Use local-context first for var lookups

Ensures that browser-globals are not used before using the local context.
Ensured resetting values in for-loops.

Fixes gh-347
Possibly related to gh-344

lib/parser.js

@@ -204,8 +204,8 @@ TokenParser.prototype = {
 
     case _t.FUNCTION:
     case _t.FUNCTIONEMPTY:
-      self.out.push('((typeof ' + match + ' !== "undefined") ? ' + match +
-        ' : ((typeof _ctx.' + match + ' !== "undefined") ? _ctx.' + match +
+      self.out.push('((typeof _ctx.' + match + ' !== "undefined") ? _ctx.' + match +
+        ' : ((typeof ' + match + ' !== "undefined") ? ' + match +
         ' : _fn))(');
       self.escape = false;
       if (token.type === _t.FUNCTIONEMPTY) {
@@ -403,7 +403,7 @@ TokenParser.prototype = {
       return '(' + checkDot(ctx) + ' ? ' + ctx + match.join('.') + ' : "")';
     }
 
-    return '(' + checkDot('') + ' ? ' + buildDot('') + ' : ' + buildDot('_ctx.') + ')';
+    return '(' + checkDot('_ctx.') + ' ? ' + buildDot('_ctx.') + ' : ' + buildDot('') + ')';
   }
 };
 

lib/tags/for.js

@@ -1,3 +1,7 @@
+var ctx = '_ctx.',
+  ctxloop = ctx + 'loop',
+  ctxloopcache = ctx + '___loopcache';
+
 /**
  * Loop over objects and arrays.
  *
@@ -55,14 +59,20 @@ exports.compile = function (compiler, args, content, parents, options, blockName
     '(function () {\n',
     '  var __l = ' + last + ';\n',
     '  if (!__l) { return; }\n',
-    '  var loop = { first: false, index: 1, index0: 0, revindex: __l.length, revindex0: __l.length - 1, length: __l.length, last: false };\n',
+    '  ' + ctxloopcache + ' = { loop: ' + ctxloop + ', ' + val + ': ' + ctx + val + ', ' + key + ': ' + ctx + key + ' };\n',
+    '  ' + ctxloop + ' = { first: false, index: 1, index0: 0, revindex: __l.length, revindex0: __l.length - 1, length: __l.length, last: false };\n',
     '  _utils.each(__l, function (' + val + ', ' + key + ') {\n',
-    '    loop.key = ' + key + ';\n',
-    '    loop.first = (loop.index0 === 0);\n',
-    '    loop.last = (loop.revindex0 === 0);\n',
+    '    ' + ctx + val + ' = ' + val + ';\n',
+    '    ' + ctx + key + ' = ' + key + ';\n',
+    '    ' + ctxloop + '.key = ' + key + ';\n',
+    '    ' + ctxloop + '.first = (' + ctxloop + '.index0 === 0);\n',
+    '    ' + ctxloop + '.last = (' + ctxloop + '.revindex0 === 0);\n',
     '    ' + compiler(content, parents, options, blockName),
-    '    loop.index += 1; loop.index0 += 1; loop.revindex -= 1; loop.revindex0 -= 1;\n',
+    '    ' + ctxloop + '.index += 1; ' + ctxloop + '.index0 += 1; ' + ctxloop + '.revindex -= 1; ' + ctxloop + '.revindex0 -= 1;\n',
     '  });\n',
+    '  ' + ctxloop + ' = ' + ctxloopcache + '.loop;\n',
+    '  ' + ctx + val + ' = ' + ctxloopcache + '.' + val + ';\n',
+    '  ' + ctx + key + ' = ' + ctxloopcache + '.' + key + ';\n',
     '})();\n'
   ].join('');
 };

lib/tags/import.js

@@ -22,12 +22,12 @@ var utils = require('../utils');
  */
 exports.compile = function (compiler, args) {
   var ctx = args.pop(),
-    out = 'var ' + ctx + ' = {};\n' +
-      '(function (exports) {\n' +
+    out = '_ctx.' + ctx + ' = {};\n' +
+      '(function (_ctx) {\n' +
       '  var _output = "";\n';
 
   out += args.join('');
-  out += '}(' + ctx + '));\n';
+  out += '}(_ctx.' + ctx + '));\n';
 
   return out;
 };
@@ -52,7 +52,6 @@ exports.parse = function (str, line, parser, types, stack, opts) {
         }
         macroName = token.args[0];
         out += token.compile(compiler, token.args, token.content, [], compileOpts) + '\n';
-        out += 'exports.' + macroName + ' = ' + macroName + ';\n';
         self.out.push(out);
       });
       return;

lib/tags/macro.js

@@ -19,12 +19,12 @@
 exports.compile = function (compiler, args, content, parents, options, blockName) {
   var fnName = args.shift();
 
-  return 'function ' + fnName + '(' + args.join('') + ') {\n' +
+  return '_ctx.' + fnName + ' = function (' + args.join('') + ') {\n' +
     '  var _output = "";\n' +
     compiler(content, parents, options, blockName) + '\n' +
     '  return _output;\n' +
     '};\n' +
-    fnName + '.safe = true;\n';
+    '_ctx.' + fnName + '.safe = true;\n';
 };
 
 exports.parse = function (str, line, parser, types) {

tests/tags/for.test.js

@@ -34,6 +34,11 @@ describe('Tag: for', function () {
     });
   });
 
+  it('resets loop and vars', function () {
+    expect(swig.render('{% for a, b in c %}{% endfor %}{{ a }}{{ b }}{{ loop }}', { locals: { loop: 'z', a: 'x', b: 'y', c: { d: 'e', f: 'g' }}}))
+      .to.equal('xyz');
+  });
+
   it('throws on numbers as any argument', function () {
     expect(function () {
       swig.render('{% for a in 32 %}{% endfor %}');