Implement handling of arrow functions in the parser

test/cctest/test-parsing.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 268 matching lines @@
 
   CcTest::i_isolate()->stack_guard()->SetStackLimit(GetCurrentStackPosition() -
                                                     128 * 1024);
 
   const char* programs[] = {
       "{label: 42}",
       "var x = 42;",
       "function foo(x, y) { return x + y; }",
       "%ArgleBargle(glop);",
       "var x = new new Function('this.x = 42');",
+      "var f = (x, y) => x + y;",
       NULL
   };
 
   uintptr_t stack_limit = CcTest::i_isolate()->stack_guard()->real_climit();
   for (int i = 0; programs[i]; i++) {
     const char* program = programs[i];
     i::Utf8ToUtf16CharacterStream stream(
         reinterpret_cast<const i::byte*>(program),
         static_cast<unsigned>(strlen(program)));
     i::CompleteParserRecorder log;
     i::Scanner scanner(CcTest::i_isolate()->unicode_cache());
     scanner.Initialize(&stream);
 
     i::PreParser preparser(&scanner, &log, stack_limit);
     preparser.set_allow_lazy(true);
     preparser.set_allow_natives_syntax(true);
+    preparser.set_allow_arrow_functions(true);
     i::PreParser::PreParseResult result = preparser.PreParseProgram();
     CHECK_EQ(i::PreParser::kPreParseSuccess, result);
     CHECK(!log.HasError());
   }
 }
 
 
 TEST(StandAlonePreParserNoNatives) {
   v8::V8::Initialize();
 
@@ skipping 863 matching lines @@
 }
 
 
 enum ParserFlag {
   kAllowLazy,
   kAllowNativesSyntax,
   kAllowHarmonyScoping,
   kAllowModules,
   kAllowGenerators,
   kAllowForOf,
-  kAllowHarmonyNumericLiterals
+  kAllowHarmonyNumericLiterals,
+  kAllowArrowFunctions
 };
 
 
 enum ParserSyncTestResult {
   kSuccessOrError,
   kSuccess,
   kError
 };
 
 template <typename Traits>
 void SetParserFlags(i::ParserBase<Traits>* parser,
                     i::EnumSet<ParserFlag> flags) {
   parser->set_allow_lazy(flags.Contains(kAllowLazy));
   parser->set_allow_natives_syntax(flags.Contains(kAllowNativesSyntax));
   parser->set_allow_harmony_scoping(flags.Contains(kAllowHarmonyScoping));
   parser->set_allow_modules(flags.Contains(kAllowModules));
   parser->set_allow_generators(flags.Contains(kAllowGenerators));
   parser->set_allow_for_of(flags.Contains(kAllowForOf));
   parser->set_allow_harmony_numeric_literals(
       flags.Contains(kAllowHarmonyNumericLiterals));
+  parser->set_allow_arrow_functions(flags.Contains(kAllowArrowFunctions));
 }
 
 
 void TestParserSyncWithFlags(i::Handle<i::String> source,
                              i::EnumSet<ParserFlag> flags,
                              ParserSyncTestResult result) {
   i::Isolate* isolate = CcTest::i_isolate();
   i::Factory* factory = isolate->factory();
 
   uintptr_t stack_limit = isolate->stack_guard()->real_climit();
@@ skipping 186 matching lines @@
 
   v8::HandleScope handles(CcTest::isolate());
   v8::Handle<v8::Context> context = v8::Context::New(CcTest::isolate());
   v8::Context::Scope context_scope(context);
 
   CcTest::i_isolate()->stack_guard()->SetStackLimit(GetCurrentStackPosition() -
                                                     128 * 1024);
 
   static const ParserFlag flags1[] = {
     kAllowLazy, kAllowHarmonyScoping, kAllowModules, kAllowGenerators,
-    kAllowForOf
+    kAllowForOf, kAllowArrowFunctions
   };
   for (int i = 0; context_data[i][0] != NULL; ++i) {
     for (int j = 0; statement_data[j] != NULL; ++j) {
       for (int k = 0; termination_data[k] != NULL; ++k) {
         int kPrefixLen = i::StrLength(context_data[i][0]);
         int kStatementLen = i::StrLength(statement_data[j]);
         int kTerminationLen = i::StrLength(termination_data[k]);
         int kSuffixLen = i::StrLength(context_data[i][1]);
         int kProgramSize = kPrefixLen + kStatementLen + kTerminationLen
             + kSuffixLen + i::StrLength("label: for (;;) {  }");
@@ skipping 56 matching lines @@
                        int always_true_flags_len = 0) {
   v8::HandleScope handles(CcTest::isolate());
   v8::Handle<v8::Context> context = v8::Context::New(CcTest::isolate());
   v8::Context::Scope context_scope(context);
 
   CcTest::i_isolate()->stack_guard()->SetStackLimit(GetCurrentStackPosition() -
                                                     128 * 1024);
 
   static const ParserFlag default_flags[] = {
     kAllowLazy, kAllowHarmonyScoping, kAllowModules, kAllowGenerators,
-    kAllowForOf, kAllowNativesSyntax
+    kAllowForOf, kAllowNativesSyntax, kAllowArrowFunctions
   };
   ParserFlag* generated_flags = NULL;
   if (flags == NULL) {
     flags = default_flags;
     flags_len = ARRAY_SIZE(default_flags);
     if (always_true_flags != NULL) {
       // Remove always_true_flags from default_flags.
       CHECK(always_true_flags_len < flags_len);
       generated_flags = new ParserFlag[flags_len - always_true_flags_len];
       int flag_index = 0;
@@ skipping 56 matching lines @@
     "var foo, eval;",
     "var foo, arguments;",
     "try { } catch (eval) { }",
     "try { } catch (arguments) { }",
     "function eval() { }",
     "function arguments() { }",
     "function foo(eval) { }",
     "function foo(arguments) { }",
     "function foo(bar, eval) { }",
     "function foo(bar, arguments) { }",
+    "(eval) => { }",
+    "(arguments) => { }",
+    "(foo, eval) => { }",
+    "(foo, arguments) => { }",
     "eval = 1;",
     "arguments = 1;",
     "var foo = eval = 1;",
     "var foo = arguments = 1;",
     "++eval;",
     "++arguments;",
     "eval++;",
     "arguments++;",
     NULL
   };
@@ skipping 36 matching lines @@
   };
 
   RunParserSyncTest(context_data, statement_data, kSuccess);
 }
 
 
 TEST(NoErrorsEvalAndArgumentsStrict) {
   const char* context_data[][2] = {
     { "\"use strict\";", "" },
     { "function test_func() { \"use strict\";", "}" },
+    { "() => { \"use strict\"; ", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "eval;",
     "arguments;",
     "var foo = eval;",
     "var foo = arguments;",
     "var foo = { eval: 1 };",
     "var foo = { arguments: 1 };",
     "var foo = { }; foo.eval = {};",
     "var foo = { }; foo.arguments = {};",
     NULL
   };
 
-  RunParserSyncTest(context_data, statement_data, kSuccess);
+  static const ParserFlag always_flags[] = {kAllowArrowFunctions};
+  RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
+                    always_flags, ARRAY_SIZE(always_flags));
 }
 
 
 TEST(ErrorsFutureStrictReservedWords) {
   // Tests that both preparsing and parsing produce the right kind of errors for
   // using future strict reserved words as identifiers. Without the strict mode,
   // it's ok to use future strict reserved words as identifiers. With the strict
   // mode, it isn't.
   const char* context_data[][2] = {
     { "\"use strict\";", "" },
     { "function test_func() {\"use strict\"; ", "}"},
+    { "() => { \"use strict\"; ", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "var interface;",
     "var foo, interface;",
     "try { } catch (interface) { }",
     "function interface() { }",
     "function foo(interface) { }",
     "function foo(bar, interface) { }",
     "interface = 1;",
     "var foo = interface = 1;",
     "++interface;",
     "interface++;",
     "var yield = 13;",
     NULL
   };
 
-  RunParserSyncTest(context_data, statement_data, kError);
+  static const ParserFlag always_flags[] = {kAllowArrowFunctions};
+  RunParserSyncTest(context_data, statement_data, kError, NULL, 0, always_flags,
+                    ARRAY_SIZE(always_flags));
 }
 
 
 TEST(NoErrorsFutureStrictReservedWords) {
   const char* context_data[][2] = {
     { "", "" },
     { "function test_func() {", "}"},
+    { "() => {", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "var interface;",
     "var foo, interface;",
     "try { } catch (interface) { }",
     "function interface() { }",
     "function foo(interface) { }",
     "function foo(bar, interface) { }",
     "interface = 1;",
     "var foo = interface = 1;",
     "++interface;",
     "interface++;",
     "var yield = 13;",
     NULL
   };
 
-  RunParserSyncTest(context_data, statement_data, kSuccess);
+  static const ParserFlag always_flags[] = {kAllowArrowFunctions};
+  RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
+                    always_flags, ARRAY_SIZE(always_flags));
 }
 
 
 TEST(ErrorsReservedWords) {
   // Tests that both preparsing and parsing produce the right kind of errors for
   // using future reserved words as identifiers. These tests don't depend on the
   // strict mode.
   const char* context_data[][2] = {
     { "", "" },
     { "\"use strict\";", "" },
     { "var eval; function test_func() {", "}"},
     { "var eval; function test_func() {\"use strict\"; ", "}"},
+    { "var eval; () => {", "}"},
+    { "var eval; () => {\"use strict\"; ", "}"},
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "var super;",
     "var foo, super;",
     "try { } catch (super) { }",
     "function super() { }",
     "function foo(super) { }",
     "function foo(bar, super) { }",
+    "(super) => { }",
+    "(bar, super) => { }",
     "super = 1;",
     "var foo = super = 1;",
     "++super;",
     "super++;",
     "function foo super",
     NULL
   };
 
   RunParserSyncTest(context_data, statement_data, kError);
 }
@@ skipping 58 matching lines @@
     "yield++;",
     "yield: 34",
     "function yield(yield) { yield: yield (yield + yield(0)); }",
     "({ yield: 1 })",
     "({ get yield() { 1 } })",
     "yield(100)",
     "yield[100]",
     NULL
   };
 
-  RunParserSyncTest(context_data, statement_data, kSuccess);
+  static const ParserFlag always_flags[] = {kAllowArrowFunctions};
+  RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
+                    always_flags, ARRAY_SIZE(always_flags));
 }
 
 
 TEST(NoErrorsYieldSloppyGeneratorsEnabled) {
   // In sloppy mode, it's okay to use "yield" as identifier, *except* inside a
   // generator (see next test).
   const char* context_data[][2] = {
     { "", "" },
     { "function not_gen() {", "}" },
     { "function * gen() { function not_gen() {", "} }" },
@@ skipping 34 matching lines @@
 
 
 TEST(ErrorsYieldStrict) {
   const char* context_data[][2] = {
     { "\"use strict\";", "" },
     { "\"use strict\"; function not_gen() {", "}" },
     { "function test_func() {\"use strict\"; ", "}"},
     { "\"use strict\"; function * gen() { function not_gen() {", "} }" },
     { "\"use strict\"; (function not_gen() {", "})" },
     { "\"use strict\"; (function * gen() { (function not_gen() {", "}) })" },
+    { "() => {\"use strict\"; ", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "var yield;",
     "var foo, yield;",
     "try { } catch (yield) { }",
     "function yield() { }",
     "(function yield() { })",
     "function foo(yield) { }",
@@ skipping 190 matching lines @@
   RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
                     always_true_flags, 1);
 }
 
 
 TEST(ErrorsIllegalWordsAsLabelsSloppy) {
   // Using future reserved words as labels is always an error.
   const char* context_data[][2] = {
     { "", ""},
     { "function test_func() {", "}" },
+    { "() => {", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "super: while(true) { break super; }",
     NULL
   };
 
   RunParserSyncTest(context_data, statement_data, kError);
 }
 
 
 TEST(ErrorsIllegalWordsAsLabelsStrict) {
   // Tests that illegal tokens as labels produce the correct errors.
   const char* context_data[][2] = {
     { "\"use strict\";", "" },
     { "function test_func() {\"use strict\"; ", "}"},
+    { "() => {\"use strict\"; ", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "super: while(true) { break super; }",
     "interface: while(true) { break interface; }",
     "yield: while(true) { break yield; }",
     NULL
   };
 
   RunParserSyncTest(context_data, statement_data, kError);
 }
 
 
 TEST(NoErrorsIllegalWordsAsLabels) {
   // Using eval and arguments as labels is legal even in strict mode.
   const char* context_data[][2] = {
     { "", ""},
     { "function test_func() {", "}" },
+    { "() => {", "}" },
     { "\"use strict\";", "" },
     { "\"use strict\"; function test_func() {", "}" },
+    { "\"use strict\"; () => {", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "mylabel: while(true) { break mylabel; }",
     "eval: while(true) { break eval; }",
     "arguments: while(true) { break arguments; }",
     NULL
   };
 
-  RunParserSyncTest(context_data, statement_data, kSuccess);
+  static const ParserFlag always_flags[] = {kAllowArrowFunctions};
+  RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
+                    always_flags, ARRAY_SIZE(always_flags));
 }
 
 
 TEST(ErrorsParenthesizedLabels) {
   // Parenthesized identifiers shouldn't be recognized as labels.
   const char* context_data[][2] = {
     { "", ""},
     { "function test_func() {", "}" },
+    { "() => {", "}" },
     { NULL, NULL }
   };
 
   const char* statement_data[] = {
     "(mylabel): while(true) { break mylabel; }",
     NULL
   };
 
   RunParserSyncTest(context_data, statement_data, kError);
 }
@@ skipping 820 matching lines @@
   LocalContext env;
   int use_counts[v8::Isolate::kUseCounterFeatureCount] = {};
   global_use_counts = use_counts;
   CcTest::isolate()->SetUseCounterCallback(MockUseCounterCallback);
   CompileRun("\"use asm\";\n"
              "var foo = 1;\n"
              "\"use asm\";\n"  // Only the first one counts.
              "function bar() { \"use asm\"; var baz = 1; }");
   CHECK_EQ(2, use_counts[v8::Isolate::kUseAsm]);
 }
+
+
+TEST(ErrorsArrowFunctions) {
+  // Tests that parser and preparser generate the same kind of errors
+  // on invalid arrow function syntax.
+  const char* context_data[][2] = {
+    {"", ";"},
+    {"v = ", ";"},
+    {"bar ? (", ") : baz;"},
+    {"bar ? baz : (", ");"},
+    {"bar[", "];"},
+    {"bar, ", ";"},
+    {"", ", bar;"},
+    {NULL, NULL}
+  };
+
+  const char* statement_data[] = {
+    "=> 0",
+    "=>",
+    "() =>",
+    "=> {}",
+    ") => {}",
+    ", => {}",
+    "(,) => {}",
+    "return => {}",
+    "() => {'value': 42}",
+
+    // Check that the early return introduced in ParsePrimaryExpression
+    // does not accept stray closing parentheses.
+    ")",
+    ") => 0",
+    "foo[()]",
+    "()",
+
+    // Parameter lists with extra parens should be recognized as errors.
+    "(()) => 0",
+    "((x)) => 0",
+    "((x, y)) => 0",
+    "(x, (y)) => 0",
+    "((x, y, z)) => 0",
+    "(x, (y, z)) => 0",
+    "((x, y), z) => 0",
+
+    // Parameter lists are always validated as strict, so those are errors.
+    "eval => {}",
+    "arguments => {}",
+    "yield => {}",
+    "interface => {}",
+    "(eval) => {}",
+    "(arguments) => {}",
+    "(yield) => {}",
+    "(interface) => {}",
+    "(eval, bar) => {}",
+    "(bar, eval) => {}",
+    "(bar, arguments) => {}",
+    "(bar, yield) => {}",
+    "(bar, interface) => {}",
+    // TODO(aperez): Detecting duplicates does not work in PreParser.
+    // "(bar, bar) => {}",
+
+    // The parameter list is parsed as an expression, but only
+    // a comma-separated list of identifier is valid.
+    "32 => {}",
+    "(32) => {}",
+    "(a, 32) => {}",
+    "if => {}",
+    "(if) => {}",
+    "(a, if) => {}",
+    "a + b => {}",
+    "(a + b) => {}",
+    "(a + b, c) => {}",
+    "(a, b - c) => {}",
+    "\"a\" => {}",
+    "(\"a\") => {}",
+    "(\"a\", b) => {}",
+    "(a, \"b\") => {}",
+    "-a => {}",
+    "(-a) => {}",
+    "(-a, b) => {}",
+    "(a, -b) => {}",
+    "{} => {}",
+    "({}) => {}",
+    "(a, {}) => {}",
+    "({}, a) => {}",
+    "a++ => {}",
+    "(a++) => {}",
+    "(a++, b) => {}",
+    "(a, b++) => {}",
+    "[] => {}",
+    "([]) => {}",
+    "(a, []) => {}",
+    "([], a) => {}",
+    "(a = b) => {}",
+    "(a = b, c) => {}",
+    "(a, b = c) => {}",
+    "(foo ? bar : baz) => {}",
+    "(a, foo ? bar : baz) => {}",
+    "(foo ? bar : baz, a) => {}",
+    NULL
+  };
+
+  RunParserSyncTest(context_data, statement_data, kError);
+}
+
+
+TEST(NoErrorsArrowFunctions) {
+  // Tests that parser and preparser accept valid arrow functions syntax.
+  const char* context_data[][2] = {
+    {"", ";"},
+    {"bar ? (", ") : baz;"},
+    {"bar ? baz : (", ");"},
+    {"bar, ", ";"},
+    {"", ", bar;"},
+    {NULL, NULL}
+  };
+
+  const char* statement_data[] = {
+    "() => {}",
+    "() => { return 42 }",
+    "x => { return x; }",
+    "(x) => { return x; }",
+    "(x, y) => { return x + y; }",
+    "(x, y, z) => { return x + y + z; }",
+    "(x, y) => { x.a = y; }",
+    "() => 42",
+    "x => x",
+    "x => x * x",
+    "(x) => x",
+    "(x) => x * x",
+    "(x, y) => x + y",
+    "(x, y, z) => x, y, z",
+    "(x, y) => x.a = y",
+    "() => ({'value': 42})",
+    "x => y => x + y",
+    "(x, y) => (u, v) => x*u + y*v",
+    "(x, y) => z => z * (x + y)",
+    "x => (y, z) => z * (x + y)",
+
+    // Those are comma-separated expressions, with arrow functions as items.
+    // They stress the code for validating arrow function parameter lists.
+    "a, b => 0",
+    "a, b, (c, d) => 0",
+    "(a, b, (c, d) => 0)",
+    "(a, b) => 0, (c, d) => 1",
+    "(a, b => {}, a => a + 1)",
+    "((a, b) => {}, (a => a + 1))",
+    "(a, (a, (b, c) => 0))",
+
+    // Arrow has more precedence, this is the same as: foo ? bar : (baz = {})
+    "foo ? bar : baz => {}",
+    NULL
+  };
+
+  static const ParserFlag always_flags[] = {kAllowArrowFunctions};
+  RunParserSyncTest(context_data, statement_data, kSuccess, NULL, 0,
+                    always_flags, ARRAY_SIZE(always_flags));
+}