"""The xonsh shell"""
import difflib
import sys
import textwrap
import time
import warnings
import xonsh.history.main as xhm
from xonsh.built_ins import XSH
from xonsh.events import events
from xonsh.history.dummy import DummyHistory
from xonsh.platform import (
best_shell_type,
has_prompt_toolkit,
minimum_required_ptk_version,
ptk_above_min_supported,
)
from xonsh.tools import XonshError, is_class, print_exception, simple_random_choice
events.doc(
"on_transform_command",
"""
on_transform_command(cmd: str) -> str | None
Fired to request xontribs to transform a command line. Return the transformed
command, or the same command if no transformation occurs. Return None to
indicate no transformation (equivalent to returning the original command).
Only done for interactive sessions.
This may be fired multiple times per command, with other transformers input or
output, so design any handlers for this carefully.
.. code-block:: python
@events.on_transform_command
def _pipe_prev_command(cmd, **kw):
'''Pipe prev command e.g. `| grep 1` will be `<prev cmd> | grep 1`.'''
if cmd and cmd.startswith('| ') and __xonsh__.history:
return __xonsh__.history[-1].cmd.rstrip() + cmd.rstrip()
return cmd
""",
)
events.doc(
"on_precommand",
"""
on_precommand(cmd: str) -> None
Fires just before a command is executed, after ``on_transform_command`` has
produced its final form. Handlers cannot modify the command — use
``on_transform_command`` if you need to change the source before it runs.
This event only fires in interactive mode.
Parameters:
* ``cmd``: The command about to be executed.
Example:
.. code-block:: python
@events.on_precommand
def _audit(cmd, **kw):
'''Log each command to a file right before execution.'''
with open('/tmp/xonsh_audit.log', 'a') as f:
f.write(cmd)
""",
)
events.doc(
"on_postcommand",
"""
on_postcommand(cmd: str, rtn: int, out: str or None, ts: list) -> None
Fires just after a command is executed. The arguments are the same as history.
This event only fires in interactive mode.
Parameters:
* ``cmd``: The command that was executed — the final form after transformation
and dedent.
* ``rtn``: The result of the command executed (``0`` for success)
* ``out``: If xonsh stores command output, this is the output
* ``ts``: Timestamps, in the order of ``[starting, ending]``
Example:
.. code-block:: python
@events.on_postcommand
def _prompt_err_command_again(cmd, rtn, out, ts):
'''If the result of executing the command is not zero, repeat the command on the next command prompt.'''
if rtn != 0:
$XONSH_PROMPT_NEXT_CMD = cmd.rstrip()
""",
)
events.doc(
"on_command_not_found",
"""
on_command_not_found(cmd: list[str]) -> list[str] | tuple[str, ...] | dict | None
Fires if a command is not found (only in interactive sessions).
Parameters:
* ``cmd``: The command that was attempted
Returns:
* ``list[str]`` or ``tuple[str, ...]``: A replacement command to execute instead.
The first valid replacement from any handler will be used.
* ``dict``: A dict with a required ``"cmd"`` key (list of command tokens) and an
optional ``"env"`` key (dict of environment variables to set for the replacement
command). Same convention as ``@Aliases.return_command``.
* ``None``: To let the error be raised normally
Note: If the replacement command also fails, the original error is shown.
Examples:
.. code-block:: python
@events.on_command_not_found
def _vim_to_vi(cmd, **kwargs):
'''If vim not found let's try to use vi.'''
if cmd[0] == 'vim':
return ['vi'] + cmd[1:]
@events.on_command_not_found
def _node_with_path(cmd, **kwargs):
'''Run node with a custom NODE_PATH.'''
if cmd[0] == 'mynode':
return {"cmd": ["node"] + cmd[1:], "env": {"NODE_PATH": "/opt/libs"}}
""",
)
events.doc(
"on_pre_prompt_format",
"""
on_pre_prompt_format() -> None
Fires before the prompt will be formatted
""",
)
events.doc(
"on_pre_prompt",
"""
on_pre_prompt() -> None
Fires just before showing the prompt
""",
)
events.doc(
"on_post_prompt",
"""
on_post_prompt() -> None
Fires just after the prompt returns
""",
)
[docs]
def deindent(src):
"""Remove leading indentation from ``src`` before compilation.
Applies ``textwrap.dedent`` to strip the common leading whitespace
from every line. If the first line ends with a line-continuation
backslash and still begins with whitespace after dedent (paste of a
subproc command where line 1 was indented deeper than the
continuation line), also ``lstrip`` the source so the first line is
flush-left.
"""
src = textwrap.dedent(src)
first_line = src.split("\n", 1)[0]
if first_line and first_line[0].isspace() and first_line.rstrip().endswith("\\"):
src = src.lstrip()
return src
[docs]
class Shell:
"""Main xonsh shell.
Initializes execution environment and decides if prompt_toolkit or
readline version of shell should be used.
"""
shell_type_aliases = {
"b": "best",
"best": "best",
"d": "dumb",
"dumb": "dumb",
"ptk": "prompt_toolkit", # there's only 1 prompt_toolkit shell (now)
"prompt-toolkit": "prompt_toolkit",
"prompt_toolkit": "prompt_toolkit",
"rand": "random",
"random": "random",
"rl": "readline",
"readline": "readline",
}
[docs]
@staticmethod
def choose_shell_type(init_shell_type=None, env=None):
# pick a valid shell -- if no shell is specified by the user,
# shell type is pulled from env
# extracted for testability
shell_type = init_shell_type
if shell_type is None and env:
shell_type = env.get("SHELL_TYPE")
if shell_type == "none":
# This bricks interactive xonsh
# Can happen from the use of .xinitrc, .xsession, etc
# odd logic. We don't override if shell.__init__( shell_type="none"),
# only if it come from environment?
shell_type = "best"
shell_type = Shell.shell_type_aliases.get(shell_type, shell_type)
if shell_type == "best" or shell_type is None:
shell_type = best_shell_type()
elif env and env.get("TERM", "") == "dumb":
shell_type = "dumb"
elif shell_type == "random":
shell_type = simple_random_choice(("readline", "prompt_toolkit"))
if shell_type == "prompt_toolkit":
if not has_prompt_toolkit():
warnings.warn(
"'prompt-toolkit' python package is not installed. Falling back to readline.",
stacklevel=2,
)
shell_type = "readline"
elif not ptk_above_min_supported():
warnings.warn(
"Installed prompt-toolkit version < v{}.{}.{} is not ".format(
*minimum_required_ptk_version
)
+ "supported. Falling back to readline.",
stacklevel=2,
)
shell_type = "readline"
if init_shell_type in ("ptk1", "prompt_toolkit1"):
warnings.warn(
f"$SHELL_TYPE='{init_shell_type}' now deprecated, please update your run control file'",
stacklevel=2,
)
return shell_type
[docs]
@staticmethod
def construct_shell_cls(backend, **kwargs):
"""Construct the history backend object."""
if is_class(backend):
cls = backend
else:
"""
There is an edge case that we're using mostly in integration tests:
`echo 'echo 1' | xonsh -i` and it's not working with `TERM=dumb` (#5462 #5517)
because `dumb` is readline where stdin is not supported yet. PR is very welcome!
So in this case we need to force using prompt_toolkit.
"""
is_stdin_to_interactive = (
XSH.env.get("XONSH_INTERACTIVE", False) and not sys.stdin.isatty()
)
if backend == "none":
from xonsh.shells.base_shell import BaseShell as cls
elif backend == "prompt_toolkit" or is_stdin_to_interactive:
from xonsh.shells.ptk_shell import PromptToolkitShell as cls
elif backend == "readline":
from xonsh.shells.readline_shell import ReadlineShell as cls
elif backend == "dumb":
from xonsh.shells.dumb_shell import DumbShell as cls
else:
raise XonshError(f"{backend} is not recognized as a shell type")
return cls(**kwargs)
def __init__(
self, execer, ctx=None, shell_type=None, history_backend=None, **kwargs
):
"""
Parameters
----------
execer : Execer
An execer instance capable of running xonsh code.
ctx : Mapping, optional
The execution context for the shell (e.g. the globals namespace).
If none, this is computed by loading the rc files. If not None,
this no additional context is computed and this is used
directly.
shell_type : str, optional
The shell type to start, such as 'readline', 'prompt_toolkit1',
or 'random'.
history_backend : str, optional
The name of the history backend to use.
"""
self.execer = execer
self.ctx = {} if ctx is None else ctx
env = XSH.env
# build history backend before creating shell
if env.get("XONSH_INTERACTIVE"):
XSH.history = hist = xhm.construct_history(
env=env.detype(),
ts=[time.time(), None],
locked=True,
filename=env.get("XONSH_HISTORY_FILE", None),
sessionid=XSH.sessionid,
backend=history_backend,
)
env["XONSH_HISTORY_FILE"] = hist.filename
else:
XSH.history = hist = DummyHistory()
env["XONSH_HISTORY_FILE"] = None
XSH.interface.history = XSH.history
shell_type = self.choose_shell_type(shell_type, env)
self.shell_type = env["SHELL_TYPE"] = shell_type
self.shell = self.construct_shell_cls(
shell_type, execer=self.execer, ctx=self.ctx, **kwargs
)
# allows history garbage collector to start running
if hist.gc is not None:
hist.gc.wait_for_shell = False
# Emit OSC 7 (CWD reporting) on directory changes so terminals can
# track the working directory (new-tab-in-cwd, session restore, etc.)
if env.get("XONSH_INTERACTIVE"):
from xonsh.prompt.env import emit_osc7
events.on_chdir(emit_osc7)
emit_osc7() # emit once at startup
def __getattr__(self, attr):
"""Delegates calls to appropriate shell instance."""
return getattr(self.shell, attr)