Source Code for Module commons.interp

 1  # -*- mode: python; tab-width: 4; indent-tabs-mode: nil; py-indent-offset: 4; -*- 
 2  # vim:ft=python:et:sw=4:ts=4 
 3   
 4  """ 
 5  String interpolation. Example:: 
 6   
 7      language="Python" 
 8      def printmsg(): 
 9          opinion = "favorite" 
10          print interp("My $opinion language is $language.") 
11  """ 
12   
13  import re, string, sys, UserDict 
14   
15 -class Chainmap(UserDict.DictMixin): 
16      """ 
17      Combine multiple mappings for sequential lookup. 
18   
19      From 
20      U{http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/305268}. 
21      Modified to support object fields, e.g. C{"${a.b}"}. 
22   
23      @copyright: Raymond Hettinger, 
24      """ 
25   
26 -    def __init__(self, *maps): 
27          self._maps = maps 
28   
29 -    def __getitem__(self, key): 
30          keys = key.split('.') 
31          key = keys[ 0 ] 
32          attrs = keys[ 1 : ] 
33          value = None 
34          has_found = False 
35          for mapping in self._maps: 
36              try: 
37                  value = mapping[ key ] 
38                  has_found = True 
39                  break 
40              except KeyError: 
41                  pass 
42          if not has_found: 
43              raise KeyError(key) 
44          for attr in attrs: 
45              value = getattr( value, attr ) 
46          return value 
47   
48 -class LaxTemplate(string.Template): 
49      """ 
50      From U{PythonPaste 
51      paste.script<http://svn.pythonpaste.org/Paste/Script/trunk/paste/script/copydir.py>}. 
52      This change of pattern allows for anything in braces, but only 
53      identifiers outside of braces. 
54   
55      @copyright: Ian Bicking 
56      @license: MIT 
57      """ 
58   
59      pattern = r""" 
60      \$(?: 
61        (?P<escaped>\$)             |   # Escape sequence of two delimiters 
62        (?P<named>[_a-z][_a-z0-9]*) |   # delimiter and a Python identifier 
63        {(?P<braced>.*?)}           |   # delimiter and a braced identifier 
64        (?P<invalid>)                   # Other ill-formed delimiter exprs 
65      ) 
66      """ 
67   
68 -def interp(s, dic = None): 
69      """ 
70      This returns a unicode object when a substitution is made. 
71   
72      From 
73      U{http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/335308}. 
74   
75      @copyright: Michele Simionato 
76   
77      @param s: The template string. 
78      @type s: str 
79   
80      @param dic: Specifies bindings to use in addition to the calling 
81      frame's locals and globals. Defaults to C{None} for no additional 
82      bindings. 
83      @type dic: dict 
84      """ 
85      caller = sys._getframe(1) 
86      if dic: 
87          m = Chainmap(dic, caller.f_locals, caller.f_globals) 
88      else: 
89          m = Chainmap(caller.f_locals, caller.f_globals) 
90      return LaxTemplate(s).substitute(m) 
91