From 2d192b352fa14ba91f487b8e1fd2f8ce188bb553 Mon Sep 17 00:00:00 2001
From: Jason LaPorte <ironwallaby@gmail.com>
Date: Tue, 13 Aug 2013 14:39:20 -0400
Subject: [PATCH] Added context passing.

---
 lib/template.js | 39 +++++++++++++++++++++++++++++----------
 test.js         | 31 +++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+), 10 deletions(-)

diff --git a/lib/template.js b/lib/template.js
index 76be0dbe..856a1b85 100644
--- a/lib/template.js
+++ b/lib/template.js
@@ -1,9 +1,16 @@
 module.exports = function(template) {
-  return function parse(expr) {
-    if(typeof expr === "number")
-      return expr.toString();
+  function parse(expr, stack) {
+    var result;
+
+    if(typeof expr === "number") {
+      stack.push(expr);
+
+      result = expr.toString();
+    }
 
     else if(typeof expr === "string") {
+      stack.push(expr);
+
       if(!template.hasOwnProperty(expr))
         throw new Error("\"" + expr + "\" not found in language template.");
 
@@ -12,7 +19,7 @@ module.exports = function(template) {
           throw new Error("\"" + expr + "\" was used in a value context, but is expected in a template context.");
 
         else
-          return template[expr];
+          result = template[expr];
       }
 
       else if(typeof template[expr] === "function") {
@@ -20,7 +27,7 @@ module.exports = function(template) {
           throw new Error("\"" + expr + "\" was used in a value context, but is expected in a template context.");
 
         else
-          return template[expr]();
+          result = template[expr].call(stack);
       }
 
       else
@@ -30,12 +37,14 @@ module.exports = function(template) {
     else if(Array.isArray(expr) &&
             expr.length &&
             typeof expr[0] === "string") {
+      stack.push(expr[0]);
+
       if(!template.hasOwnProperty(expr[0]))
         throw new Error("\"" + expr[0] + "\" not found in language template.");
 
       else if(typeof template[expr[0]] === "string")
-        return template[expr[0]].replace(/\$\d+/g, function(n) {
-          return parse(expr[n.slice(1)|0]);
+        result = template[expr[0]].replace(/\$\d+/g, function(n) {
+          return parse(expr[n.slice(1)|0], stack);
         });
 
       else if(typeof template[expr[0]] === "function") {
@@ -46,9 +55,12 @@ module.exports = function(template) {
           throw new Error("Template \"" + expr[0] + "\" did not expect " + (expr.length - 1) + " arguments.");
 
         else
-          return template[expr[0]].apply(null, expr.slice(1).map(function(arg) {
-            return parse(arg);
-          }));
+          result = template[expr[0]].apply(
+            stack,
+            expr.slice(1).map(function(arg) {
+              return parse(arg, stack);
+            })
+          );
       }
 
       else
@@ -57,5 +69,12 @@ module.exports = function(template) {
 
     else
       throw new Error("Invalid expression.");
+
+    stack.pop();
+    return result;
   };
+
+  return function(expr) {
+    return parse(expr, []);
+  }
 };
diff --git a/test.js b/test.js
index 2cf5e90f..063326f6 100644
--- a/test.js
+++ b/test.js
@@ -79,6 +79,37 @@ describe("translation", function() {
     it("should fail to apply a function template given a value", function() {
       expect(function() { convert("baz"); }).to.throw();
     });
+
+    it("should provide context to functions", function() {
+      var convert = template({
+            "foo": function(a, b, c) {
+              expect(this).to.deep.equal(["foo"]);
+              return "Moop.";
+            },
+            "bar": function() {
+              expect(this).to.deep.equal(["foo", "bar"]);
+              return "Boop.";
+            },
+            "baz": function(a) {
+              expect(this).to.deep.equal(["foo", "baz"]);
+              return "Soup.";
+            },
+            "quux": function() {
+              expect(this).to.deep.equal(["foo", "baz", "quux"]);
+              return "Floop.";
+            },
+            "neem": function(a) {
+              expect(this).to.deep.equal(["foo", "neem"]);
+              return "Bloop.";
+            },
+            "glorp": function(a) {
+              expect(this).to.deep.equal(["foo", "neem", "glorp"]);
+              return "Rope?";
+            }
+          });
+
+      convert(["foo", "bar", ["baz", "quux"], ["neem", ["glorp", 42]]]);
+    });
   });
 
   describe("language", function() {