Add an API function to calculate the UTF-8 encoded string size from Jerry string. (#1450)

JerryScript-DCO-1.0-Signed-off-by: Robert Sipka rsipka.uszeged@partner.samsung.com

jerry-core/lit/lit-strings.c

@@ -281,6 +281,40 @@ lit_utf8_string_length (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string */
   return length;
 } /* lit_utf8_string_length */
 
+/**
+ * Calculate the required size of an utf-8 encoded string from cesu-8 encoded string
+ *
+ * @return size of an utf-8 encoded string
+ */
+lit_utf8_size_t
+lit_get_utf8_size_of_cesu8_string (const lit_utf8_byte_t *cesu8_buf_p, /**< cesu-8 string */
+                                   lit_utf8_size_t cesu8_buf_size) /**< string size */
+{
+  lit_utf8_size_t offset = 0;
+  lit_utf8_size_t utf8_buf_size = cesu8_buf_size;
+
+  while (offset < cesu8_buf_size)
+  {
+    ecma_char_t ch;
+    offset += lit_read_code_unit_from_utf8 (cesu8_buf_p + offset, &ch);
+
+    if (lit_is_code_point_utf16_high_surrogate (ch) && (offset < cesu8_buf_size))
+    {
+      ecma_char_t next_ch;
+      offset += lit_read_code_unit_from_utf8 (cesu8_buf_p + offset, &next_ch);
+
+      if (lit_is_code_point_utf16_low_surrogate (next_ch))
+      {
+        utf8_buf_size -= 2;
+      }
+    }
+  }
+
+  JERRY_ASSERT (offset == cesu8_buf_size);
+
+  return utf8_buf_size;
+} /* lit_get_utf8_size_of_cesu8_string */
+
 /**
  * Decodes a unicode code point from non-empty utf-8-encoded buffer
  *

jerry-core/lit/lit-strings.h

@@ -95,6 +95,7 @@ bool lit_is_code_point_utf16_high_surrogate (lit_code_point_t);
 
 /* size */
 lit_utf8_size_t lit_zt_utf8_string_size (const lit_utf8_byte_t *);
+lit_utf8_size_t lit_get_utf8_size_of_cesu8_string (const lit_utf8_byte_t *, lit_utf8_size_t);
 
 /* length */
 ecma_length_t lit_utf8_string_length (const lit_utf8_byte_t *, lit_utf8_size_t);