Add TokenInputTransformer

IPython/core/inputtransformer.py

@@ -1,397 +1,441 b''
 import abc
 import functools
 import re
 from StringIO import StringIO
 import tokenize
 
 from IPython.core.splitinput import split_user_input, LineInfo
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 # The escape sequences that define the syntax transformations IPython will
 # apply to user input.  These can NOT be just changed here: many regular
 # expressions and other parts of the code may use their hardcoded values, and
 # for all intents and purposes they constitute the 'IPython syntax', so they
 # should be considered fixed.
 
 ESC_SHELL  = '!'     # Send line to underlying system shell
 ESC_SH_CAP = '!!'    # Send line to system shell and capture output
 ESC_HELP   = '?'     # Find information about object
 ESC_HELP2  = '??'    # Find extra-detailed information about object
 ESC_MAGIC  = '%'     # Call magic function
 ESC_MAGIC2 = '%%'    # Call cell-magic function
 ESC_QUOTE  = ','     # Split args on whitespace, quote each as string and call
 ESC_QUOTE2 = ';'     # Quote all args as a single string, call
 ESC_PAREN  = '/'     # Call first argument with rest of line as arguments
 
 ESC_SEQUENCES = [ESC_SHELL, ESC_SH_CAP, ESC_HELP ,\
                  ESC_HELP2, ESC_MAGIC, ESC_MAGIC2,\
                  ESC_QUOTE, ESC_QUOTE2, ESC_PAREN ]
 
 
 class InputTransformer(object):
     """Abstract base class for line-based input transformers."""
     __metaclass__ = abc.ABCMeta
     
     @abc.abstractmethod
     def push(self, line):
         """Send a line of input to the transformer, returning the transformed
         input or None if the transformer is waiting for more input.
         
         Must be overridden by subclasses.
         """
         pass
     
     @abc.abstractmethod
     def reset(self):
         """Return, transformed any lines that the transformer has accumulated,
         and reset its internal state.
         
         Must be overridden by subclasses.
         """
         pass
     
     # Set this to True to allow the transformer to act on lines inside strings.
     look_in_string = False
     
     @classmethod
     def wrap(cls, func):
         """Can be used by subclasses as a decorator, to return a factory that
         will allow instantiation with the decorated object.
         """
         @functools.wraps(func)
         def transformer_factory():
             transformer = cls(func)
             if getattr(transformer_factory, 'look_in_string', False):
                 transformer.look_in_string = True
             return transformer
         
         return transformer_factory
 
 class StatelessInputTransformer(InputTransformer):
     """Wrapper for a stateless input transformer implemented as a function."""
     def __init__(self, func):
         self.func = func
     
     def __repr__(self):
         return "StatelessInputTransformer(func={!r})".format(self.func)
     
     def push(self, line):
         """Send a line of input to the transformer, returning the
         transformed input."""
         return self.func(line)
     
     def reset(self):
         """No-op - exists for compatibility."""
         pass
 
 class CoroutineInputTransformer(InputTransformer):
     """Wrapper for an input transformer implemented as a coroutine."""
     def __init__(self, coro):
         # Prime it
         self.coro = coro()
         next(self.coro)
     
     def __repr__(self):
         return "CoroutineInputTransformer(coro={!r})".format(self.coro)
     
     def push(self, line):
         """Send a line of input to the transformer, returning the
         transformed input or None if the transformer is waiting for more
         input.
         """
         return self.coro.send(line)
     
     def reset(self):
         """Return, transformed any lines that the transformer has
         accumulated, and reset its internal state.
         """
         return self.coro.send(None)
 
+class TokenInputTransformer(InputTransformer):
+    """Wrapper for a token-based input transformer.
+    
+    func should accept a list of tokens (5-tuples, see tokenize docs), and
+    return an iterable which can be passed to tokenize.untokenize().
+    """
+    def __init__(self, func):
+        self.func = func
+        self.current_line = ""
+        self.tokenizer = tokenize.generate_tokens(self.get_line)
+        self.line_used= False
+    
+    def get_line(self):
+        if self.line_used:
+            raise tokenize.TokenError
+        self.line_used = True
+        return self.current_line
+    
+    def push(self, line):
+        self.current_line += line + "\n"
+        self.line_used = False
+        tokens = []
+        try:
+            for intok in self.tokenizer:
+                tokens.append(intok)
+                if intok[0] in (tokenize.NEWLINE, tokenize.NL):
+                    # Stop before we try to pull a line we don't have yet
+                    break
+        except tokenize.TokenError:
+            # Multi-line statement - stop and try again with the next line
+            self.tokenizer = tokenize.generate_tokens(self.get_line)
+            return None
+        
+        self.current_line = ""
+        # Python bug 8478 - untokenize doesn't work quite correctly with a
+        # generator. We call list() to avoid this.
+        return tokenize.untokenize(list(self.func(tokens))).rstrip('\n')
+    
+    def reset(self):
+        l = self.current_line
+        self.current_line = ""
+        if l:
+            return l.rstrip('\n')
+
 
 # Utilities
 def _make_help_call(target, esc, lspace, next_input=None):
     """Prepares a pinfo(2)/psearch call from a target name and the escape
     (i.e. ? or ??)"""
     method  = 'pinfo2' if esc == '??' \
                 else 'psearch' if '*' in target \
                 else 'pinfo'
     arg = " ".join([method, target])
     if next_input is None:
         return '%sget_ipython().magic(%r)' % (lspace, arg)
     else:
         return '%sget_ipython().set_next_input(%r);get_ipython().magic(%r)' % \
            (lspace, next_input, arg)
 
 @CoroutineInputTransformer.wrap
 def escaped_transformer():
     """Translate lines beginning with one of IPython's escape characters.
     
     This is stateful to allow magic commands etc. to be continued over several
     lines using explicit line continuations (\ at the end of a line).
     """
     
     # These define the transformations for the different escape characters.
     def _tr_system(line_info):
         "Translate lines escaped with: !"
         cmd = line_info.line.lstrip().lstrip(ESC_SHELL)
         return '%sget_ipython().system(%r)' % (line_info.pre, cmd)
 
     def _tr_system2(line_info):
         "Translate lines escaped with: !!"
         cmd = line_info.line.lstrip()[2:]
         return '%sget_ipython().getoutput(%r)' % (line_info.pre, cmd)
 
     def _tr_help(line_info):
         "Translate lines escaped with: ?/??"
         # A naked help line should just fire the intro help screen
         if not line_info.line[1:]:
             return 'get_ipython().show_usage()'
 
         return _make_help_call(line_info.ifun, line_info.esc, line_info.pre)
 
     def _tr_magic(line_info):
         "Translate lines escaped with: %"
         tpl = '%sget_ipython().magic(%r)'
         cmd = ' '.join([line_info.ifun, line_info.the_rest]).strip()
         return tpl % (line_info.pre, cmd)
 
     def _tr_quote(line_info):
         "Translate lines escaped with: ,"
         return '%s%s("%s")' % (line_info.pre, line_info.ifun,
                              '", "'.join(line_info.the_rest.split()) )
 
     def _tr_quote2(line_info):
         "Translate lines escaped with: ;"
         return '%s%s("%s")' % (line_info.pre, line_info.ifun,
                                line_info.the_rest)
 
     def _tr_paren(line_info):
         "Translate lines escaped with: /"
         return '%s%s(%s)' % (line_info.pre, line_info.ifun,
                              ", ".join(line_info.the_rest.split()))
     
     tr = { ESC_SHELL  : _tr_system,
            ESC_SH_CAP : _tr_system2,
            ESC_HELP   : _tr_help,
            ESC_HELP2  : _tr_help,
            ESC_MAGIC  : _tr_magic,
            ESC_QUOTE  : _tr_quote,
            ESC_QUOTE2 : _tr_quote2,
            ESC_PAREN  : _tr_paren }
     
     line = ''
     while True:
         line = (yield line)
         if not line or line.isspace():
             continue
         lineinf = LineInfo(line)
         if lineinf.esc not in tr:
             continue
         
         parts = []
         while line is not None:
             parts.append(line.rstrip('\\'))
             if not line.endswith('\\'):
                 break
             line = (yield None)
         
         # Output
         lineinf = LineInfo(' '.join(parts))
         line = tr[lineinf.esc](lineinf)
 
 _initial_space_re = re.compile(r'\s*')
 
 _help_end_re = re.compile(r"""(%{0,2}
                               [a-zA-Z_*][\w*]*        # Variable name
                               (\.[a-zA-Z_*][\w*]*)*   # .etc.etc
                               )
                               (\?\??)$                # ? or ??""",
                               re.VERBOSE)
 
 def has_comment(src):
     """Indicate whether an input line has (i.e. ends in, or is) a comment.
 
     This uses tokenize, so it can distinguish comments from # inside strings.
 
     Parameters
     ----------
     src : string
       A single line input string.
 
     Returns
     -------
     Boolean: True if source has a comment.
     """
     readline = StringIO(src).readline
     toktypes = set()
     try:
         for t in tokenize.generate_tokens(readline):
             toktypes.add(t[0])
     except tokenize.TokenError:
         pass
     return(tokenize.COMMENT in toktypes)
 
 
 @StatelessInputTransformer.wrap
 def help_end(line):
     """Translate lines with ?/?? at the end"""
     m = _help_end_re.search(line)
     if m is None or has_comment(line):
         return line
     target = m.group(1)
     esc = m.group(3)
     lspace = _initial_space_re.match(line).group(0)
 
     # If we're mid-command, put it back on the next prompt for the user.
     next_input = line.rstrip('?') if line.strip() != m.group(0) else None
 
     return _make_help_call(target, esc, lspace, next_input)
 
 
 @CoroutineInputTransformer.wrap
 def cellmagic():
     """Captures & transforms cell magics.
     
     After a cell magic is started, this stores up any lines it gets until it is
     reset (sent None).
     """
     tpl = 'get_ipython().run_cell_magic(%r, %r, %r)'
     cellmagic_help_re = re.compile('%%\w+\?')
     line = ''
     while True:
         line = (yield line)
         if (not line) or (not line.startswith(ESC_MAGIC2)):
             continue
         
         if cellmagic_help_re.match(line):
             # This case will be handled by help_end
             continue
         
         first = line
         body = []
         line = (yield None)
         while (line is not None) and (line.strip() != ''):
             body.append(line)
             line = (yield None)
         
         # Output
         magic_name, _, first = first.partition(' ')
         magic_name = magic_name.lstrip(ESC_MAGIC2)
         line = tpl % (magic_name, first, u'\n'.join(body))
 
 
 def _strip_prompts(prompt1_re, prompt2_re):
     """Remove matching input prompts from a block of input."""
     line = ''
     while True:
         line = (yield line)
         
         if line is None:
             continue
         
         m = prompt1_re.match(line)
         if m:
             while m:
                 line = (yield line[len(m.group(0)):])
                 if line is None:
                     break
                 m = prompt2_re.match(line)
         else:
             # Prompts not in input - wait for reset
             while line is not None:
                 line = (yield line)
 
 @CoroutineInputTransformer.wrap
 def classic_prompt():
     """Strip the >>>/... prompts of the Python interactive shell."""
     prompt1_re = re.compile(r'^(>>> )')
     prompt2_re = re.compile(r'^(>>> |^\.\.\. )')
     return _strip_prompts(prompt1_re, prompt2_re)
 
 classic_prompt.look_in_string = True
 
 @CoroutineInputTransformer.wrap
 def ipy_prompt():
     """Strip IPython's In [1]:/...: prompts."""
     prompt1_re = re.compile(r'^In \[\d+\]: ')
     prompt2_re = re.compile(r'^(In \[\d+\]: |^\ \ \ \.\.\.+: )')
     return _strip_prompts(prompt1_re, prompt2_re)
 
 ipy_prompt.look_in_string = True
 
 
 @CoroutineInputTransformer.wrap
 def leading_indent():
     """Remove leading indentation.
     
     If the first line starts with a spaces or tabs, the same whitespace will be
     removed from each following line until it is reset.
     """
     space_re = re.compile(r'^[ \t]+')
     line = ''
     while True:
         line = (yield line)
         
         if line is None:
             continue
         
         m = space_re.match(line)
         if m:
             space = m.group(0)
             while line is not None:
                 if line.startswith(space):
                     line = line[len(space):]
                 line = (yield line)
         else:
             # No leading spaces - wait for reset
             while line is not None:
                 line = (yield line)
 
 leading_indent.look_in_string = True
 
 
 def _special_assignment(assignment_re, template):
     """Transform assignment from system & magic commands.
     
     This is stateful so that it can handle magic commands continued on several
     lines.
     """
     line = ''
     while True:
         line = (yield line)
         if not line or line.isspace():
             continue
         
         m = assignment_re.match(line)
         if not m:
             continue
         
         parts = []
         while line is not None:
             parts.append(line.rstrip('\\'))
             if not line.endswith('\\'):
                 break
             line = (yield None)
         
         # Output
         whole = assignment_re.match(' '.join(parts))
         line = template % (whole.group('lhs'), whole.group('cmd'))
 
 @CoroutineInputTransformer.wrap
 def assign_from_system():
     """Transform assignment from system commands (e.g. files = !ls)"""
     assignment_re = re.compile(r'(?P<lhs>(\s*)([\w\.]+)((\s*,\s*[\w\.]+)*))'
                                r'\s*=\s*!\s*(?P<cmd>.*)')
     template = '%s = get_ipython().getoutput(%r)'
     return _special_assignment(assignment_re, template)
 
 @CoroutineInputTransformer.wrap
 def assign_from_magic():
     """Transform assignment from magic commands (e.g. a = %who_ls)"""
     assignment_re = re.compile(r'(?P<lhs>(\s*)([\w\.]+)((\s*,\s*[\w\.]+)*))'
                                r'\s*=\s*%\s*(?P<cmd>.*)')
     template = '%s = get_ipython().magic(%r)'
     return _special_assignment(assignment_re, template)

IPython/core/tests/test_inputtransformer.py

@@ -1,326 +1,368 b''
+import tokenize
 import unittest
 import nose.tools as nt
 
 from IPython.testing import tools as tt
 from IPython.utils import py3compat
 u_fmt = py3compat.u_format
 
 from IPython.core import inputtransformer as ipt
 
 def transform_and_reset(transformer):
     transformer = transformer()
     def transform(inp):
         try:
             return transformer.push(inp)
         finally:
             transformer.reset()
     
     return transform
 
 # Transformer tests
 def transform_checker(tests, transformer):
     """Utility to loop over test inputs"""
     transformer = transformer()
     try:
         for inp, tr in tests:
             if inp is None:
                 out = transformer.reset()
             else:
                 out = transformer.push(inp)
             nt.assert_equal(out, tr)
     finally:
         transformer.reset()
 
 # Data for all the syntax tests in the form of lists of pairs of
 # raw/transformed input.  We store it here as a global dict so that we can use
 # it both within single-function tests and also to validate the behavior of the
 # larger objects
 
 syntax = \
   dict(assign_system =
        [(i,py3compat.u_format(o)) for i,o in \
        [(u'a =! ls', "a = get_ipython().getoutput({u}'ls')"),
         (u'b = !ls', "b = get_ipython().getoutput({u}'ls')"),
         ('x=1', 'x=1'), # normal input is unmodified
         ('    ','    '),  # blank lines are kept intact
         ]],
 
        assign_magic =
        [(i,py3compat.u_format(o)) for i,o in \
        [(u'a =% who', "a = get_ipython().magic({u}'who')"),
         (u'b = %who', "b = get_ipython().magic({u}'who')"),
         ('x=1', 'x=1'), # normal input is unmodified
         ('    ','    '),  # blank lines are kept intact
         ]],
 
        classic_prompt =
        [('>>> x=1', 'x=1'),
         ('x=1', 'x=1'), # normal input is unmodified
         ('    ', '    '),  # blank lines are kept intact
         ],
 
        ipy_prompt =
        [('In [1]: x=1', 'x=1'),
         ('x=1', 'x=1'), # normal input is unmodified
         ('    ','    '),  # blank lines are kept intact
         ],
 
        # Tests for the escape transformer to leave normal code alone
        escaped_noesc =
        [ ('    ', '    '),
          ('x=1', 'x=1'),
          ],
 
        # System calls
        escaped_shell =
        [(i,py3compat.u_format(o)) for i,o in \
        [ (u'!ls', "get_ipython().system({u}'ls')"),
          # Double-escape shell, this means to capture the output of the
          # subprocess and return it
          (u'!!ls', "get_ipython().getoutput({u}'ls')"),
          ]],
 
        # Help/object info
        escaped_help =
        [(i,py3compat.u_format(o)) for i,o in \
        [ (u'?', 'get_ipython().show_usage()'),
          (u'?x1', "get_ipython().magic({u}'pinfo x1')"),
          (u'??x2', "get_ipython().magic({u}'pinfo2 x2')"),
          (u'?a.*s', "get_ipython().magic({u}'psearch a.*s')"),
          (u'?%hist1', "get_ipython().magic({u}'pinfo %hist1')"),
          (u'?%%hist2', "get_ipython().magic({u}'pinfo %%hist2')"),
          (u'?abc = qwe', "get_ipython().magic({u}'pinfo abc')"),
          ]],
 
       end_help =
       [(i,py3compat.u_format(o)) for i,o in \
       [ (u'x3?', "get_ipython().magic({u}'pinfo x3')"),
         (u'x4??', "get_ipython().magic({u}'pinfo2 x4')"),
         (u'%hist1?', "get_ipython().magic({u}'pinfo %hist1')"),
         (u'%hist2??', "get_ipython().magic({u}'pinfo2 %hist2')"),
         (u'%%hist3?', "get_ipython().magic({u}'pinfo %%hist3')"),
         (u'%%hist4??', "get_ipython().magic({u}'pinfo2 %%hist4')"),
         (u'f*?', "get_ipython().magic({u}'psearch f*')"),
         (u'ax.*aspe*?', "get_ipython().magic({u}'psearch ax.*aspe*')"),
         (u'a = abc?', "get_ipython().set_next_input({u}'a = abc');"
                       "get_ipython().magic({u}'pinfo abc')"),
         (u'a = abc.qe??', "get_ipython().set_next_input({u}'a = abc.qe');"
                           "get_ipython().magic({u}'pinfo2 abc.qe')"),
         (u'a = *.items?', "get_ipython().set_next_input({u}'a = *.items');"
                           "get_ipython().magic({u}'psearch *.items')"),
         (u'plot(a?', "get_ipython().set_next_input({u}'plot(a');"
                      "get_ipython().magic({u}'pinfo a')"),
         (u'a*2 #comment?', 'a*2 #comment?'),
         ]],
 
        # Explicit magic calls
        escaped_magic =
        [(i,py3compat.u_format(o)) for i,o in \
        [ (u'%cd', "get_ipython().magic({u}'cd')"),
          (u'%cd /home', "get_ipython().magic({u}'cd /home')"),
          # Backslashes need to be escaped.
          (u'%cd C:\\User', "get_ipython().magic({u}'cd C:\\\\User')"),
          (u'    %magic', "    get_ipython().magic({u}'magic')"),
          ]],
 
        # Quoting with separate arguments
        escaped_quote =
        [ (',f', 'f("")'),
          (',f x', 'f("x")'),
          ('  ,f y', '  f("y")'),
          (',f a b', 'f("a", "b")'),
          ],
 
        # Quoting with single argument
        escaped_quote2 =
        [ (';f', 'f("")'),
          (';f x', 'f("x")'),
          ('  ;f y', '  f("y")'),
          (';f a b', 'f("a b")'),
          ],
 
        # Simply apply parens
        escaped_paren =
        [ ('/f', 'f()'),
          ('/f x', 'f(x)'),
          ('  /f y', '  f(y)'),
          ('/f a b', 'f(a, b)'),
          ],
 
        # Check that we transform prompts before other transforms
        mixed =
        [(i,py3compat.u_format(o)) for i,o in \
        [ (u'In [1]: %lsmagic', "get_ipython().magic({u}'lsmagic')"),
          (u'>>> %lsmagic', "get_ipython().magic({u}'lsmagic')"),
          (u'In [2]: !ls', "get_ipython().system({u}'ls')"),
          (u'In [3]: abs?', "get_ipython().magic({u}'pinfo abs')"),
          (u'In [4]: b = %who', "b = get_ipython().magic({u}'who')"),
          ]],
        )
 
 # multiline syntax examples.  Each of these should be a list of lists, with
 # each entry itself having pairs of raw/transformed input.  The union (with
 # '\n'.join() of the transformed inputs is what the splitter should produce
 # when fed the raw lines one at a time via push.
 syntax_ml = \
   dict(classic_prompt =
        [ [('>>> for i in range(10):','for i in range(10):'),
           ('...     print i','    print i'),
           ('... ', ''),
           ],
          [('>>> a="""','a="""'),
           ('... 123"""','123"""'),
           ],
          [('a="""','a="""'),
           ('... 123"""','... 123"""'),
           ],
         ],
 
        ipy_prompt =
        [ [('In [24]: for i in range(10):','for i in range(10):'),
           ('   ....:     print i','    print i'),
           ('   ....: ', ''),
           ],
          [('In [2]: a="""','a="""'),
           ('   ...: 123"""','123"""'),
           ],
          [('a="""','a="""'),
           ('   ...: 123"""','   ...: 123"""'),
           ],
          ],
 
        multiline_datastructure =
        [ [('>>> a = [1,','a = [1,'),
           ('... 2]','2]'),
          ],
        ],
        
        leading_indent =
        [ [('    print "hi"','print "hi"'),
           ],
          [('  for a in range(5):','for a in range(5):'),
           ('    a*2','  a*2'),
           ],
          [('    a="""','a="""'),
           ('    123"""','123"""'),
            ],
          [('a="""','a="""'),
           ('    123"""','    123"""'),
           ],
        ],
        
        cellmagic =
        [ [(u'%%foo a', None),
           (None, u_fmt("get_ipython().run_cell_magic({u}'foo', {u}'a', {u}'')")),
           ],
          [(u'%%bar 123', None),
           (u'hello', None),
           (u'', u_fmt("get_ipython().run_cell_magic({u}'bar', {u}'123', {u}'hello')")),
           ],
        ],
        
        escaped =
        [ [('%abc def \\', None),
           ('ghi', u_fmt("get_ipython().magic({u}'abc def  ghi')")),
           ],
          [('%abc def \\', None),
           ('ghi\\', None),
           (None, u_fmt("get_ipython().magic({u}'abc def  ghi')")),
           ],
        ],
        
        assign_magic =
        [ [(u'a = %bc de \\', None),
           (u'fg', u_fmt("a = get_ipython().magic({u}'bc de  fg')")),
           ],
          [(u'a = %bc de \\', None),
           (u'fg\\', None),
           (None, u_fmt("a = get_ipython().magic({u}'bc de  fg')")),
           ],
        ],
        
        assign_system =
        [ [(u'a = !bc de \\', None),
           (u'fg', u_fmt("a = get_ipython().getoutput({u}'bc de  fg')")),
           ],
          [(u'a = !bc de \\', None),
           (u'fg\\', None),
           (None, u_fmt("a = get_ipython().getoutput({u}'bc de  fg')")),
           ],
        ],
        )
 
 
 def test_assign_system():
     tt.check_pairs(transform_and_reset(ipt.assign_from_system), syntax['assign_system'])
     for example in syntax_ml['assign_system']:
         transform_checker(example, ipt.assign_from_system)
 
 def test_assign_magic():
     tt.check_pairs(transform_and_reset(ipt.assign_from_magic), syntax['assign_magic'])
     for example in syntax_ml['assign_magic']:
         transform_checker(example, ipt.assign_from_magic)
 
 
 def test_classic_prompt():
     tt.check_pairs(transform_and_reset(ipt.classic_prompt), syntax['classic_prompt'])
     for example in syntax_ml['classic_prompt']:
         transform_checker(example, ipt.classic_prompt)
     for example in syntax_ml['multiline_datastructure']:
         transform_checker(example, ipt.classic_prompt)
 
 
 def test_ipy_prompt():
     tt.check_pairs(transform_and_reset(ipt.ipy_prompt), syntax['ipy_prompt'])
     for example in syntax_ml['ipy_prompt']:
         transform_checker(example, ipt.ipy_prompt)
 
 def test_help_end():
     tt.check_pairs(transform_and_reset(ipt.help_end), syntax['end_help'])
 
 def test_escaped_noesc():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_noesc'])
 
 
 def test_escaped_shell():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_shell'])
 
 
 def test_escaped_help():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_help'])
 
 
 def test_escaped_magic():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_magic'])
 
 
 def test_escaped_quote():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_quote'])
 
 
 def test_escaped_quote2():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_quote2'])
 
 
 def test_escaped_paren():
     tt.check_pairs(transform_and_reset(ipt.escaped_transformer), syntax['escaped_paren'])
 
 def test_escaped_multiline():
     for example in syntax_ml['escaped']:
         transform_checker(example, ipt.escaped_transformer)
 
 def test_cellmagic():
     for example in syntax_ml['cellmagic']:
         transform_checker(example, ipt.cellmagic)
 
 def test_has_comment():
     tests = [('text', False),
              ('text #comment', True),
              ('text #comment\n', True),
              ('#comment', True),
              ('#comment\n', True),
              ('a = "#string"', False),
              ('a = "#string" # comment', True),
              ('a #comment not "string"', True),
              ]
     tt.check_pairs(ipt.has_comment, tests)
+
[e-mail]
+def decistmt(tokens):
+    """Substitute Decimals for floats in a string of statements.
+
+    Based on an example from the tokenize module docs.
+    """
+    result = []
+    for toknum, tokval, _, _, _  in tokens:
+        if toknum == tokenize.NUMBER and '.' in tokval:  # replace NUMBER tokens
+            for newtok in [
+                (tokenize.NAME, 'Decimal'),
+                (tokenize.OP, '('),
+                (tokenize.STRING, repr(tokval)),
+                (tokenize.OP, ')')
+            ]:
+                yield newtok
+        else:
+            yield (toknum, tokval)
+
+
+
+def test_token_input_transformer():
+    tests = [(u'1.2', u_fmt(u"Decimal ({u}'1.2')")),
+             (u'"1.2"', u'"1.2"'),
+             ]
+    tt.check_pairs(transform_and_reset(decistmt), tests)
+    ml_tests = \
+    [ [(u"a = 1.2; b = '''x", None),
+       (u"y'''", u_fmt(u"a =Decimal ({u}'1.2');b ='''x\ny'''")),
+      ],
+      [(u"a = [1.2,", u_fmt(u"a =[Decimal ({u}'1.2'),")),
+       (u"3]", u"3 ]"),
+      ],
+      [(u"a = '''foo", None),  # Test resetting when within a multi-line string
+       (u"bar", None),
+       (None, u"a = '''foo\nbar"),
+      ],
+    ]
+    for example in ml_tests:
+        transform_checker(example, decistmt)