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Prototype transformer to assemble logical lines
Prototype transformer to assemble logical lines

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inputtransformer.py
454 lines | 14.5 KiB | text/x-python | PythonLexer
import abc
import functools
import re
from StringIO import StringIO
import tokenize
try:
generate_tokens = tokenize.generate_tokens
except AttributeError:
# Python 3. Note that we use the undocumented _tokenize because it expects
# strings, not bytes. See also Python issue #9969.
generate_tokens = tokenize._tokenize
from IPython.core.splitinput import split_user_input, LineInfo
from IPython.utils.untokenize import untokenize
#-----------------------------------------------------------------------------
# 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.line_used= False
self.reset_tokenizer()
def reset_tokenizer(self):
self.tokenizer = generate_tokens(self.get_line)
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.reset_tokenizer()
return None
self.current_line = ""
self.reset_tokenizer()
return untokenize(self.func(tokens)).rstrip('\n')
def reset(self):
l = self.current_line
self.current_line = ""
if l:
return l.rstrip('\n')
@TokenInputTransformer.wrap
def assemble_logical_lines(tokens):
return tokens
# 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)