Fix support for groovy

* Add support for calling `Prism.highlight` from inside grammars
* Add support for passing a grammar instead of a name to
  `refract.highlight`

Closes GH-13.
Closes GH-14.

core.js

@@ -63,20 +63,29 @@ function register(grammar) {
 
 function highlight(value, name) {
   var sup = Prism.highlight
+  var grammar
 
   if (typeof value !== 'string') {
     throw new Error('Expected `string` for `value`, got `' + value + '`')
   }
 
-  if (typeof name !== 'string') {
-    throw new Error('Expected `string` for `name`, got `' + name + '`')
-  }
+  /* `name` is a grammar object */
+  if (refract.util.type(name) === 'Object') {
+    grammar = name
+    name = null
+  } else {
+    if (typeof name !== 'string') {
+      throw new Error('Expected `string` for `name`, got `' + name + '`')
+    }
 
-  if (!own.call(refract.languages, name)) {
-    throw new Error('Unknown language: `' + name + '` is not registered')
+    if (own.call(refract.languages, name)) {
+      grammar = refract.languages[name]
+    } else {
+      throw new Error('Unknown language: `' + name + '` is not registered')
+    }
   }
 
-  return sup.call(this, value, refract.languages[name], name)
+  return sup.call(this, value, grammar, name)
 }
 
 function registered(language) {

lang/groovy.js

@@ -52,7 +52,7 @@ function groovy(Prism) {
         env.content.value = env.content.value
           .replace(/&lt;/g, '<')
           .replace(/&amp;/g, '&')
-        env.content.value = Prism.highlight(env.content.value, {
+        env.content = Prism.highlight(env.content.value, {
           expression: {
             pattern: pattern,
             lookbehind: true,

script/languages.js

@@ -120,6 +120,7 @@ function fixWrapHook() {
 
   return {
     visitor: {
+      // We only perform the later changes inside `wrap` hooks, just to be safe.
       CallExpression: {
         enter: function(path) {
           if (isWrapHook(path)) {
@@ -132,9 +133,27 @@ function fixWrapHook() {
           }
         }
       },
+      // If a syntax is assigning `Prism.highlight` to `env.content`, we should
+      // add the result to `env.content` instead of `env.content.value`.
+      AssignmentExpression: {
+        enter: function(path) {
+          if (
+            path.get('right.callee').matchesPattern('Prism.highlight') &&
+            path.get('left').matchesPattern('env.content')
+          ) {
+            path.get('left').node.ignoreValueSuffix = true
+          }
+        }
+      },
+      // If a syntax is using `env.content`, it probably expects a string value,
+      // those are stored at `env.content.value`.
       MemberExpression: {
         enter: function(path) {
-          if (this.inWrapHook && path.matchesPattern('env.content')) {
+          if (
+            this.inWrapHook &&
+            !path.node.ignoreValueSuffix &&
+            path.matchesPattern('env.content')
+          ) {
             path.node.object = t.memberExpression(
               path.node.object,
               t.identifier('content')

test/fixtures/groovy-string-interpolation/input.txt

@@ -0,0 +1 @@
+def sum = "The sum of 2 and 3 equals ${2 + 3}"

test/fixtures/groovy-string-interpolation/output.html

@@ -0,0 +1 @@
+<span class="token keyword">def</span> sum <span class="token operator">=</span> <span class="token string gstring">"The sum of 2 and 3 equals <span class="token expression"><span class="token punctuation">$</span><span class="token punctuation">{</span><span class="token number">2</span> <span class="token operator">+</span> <span class="token number">3</span><span class="token punctuation">}</span></span>"</span>