string.empty?

Summary: Basic string operation

Differential Revision: D68424373

fbshipit-source-id: aabce9baae8aa5559aa5cc5106430dfaa56d005c

thrift/compiler/whisker/standard_library.cc

@@ -240,6 +240,24 @@ map::value_type create_string_functions() {
         return i64(ctx.argument<string>(0)->length());
       });
 
+  /**
+   * Checks a string for emptiness.
+   *
+   * Name: string.empty?
+   *
+   * Arguments:
+   *   - [string] — The string to check for emptiness.
+   *
+   * Returns:
+   *   [boolean] indicating whether the string is empty.
+   */
+  string_functions["empty?"] = dsl::make_function(
+      "string.empty?", [](dsl::function::context ctx) -> boolean {
+        ctx.declare_named_arguments({});
+        ctx.declare_arity(1);
+        return ctx.argument<string>(0)->empty();
+      });
+
   /**
    * Produces the provided string concatenated together.
    *