Add support for function argument initializers. (#2571)

EcmaScript 2015 14.1.

Note: arrow functions with default arguments are not supported yet.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/config.h

@@ -39,6 +39,7 @@
 # define CONFIG_DISABLE_ES2015_ARROW_FUNCTION
 # define CONFIG_DISABLE_ES2015_BUILTIN
 # define CONFIG_DISABLE_ES2015_CLASS
+# define CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
 # define CONFIG_DISABLE_ES2015_MAP_BUILTIN
 # define CONFIG_DISABLE_ES2015_OBJECT_INITIALIZER
 # define CONFIG_DISABLE_ES2015_PROMISE_BUILTIN

jerry-core/parser/js/js-parser-scanner.c

@@ -74,6 +74,9 @@ typedef enum
   SCAN_STACK_CLASS,                        /**< class language element */
   SCAN_STACK_CLASS_EXTENDS,                /**< class extends expression */
 #endif /* !CONFIG_DISABLE_ES2015_CLASS */
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+  SCAN_STACK_FUNCTION_PARAMETERS,          /**< function parameter initializer */
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
 } scan_stack_modes_t;
 
 /**
@@ -420,6 +423,22 @@ parser_scan_primary_expression_end (parser_context_t *context_p, /**< context */
   }
 #endif /* !CONFIG_DISABLE_ES2015_OBJECT_INITIALIZER */
 
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+  if (context_p->token.type == LEXER_RIGHT_PAREN && stack_top == SCAN_STACK_FUNCTION_PARAMETERS)
+  {
+    lexer_next_token (context_p);
+
+    parser_stack_pop_uint8 (context_p);
+
+    if (context_p->token.type != LEXER_LEFT_BRACE)
+    {
+      parser_raise_error (context_p, PARSER_ERR_LEFT_BRACE_EXPECTED);
+    }
+    *mode = SCAN_MODE_STATEMENT;
+    return false;
+  }
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
+
   /* Check whether we can enter to statement mode. */
   if (stack_top != SCAN_STACK_BLOCK_STATEMENT
       && stack_top != SCAN_STACK_BLOCK_EXPRESSION
@@ -861,6 +880,15 @@ parser_scan_until (parser_context_t *context_p, /**< context */
           }
         }
 
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+        if (context_p->token.type == LEXER_ASSIGN)
+        {
+          parser_stack_push_uint8 (context_p, SCAN_STACK_FUNCTION_PARAMETERS);
+          mode = SCAN_MODE_PRIMARY_EXPRESSION;
+          break;
+        }
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
+
         if (context_p->token.type != LEXER_RIGHT_PAREN)
         {
           parser_raise_error (context_p, PARSER_ERR_RIGHT_PAREN_EXPECTED);

jerry-core/parser/js/js-parser-statm.c

@@ -324,8 +324,6 @@ parser_parse_var_statement (parser_context_t *context_p) /**< context */
 
     context_p->lit_object.literal_p->status_flags |= LEXER_FLAG_VAR;
 
-    parser_emit_cbc_literal_from_token (context_p, CBC_PUSH_LITERAL);
-
     lexer_next_token (context_p);
 
     if (context_p->token.type == LEXER_ASSIGN)
@@ -334,19 +332,11 @@ parser_parse_var_statement (parser_context_t *context_p) /**< context */
       if ((JERRY_CONTEXT (debugger_flags) & JERRY_DEBUGGER_CONNECTED)
           && ident_line_counter != context_p->last_breakpoint_line)
       {
-        JERRY_ASSERT (context_p->last_cbc_opcode == CBC_PUSH_LITERAL);
-
-        cbc_argument_t last_cbc = context_p->last_cbc;
-        context_p->last_cbc_opcode = PARSER_CBC_UNAVAILABLE;
-
         parser_emit_cbc (context_p, CBC_BREAKPOINT_DISABLED);
         parser_flush_cbc (context_p);
 
         parser_append_breakpoint_info (context_p, JERRY_DEBUGGER_BREAKPOINT_LIST, ident_line_counter);
 
-        context_p->last_cbc_opcode = CBC_PUSH_LITERAL;
-        context_p->last_cbc = last_cbc;
-
         context_p->last_breakpoint_line = ident_line_counter;
       }
 #endif /* JERRY_DEBUGGER */
@@ -358,16 +348,10 @@ parser_parse_var_statement (parser_context_t *context_p) /**< context */
       }
 #endif /* JERRY_ENABLE_LINE_INFO */
 
+      parser_emit_cbc_literal_from_token (context_p, CBC_PUSH_LITERAL);
       parser_parse_expression (context_p,
                                PARSE_EXPR_STATEMENT | PARSE_EXPR_NO_COMMA | PARSE_EXPR_HAS_LITERAL);
     }
-    else
-    {
-      JERRY_ASSERT (context_p->last_cbc_opcode == CBC_PUSH_LITERAL
-                    && context_p->last_cbc.literal_type == LEXER_IDENT_LITERAL);
-      /* We don't need to assign anything to this variable. */
-      context_p->last_cbc_opcode = PARSER_CBC_UNAVAILABLE;
-    }
 
     if (context_p->token.type != LEXER_COMMA)
     {

jerry-core/parser/js/js-parser-util.c

@@ -1038,6 +1038,12 @@ parser_error_to_string (parser_error_t error) /**< error code */
     {
       return "Duplicated label.";
     }
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+    case PARSER_ERR_DUPLICATED_ARGUMENT_NAMES:
+    {
+      return "Duplicated function argument names are not allowed here.";
+    }
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
     case PARSER_ERR_OBJECT_PROPERTY_REDEFINED:
     {
       return "Property of object literal redefined.";

jerry-core/parser/js/js-parser.c

@@ -2177,6 +2177,11 @@ static void
 parser_parse_function_arguments (parser_context_t *context_p, /**< context */
                                  lexer_token_type_t end_type) /**< expected end type */
 {
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+  bool duplicated_argument_names = false;
+  bool initializer_found = false;
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
+
   if (context_p->token.type == end_type)
   {
     return;
@@ -2218,6 +2223,14 @@ parser_parse_function_arguments (parser_context_t *context_p, /**< context */
     {
       lexer_literal_t *literal_p;
 
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+      if (initializer_found)
+      {
+        parser_raise_error (context_p, PARSER_ERR_DUPLICATED_ARGUMENT_NAMES);
+      }
+      duplicated_argument_names = true;
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
+
       if (context_p->literal_count >= PARSER_MAXIMUM_NUMBER_OF_LITERALS)
       {
         parser_raise_error (context_p, PARSER_ERR_LITERAL_LIMIT_REACHED);
@@ -2254,6 +2267,29 @@ parser_parse_function_arguments (parser_context_t *context_p, /**< context */
 
     lexer_next_token (context_p);
 
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+    if (context_p->token.type == LEXER_ASSIGN)
+    {
+      parser_branch_t skip_init;
+
+      if (duplicated_argument_names)
+      {
+        parser_raise_error (context_p, PARSER_ERR_DUPLICATED_ARGUMENT_NAMES);
+      }
+      initializer_found = true;
+
+      /* LEXER_ASSIGN does not overwrite lit_object. */
+      parser_emit_cbc (context_p, CBC_PUSH_UNDEFINED);
+      parser_emit_cbc_literal (context_p, CBC_STRICT_EQUAL_RIGHT_LITERAL, context_p->lit_object.index);
+      parser_emit_cbc_forward_branch (context_p, CBC_BRANCH_IF_FALSE_FORWARD, &skip_init);
+
+      parser_emit_cbc_literal_from_token (context_p, CBC_PUSH_LITERAL);
+      parser_parse_expression (context_p, PARSE_EXPR_STATEMENT | PARSE_EXPR_NO_COMMA | PARSE_EXPR_HAS_LITERAL);
+
+      parser_set_branch_to_current_position (context_p, &skip_init);
+    }
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
+
     if (context_p->token.type != LEXER_COMMA)
     {
       break;

jerry-core/parser/js/js-parser.h

@@ -119,6 +119,9 @@ typedef enum
   PARSER_ERR_INVALID_RETURN,                          /**< return must be inside a function */
   PARSER_ERR_INVALID_RIGHT_SQUARE,                    /**< right square must terminate a block */
   PARSER_ERR_DUPLICATED_LABEL,                        /**< duplicated label */
+#ifndef CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+  PARSER_ERR_DUPLICATED_ARGUMENT_NAMES,               /**< duplicated argument names */
+#endif /* !CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER */
   PARSER_ERR_OBJECT_PROPERTY_REDEFINED,               /**< property of object literal redefined */
   PARSER_ERR_NON_STRICT_ARG_DEFINITION                /**< non-strict argument definition */
 } parser_error_t;

jerry-core/profiles/README.md

@@ -32,6 +32,9 @@ Alternatively, if you want to use a custom profile at
 # Turn off every ES2015 feature EXCEPT the arrow functions
 CONFIG_DISABLE_ES2015_BUILTIN
 CONFIG_DISABLE_ES2015_CLASS
+CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER
+CONFIG_DISABLE_ES2015_MAP_BUILTIN
+CONFIG_DISABLE_ES2015_OBJECT_INITIALIZER
 CONFIG_DISABLE_ES2015_PROMISE_BUILTIN
 CONFIG_DISABLE_ES2015_TEMPLATE_STRINGS
 CONFIG_DISABLE_ES2015_TYPEDARRAY_BUILTIN
@@ -87,6 +90,8 @@ In JerryScript all of the features are enabled by default, so an empty profile f
   Disable the built-in updates of the 5.1 standard. There are some differences in those built-ins which available in both [5.1](http://www.ecma-international.org/ecma-262/5.1/) and [2015](http://www.ecma-international.org/ecma-262/6.0/) versions of the standard. JerryScript uses the latest definition by default.
 * `CONFIG_DISABLE_ES2015_CLASS`:
   Disable the [class](https://www.ecma-international.org/ecma-262/6.0/#sec-class-definitions) language element.
+* `CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER`:
+  Disable the [default value](http://www.ecma-international.org/ecma-262/6.0/#sec-function-definitions) for formal parameters.
 * `CONFIG_DISABLE_ES2015_MAP_BUILTIN`:
   Disable the [Map](http://www.ecma-international.org/ecma-262/6.0/#sec-keyed-collection) built-ins.
 * `CONFIG_DISABLE_ES2015_OBJECT_INITIALIZER`:
@@ -98,4 +103,6 @@ In JerryScript all of the features are enabled by default, so an empty profile f
 * `CONFIG_DISABLE_ES2015_TYPEDARRAY_BUILTIN`:
   Disable the [ArrayBuffer](http://www.ecma-international.org/ecma-262/6.0/#sec-arraybuffer-objects) and [TypedArray](http://www.ecma-international.org/ecma-262/6.0/#sec-typedarray-objects) built-ins.
 * `CONFIG_DISABLE_ES2015`: Disable all of the implemented [ECMAScript2015 features](http://www.ecma-international.org/ecma-262/6.0/).
-  (equivalent to `CONFIG_DISABLE_ES2015_ARROW_FUNCTION`, `CONFIG_DISABLE_ES2015_BUILTIN`, `CONFIG_DISABLE_ES2015_CLASS`, `CONFIG_DISABLE_ES2015_PROMISE_BUILTIN`, `CONFIG_DISABLE_ES2015_TEMPLATE_STRINGS`, and `CONFIG_DISABLE_ES2015_TYPEDARRAY_BUILTIN`).
+  (equivalent to `CONFIG_DISABLE_ES2015_ARROW_FUNCTION`, `CONFIG_DISABLE_ES2015_BUILTIN`, `CONFIG_DISABLE_ES2015_CLASS`,
+  `CONFIG_DISABLE_ES2015_FUNCTION_PARAMETER_INITIALIZER`, `CONFIG_DISABLE_ES2015_MAP_BUILTIN`, `CONFIG_DISABLE_ES2015_OBJECT_INITIALIZER`,
+  `CONFIG_DISABLE_ES2015_PROMISE_BUILTIN`, `CONFIG_DISABLE_ES2015_TEMPLATE_STRINGS`, and `CONFIG_DISABLE_ES2015_TYPEDARRAY_BUILTIN`).

tests/jerry/es2015/function-param-init.js

@@ -0,0 +1,81 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var local = 0;
+
+switch(0) { /* This switch forces a pre-scanner run. */
+default:
+
+  function f(a = (5, local = 6),
+             b = ((5 + function(a = 6) { return a }() * 3)),
+             c,
+             d = true ? 1 : 2)
+  {
+    return "" + a + ", " + b + ", " + c + ", " + d;
+  }
+
+  assert(f() === "6, 23, undefined, 1");
+  assert(local === 6);
+
+  var obj = {
+    f: function(a = [10,,20],
+                b,
+                c = Math.cos(0),
+                d)
+    {
+      return "" + a + ", " + b + ", " + c + ", " + d;
+    }
+  };
+
+  assert(obj.f() === "10,,20, undefined, 1, undefined");
+
+  function g(a, b = (local = 7)) { }
+
+  local = 0;
+  g();
+  assert(local === 7);
+
+  local = 0;
+  g(0);
+  assert(local === 7);
+
+  local = 0;
+  g(0, undefined);
+  assert(local === 7);
+
+  local = 0;
+  g(0, null);
+  assert(local === 0);
+
+  local = 0;
+  g(0, false);
+  assert(local === 0);
+  break;
+}
+
+function CheckSyntaxError(str)
+{
+  try {
+    eval(str);
+    assert(false);
+  } catch (e) {
+    assert(e instanceof SyntaxError);
+  }
+}
+
+CheckSyntaxError('function x(a += 5) {}');
+CheckSyntaxError('function x(a =, b) {}');
+CheckSyntaxError('function x(a = (b) {}');
+CheckSyntaxError('function x(a, a = 5) {}');
+CheckSyntaxError('function x(a = 5, a) {}');