Implement optional chaining (jerryscript-project#5164)

The work is based on PR jerryscript-project#4843, only fixed some conflicts and cppcheck errors.

Co-authored-by: Robert Fancsik [email protected]
JerryScript-DCO-1.0-Signed-off-by: Gergo Csizi [email protected]

Author: gergocs

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

@@ -28,7 +28,7 @@ JERRY_STATIC_ASSERT (offsetof (cbc_uint8_arguments_t, script_value) == offsetof
  * whenever new bytecodes are introduced or existing ones have been deleted.
  */
 JERRY_STATIC_ASSERT (CBC_END == 238, number_of_cbc_opcodes_changed);
-JERRY_STATIC_ASSERT (CBC_EXT_END == 167, number_of_cbc_ext_opcodes_changed);
+JERRY_STATIC_ASSERT (CBC_EXT_END == 170, number_of_cbc_ext_opcodes_changed);
 
 /** \addtogroup parser Parser
  * @{

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

@@ -497,9 +497,9 @@
   CBC_FORWARD_BRANCH (CBC_EXT_DEFAULT_INITIALIZER, -1, VM_OC_DEFAULT_INITIALIZER)                                      \
   CBC_OPCODE (CBC_EXT_ERROR, CBC_NO_FLAG, 0, VM_OC_ERROR)                                                              \
   CBC_FORWARD_BRANCH (CBC_EXT_BRANCH_IF_NULLISH, -1, VM_OC_BRANCH_IF_NULLISH)                                          \
-                                                                                                                       \
-  /* Basic opcodes. */                                                                                                 \
   CBC_OPCODE (CBC_EXT_POP_REFERENCE, CBC_NO_FLAG, -2, VM_OC_POP_REFERENCE)                                             \
+  CBC_FORWARD_BRANCH (CBC_EXT_BRANCH_OPTIONAL_CHAIN, 0, VM_OC_BRANCH_OPTIONAL_CHAIN)                                   \
+  /* Basic opcodes. */                                                                                                 \
   CBC_OPCODE (CBC_EXT_CREATE_ARGUMENTS, CBC_HAS_LITERAL_ARG, 0, VM_OC_CREATE_ARGUMENTS)                                \
   CBC_OPCODE (CBC_EXT_CREATE_VAR_EVAL, CBC_HAS_LITERAL_ARG, 0, VM_OC_EXT_VAR_EVAL)                                     \
   CBC_OPCODE (CBC_EXT_CREATE_VAR_FUNC_EVAL, CBC_HAS_LITERAL_ARG | CBC_HAS_LITERAL_ARG2, 0, VM_OC_EXT_VAR_EVAL)         \

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

@@ -381,6 +381,29 @@ lexer_skip_spaces (parser_context_t *context_p) /**< context */
   }
 } /* lexer_skip_spaces */
 
+/**
+ * Checks the next token start character.
+ *
+ * @return LIT_INVALID_CP - if there is no more characters to read
+ *         next byte - otherwise
+ */
+lit_code_point_t
+lexer_peek_next_character (parser_context_t *context_p) /**< context */
+{
+  if (!(context_p->token.flags & LEXER_NO_SKIP_SPACES))
+  {
+    lexer_skip_spaces (context_p);
+    context_p->token.flags = (uint8_t) (context_p->token.flags | LEXER_NO_SKIP_SPACES);
+  }
+
+  if (context_p->source_p < context_p->source_end_p)
+  {
+    return context_p->source_p[0];
+  }
+
+  return LIT_INVALID_CP;
+} /* lexer_check_next_character */
+
 /**
  * Skip all the continuous empty statements.
  */
@@ -1738,6 +1761,13 @@ lexer_next_token (parser_context_t *context_p) /**< context */
           length = 2;
           break;
         }
+        if (context_p->source_p[1] == (uint8_t) LIT_CHAR_DOT
+            && (length < 3 || !lit_char_is_decimal_digit (context_p->source_p[2])))
+        {
+          context_p->token.type = LEXER_QUESTION_MARK_DOT;
+          length = 2;
+          break;
+        }
       }
 
       context_p->token.type = LEXER_QUESTION_MARK;

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

@@ -154,6 +154,7 @@ typedef enum
   LEXER_RIGHT_PAREN, /**< ")" */
   LEXER_RIGHT_SQUARE, /**< "]" */
   LEXER_DOT, /**< "." */
+  LEXER_QUESTION_MARK_DOT, /**< "?." */
   LEXER_SEMICOLON, /**< ";" */
   LEXER_COLON, /**< ":" */
   LEXER_COMMA, /**< "," */