/00-atoms
+          const tempPartial = partial.replace(
+            `@${selectedNamespace[0].id}`,
+            path
+          );
+
+          try {
+            // Check to see if the file exists.
+            if (fs.existsSync(tempPartial)) {
+              // If it does, find the last directory in the namespace path.
+              // i.e. source/_patterns/00-atoms -> 00-atoms.
+              const lastDirectory = path.split('/').reverse()[0];
+              // Replace the namespace in the path with the directory name.
+              // i.e. @atoms/04-images/04-avatar.twig -> 00-atoms/04-images/04-avatar.twig
+              namespaceResolvedPartial = partial.replace(
+                `@${selectedNamespace[0].id}`,
+                lastDirectory
+              );
+              // After it matches one time, set the resolved partial and exit the loop.
+              break;
+            }
+          } catch (err) {
+            console.error(err);
+          }
+        }
+      }
+      // Return the path with the namespace resolved OR the regex'd partial.
+      return namespaceResolvedPartial || partial;
+    } catch (err) {
+      console.error(
+        'Error occured when trying to find partial name in: ' + partialString
+      );
+      return null;
+    }
   },
 
   patternMatcher(pattern, regex) {