1 files changed, 58 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/Scripts/lazywriter.py b/Source/JavaScriptCore/Scripts/lazywriter.py
new file mode 100644
index 000000000..f93a2c697
--- /dev/null
+++ b/Source/JavaScriptCore/Scripts/lazywriter.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2015 Apple Inc. All rights reserved.
+# Copyright (c) 2009 Google Inc. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+# THE POSSIBILITY OF SUCH DAMAGE.
+
+# A writer that only updates file if it actually changed.
+
+
+class LazyFileWriter:
+    def __init__(self, filepath, force_output):
+        self._filepath = filepath
+        self._output = ""
+        self.force_output = force_output
+
+    def write(self, text):
+        self._output += text
+
+    def close(self):
+        text_changed = True
+        self._output = self._output.rstrip() + "\n"
+
+        try:
+            if self.force_output:
+                raise
+
+            read_file = open(self._filepath, "r")
+            old_text = read_file.read()
+            read_file.close()
+            text_changed = old_text != self._output
+        except:
+            # Ignore, just overwrite by default
+            pass
+
+        if text_changed or self.force_output:
+            out_file = open(self._filepath, "w")
+            out_file.write(self._output)
+            out_file.close()