darwin/cogapp/whiteutils.py

8fbfd1f382 Oliv*0001 """ Indentation utilities for Cog.
                0002 """
                0003
                0004 import re
d775ee353a Oliv*0005
8fbfd1f382 Oliv*0006
                0007 def whitePrefix(strings):
                0008     """ Determine the whitespace prefix common to all non-blank lines
                0009         in the argument list.
                0010     """
                0011     # Remove all blank lines from the list
                0012     strings = [s for s in strings if s.strip() != '']
                0013
                0014     if not strings: return ''
                0015
                0016     # Find initial whitespace chunk in the first line.
                0017     # This is the best prefix we can hope for.
                0018     pat = r'\s*'
d775ee353a Oliv*0019     if isinstance(strings[0], bytes):
                0020         pat = pat.encode("utf-8")
8fbfd1f382 Oliv*0021     prefix = re.match(pat, strings[0]).group(0)
                0022
                0023     # Loop over the other strings, keeping only as much of
                0024     # the prefix as matches each string.
                0025     for s in strings:
                0026         for i in range(len(prefix)):
                0027             if prefix[i] != s[i]:
                0028                 prefix = prefix[:i]
                0029                 break
                0030     return prefix
                0031
                0032 def reindentBlock(lines, newIndent=''):
                0033     """ Take a block of text as a string or list of lines.
                0034         Remove any common whitespace indentation.
                0035         Re-indent using newIndent, and return it as a single string.
                0036     """
                0037     sep, nothing = '\n', ''
d775ee353a Oliv*0038     if isinstance(lines, bytes):
                0039         sep, nothing = b'\n', b''
                0040     if isinstance(lines, (bytes, str)):
8fbfd1f382 Oliv*0041         lines = lines.split(sep)
                0042     oldIndent = whitePrefix(lines)
                0043     outLines = []
                0044     for l in lines:
                0045         if oldIndent:
                0046             l = l.replace(oldIndent, nothing, 1)
                0047         if l and newIndent:
                0048             l = newIndent + l
                0049         outLines.append(l)
                0050     return sep.join(outLines)
                0051
                0052 def commonPrefix(strings):
                0053     """ Find the longest string that is a prefix of all the strings.
                0054     """
                0055     if not strings:
                0056         return ''
                0057     prefix = strings[0]
                0058     for s in strings:
                0059         if len(s) < len(prefix):
                0060             prefix = prefix[:len(s)]
                0061         if not prefix:
                0062             return ''
                0063         for i in range(len(prefix)):
                0064             if prefix[i] != s[i]:
                0065                 prefix = prefix[:i]
                0066                 break
                0067     return prefix