third_party/cython/src/Cython/StringIOTree.py

   1 from cStringIO import StringIO
   2
   3 class StringIOTree(object):
   4     """
   5     See module docs.
   6     """
   7
   8     def __init__(self, stream=None):
   9         self.prepended_children = []
  10         if stream is None:
  11             stream = StringIO()
  12         self.stream = stream
  13         self.write = stream.write
  14         self.markers = []
  15
  16     def getvalue(self):
  17         content = [x.getvalue() for x in self.prepended_children]
  18         content.append(self.stream.getvalue())
  19         return "".join(content)
  20
  21     def copyto(self, target):
  22         """Potentially cheaper than getvalue as no string concatenation
  23         needs to happen."""
  24         for child in self.prepended_children:
  25             child.copyto(target)
  26         stream_content = self.stream.getvalue()
  27         if stream_content:
  28             target.write(stream_content)
  29
  30     def commit(self):
  31         # Save what we have written until now so that the buffer
  32         # itself is empty -- this makes it ready for insertion
  33         if self.stream.tell():
  34             self.prepended_children.append(StringIOTree(self.stream))
  35             self.prepended_children[-1].markers = self.markers
  36             self.markers = []
  37             self.stream = StringIO()
  38             self.write = self.stream.write
  39
  40     def insert(self, iotree):
  41         """
  42         Insert a StringIOTree (and all of its contents) at this location.
  43         Further writing to self appears after what is inserted.
  44         """
  45         self.commit()
  46         self.prepended_children.append(iotree)
  47
  48     def insertion_point(self):
  49         """
  50         Returns a new StringIOTree, which is left behind at the current position
  51         (it what is written to the result will appear right before whatever is
  52         next written to self).
  53
  54         Calling getvalue() or copyto() on the result will only return the
  55         contents written to it.
  56         """
  57         # Save what we have written until now
  58         # This is so that getvalue on the result doesn't include it.
  59         self.commit()
  60         # Construct the new forked object to return
  61         other = StringIOTree()
  62         self.prepended_children.append(other)
  63         return other
  64
  65     def allmarkers(self):
  66         children = self.prepended_children
  67         return [m for c in children for m in c.allmarkers()] + self.markers
  68
  69
  70 __doc__ = r"""
  71 Implements a buffer with insertion points. When you know you need to
  72 "get back" to a place and write more later, simply call insertion_point()
  73 at that spot and get a new StringIOTree object that is "left behind".
  74
  75 EXAMPLE:
  76
  77 >>> a = StringIOTree()
  78 >>> a.write('first\n')
  79 >>> b = a.insertion_point()
  80 >>> a.write('third\n')
  81 >>> b.write('second\n')
  82 >>> a.getvalue().split()
  83 ['first', 'second', 'third']
  84
  85 >>> c = b.insertion_point()
  86 >>> d = c.insertion_point()
  87 >>> d.write('alpha\n')
  88 >>> b.write('gamma\n')
  89 >>> c.write('beta\n')
  90 >>> b.getvalue().split()
  91 ['second', 'alpha', 'beta', 'gamma']
  92 >>> i = StringIOTree()
  93 >>> d.insert(i)
  94 >>> i.write('inserted\n')
  95 >>> out = StringIO()
  96 >>> a.copyto(out)
  97 >>> out.getvalue().split()
  98 ['first', 'second', 'alpha', 'inserted', 'beta', 'gamma', 'third']
  99 """