"""Implements the xonsh executer."""
import builtins
import collections.abc as cabc
import inspect
import sys
import types
from xonsh.ast import CtxAwareTransformer
from xonsh.parser import Parser
from xonsh.tools import (
balanced_parens,
ends_with_colon_token,
find_next_break,
get_logical_line,
replace_logical_line,
starting_whitespace,
subproc_toks,
)
[docs]
class Execer:
"""Executes xonsh code in a context."""
def __init__(
self,
filename="<xonsh-code>",
debug_level=0,
parser_args=None,
scriptcache=True,
cacheall=False,
):
"""Parameters
----------
filename : str, optional
File we are to execute.
debug_level : int, optional
Debugging level to use in lexing and parsing.
parser_args : dict, optional
Arguments to pass down to the parser.
scriptcache : bool, optional
Whether or not to use a precompiled bytecode cache when execing
code, default: True.
cacheall : bool, optional
Whether or not to cache all xonsh code, and not just files. If this
is set to true, it will cache command line input too, default: False.
"""
parser_args = parser_args or {}
self.parser = Parser(**parser_args)
self.filename = filename
self._default_filename = filename
self.debug_level = debug_level
self.scriptcache = scriptcache
self.cacheall = cacheall
self.ctxtransformer = CtxAwareTransformer(self.parser)
[docs]
def parse(self, input, ctx, mode="exec", filename=None, transform=True):
"""Parses xonsh code in a context-aware fashion. For context-free
parsing, please use the Parser class directly or pass in
transform=False.
"""
if filename is None:
filename = self.filename
if not transform:
return self.parser.parse(
input, filename=filename, mode=mode, debug_level=(self.debug_level >= 2)
)
# [Phase 1]
# Parsing actually happens in a couple of phases. The first is a
# shortcut for a context-free parser. Normally, all subprocess
# lines should be wrapped in $(), to indicate that they are a
# subproc. But that would be super annoying. Unfortunately, Python
# mode - after indentation - is whitespace agnostic while, using
# the Python token, subproc mode is whitespace aware. That is to say,
# in Python mode "ls -l", "ls-l", and "ls - l" all parse to the
# same AST because whitespace doesn't matter to the minus binary op.
# However, these phases all have very different meaning in subproc
# mode. The 'right' way to deal with this is to make the entire
# grammar whitespace aware, and then ignore all of the whitespace
# tokens for all of the Python rules. The lazy way implemented here
# is to parse a line a second time with a $() wrapper if it fails
# the first time. This is a context-free phase. By the end of this
# parse operation, we will have a tree which contains *some* subproc
# nodes, and some subproc-as-Python nodes. We now need a context-
# aware phase to disambiguate the two.
tree, input = self._parse_ctx_free(input, mode=mode, filename=filename)
if tree is None:
return None
# [Phase 2]
# Now we need to perform context-aware AST transformation. This is
# because the "ls -l" is valid Python. The only way that we know
# it is not actually Python is by checking to see if the first token
# (ls) is part of the execution context. If it isn't, then we will
# assume that this line is supposed to be a subprocess line, assuming
# it also is valid as a subprocess line.
if ctx is None:
ctx = set()
elif isinstance(ctx, cabc.Mapping):
ctx = set(ctx.keys())
tree = self.ctxtransformer.ctxvisit(
tree, input, ctx, mode=mode, debug_level=self.debug_level
)
return tree
[docs]
def compile(
self,
input,
mode="exec",
glbs=None,
locs=None,
stacklevel=2,
filename=None,
transform=True,
compile_empty_tree=True,
):
"""Compiles xonsh code into a Python code object, which may then
be execed or evaled.
"""
if filename is None:
filename = self.filename
self.filename = self._default_filename
if glbs is None or locs is None:
frame = inspect.currentframe()
for _ in range(stacklevel):
frame = frame.f_back
glbs = frame.f_globals if glbs is None else glbs
locs = frame.f_locals if locs is None else locs
ctx = set(dir(builtins)) | set(glbs.keys()) | set(locs.keys())
tree = self.parse(input, ctx, mode=mode, filename=filename, transform=transform)
if tree is None:
return (
compile("pass", filename, mode) if compile_empty_tree else None
) # handles comment only input
try:
code = compile(tree, filename, mode)
except SyntaxError as e:
# Some syntax errors do not occur during parsing, but only later during compiling,
# such as a "'return' outside function", or some validations regarding the match statement.
# In such a case, the offending line of source code (e.text) is not attached to the exception.
if e.text is None:
lines = input.splitlines()
i = max(
0, min(e.lineno - 1, len(lines) - 1)
) # clamp so no invalid access due to invalid lineno can occur
e.text = lines[i]
raise e
return code
[docs]
def eval(
self, input, glbs=None, locs=None, stacklevel=2, filename=None, transform=True
):
"""Evaluates (and returns) xonsh code."""
if glbs is None:
glbs = {}
if isinstance(input, types.CodeType):
code = input
else:
input = input.rstrip("\n")
if filename is None:
filename = self.filename
code = self.compile(
input=input,
glbs=glbs,
locs=locs,
mode="eval",
stacklevel=stacklevel,
filename=filename,
transform=transform,
)
if code is None:
return None # handles comment only input
return eval(code, glbs, locs)
[docs]
def exec(
self,
input,
mode="exec",
glbs=None,
locs=None,
stacklevel=2,
filename=None,
transform=True,
):
"""Execute xonsh code."""
if glbs is None:
glbs = {}
if isinstance(input, types.CodeType):
code = input
else:
if not input.endswith("\n"):
input += "\n"
if filename is None:
filename = self.filename
code = self.compile(
input=input,
glbs=glbs,
locs=locs,
mode=mode,
stacklevel=stacklevel,
filename=filename,
transform=transform,
)
if code is None:
return None # handles comment only input
return exec(code, glbs, locs)
def _print_debug_wrapping(
self, line, sbpline, last_error_line, last_error_col, maxcol=None
):
"""print some debugging info if asked for."""
if self.debug_level >= 1:
msg = "{0}:{1}:{2}{3} - {4}\n" "{0}:{1}:{2}{3} + {5}"
mstr = "" if maxcol is None else ":" + str(maxcol)
msg = msg.format(
self.filename, last_error_line, last_error_col, mstr, line, sbpline
)
print(msg, file=sys.stderr)
def _parse_ctx_free(self, input, mode="exec", filename=None, logical_input=False):
if filename is None:
filename = self.filename
def _try_parse(input, greedy):
last_error_line = last_error_col = -1
parsed = False
original_error = None
if logical_input:
beg_spaces = starting_whitespace(input)
input = input[len(beg_spaces) :]
while not parsed:
try:
tree = self.parser.parse(
input,
filename=filename,
mode=mode,
debug_level=(self.debug_level >= 2),
)
parsed = True
except IndentationError as e:
if original_error is None:
raise e
else:
raise original_error from None
except SyntaxError as e:
if original_error is None:
original_error = e
if (e.loc is None) or (
last_error_line == e.loc.lineno
and last_error_col in (e.loc.column + 1, e.loc.column)
):
raise original_error from None
elif last_error_line != e.loc.lineno:
original_error = e
last_error_col = e.loc.column
last_error_line = e.loc.lineno
idx = last_error_line - 1
lines = input.splitlines()
if input.endswith("\n"):
lines.append("")
line, nlogical, idx = get_logical_line(lines, idx)
if nlogical > 1 and not logical_input:
_, sbpline = self._parse_ctx_free(
line, mode=mode, filename=filename, logical_input=True
)
self._print_debug_wrapping(
line, sbpline, last_error_line, last_error_col, maxcol=None
)
replace_logical_line(lines, sbpline, idx, nlogical)
last_error_col += 3
input = "\n".join(lines)
continue
if len(line.strip()) == 0:
# whitespace only lines are not valid syntax in Python's
# interactive mode='single', who knew?! Just ignore them.
# this might cause actual syntax errors to have bad line
# numbers reported, but should only affect interactive mode
del lines[idx]
last_error_line = last_error_col = -1
input = "\n".join(lines)
continue
if last_error_line > 1 and ends_with_colon_token(lines[idx - 1]):
# catch non-indented blocks and raise error.
prev_indent = len(lines[idx - 1]) - len(lines[idx - 1].lstrip())
curr_indent = len(lines[idx]) - len(lines[idx].lstrip())
if prev_indent == curr_indent:
raise original_error from None
lexer = self.parser.lexer
maxcol = (
None
if greedy
else find_next_break(line, mincol=last_error_col, lexer=lexer)
)
if not greedy and maxcol in (e.loc.column + 1, e.loc.column):
# go greedy the first time if the syntax error was because
# we hit an end token out of place. This usually indicates
# a subshell or maybe a macro.
if not balanced_parens(line, maxcol=maxcol):
greedy = True
maxcol = None
sbpline = subproc_toks(
line, returnline=True, greedy=greedy, maxcol=maxcol, lexer=lexer
)
if sbpline is None:
# subprocess line had no valid tokens,
if len(line.partition("#")[0].strip()) == 0:
# likely because it only contained a comment.
del lines[idx]
last_error_line = last_error_col = -1
input = "\n".join(lines)
continue
elif not greedy:
greedy = True
continue
else:
# or for some other syntax error
raise original_error from None
elif sbpline[last_error_col:].startswith(
"![!["
) or sbpline.lstrip().startswith("![!["):
# if we have already wrapped this in subproc tokens
# and it still doesn't work, adding more won't help
# anything
if not greedy:
greedy = True
continue
else:
raise original_error from None
# replace the line
self._print_debug_wrapping(
line, sbpline, last_error_line, last_error_col, maxcol=maxcol
)
replace_logical_line(lines, sbpline, idx, nlogical)
last_error_col += 3
input = "\n".join(lines)
if logical_input:
input = beg_spaces + input
return tree, input
try:
return _try_parse(input, greedy=False)
except SyntaxError:
return _try_parse(input, greedy=True)