giscanner: Use unicode literals in all Python files

Add unicode_literals future import which turns any string literal
into a unicode string. Return unicode strings from the Python C extension
module. Force writing of annotations (g-ir-annotation-tool) to output utf8
encoded data to stdout.
This is an initial pass at following the "unicode sandwich"
model of programming (http://nedbatchelder.com/text/unipain.html)
needed for supporting Python 3.

https://bugzilla.gnome.org/show_bug.cgi?id=679438

1 files changed, 34 insertions, 10 deletions

diff --git a/giscanner/annotationmain.py b/giscanner/annotationmain.py
index 190269e2..b82ff818 100644
--- a/giscanner/annotationmain.py
+++ b/giscanner/annotationmain.py
@@ -21,8 +21,12 @@
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
+from __future__ import unicode_literals
 
+import sys
 import optparse
+import codecs
+from contextlib import contextmanager
 
 from giscanner import message
 from giscanner.annotationparser import GtkDocCommentBlockParser, GtkDocCommentBlockWriter
@@ -31,6 +35,24 @@ from giscanner.scannermain import (get_preprocessor_option_group,
                                    process_packages)
 
 
+@contextmanager
+def encode_stdout(encoding):
+    """Force stdout into a specific encoding."""
+    # Python 2 does not encode stdout writes so wrap it with 'encoding' encoded writer.
+    # Python 3 uses a io.TextIOBase wrapped stdout with the system default encoding.
+    # Re-wrap the underlying buffer with a new writer with the given 'encoding'.
+    # See: https://docs.python.org/3/library/sys.html#sys.stdout
+    old_stdout = sys.stdout
+    if sys.version_info.major < 3:
+        binary_stdout = sys.stdout
+    else:
+        binary_stdout = sys.stdout.buffer
+
+    sys.stdout = codecs.getwriter(encoding)(binary_stdout)
+    yield
+    sys.stdout = old_stdout
+
+
 def annotation_main(args):
     parser = optparse.OptionParser('%prog [options] sources')
 
@@ -65,16 +87,18 @@ def annotation_main(args):
         parser = GtkDocCommentBlockParser()
         writer = GtkDocCommentBlockWriter(indent=False)
         blocks = parser.parse_comment_blocks(ss.get_comments())
-        print('/' + ('*' * 60) + '/')
-        print('/* THIS FILE IS GENERATED DO NOT EDIT */')
-        print('/' + ('*' * 60) + '/')
-        print('')
-        for block in sorted(blocks.values()):
-            print(writer.write(block))
+
+        with encode_stdout('utf-8'):
+            print('/' + ('*' * 60) + '/')
+            print('/* THIS FILE IS GENERATED DO NOT EDIT */')
+            print('/' + ('*' * 60) + '/')
+            print('')
+            for block in sorted(blocks.values()):
+                print(writer.write(block))
+                print('')
             print('')
-        print('')
-        print('/' + ('*' * 60) + '/')
-        print('/* THIS FILE IS GENERATED DO NOT EDIT */')
-        print('/' + ('*' * 60) + '/')
+            print('/' + ('*' * 60) + '/')
+            print('/* THIS FILE IS GENERATED DO NOT EDIT */')
+            print('/' + ('*' * 60) + '/')
 
     return 0