|
|
"""Analysis of text input into executable blocks.
|
|
|
|
|
|
This is a simple example of how an interactive terminal-based client can use
|
|
|
this tool::
|
|
|
|
|
|
bb = BlockBreaker()
|
|
|
while not bb.interactive_block_ready():
|
|
|
bb.push(raw_input('>>> '))
|
|
|
print 'Input source was:\n', bb.source,
|
|
|
"""
|
|
|
#-----------------------------------------------------------------------------
|
|
|
# Copyright (C) 2010 The IPython Development Team
|
|
|
#
|
|
|
# Distributed under the terms of the BSD License. The full license is in
|
|
|
# the file COPYING, distributed as part of this software.
|
|
|
#-----------------------------------------------------------------------------
|
|
|
|
|
|
#-----------------------------------------------------------------------------
|
|
|
# Imports
|
|
|
#-----------------------------------------------------------------------------
|
|
|
# stdlib
|
|
|
import codeop
|
|
|
import re
|
|
|
import sys
|
|
|
|
|
|
#-----------------------------------------------------------------------------
|
|
|
# Utilities
|
|
|
#-----------------------------------------------------------------------------
|
|
|
|
|
|
# FIXME: move these utilities to the general ward...
|
|
|
|
|
|
# compiled regexps for autoindent management
|
|
|
dedent_re = re.compile(r'^\s+raise|^\s+return|^\s+pass')
|
|
|
ini_spaces_re = re.compile(r'^([ \t\r\f\v]+)')
|
|
|
|
|
|
|
|
|
def num_ini_spaces(s):
|
|
|
"""Return the number of initial spaces in a string.
|
|
|
|
|
|
Note that tabs are counted as a single space. For now, we do *not* support
|
|
|
mixing of tabs and spaces in the user's input.
|
|
|
|
|
|
Parameters
|
|
|
----------
|
|
|
s : string
|
|
|
"""
|
|
|
|
|
|
ini_spaces = ini_spaces_re.match(s)
|
|
|
if ini_spaces:
|
|
|
return ini_spaces.end()
|
|
|
else:
|
|
|
return 0
|
|
|
|
|
|
|
|
|
def remove_comments(src):
|
|
|
"""Remove all comments from input source.
|
|
|
|
|
|
Note: comments are NOT recognized inside of strings!
|
|
|
|
|
|
Parameters
|
|
|
----------
|
|
|
src : string
|
|
|
A single or multiline input string.
|
|
|
|
|
|
Returns
|
|
|
-------
|
|
|
String with all Python comments removed.
|
|
|
"""
|
|
|
|
|
|
return re.sub('#.*', '', src)
|
|
|
|
|
|
|
|
|
def get_input_encoding():
|
|
|
"""Return the default standard input encoding."""
|
|
|
return getattr(sys.stdin, 'encoding', 'ascii')
|
|
|
|
|
|
#-----------------------------------------------------------------------------
|
|
|
# Classes and functions
|
|
|
#-----------------------------------------------------------------------------
|
|
|
|
|
|
class BlockBreaker(object):
|
|
|
# Command compiler
|
|
|
compile = None
|
|
|
# Number of spaces of indentation
|
|
|
indent_spaces = 0
|
|
|
# String, indicating the default input encoding
|
|
|
encoding = ''
|
|
|
# String where the current full source input is stored, properly encoded
|
|
|
source = ''
|
|
|
# Code object corresponding to the current source
|
|
|
code = None
|
|
|
# Boolean indicating whether the current block is complete
|
|
|
is_complete = None
|
|
|
# Input mode
|
|
|
input_mode = 'append'
|
|
|
|
|
|
# Private attributes
|
|
|
|
|
|
# List
|
|
|
_buffer = None
|
|
|
|
|
|
def __init__(self, input_mode=None):
|
|
|
"""Create a new BlockBreaker instance.
|
|
|
|
|
|
Parameters
|
|
|
----------
|
|
|
input_mode : str
|
|
|
|
|
|
One of 'append', 'replace', default is 'append'. This controls how
|
|
|
new inputs are used: in 'append' mode, they are appended to the
|
|
|
existing buffer and the whole buffer is compiled; in 'replace' mode,
|
|
|
each new input completely replaces all prior inputs. Replace mode is
|
|
|
thus equivalent to prepending a full reset() to every push() call.
|
|
|
|
|
|
In practice, line-oriented clients likely want to use 'append' mode
|
|
|
while block-oriented ones will want to use 'replace'.
|
|
|
"""
|
|
|
self._buffer = []
|
|
|
self.compile = codeop.CommandCompiler()
|
|
|
self.encoding = get_input_encoding()
|
|
|
self.input_mode = BlockBreaker.input_mode if input_mode is None \
|
|
|
else input_mode
|
|
|
|
|
|
def reset(self):
|
|
|
"""Reset the input buffer and associated state."""
|
|
|
self.indent_spaces = 0
|
|
|
self._buffer[:] = []
|
|
|
self.source = ''
|
|
|
self.code = None
|
|
|
|
|
|
def source_reset(self):
|
|
|
"""Return the input source and perform a full reset.
|
|
|
"""
|
|
|
out = self.source
|
|
|
self.reset()
|
|
|
return out
|
|
|
|
|
|
def push(self, lines):
|
|
|
"""Push one ore more lines of input.
|
|
|
|
|
|
This stores the given lines and returns a status code indicating
|
|
|
whether the code forms a complete Python block or not.
|
|
|
|
|
|
Any exceptions generated in compilation are allowed to propagate.
|
|
|
|
|
|
Parameters
|
|
|
----------
|
|
|
lines : string
|
|
|
One or more lines of Python input.
|
|
|
|
|
|
Returns
|
|
|
-------
|
|
|
is_complete : boolean
|
|
|
True if the current input source (the result of the current input
|
|
|
plus prior inputs) forms a complete Python execution block. Note that
|
|
|
this value is also stored as an attribute so it can be queried at any
|
|
|
time.
|
|
|
"""
|
|
|
if self.input_mode == 'replace':
|
|
|
self.reset()
|
|
|
|
|
|
# If the source code has leading blanks, add 'if 1:\n' to it
|
|
|
# this allows execution of indented pasted code. It is tempting
|
|
|
# to add '\n' at the end of source to run commands like ' a=1'
|
|
|
# directly, but this fails for more complicated scenarios
|
|
|
if not self._buffer and lines[:1] in [' ', '\t']:
|
|
|
lines = 'if 1:\n%s' % lines
|
|
|
|
|
|
self._store(lines)
|
|
|
source = self.source
|
|
|
|
|
|
# Before calling compile(), reset the code object to None so that if an
|
|
|
# exception is raised in compilation, we don't mislead by having
|
|
|
# inconsistent code/source attributes.
|
|
|
self.code, self.is_complete = None, None
|
|
|
try:
|
|
|
self.code = self.compile(source)
|
|
|
# Invalid syntax can produce any of a number of different errors from
|
|
|
# inside the compiler, so we have to catch them all. Syntax errors
|
|
|
# immediately produce a 'ready' block, so the invalid Python can be
|
|
|
# sent to the kernel for evaluation with possible ipython
|
|
|
# special-syntax conversion.
|
|
|
except (SyntaxError, OverflowError, ValueError, TypeError, MemoryError):
|
|
|
self.is_complete = True
|
|
|
else:
|
|
|
# Compilation didn't produce any exceptions (though it may not have
|
|
|
# given a complete code object)
|
|
|
self.is_complete = self.code is not None
|
|
|
self._update_indent(lines)
|
|
|
|
|
|
return self.is_complete
|
|
|
|
|
|
def interactive_block_ready(self):
|
|
|
"""Return whether a block of interactive input is ready for execution.
|
|
|
|
|
|
This method is meant to be used by line-oriented frontends, who need to
|
|
|
guess whether a block is complete or not based solely on prior and
|
|
|
current input lines. The BlockBreaker considers it has a complete
|
|
|
interactive block when *all* of the following are true:
|
|
|
|
|
|
1. The input compiles to a complete statement.
|
|
|
|
|
|
2. The indentation level is flush-left (because if we are indented,
|
|
|
like inside a function definition or for loop, we need to keep
|
|
|
reading new input).
|
|
|
|
|
|
3. There is one extra line consisting only of whitespace.
|
|
|
|
|
|
Because of condition #3, this method should be used only by
|
|
|
*line-oriented* frontends, since it means that intermediate blank lines
|
|
|
are not allowed in function definitions (or any other indented block).
|
|
|
|
|
|
Block-oriented frontends that have a separate keyboard event to
|
|
|
indicate execution should use the :meth:`split_blocks` method instead.
|
|
|
"""
|
|
|
if not self.is_complete:
|
|
|
return False
|
|
|
if self.indent_spaces==0:
|
|
|
return True
|
|
|
last_line = self.source.splitlines()[-1]
|
|
|
if not last_line or last_line.isspace():
|
|
|
return True
|
|
|
else:
|
|
|
return False
|
|
|
|
|
|
def split_blocks(self, lines):
|
|
|
"""Split a multiline string into multiple input blocks"""
|
|
|
raise NotImplementedError
|
|
|
|
|
|
#------------------------------------------------------------------------
|
|
|
# Private interface
|
|
|
#------------------------------------------------------------------------
|
|
|
|
|
|
def _update_indent(self, lines):
|
|
|
"""Keep track of the indent level."""
|
|
|
|
|
|
for line in remove_comments(lines).splitlines():
|
|
|
|
|
|
if line and not line.isspace():
|
|
|
if self.code is not None:
|
|
|
inisp = num_ini_spaces(line)
|
|
|
if inisp < self.indent_spaces:
|
|
|
self.indent_spaces = inisp
|
|
|
|
|
|
if line[-1] == ':':
|
|
|
self.indent_spaces += 4
|
|
|
elif dedent_re.match(line):
|
|
|
self.indent_spaces -= 4
|
|
|
|
|
|
def _store(self, lines):
|
|
|
"""Store one or more lines of input.
|
|
|
|
|
|
If input lines are not newline-terminated, a newline is automatically
|
|
|
appended."""
|
|
|
|
|
|
if lines.endswith('\n'):
|
|
|
self._buffer.append(lines)
|
|
|
else:
|
|
|
self._buffer.append(lines+'\n')
|
|
|
self.source = ''.join(self._buffer).encode(self.encoding)
|
|
|
|
