HTTP Link Header Parser

github3/api.py

@@ -8,6 +8,7 @@ This module provies the core GitHub3 API interface.
 """
 
 from .packages import omnijson as json
+from .packages.link_header import parse_link_value
 
 from .models import *
 from .helpers import is_collection, to_python, to_api, get_scope

github3/packages/link_header.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+
+"""
+HTTP Link Header Parsing
+
+Simple routines to parse and manipulate Link headers.
+"""
+
+__license__ = """
+Copyright (c) 2009 Mark Nottingham
+ 
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+ 
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+ 
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+"""
+
+import re
+
+TOKEN = r'(?:[^\(\)<>@,;:\\"/\[\]\?={} \t]+?)'
+QUOTED_STRING = r'(?:"(?:\\"|[^"])*")'
+PARAMETER = r'(?:%(TOKEN)s(?:=(?:%(TOKEN)s|%(QUOTED_STRING)s))?)' % locals()
+LINK = r'<[^>]*>\s*(?:;\s*%(PARAMETER)s?\s*)*' % locals()
+COMMA = r'(?:\s*(?:,\s*)+)'
+LINK_SPLIT = r'%s(?=%s|\s*$)' % (LINK, COMMA)
+
+def _unquotestring(instr):
+    if instr[0] == instr[-1] == '"':
+        instr = instr[1:-1]
+        instr = re.sub(r'\\(.)', r'\1', instr)
+    return instr
+def _splitstring(instr, item, split):
+    if not instr: 
+        return []
+    return [ h.strip() for h in re.findall(r'%s(?=%s|\s*$)' % (item, split), instr)]
+
+link_splitter = re.compile(LINK_SPLIT)
+
+def parse_link_value(instr):
+	"""
+	Given a link-value (i.e., after separating the header-value on commas), 
+	return a dictionary whose keys are link URLs and values are dictionaries
+	of the parameters for their associated links.
+	
+	Note that internationalised parameters (e.g., title*) are 
+	NOT percent-decoded.
+	
+	Also, only the last instance of a given parameter will be included.
+	
+	For example, 
+	
+	>>> parse_link_value('</foo>; rel="self"; title*=utf-8\'de\'letztes%20Kapitel')
+	{'/foo': {'title*': "utf-8'de'letztes%20Kapitel", 'rel': 'self'}}
+	
+	"""
+	out = {}
+	if not instr: 
+		return out
+	for link in [h.strip() for h in link_splitter.findall(instr)]:
+		url, params = link.split(">", 1)
+		url = url[1:]
+		param_dict = {}
+		for param in _splitstring(params, PARAMETER, "\s*;\s*"):
+			try:
+				a, v = param.split("=", 1)
+				param_dict[a.lower()] = _unquotestring(v)
+			except ValueError:
+				param_dict[param.lower()] = None
+		out[url] = param_dict
+	return out
+	
+	
+if __name__ == '__main__':
+	import sys
+	if len(sys.argv) > 1:
+		print parse_link_value(sys.argv[1])