Implement the core of let/const statement. (#3239)

This patch implements the core part of let/const statements. Redeclarations are correctly
detected and separate contexts are correctly created for these statements. Register
optimizations are also emplyed whenever possible.

Lots of features are still missing:
 - checking the var statements in eval
 - const are treated as lets
 - single statement checks are missing
 - export declarations are exported as vars, let/const export is not supported

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

tests/jerry-test-suite/07/07.06/07.06.01/07.06.01-001.js

@@ -12,4 +12,4 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-var let = 1;
+var package = 1;

tests/jerry/es2015/let1.js

@@ -0,0 +1,42 @@
+/* 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 a = 5;
+var a = 6;
+let b = 7;
+
+assert (a === 6);
+assert (this.a === 6);
+assert (b === 7);
+assert (this.b === undefined);
+
+{
+  let c;
+  c = 8;
+
+  {
+    let c = 9;
+    assert (c === 9);
+  }
+
+  {
+    function c() { return 10 }
+    assert (c() === 10);
+  }
+
+  assert (c === 8);
+}
+assert (typeof c === "undefined");
+

tests/jerry/es2015/let2.js

@@ -0,0 +1,44 @@
+/* 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.
+ */
+
+function check_syntax_error (code)
+{
+  try {
+    eval (code);
+    assert (false);
+  } catch (e) {
+    assert (e instanceof SyntaxError);
+  }
+}
+
+check_syntax_error ("let a; let b; let a");
+check_syntax_error ("let a, b, a");
+check_syntax_error ("var a; let a;");
+check_syntax_error ("var a; const a = 3;");
+check_syntax_error ("let a; var a;");
+check_syntax_error ("const a = 3; var x, y, a;");
+check_syntax_error ("let a; { let b; { var a; } }");
+check_syntax_error ("{ { var a = 4; } }; let a = 3");
+check_syntax_error ("function a() {}; let a;");
+check_syntax_error ("let a; function a() {};");
+check_syntax_error ("{ { function a() {}; let a; } }");
+check_syntax_error ("{ { let a; function a() {}; } }");
+check_syntax_error ("let a = 1; const b = 5; const a = 2;");
+check_syntax_error ("try {} catch (e) { let e; }");
+check_syntax_error ("try {} catch (e) { const e = 1; }");
+check_syntax_error ("let A; class A {}");
+check_syntax_error ("const A; class A {}");
+check_syntax_error ("class A {}; let A");
+check_syntax_error ("class A {}; const A");

tests/jerry/es2015/let3.js

@@ -0,0 +1,68 @@
+/* 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 g = -1;
+
+function f1() {
+  /* Function hoisted as var. */
+  assert (g === undefined);
+
+  {
+    assert (g() === 1);
+
+    {
+      assert (g() === 2);
+
+      function g() { return 2 };
+    }
+
+    function g() { return 1 };
+
+    assert (g() === 2);
+  }
+
+  assert (g() === 2);
+}
+f1();
+
+function f2() {
+  /* Function hoisted as let. */
+  assert (g === -1);
+
+  {
+    let g = 1;
+
+    {
+      if (true)
+      {
+        assert (g() === 2);
+
+        if (true)
+        {
+          assert (g() === 2);
+        }
+
+        function g() { return 2 };
+      }
+
+      assert (g === 1);
+    }
+
+    assert (g === 1);
+  }
+
+  assert (g === -1);
+}
+f2();

tests/jerry/es2015/let4.js

@@ -0,0 +1,68 @@
+/* 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 g = -1;
+
+function f1() {
+  /* Function hoisted as var. */
+  assert (g === undefined);
+
+  {
+    assert (g() === 1);
+
+    {
+      eval("assert (g() === 2)");
+
+      function g() { return 2 };
+    }
+
+    function g() { return 1 };
+
+    assert (g() === 2);
+  }
+
+  assert (g() === 2);
+}
+f1();
+
+function f2() {
+  /* Function hoisted as let. */
+  assert (g === -1);
+
+  {
+    let g = 1;
+
+    {
+      if (true)
+      {
+        assert (g() === 2);
+
+        if (true)
+        {
+          eval("assert (g() === 2)");
+        }
+
+        function g() { return 2 };
+      }
+
+      assert (g === 1);
+    }
+
+    assert (g === 1);
+  }
+
+  assert (g === -1);
+}
+f2();

tests/jerry/es2015/let5.js

@@ -0,0 +1,35 @@
+/* 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.
+ */
+
+let arr = [];
+
+for (var a = 0; a < 10; a++)
+{
+  let j = a;
+  var f;
+
+  {
+    f = function () { return j; }
+
+    let j = (a & 0x1) ? a + 10 : a + 100;
+  }
+
+  arr[j] = f;
+}
+
+for (var a = 0; a < 10; a++)
+{
+  assert (arr[a]() == ((a & 0x1) ? a + 10 : a + 100))
+}

tests/jerry/es2015/let6.js

@@ -0,0 +1,79 @@
+/* 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.
+ */
+
+try {
+  let a = 1;
+  eval ("assert(a === 1)");
+} catch (e) {
+  assert (false);
+}
+
+assert (typeof a === "undefined");
+
+try {
+  let a = 2;
+  eval ("assert(a === 2)");
+
+  assert (typeof b === "undefined");
+  throw 3;
+} catch (e) {
+  let b = e;
+  eval ("assert(b === 3)");
+
+  assert (typeof a === "undefined");
+}
+
+assert (typeof a === "undefined");
+assert (typeof b === "undefined");
+
+try {
+  let a = 4;
+  eval ("assert(a === 4)");
+
+  assert (typeof b === "undefined");
+} finally {
+  let b = 5;
+  eval ("assert(b === 5)");
+
+  assert (typeof a === "undefined");
+}
+
+assert (typeof a === "undefined");
+assert (typeof b === "undefined");
+
+try {
+  let a = 6;
+  eval ("assert(a === 6)");
+
+  assert (typeof b === "undefined");
+  assert (typeof c === "undefined");
+  throw 7;
+} catch (e) {
+  let b = e;
+  eval ("assert(b === 7)");
+
+  assert (typeof a === "undefined");
+  assert (typeof c === "undefined");
+} finally {
+  let c = 8;
+  eval ("assert(c === 8)");
+
+  assert (typeof a === "undefined");
+  assert (typeof b === "undefined");
+}
+
+assert (typeof a === "undefined");
+assert (typeof b === "undefined");
+assert (typeof c === "undefined");

tests/jerry/es2015/let7.js

@@ -0,0 +1,68 @@
+/* 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.
+ */
+
+
+assert (typeof f === "undefined");
+
+function g() { return 6; }
+
+switch (g()) {
+case f():
+
+  let g = 9;
+
+  assert (g === 9);
+
+  function f() { return 6; }
+  break;
+
+default:
+  assert (false);
+}
+
+assert (f() === 6);
+
+switch (g()) {
+case f() - 2:
+
+  let g = 9;
+
+  assert ((function() { return g + f(); })() === 17);
+
+  function f() { return 8; }
+  break;
+
+default:
+  assert (false);
+}
+
+assert (f() === 8);
+
+switch (g()) {
+case g() * 2:
+
+  {
+    let g = 4;
+    assert (g == 4);
+  }
+
+  function g() { return 3; }
+  break;
+
+default:
+  assert (false);
+}
+
+assert (g() === 3);

tests/jerry/es2015/let8.js

@@ -0,0 +1,58 @@
+/* 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.
+ */
+
+assert (typeof A === "undefined");
+
+{
+  class A {};
+
+  {
+    let A = 6;
+
+    assert (A === 6);
+  }
+
+  assert (typeof A === "function");
+}
+
+assert (typeof A === "undefined");
+
+{
+  let A = 5;
+  {
+    {
+      class A {};
+
+      assert (typeof A === "function");
+    }
+
+    assert (A === 5);
+  }
+}
+
+assert (typeof A === "undefined");
+
+{
+  let A = 5;
+  {
+    {
+      class A {};
+
+      eval ('assert (typeof A === "function")');
+    }
+
+    eval ('assert (A === 5)');
+  }
+}

tests/jerry/es5.1/func-decl.js

@@ -0,0 +1,25 @@
+// 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.
+
+function f() {
+    return 'foo';
+}
+assert ((function() {
+    if (1 === 0) {
+        function f() {
+            return 'bar';
+        }
+    }
+    return f();
+})() === 'bar');

tests/jerry/func-decl.js

@@ -16,7 +16,7 @@ function f() {
     return 'foo';
 }
 assert ((function() {
-    if (1 === 0) {
+    if (1 === 1) {
         function f() {
             return 'bar';
         }

tests/unit-core/test-snapshot.c

@@ -223,15 +223,15 @@ main (void)
     /* Check the snapshot data. Unused bytes should be filled with zeroes */
     const uint8_t expected_data[] =
     {
-      0x4A, 0x52, 0x52, 0x59, 0x19, 0x00, 0x00, 0x00,
+      0x4A, 0x52, 0x52, 0x59, 0x1A, 0x00, 0x00, 0x00,
       0x00, 0x00, 0x00, 0x00, 0x48, 0x00, 0x00, 0x00,
       0x01, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00,
       0x03, 0x00, 0x01, 0x00, 0x21, 0x00, 0x01, 0x00,
       0x00, 0x00, 0x00, 0x01, 0x18, 0x00, 0x00, 0x00,
-      0x28, 0x00, 0xB7, 0x45, 0x00, 0x00, 0x00, 0x00,
+      0x2C, 0x00, 0xBC, 0x4A, 0x00, 0x00, 0x00, 0x00,
       0x03, 0x00, 0x01, 0x00, 0x21, 0x00, 0x00, 0x00,
       0x00, 0x00, 0x01, 0x01, 0x07, 0x00, 0x00, 0x00,
-      0x46, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x4B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
       0x14, 0x00, 0x73, 0x74, 0x72, 0x69, 0x6E, 0x67,
       0x20, 0x66, 0x72, 0x6F, 0x6D, 0x20, 0x73, 0x6E,
       0x61, 0x70, 0x73, 0x68, 0x6F, 0x74,