"""Input transformer machinery to support IPython special syntax. This includes the machinery to recognise and transform ``%magic`` commands, ``!system`` commands, ``help?`` querying, prompt stripping, and so forth. Added: IPython 7.0. Replaces inputsplitter and inputtransformer which were deprecated in 7.0. """ # Copyright (c) IPython Development Team. # Distributed under the terms of the Modified BSD License. from codeop import compile_command import re import tokenize from typing import List, Tuple import warnings _indent_re = re.compile(r'^[ \t]+') def leading_indent(lines): """Remove leading indentation. If the first line starts with a spaces or tabs, the same whitespace will be removed from each following line in the cell. """ if not lines: return lines m = _indent_re.match(lines[0]) if not m: return lines space = m.group(0) n = len(space) return [l[n:] if l.startswith(space) else l for l in lines] class PromptStripper: """Remove matching input prompts from a block of input. Parameters ---------- prompt_re : regular expression A regular expression matching any input prompt (including continuation, e.g. ``...``) initial_re : regular expression, optional A regular expression matching only the initial prompt, but not continuation. If no initial expression is given, prompt_re will be used everywhere. Used mainly for plain Python prompts (``>>>``), where the continuation prompt ``...`` is a valid Python expression in Python 3, so shouldn't be stripped. If initial_re and prompt_re differ, only initial_re will be tested against the first line. If any prompt is found on the first two lines, prompts will be stripped from the rest of the block. """ def __init__(self, prompt_re, initial_re=None): self.prompt_re = prompt_re self.initial_re = initial_re or prompt_re def _strip(self, lines): return [self.prompt_re.sub('', l, count=1) for l in lines] def __call__(self, lines): if not lines: return lines if self.initial_re.match(lines[0]) or \ (len(lines) > 1 and self.prompt_re.match(lines[1])): return self._strip(lines) return lines classic_prompt = PromptStripper( prompt_re=re.compile(r'^(>>>|\.\.\.)( |$)'), initial_re=re.compile(r'^>>>( |$)') ) ipython_prompt = PromptStripper(re.compile(r'^(In \[\d+\]: |\s*\.{3,}: ?)')) def cell_magic(lines): if not lines or not lines[0].startswith('%%'): return lines if re.match('%%\w+\?', lines[0]): # This case will be handled by help_end return lines magic_name, _, first_line = lines[0][2:-1].partition(' ') body = ''.join(lines[1:]) return ['get_ipython().run_cell_magic(%r, %r, %r)\n' % (magic_name, first_line, body)] def _find_assign_op(token_line): """Get the index of the first assignment in the line ('=' not inside brackets) Note: We don't try to support multiple special assignment (a = b = %foo) """ paren_level = 0 for i, ti in enumerate(token_line): s = ti.string if s == '=' and paren_level == 0: return i if s in '([{': paren_level += 1 elif s in ')]}': if paren_level > 0: paren_level -= 1 def find_end_of_continued_line(lines, start_line: int): """Find the last line of a line explicitly extended using backslashes. Uses 0-indexed line numbers. """ end_line = start_line while lines[end_line].endswith('\\\n'): end_line += 1 if end_line >= len(lines): break return end_line def assemble_continued_line(lines, start: Tuple[int, int], end_line: int): """Assemble a single line from multiple continued line pieces Continued lines are lines ending in ``\``, and the line following the last ``\`` in the block. For example, this code continues over multiple lines:: if (assign_ix is not None) \ and (len(line) >= assign_ix + 2) \ and (line[assign_ix+1].string == '%') \ and (line[assign_ix+2].type == tokenize.NAME): This statement contains four continued line pieces. Assembling these pieces into a single line would give:: if (assign_ix is not None) and (len(line) >= assign_ix + 2) and (line[... This uses 0-indexed line numbers. *start* is (lineno, colno). Used to allow ``%magic`` and ``!system`` commands to be continued over multiple lines. """ parts = [lines[start[0]][start[1]:]] + lines[start[0]+1:end_line+1] return ' '.join([p[:-2] for p in parts[:-1]] # Strip backslash+newline + [parts[-1][:-1]]) # Strip newline from last line class TokenTransformBase: """Base class for transformations which examine tokens. Special syntax should not be transformed when it occurs inside strings or comments. This is hard to reliably avoid with regexes. The solution is to tokenise the code as Python, and recognise the special syntax in the tokens. IPython's special syntax is not valid Python syntax, so tokenising may go wrong after the special syntax starts. These classes therefore find and transform *one* instance of special syntax at a time into regular Python syntax. After each transformation, tokens are regenerated to find the next piece of special syntax. Subclasses need to implement one class method (find) and one regular method (transform). The priority attribute can select which transformation to apply if multiple transformers match in the same place. Lower numbers have higher priority. This allows "%magic?" to be turned into a help call rather than a magic call. """ # Lower numbers -> higher priority (for matches in the same location) priority = 10 def sortby(self): return self.start_line, self.start_col, self.priority def __init__(self, start): self.start_line = start[0] - 1 # Shift from 1-index to 0-index self.start_col = start[1] @classmethod def find(cls, tokens_by_line): """Find one instance of special syntax in the provided tokens. Tokens are grouped into logical lines for convenience, so it is easy to e.g. look at the first token of each line. *tokens_by_line* is a list of lists of tokenize.TokenInfo objects. This should return an instance of its class, pointing to the start position it has found, or None if it found no match. """ raise NotImplementedError def transform(self, lines: List[str]): """Transform one instance of special syntax found by ``find()`` Takes a list of strings representing physical lines, returns a similar list of transformed lines. """ raise NotImplementedError class MagicAssign(TokenTransformBase): """Transformer for assignments from magics (a = %foo)""" @classmethod def find(cls, tokens_by_line): """Find the first magic assignment (a = %foo) in the cell. """ for line in tokens_by_line: assign_ix = _find_assign_op(line) if (assign_ix is not None) \ and (len(line) >= assign_ix + 2) \ and (line[assign_ix+1].string == '%') \ and (line[assign_ix+2].type == tokenize.NAME): return cls(line[assign_ix+1].start) def transform(self, lines: List[str]): """Transform a magic assignment found by the ``find()`` classmethod. """ start_line, start_col = self.start_line, self.start_col lhs = lines[start_line][:start_col] end_line = find_end_of_continued_line(lines, start_line) rhs = assemble_continued_line(lines, (start_line, start_col), end_line) assert rhs.startswith('%'), rhs magic_name, _, args = rhs[1:].partition(' ') lines_before = lines[:start_line] call = "get_ipython().run_line_magic({!r}, {!r})".format(magic_name, args) new_line = lhs + call + '\n' lines_after = lines[end_line+1:] return lines_before + [new_line] + lines_after class SystemAssign(TokenTransformBase): """Transformer for assignments from system commands (a = !foo)""" @classmethod def find(cls, tokens_by_line): """Find the first system assignment (a = !foo) in the cell. """ for line in tokens_by_line: assign_ix = _find_assign_op(line) if (assign_ix is not None) \ and not line[assign_ix].line.strip().startswith('=') \ and (len(line) >= assign_ix + 2) \ and (line[assign_ix + 1].type == tokenize.ERRORTOKEN): ix = assign_ix + 1 while ix < len(line) and line[ix].type == tokenize.ERRORTOKEN: if line[ix].string == '!': return cls(line[ix].start) elif not line[ix].string.isspace(): break ix += 1 def transform(self, lines: List[str]): """Transform a system assignment found by the ``find()`` classmethod. """ start_line, start_col = self.start_line, self.start_col lhs = lines[start_line][:start_col] end_line = find_end_of_continued_line(lines, start_line) rhs = assemble_continued_line(lines, (start_line, start_col), end_line) assert rhs.startswith('!'), rhs cmd = rhs[1:] lines_before = lines[:start_line] call = "get_ipython().getoutput({!r})".format(cmd) new_line = lhs + call + '\n' lines_after = lines[end_line + 1:] return lines_before + [new_line] + lines_after # 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 ESCAPE_SINGLES = {'!', '?', '%', ',', ';', '/'} ESCAPE_DOUBLES = {'!!', '??'} # %% (cell magic) is handled separately def _make_help_call(target, esc, 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]) #Prepare arguments for get_ipython().run_line_magic(magic_name, magic_args) t_magic_name, _, t_magic_arg_s = arg.partition(' ') t_magic_name = t_magic_name.lstrip(ESC_MAGIC) if next_input is None: return 'get_ipython().run_line_magic(%r, %r)' % (t_magic_name, t_magic_arg_s) else: return 'get_ipython().set_next_input(%r);get_ipython().run_line_magic(%r, %r)' % \ (next_input, t_magic_name, t_magic_arg_s) def _tr_help(content): """Translate lines escaped with: ? A naked help line should fire the intro help screen (shell.show_usage()) """ if not content: return 'get_ipython().show_usage()' return _make_help_call(content, '?') def _tr_help2(content): """Translate lines escaped with: ?? A naked help line should fire the intro help screen (shell.show_usage()) """ if not content: return 'get_ipython().show_usage()' return _make_help_call(content, '??') def _tr_magic(content): "Translate lines escaped with a percent sign: %" name, _, args = content.partition(' ') return 'get_ipython().run_line_magic(%r, %r)' % (name, args) def _tr_quote(content): "Translate lines escaped with a comma: ," name, _, args = content.partition(' ') return '%s("%s")' % (name, '", "'.join(args.split()) ) def _tr_quote2(content): "Translate lines escaped with a semicolon: ;" name, _, args = content.partition(' ') return '%s("%s")' % (name, args) def _tr_paren(content): "Translate lines escaped with a slash: /" name, _, args = content.partition(' ') return '%s(%s)' % (name, ", ".join(args.split())) tr = { ESC_SHELL : 'get_ipython().system({!r})'.format, ESC_SH_CAP : 'get_ipython().getoutput({!r})'.format, ESC_HELP : _tr_help, ESC_HELP2 : _tr_help2, ESC_MAGIC : _tr_magic, ESC_QUOTE : _tr_quote, ESC_QUOTE2 : _tr_quote2, ESC_PAREN : _tr_paren } class EscapedCommand(TokenTransformBase): """Transformer for escaped commands like %foo, !foo, or /foo""" @classmethod def find(cls, tokens_by_line): """Find the first escaped command (%foo, !foo, etc.) in the cell. """ for line in tokens_by_line: if not line: continue ix = 0 ll = len(line) while ll > ix and line[ix].type in {tokenize.INDENT, tokenize.DEDENT}: ix += 1 if ix >= ll: continue if line[ix].string in ESCAPE_SINGLES: return cls(line[ix].start) def transform(self, lines): """Transform an escaped line found by the ``find()`` classmethod. """ start_line, start_col = self.start_line, self.start_col indent = lines[start_line][:start_col] end_line = find_end_of_continued_line(lines, start_line) line = assemble_continued_line(lines, (start_line, start_col), end_line) if len(line) > 1 and line[:2] in ESCAPE_DOUBLES: escape, content = line[:2], line[2:] else: escape, content = line[:1], line[1:] if escape in tr: call = tr[escape](content) else: call = '' lines_before = lines[:start_line] new_line = indent + call + '\n' lines_after = lines[end_line + 1:] return lines_before + [new_line] + lines_after _help_end_re = re.compile(r"""(%{0,2} [a-zA-Z_*][\w*]* # Variable name (\.[a-zA-Z_*][\w*]*)* # .etc.etc ) (\?\??)$ # ? or ?? """, re.VERBOSE) class HelpEnd(TokenTransformBase): """Transformer for help syntax: obj? and obj??""" # This needs to be higher priority (lower number) than EscapedCommand so # that inspecting magics (%foo?) works. priority = 5 def __init__(self, start, q_locn): super().__init__(start) self.q_line = q_locn[0] - 1 # Shift from 1-indexed to 0-indexed self.q_col = q_locn[1] @classmethod def find(cls, tokens_by_line): """Find the first help command (foo?) in the cell. """ for line in tokens_by_line: # Last token is NEWLINE; look at last but one if len(line) > 2 and line[-2].string == '?': # Find the first token that's not INDENT/DEDENT ix = 0 while line[ix].type in {tokenize.INDENT, tokenize.DEDENT}: ix += 1 return cls(line[ix].start, line[-2].start) def transform(self, lines): """Transform a help command found by the ``find()`` classmethod. """ piece = ''.join(lines[self.start_line:self.q_line+1]) indent, content = piece[:self.start_col], piece[self.start_col:] lines_before = lines[:self.start_line] lines_after = lines[self.q_line + 1:] m = _help_end_re.search(content) if not m: raise SyntaxError(content) assert m is not None, content target = m.group(1) esc = m.group(3) # If we're mid-command, put it back on the next prompt for the user. next_input = None if (not lines_before) and (not lines_after) \ and content.strip() != m.group(0): next_input = content.rstrip('?\n') call = _make_help_call(target, esc, next_input=next_input) new_line = indent + call + '\n' return lines_before + [new_line] + lines_after def make_tokens_by_line(lines): """Tokenize a series of lines and group tokens by line. The tokens for a multiline Python string or expression are grouped as one line. """ # NL tokens are used inside multiline expressions, but also after blank # lines or comments. This is intentional - see https://bugs.python.org/issue17061 # We want to group the former case together but split the latter, so we # track parentheses level, similar to the internals of tokenize. NEWLINE, NL = tokenize.NEWLINE, tokenize.NL tokens_by_line = [[]] parenlev = 0 try: for token in tokenize.generate_tokens(iter(lines).__next__): tokens_by_line[-1].append(token) if (token.type == NEWLINE) \ or ((token.type == NL) and (parenlev <= 0)): tokens_by_line.append([]) elif token.string in {'(', '[', '{'}: parenlev += 1 elif token.string in {')', ']', '}'}: if parenlev > 0: parenlev -= 1 except tokenize.TokenError: # Input ended in a multiline string or expression. That's OK for us. pass if not tokens_by_line[-1]: tokens_by_line.pop() return tokens_by_line def show_linewise_tokens(s: str): """For investigation and debugging""" if not s.endswith('\n'): s += '\n' lines = s.splitlines(keepends=True) for line in make_tokens_by_line(lines): print("Line -------") for tokinfo in line: print(" ", tokinfo) # Arbitrary limit to prevent getting stuck in infinite loops TRANSFORM_LOOP_LIMIT = 500 class TransformerManager: """Applies various transformations to a cell or code block. The key methods for external use are ``transform_cell()`` and ``check_complete()``. """ def __init__(self): self.cleanup_transforms = [ leading_indent, classic_prompt, ipython_prompt, ] self.line_transforms = [ cell_magic, ] self.token_transformers = [ MagicAssign, SystemAssign, EscapedCommand, HelpEnd, ] def do_one_token_transform(self, lines): """Find and run the transform earliest in the code. Returns (changed, lines). This method is called repeatedly until changed is False, indicating that all available transformations are complete. The tokens following IPython special syntax might not be valid, so the transformed code is retokenised every time to identify the next piece of special syntax. Hopefully long code cells are mostly valid Python, not using lots of IPython special syntax, so this shouldn't be a performance issue. """ tokens_by_line = make_tokens_by_line(lines) candidates = [] for transformer_cls in self.token_transformers: transformer = transformer_cls.find(tokens_by_line) if transformer: candidates.append(transformer) if not candidates: # Nothing to transform return False, lines ordered_transformers = sorted(candidates, key=TokenTransformBase.sortby) for transformer in ordered_transformers: try: return True, transformer.transform(lines) except SyntaxError: pass return False, lines def do_token_transforms(self, lines): for _ in range(TRANSFORM_LOOP_LIMIT): changed, lines = self.do_one_token_transform(lines) if not changed: return lines raise RuntimeError("Input transformation still changing after " "%d iterations. Aborting." % TRANSFORM_LOOP_LIMIT) def transform_cell(self, cell: str) -> str: """Transforms a cell of input code""" if not cell.endswith('\n'): cell += '\n' # Ensure the cell has a trailing newline lines = cell.splitlines(keepends=True) for transform in self.cleanup_transforms + self.line_transforms: lines = transform(lines) lines = self.do_token_transforms(lines) return ''.join(lines) def check_complete(self, cell: str): """Return whether a block of code is ready to execute, or should be continued Parameters ---------- source : string Python input code, which can be multiline. Returns ------- status : str One of 'complete', 'incomplete', or 'invalid' if source is not a prefix of valid code. indent_spaces : int or None The number of spaces by which to indent the next line of code. If status is not 'incomplete', this is None. """ # Remember if the lines ends in a new line. ends_with_newline = False for character in reversed(cell): if character == '\n': ends_with_newline = True break elif character.strip(): break else: continue if ends_with_newline: # Append an newline for consistent tokenization # See https://bugs.python.org/issue33899 cell += '\n' lines = cell.splitlines(keepends=True) if not lines: return 'complete', None if lines[-1].endswith('\\'): # Explicit backslash continuation return 'incomplete', find_last_indent(lines) try: for transform in self.cleanup_transforms: lines = transform(lines) except SyntaxError: return 'invalid', None if lines[0].startswith('%%'): # Special case for cell magics - completion marked by blank line if lines[-1].strip(): return 'incomplete', find_last_indent(lines) else: return 'complete', None try: for transform in self.line_transforms: lines = transform(lines) lines = self.do_token_transforms(lines) except SyntaxError: return 'invalid', None tokens_by_line = make_tokens_by_line(lines) if not tokens_by_line: return 'incomplete', find_last_indent(lines) if tokens_by_line[-1][-1].type != tokenize.ENDMARKER: # We're in a multiline string or expression return 'incomplete', find_last_indent(lines) newline_types = {tokenize.NEWLINE, tokenize.COMMENT, tokenize.ENDMARKER} # Remove newline_types for the list of tokens while len(tokens_by_line) > 1 and len(tokens_by_line[-1]) == 1 \ and tokens_by_line[-1][-1].type in newline_types: tokens_by_line.pop() while tokens_by_line[-1] and tokens_by_line[-1][-1].type in newline_types: tokens_by_line[-1].pop() if len(tokens_by_line) == 1 and not tokens_by_line[-1]: return 'incomplete', 0 if tokens_by_line[-1][-1].string == ':': # The last line starts a block (e.g. 'if foo:') ix = 0 while tokens_by_line[-1][ix].type in {tokenize.INDENT, tokenize.DEDENT}: ix += 1 indent = tokens_by_line[-1][ix].start[1] return 'incomplete', indent + 4 if tokens_by_line[-1][0].line.endswith('\\'): return 'incomplete', None # At this point, our checks think the code is complete (or invalid). # We'll use codeop.compile_command to check this with the real parser try: with warnings.catch_warnings(): warnings.simplefilter('error', SyntaxWarning) res = compile_command(''.join(lines), symbol='exec') except (SyntaxError, OverflowError, ValueError, TypeError, MemoryError, SyntaxWarning): return 'invalid', None else: if res is None: return 'incomplete', find_last_indent(lines) if tokens_by_line[-1][-1].type == tokenize.DEDENT: if ends_with_newline: return 'complete', None return 'incomplete', find_last_indent(lines) # If there's a blank line at the end, assume we're ready to execute if not lines[-1].strip(): return 'complete', None return 'complete', None def find_last_indent(lines): m = _indent_re.match(lines[-1]) if not m: return 0 return len(m.group(0).replace('\t', ' '*4))