inliner: inline expr body of while/for/if

Fix: bem/bem-xjst#26

lib/xjst/compiler/helpers/inliner.js

@@ -27,6 +27,43 @@ Inliner.prototype.inline = function run(ast) {
 };
 
 Inliner.prototype.enter = function enter(node, parent) {
+  // while (...) (function() {})()
+  // for (...) (function() {})()
+  if ((node.type === 'WhileStatement' ||
+       node.type === 'ForStatement') &&
+      node.body.type === 'ExpressionStatement') {
+    var block = { type: 'BlockStatement', body: [ node.body ] };
+    return {
+      type: node.type,
+      init: node.init,
+      test: node.test,
+      update: node.update,
+      body: block
+    };
+
+  // if (...) (function() {})()
+  } else if (node.type === 'IfStatement') {
+    var clone = {
+      type: node.type,
+      test: node.test,
+      consequent: node.consequent,
+      alternate: node.alternate
+    };
+
+    var change = false;
+    if (clone.consequent.type === 'ExpressionStatement') {
+      change = true;
+      clone.consequent = { type: 'BlockStatement', body: [ clone.consequent ] };
+    }
+    if (clone.alternate && clone.alternate.type === 'ExpressionStatement') {
+      change = true;
+      clone.alternate = { type: 'BlockStatement', body: [ clone.alternate ] };
+    }
+
+    if (change)
+      return clone;
+  }
+
   if (Array.isArray(node.body)) {
     this.blockHistory.push(node);
     this.lastBlock = node;