Merge consecutive buffer appends

lib/handlebars/compiler/compiler.js

@@ -392,7 +392,11 @@ Handlebars.JavaScriptCompiler = function() {};
       if (this.environment.isSimple) {
         return "return " + string + ";";
       } else {
-        return "buffer += " + string + ";";
+        return {
+          appendToBuffer: true,
+          content: string,
+          toString: function() { return "buffer += " + string + ";"; }
+        };
       }
     },
 
@@ -510,12 +514,34 @@ Handlebars.JavaScriptCompiler = function() {};
         params.push("depth" + this.environment.depths.list[i]);
       }
 
+      // Perform a second pass over the output to merge content when possible
+      // WARN: We are not handling the case where buffer is still populated as the source should
+      // not have buffer append operations as their final action.
+      var source = '',
+          buffer;
+      for (var i = 0, len = this.source.length; i < len; i++) {
+        var line = this.source[i];
+        if (line.appendToBuffer) {
+          if (buffer) {
+            buffer = buffer + '\n    + ' + line.content;
+          } else {
+            buffer = line.content;
+          }
+        } else {
+          if (buffer) {
+            source += 'buffer += ' + buffer + ';\n  ';
+            buffer = undefined;
+          }
+          source += line + '\n  ';
+        }
+      }
+
       if (asObject) {
-        params.push(this.source.join("\n  "));
+        params.push(source);
 
         return Function.apply(this, params);
       } else {
-        var functionSource = 'function ' + (this.name || '') + '(' + params.join(',') + ') {\n  ' + this.source.join("\n  ") + '}';
+        var functionSource = 'function ' + (this.name || '') + '(' + params.join(',') + ') {\n  ' + source + '}';
         Handlebars.log(Handlebars.logger.DEBUG, functionSource + "\n\n");
         return functionSource;
       }
@@ -600,15 +626,9 @@ Handlebars.JavaScriptCompiler = function() {};
     //
     // Escape `value` and append it to the buffer
     appendEscaped: function() {
-      var opcode = this.nextOpcode(), extra = "";
       this.context.aliases.escapeExpression = 'this.escapeExpression';
 
-      if(opcode && opcode.opcode === 'appendContent') {
-        extra = " + " + this.quotedString(opcode.args[0]);
-        this.eat(opcode);
-      }
-
-      this.source.push(this.appendToBuffer("escapeExpression(" + this.popStack() + ")" + extra));
+      this.source.push(this.appendToBuffer("escapeExpression(" + this.popStack() + ")"));
     },
 
     // [getContext]