Implement template literals. (#2025)

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

tests/jerry/es2015/template_string.js

@@ -0,0 +1,92 @@
+/* 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 must_throw (str)
+{
+  try
+  {
+    eval ("switch (1) { default: " + str + "}");
+    assert (false);
+  }
+  catch (e)
+  {
+  }
+
+  try
+  {
+    eval (str);
+    assert (false);
+  }
+  catch (e)
+  {
+  }
+}
+
+var a = 'A';
+var b = 'B';
+
+switch (1)
+{
+default:
+
+  ``
+  `abc`
+  `ab${a+b}${ `x` }c`
+
+  assert (`` === '');
+  assert (`abc` === 'abc');
+  assert (`ab\
+  c` === 'ab  c');
+  assert (`ab
+  c` === 'ab\n  c');
+
+  assert (`prefix${a}` === 'prefixA');
+  assert (`${a}postfix` === 'Apostfix');
+  assert (`prefix${a}postfix` === 'prefixApostfix');
+
+  assert (`${a}${b}` === 'AB');
+  assert (`${a},${b}` === 'A,B');
+  assert (`${a}${b}${a}${b}` === 'ABAB');
+  assert (`${a},${b},${a},${b}` === 'A,B,A,B');
+  assert (`$${a},${b},${a},${b}$` === '$A,B,A,B$');
+
+  assert (`\${}` === '${}');
+  assert (`$\{}` === '${}');
+  assert (`x${  `y` + `z`  }x` === 'xyzx');
+  assert (`x${  `y` , `z`  }x` === 'xzx');
+
+  function f(x) { return x + 1; }
+
+  /* Precedence. */
+  var c = 1;
+  assert (`x${  f(1) * f(2)  }x${ c = 4 }` === 'x6x4');
+  assert (c === 4);
+  assert (`m${0 || 93}n${7 && 0}o` === 'm93n0o');
+
+  /* Result is always a string. */
+  assert (`${  function() { return true } () }` === 'true');
+  assert (`${  function() { return a.length } () }` === '1');
+
+  /* Result is a single string with its properties. */
+  assert(`${a}${b}${a}${b}`.length === 4);
+}
+
+must_throw ("`");
+must_throw ("`${");
+must_throw ("`${7");
+must_throw ("`${}`");
+must_throw ("`${1}");
+must_throw ("`${1}.${");
+must_throw ("`${1}.${2}");