Revision: 12174
Author:   [email protected]
Date:     Mon Jul 23 07:22:46 2012
Log:      Improve String::WriteAscii and add PRESERVE_ASCII_NULL option.

The PRESERVE_ASCII_NULL option prevents WriteAscii from converting
\0 to white space.

[email protected]
BUG=v8:2252
TEST=test-api/StringWrite

Review URL: https://chromiumcodereview.appspot.com/10810056
http://code.google.com/p/v8/source/detail?r=12174

Modified:
 /branches/bleeding_edge/include/v8.h
 /branches/bleeding_edge/src/api.cc
 /branches/bleeding_edge/test/cctest/test-api.cc

=======================================
--- /branches/bleeding_edge/include/v8.h        Tue Jul 17 08:18:15 2012
+++ /branches/bleeding_edge/include/v8.h        Mon Jul 23 07:22:46 2012
@@ -1064,7 +1064,8 @@
   enum WriteOptions {
     NO_OPTIONS = 0,
     HINT_MANY_WRITES_EXPECTED = 1,
-    NO_NULL_TERMINATION = 2
+    NO_NULL_TERMINATION = 2,
+    PRESERVE_ASCII_NULL = 4
   };

   // 16-bit character codes.
=======================================
--- /branches/bleeding_edge/src/api.cc  Wed Jul 18 07:15:02 2012
+++ /branches/bleeding_edge/src/api.cc  Mon Jul 23 07:22:46 2012
@@ -3847,6 +3847,9 @@
   LOG_API(isolate, "String::WriteUtf8");
   ENTER_V8(isolate);
   i::Handle<i::String> str = Utils::OpenHandle(this);
+  if (options & HINT_MANY_WRITES_EXPECTED) {
+    FlattenString(str);  // Flatten the string for efficiency.
+  }
   int string_length = str->length();
   if (str->IsAsciiRepresentation()) {
     int len;
@@ -3903,11 +3906,7 @@
   // Slow case.
i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
   isolate->string_tracker()->RecordWrite(str);
-  if (options & HINT_MANY_WRITES_EXPECTED) {
-    // Flatten the string for efficiency.  This applies whether we are
-    // using StringInputBuffer or Get(i) to access the characters.
-    FlattenString(str);
-  }
+
   write_input_buffer.Reset(0, *str);
   int len = str->length();
   // Encode the first K - 3 bytes directly into the buffer since we
@@ -3949,8 +3948,9 @@
                                   c,
                                   unibrow::Utf16::kNoPreviousCharacter);
         if (pos + written <= capacity) {
-          for (int j = 0; j < written; j++)
+          for (int j = 0; j < written; j++) {
             buffer[pos + j] = intermediate[j];
+          }
           pos += written;
           nchars++;
         } else {
@@ -3963,8 +3963,9 @@
   }
   if (nchars_ref != NULL) *nchars_ref = nchars;
   if (!(options & NO_NULL_TERMINATION) &&
-      (i == len && (capacity == -1 || pos < capacity)))
+      (i == len && (capacity == -1 || pos < capacity))) {
     buffer[pos++] = '\0';
+  }
   return pos;
 }

@@ -3977,28 +3978,45 @@
   if (IsDeadCheck(isolate, "v8::String::WriteAscii()")) return 0;
   LOG_API(isolate, "String::WriteAscii");
   ENTER_V8(isolate);
- i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
   ASSERT(start >= 0 && length >= -1);
   i::Handle<i::String> str = Utils::OpenHandle(this);
   isolate->string_tracker()->RecordWrite(str);
   if (options & HINT_MANY_WRITES_EXPECTED) {
-    // Flatten the string for efficiency.  This applies whether we are
-    // using StringInputBuffer or Get(i) to access the characters.
-    str->TryFlatten();
-  }
+    FlattenString(str);  // Flatten the string for efficiency.
+  }
+
+  if (str->IsAsciiRepresentation()) {
+    // WriteToFlat is faster than using the StringInputBuffer.
+    if (length == -1) length = str->length() + 1;
+    int len = i::Min(length, str->length() - start);
+    i::String::WriteToFlat(*str, buffer, start, start + len);
+    if (!(options & PRESERVE_ASCII_NULL)) {
+      for (int i = 0; i < len; i++) {
+        if (buffer[i] == '\0') buffer[i] = ' ';
+      }
+    }
+    if (!(options & NO_NULL_TERMINATION) && length > len) {
+      buffer[len] = '\0';
+    }
+    return len;
+  }
+
+ i::StringInputBuffer& write_input_buffer = *isolate->write_input_buffer();
   int end = length;
-  if ( (length == -1) || (length > str->length() - start) )
+  if ((length == -1) || (length > str->length() - start)) {
     end = str->length() - start;
+  }
   if (end < 0) return 0;
   write_input_buffer.Reset(start, *str);
   int i;
   for (i = 0; i < end; i++) {
     char c = static_cast<char>(write_input_buffer.GetNext());
-    if (c == '\0') c = ' ';
+    if (c == '\0' && !(options & PRESERVE_ASCII_NULL)) c = ' ';
     buffer[i] = c;
   }
-  if (!(options & NO_NULL_TERMINATION) && (length == -1 || i < length))
+  if (!(options & NO_NULL_TERMINATION) && (length == -1 || i < length)) {
     buffer[i] = '\0';
+  }
   return i;
 }

@@ -4017,7 +4035,7 @@
   if (options & HINT_MANY_WRITES_EXPECTED) {
     // Flatten the string for efficiency.  This applies whether we are
     // using StringInputBuffer or Get(i) to access the characters.
-    str->TryFlatten();
+    FlattenString(str);
   }
   int end = start + length;
   if ((length == -1) || (length > str->length() - start) )
@@ -4203,8 +4221,9 @@
     i::Handle<i::Foreign> foreign =
         isolate->factory()->NewForeign(
             reinterpret_cast<i::Address>(value), i::TENURED);
-    if (!foreign.is_null())
-        Utils::OpenHandle(this)->SetInternalField(index, *foreign);
+    if (!foreign.is_null()) {
+      Utils::OpenHandle(this)->SetInternalField(index, *foreign);
+    }
   }
   ASSERT_EQ(value, GetPointerFromInternalField(index));
 }
=======================================
--- /branches/bleeding_edge/test/cctest/test-api.cc     Fri Jul 20 01:03:46 2012
+++ /branches/bleeding_edge/test/cctest/test-api.cc     Mon Jul 23 07:22:46 2012
@@ -5570,6 +5570,7 @@
   v8::Handle<String> str = v8_str("abcde");
   // abc<Icelandic eth><Unicode snowman>.
   v8::Handle<String> str2 = v8_str("abc\303\260\342\230\203");
+  v8::Handle<String> str3 = v8::String::New("abc\0def", 7);
   const int kStride = 4;  // Must match stride in for loops in JS below.
   CompileRun(
       "var left = '';"
@@ -5780,6 +5781,28 @@
   CHECK_NE(0, strcmp(utf8buf, "abc\303\260\342\230\203"));
   utf8buf[8] = '\0';
   CHECK_EQ(0, strcmp(utf8buf, "abc\303\260\342\230\203"));
+
+  memset(utf8buf, 0x1, sizeof(utf8buf));
+  utf8buf[5] = 'X';
+  len = str->WriteUtf8(utf8buf, sizeof(utf8buf), &charlen,
+                        String::NO_NULL_TERMINATION);
+  CHECK_EQ(5, len);
+ CHECK_EQ('X', utf8buf[5]); // Test that the sixth character is untouched.
+  CHECK_EQ(5, charlen);
+  utf8buf[5] = '\0';
+  CHECK_EQ(0, strcmp(utf8buf, "abcde"));
+
+  memset(buf, 0x1, sizeof(buf));
+  len = str3->WriteAscii(buf);
+  CHECK_EQ(7, len);
+  CHECK_EQ(0, strcmp("abc def", buf));
+
+  memset(buf, 0x1, sizeof(buf));
+  len = str3->WriteAscii(buf, 0, -1, String::PRESERVE_ASCII_NULL);
+  CHECK_EQ(7, len);
+  CHECK_EQ(0, strcmp("abc", buf));
+  CHECK_EQ(0, buf[3]);
+  CHECK_EQ(0, strcmp("def", buf + 4));
 }


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