russ.py
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- """
- @file russ.py
- @brief Recursive URL Substitution Syntax helpers
- @author Phoenix
- Many details on how this should work is available on the wiki:
- https://wiki.secondlife.com/wiki/Recursive_URL_Substitution_Syntax
- Adding features to this should be reflected in that page in the
- implementations section.
- $LicenseInfo:firstyear=2007&license=mit$
- Copyright (c) 2007-2010, Linden Research, Inc.
- 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.
- $/LicenseInfo$
- """
- import urllib
- from indra.ipc import llsdhttp
- class UnbalancedBraces(Exception):
- pass
- class UnknownDirective(Exception):
- pass
- class BadDirective(Exception):
- pass
- def format_value_for_path(value):
- if type(value) in [list, tuple]:
- # *NOTE: treat lists as unquoted path components so that the quoting
- # doesn't get out-of-hand. This is a workaround for the fact that
- # russ always quotes, even if the data it's given is already quoted,
- # and it's not safe to simply unquote a path directly, so if we want
- # russ to substitute urls parts inside other url parts we always
- # have to do so via lists of unquoted path components.
- return '/'.join([urllib.quote(str(item)) for item in value])
- else:
- return urllib.quote(str(value))
- def format(format_str, context):
- """@brief Format format string according to rules for RUSS.
- @see https://osiris.lindenlab.com/mediawiki/index.php/Recursive_URL_Substitution_Syntax
- @param format_str The input string to format.
- @param context A map used for string substitutions.
- @return Returns the formatted string. If no match, the braces remain intact.
- """
- while True:
- #print "format_str:", format_str
- all_matches = _find_sub_matches(format_str)
- if not all_matches:
- break
- substitutions = 0
- while True:
- matches = all_matches.pop()
- # we work from right to left to make sure we do not
- # invalidate positions earlier in format_str
- matches.reverse()
- for pos in matches:
- # Use index since _find_sub_matches should have raised
- # an exception, and failure to find now is an exception.
- end = format_str.index('}', pos)
- #print "directive:", format_str[pos+1:pos+5]
- if format_str[pos + 1] == '$':
- value = context[format_str[pos + 2:end]]
- if value is not None:
- value = format_value_for_path(value)
- elif format_str[pos + 1] == '%':
- value = _build_query_string(
- context.get(format_str[pos + 2:end]))
- elif format_str[pos+1:pos+5] == 'http' or format_str[pos+1:pos+5] == 'file':
- value = _fetch_url_directive(format_str[pos + 1:end])
- else:
- raise UnknownDirective, format_str[pos:end + 1]
- if value is not None:
- format_str = format_str[:pos]+str(value)+format_str[end+1:]
- substitutions += 1
- # If there were any substitutions at this depth, re-parse
- # since this may have revealed new things to substitute
- if substitutions:
- break
- if not all_matches:
- break
- # If there were no substitutions at all, and we have exhausted
- # the possible matches, bail.
- if not substitutions:
- break
- return format_str
- def _find_sub_matches(format_str):
- """@brief Find all of the substitution matches.
- @param format_str the RUSS conformant format string.
- @return Returns an array of depths of arrays of positional matches in input.
- """
- depth = 0
- matches = []
- for pos in range(len(format_str)):
- if format_str[pos] == '{':
- depth += 1
- if not len(matches) == depth:
- matches.append([])
- matches[depth - 1].append(pos)
- continue
- if format_str[pos] == '}':
- depth -= 1
- continue
- if not depth == 0:
- raise UnbalancedBraces, format_str
- return matches
- def _build_query_string(query_dict):
- """
- @breif given a dict, return a query string. utility wrapper for urllib.
- @param query_dict input query dict
- @returns Returns an urlencoded query string including leading '?'.
- """
- if query_dict:
- keys = query_dict.keys()
- keys.sort()
- def stringize(value):
- if type(value) in (str,unicode):
- return value
- else:
- return str(value)
- query_list = [urllib.quote(str(key)) + '=' + urllib.quote(stringize(query_dict[key])) for key in keys]
- return '?' + '&'.join(query_list)
- else:
- return ''
- def _fetch_url_directive(directive):
- "*FIX: This only supports GET"
- commands = directive.split('|')
- resource = llsdhttp.get(commands[0])
- if len(commands) == 3:
- resource = _walk_resource(resource, commands[2])
- return resource
- def _walk_resource(resource, path):
- path = path.split('/')
- for child in path:
- if not child:
- continue
- resource = resource[child]
- return resource