Added ignore missing tokens to include tag

Allow includes to pass over missing includes and not throw an error.

docs/tags.md

@@ -36,11 +36,15 @@ See [Template inheritance](inheritance.md) for more information.
 
 ### include <a name="include" href="#include">#</a>
 
-Includes a template in it's place. The template is rendered within the current context. Does not use and {% endinclude %}.
+Includes a template in it's place. The template is rendered within the current context.
 
     {% include template_path %}
     {% include "path/to/template.js" %}
 
+You can mark an include to `ignore missing` so that if the template does not exist, it will be ignored and no error will be thrown.
+
+    {% include "foobar.html" ignore missing %}
+
 Locally declared context variables are _not_ passed to the included template by default. For example, in the following situations, your `inc.html` will not know about the variables `foo` nor `bar`:
 
     {% set foo = "bar" %}

lib/tags/include.js

@@ -8,6 +8,8 @@ module.exports = function (indent, parentBlock, parser) {
     var args = _.clone(this.args),
         template = args.shift(),
         context = '_context',
+        ignore = false,
+        out = '',
         ctx;
 
     indent = indent || '';
@@ -22,6 +24,12 @@ module.exports = function (indent, parentBlock, parser) {
             args.pop();
         }
 
+        if (args.length > 1 && args[0] === 'ignore' & args[1] === 'missing') {
+            args.shift();
+            args.shift();
+            ignore = true;
+        }
+
         if (args.length && args[0] !== 'with') {
             throw new Error('Invalid arguments passed to \'include\' tag.');
         }
@@ -38,15 +46,22 @@ module.exports = function (indent, parentBlock, parser) {
         }
     }
 
+    out = '(function () {\n' +
+        helpers.setVar('__template', parser.parseVariable(template)) + '\n' +
+        '    var includeContext = ' + context + ';\n';
+
+    if (ignore) {
+        out += 'try {\n';
+    }
+
+    out += '    if (typeof __template === "string") {\n';
+    out += '        _output += _this.compileFile(__template).render(includeContext, _parents);\n';
+    out += '    }\n';
+
+    if (ignore) {
+        out += '} catch (e) {}\n';
+    }
+    out += '})();\n';
 
-    // Circular includes are VERBOTTEN. This will crash the server.
-    return [
-        '(function () {',
-        helpers.setVar('__template', parser.parseVariable(template)),
-        '    var includeContext = ' + context + ';',
-        '    if (typeof __template === "string") {',
-        '        _output += _this.compileFile(__template).render(includeContext, _parents);',
-        '    }',
-        '})();'
-    ].join('\n' + indent);
+    return out;
 };

lib/tags/include.test.js

@@ -61,5 +61,11 @@ exports.include = testCase({
         var tpl = swig.compile('{% set foo = { bar: "baz" } %}{% set bar = "hi" %}{% include "withcontext" with foo only %}');
         test.strictEqual(tpl(), 'baz');
         test.done();
+    },
+
+    'ignore missing': function (test) {
+        // does not throw
+        swig.compile('{% include "foobarbazbop" ignore missing %}')();
+        test.done();
     }
 });