"""Lexer for xonsh code.
Written using a hybrid of ``tokenize`` and PLY.
"""
import io
# 'keyword' interferes with ast.keyword
import keyword as kwmod
import re
import typing as tp
from xonsh.lazyasd import lazyobject
from xonsh.platform import PYTHON_VERSION_INFO
from xonsh.ply.ply.lex import LexToken
from xonsh.tokenize import (
CASE,
COMMENT,
DEDENT,
DOLLARNAME,
ENCODING,
ENDMARKER,
ERRORTOKEN,
GREATER,
INDENT,
IOREDIRECT1,
IOREDIRECT2,
LESS,
MATCH,
NAME,
NEWLINE,
NL,
NUMBER,
OP,
RIGHTSHIFT,
SEARCHPATH,
STRING,
TokenError,
tokenize,
)
@lazyobject
def token_map():
"""Mapping from ``tokenize`` tokens (or token types) to PLY token types. If
a simple one-to-one mapping from ``tokenize`` to PLY exists, the lexer will
look it up here and generate a single PLY token of the given type.
Otherwise, it will fall back to handling that token using one of the
handlers in``special_handlers``.
"""
tm = {}
# operators
_op_map = {
# punctuation
",": "COMMA",
".": "PERIOD",
";": "SEMI",
":": "COLON",
"...": "ELLIPSIS",
# basic operators
"+": "PLUS",
"-": "MINUS",
"*": "TIMES",
"@": "AT",
"/": "DIVIDE",
"//": "DOUBLEDIV",
"%": "MOD",
"**": "POW",
"|": "PIPE",
"~": "TILDE",
"^": "XOR",
"<<": "LSHIFT",
">>": "RSHIFT",
"<": "LT",
"<=": "LE",
">": "GT",
">=": "GE",
"==": "EQ",
"!=": "NE",
"->": "RARROW",
# assignment operators
"=": "EQUALS",
"+=": "PLUSEQUAL",
"-=": "MINUSEQUAL",
"*=": "TIMESEQUAL",
"@=": "ATEQUAL",
"/=": "DIVEQUAL",
"%=": "MODEQUAL",
"**=": "POWEQUAL",
"<<=": "LSHIFTEQUAL",
">>=": "RSHIFTEQUAL",
"&=": "AMPERSANDEQUAL",
"^=": "XOREQUAL",
"|=": "PIPEEQUAL",
"//=": "DOUBLEDIVEQUAL",
# extra xonsh operators
"?": "QUESTION",
"??": "DOUBLE_QUESTION",
"@$": "ATDOLLAR",
"&": "AMPERSAND",
":=": "COLONEQUAL",
}
for op, typ in _op_map.items():
tm[(OP, op)] = typ
tm[IOREDIRECT1] = "IOREDIRECT1"
tm[IOREDIRECT2] = "IOREDIRECT2"
tm[STRING] = "STRING"
tm[DOLLARNAME] = "DOLLAR_NAME"
tm[NUMBER] = "NUMBER"
tm[SEARCHPATH] = "SEARCHPATH"
tm[NEWLINE] = "NEWLINE"
tm[INDENT] = "INDENT"
tm[DEDENT] = "DEDENT"
# python 3.10 (backwards and name token compatible) tokens
tm[MATCH] = "MATCH"
tm[CASE] = "CASE"
return tm
NEED_WHITESPACE = frozenset(["and", "or"])
@lazyobject
def RE_NEED_WHITESPACE():
pattern = r"\s?(" + "|".join(NEED_WHITESPACE) + r")(\s|[\\]$)"
return re.compile(pattern)
[docs]
def handle_name(state, token):
"""Function for handling name tokens"""
typ = "NAME"
state["last"] = token
needs_whitespace = token.string in NEED_WHITESPACE
has_whitespace = needs_whitespace and RE_NEED_WHITESPACE.match(
token.line[max(0, token.start[1] - 1) :]
)
if state["pymode"][-1][0]:
if needs_whitespace and not has_whitespace:
pass
elif token.string in kwmod.kwlist + ["match", "case"]:
typ = token.string.upper()
yield _new_token(typ, token.string, token.start)
else:
if has_whitespace and token.string == "and":
yield _new_token("AND", token.string, token.start)
elif has_whitespace and token.string == "or":
yield _new_token("OR", token.string, token.start)
else:
yield _new_token("NAME", token.string, token.start)
def _end_delimiter(state, token):
py = state["pymode"]
s = token.string
l, c = token.start
if len(py) > 1:
mode, orig, match, pos = py.pop()
if s != match:
e = '"{}" at {} ends "{}" at {} (expected "{}")'
return e.format(s, (l, c), orig, pos, match)
else:
return f'Unmatched "{s}" at line {l}, column {c}'
[docs]
def handle_rparen(state, token):
"""
Function for handling ``)``
"""
e = _end_delimiter(state, token)
if e is None or state["tolerant"]:
state["last"] = token
yield _new_token("RPAREN", ")", token.start)
else:
yield _new_token("ERRORTOKEN", e, token.start)
[docs]
def handle_rbrace(state, token):
"""Function for handling ``}``"""
e = _end_delimiter(state, token)
if e is None or state["tolerant"]:
state["last"] = token
yield _new_token("RBRACE", "}", token.start)
else:
yield _new_token("ERRORTOKEN", e, token.start)
[docs]
def handle_rbracket(state, token):
"""
Function for handling ``]``
"""
e = _end_delimiter(state, token)
if e is None or state["tolerant"]:
state["last"] = token
yield _new_token("RBRACKET", "]", token.start)
else:
yield _new_token("ERRORTOKEN", e, token.start)
[docs]
def handle_error_space(state, token):
"""
Function for handling special whitespace characters in subprocess mode
"""
if not state["pymode"][-1][0]:
state["last"] = token
yield _new_token("WS", token.string, token.start)
else:
yield from []
[docs]
def handle_error_linecont(state, token):
"""Function for handling special line continuations as whitespace
characters in subprocess mode.
"""
if state["pymode"][-1][0]:
return
prev = state["last"]
if prev.end != token.start:
return # previous token is separated by whitespace
state["last"] = token
yield _new_token("WS", "\\", token.start)
[docs]
def handle_error_token(state, token):
"""
Function for handling error tokens
"""
state["last"] = token
if token.string == "!":
typ = "BANG"
elif not state["pymode"][-1][0]:
typ = "NAME"
else:
typ = "ERRORTOKEN"
yield _new_token(typ, token.string, token.start)
[docs]
def handle_ignore(state, token):
"""Function for handling tokens that should be ignored"""
yield from []
[docs]
def handle_double_amps(state, token):
yield _new_token("AND", "and", token.start)
[docs]
def handle_double_pipe(state, token):
yield _new_token("OR", "or", token.start)
[docs]
def handle_redirect(state, token):
# The parser expects whitespace after a redirection in subproc mode.
# If whitespace does not exist, we'll issue an empty whitespace
# token before proceeding.
state["last"] = token
typ = token.type
st = token.string
key = (typ, st) if (typ, st) in token_map else typ
new_tok = _new_token(token_map[key], st, token.start)
if state["pymode"][-1][0]:
if typ in (IOREDIRECT1, IOREDIRECT2):
# Fix Python mode code that was incorrectly recognized as an
# IOREDIRECT by the tokenizer (see issue #4994).
# The tokenizer does not know when the code should be tokenized in
# Python mode. By default, when it sees code like `2>`, it produces
# an IOREDIRECT token. This call to `get_tokens` makes the
# tokenizer run over the code again, knowing that it is *not* an
# IOREDIRECT token.
lineno, lexpos = token.start
for tok in get_tokens(
token.string, state["tolerant"], tokenize_ioredirects=False
):
yield _new_token(tok.type, tok.value, (lineno, lexpos + tok.lexpos))
else:
yield new_tok
return
yield new_tok
# add a whitespace token after a redirection, if we need to
next_tok = next(state["stream"])
if next_tok.start == token.end:
yield _new_token("WS", "", token.end)
yield from handle_token(state, next_tok)
def _make_matcher_handler(tok, typ, pymode, ender, handlers):
matcher = (
")"
if tok.endswith("(")
else "}"
if tok.endswith("{")
else "]"
if tok.endswith("[")
else None
)
def _inner_handler(state, token):
state["pymode"].append((pymode, tok, matcher, token.start))
state["last"] = token
yield _new_token(typ, tok, token.start)
handlers[(OP, tok)] = _inner_handler
@lazyobject
def special_handlers():
"""Mapping from ``tokenize`` tokens (or token types) to the proper
function for generating PLY tokens from them. In addition to
yielding PLY tokens, these functions may manipulate the Lexer's state.
"""
sh = {
NL: handle_ignore,
COMMENT: handle_ignore,
ENCODING: handle_ignore,
ENDMARKER: handle_ignore,
NAME: handle_name,
ERRORTOKEN: handle_error_token,
LESS: handle_redirect,
GREATER: handle_redirect,
RIGHTSHIFT: handle_redirect,
IOREDIRECT1: handle_redirect,
IOREDIRECT2: handle_redirect,
(OP, "<"): handle_redirect,
(OP, ">"): handle_redirect,
(OP, ">>"): handle_redirect,
(OP, ")"): handle_rparen,
(OP, "}"): handle_rbrace,
(OP, "]"): handle_rbracket,
(OP, "&&"): handle_double_amps,
(OP, "||"): handle_double_pipe,
(ERRORTOKEN, " "): handle_error_space,
(ERRORTOKEN, "\\\n"): handle_error_linecont,
(ERRORTOKEN, "\\\r\n"): handle_error_linecont,
}
_make_matcher_handler("(", "LPAREN", True, ")", sh)
_make_matcher_handler("[", "LBRACKET", True, "]", sh)
_make_matcher_handler("{", "LBRACE", True, "}", sh)
_make_matcher_handler("$(", "DOLLAR_LPAREN", False, ")", sh)
_make_matcher_handler("$[", "DOLLAR_LBRACKET", False, "]", sh)
_make_matcher_handler("${", "DOLLAR_LBRACE", True, "}", sh)
_make_matcher_handler("!(", "BANG_LPAREN", False, ")", sh)
_make_matcher_handler("![", "BANG_LBRACKET", False, "]", sh)
_make_matcher_handler("@(", "AT_LPAREN", True, ")", sh)
_make_matcher_handler("@$(", "ATDOLLAR_LPAREN", False, ")", sh)
return sh
[docs]
def handle_token(state, token):
"""
General-purpose token handler. Makes use of ``token_map`` or
``special_map`` to yield one or more PLY tokens from the given input.
Parameters
----------
state
The current state of the lexer, including information about whether
we are in Python mode or subprocess mode, which changes the lexer's
behavior. Also includes the stream of tokens yet to be considered.
token
The token (from ``tokenize``) currently under consideration
"""
typ = token.type
st = token.string
pymode = state["pymode"][-1][0]
if not pymode:
if state["last"] is not None and state["last"].end != token.start:
cur = token.start
old = state["last"].end
if cur[0] == old[0] and cur[1] > old[1]:
yield _new_token("WS", token.line[old[1] : cur[1]], old)
if (typ, st) in special_handlers:
yield from special_handlers[(typ, st)](state, token)
elif (typ, st) in token_map:
state["last"] = token
yield _new_token(token_map[(typ, st)], st, token.start)
elif typ in special_handlers:
yield from special_handlers[typ](state, token)
elif typ in token_map:
state["last"] = token
yield _new_token(token_map[typ], st, token.start)
else:
m = f"Unexpected token: {token}"
yield _new_token("ERRORTOKEN", m, token.start)
[docs]
def get_tokens(s, tolerant, pymode=True, tokenize_ioredirects=True):
"""
Given a string containing xonsh code, generates a stream of relevant PLY
tokens using ``handle_token``.
"""
state = {
"indents": [0],
"last": None,
"pymode": [(pymode, "", "", (0, 0))],
"stream": tokenize(
io.BytesIO(s.encode("utf-8")).readline, tolerant, tokenize_ioredirects
),
"tolerant": tolerant,
}
while True:
try:
token = next(state["stream"])
yield from handle_token(state, token)
except StopIteration:
if len(state["pymode"]) > 1 and not tolerant:
pm, o, m, p = state["pymode"][-1]
l, c = p
e = 'Unmatched "{}" at line {}, column {}'
yield _new_token("ERRORTOKEN", e.format(o, l, c), (0, 0))
break
except TokenError as e:
# this is recoverable in single-line mode (from the shell)
# (e.g., EOF while scanning string literal)
yield _new_token("ERRORTOKEN", e.args[0], (0, 0))
break
except IndentationError as e:
# this is never recoverable
yield _new_token("ERRORTOKEN", e, (0, 0))
break
# synthesize a new PLY token
def _new_token(type, value, pos):
o = LexToken()
o.type = type
o.value = value
o.lineno, o.lexpos = pos
return o
[docs]
class Lexer:
"""Implements a lexer for the xonsh language."""
_tokens: tp.Optional[tuple[str, ...]] = None
def __init__(self, tolerant=False, pymode=True):
"""
Attributes
----------
fname : str
Filename
last : token
The last token seen.
lineno : int
The last line number seen.
tolerant : bool
Tokenize without extra checks (e.g. paren matching).
When True, ERRORTOKEN contains the erroneous string instead of an error msg.
pymode : bool
Start the lexer in Python mode.
"""
self.fname = ""
self.last = None
self.beforelast = None
self._tolerant = tolerant
self._pymode = pymode
self._token_stream = iter(())
@property
def tolerant(self):
return self._tolerant
[docs]
def build(self, **kwargs):
"""Part of the PLY lexer API."""
pass
[docs]
def reset(self):
self._token_stream = iter(())
self.last = None
self.beforelast = None
[docs]
def token(self):
"""Retrieves the next token."""
self.beforelast, self.last = self.last, next(self._token_stream, None)
return self.last
def __iter__(self):
t = self.token()
while t is not None:
yield t
t = self.token()
[docs]
def split(self, s):
"""Splits a string into a list of strings which are whitespace-separated
tokens.
"""
self.input(s)
elements = []
l = c = -1
ws = "WS"
nl = "\n"
for token in self:
if token.type == ws:
continue
elif l < token.lineno:
elements.append(token.value)
elif len(elements) > 0 and c == token.lexpos:
elements[-1] = elements[-1] + token.value
else:
elements.append(token.value)
nnl = token.value.count(nl)
if nnl == 0:
l = token.lineno
c = token.lexpos + len(token.value)
else:
l = token.lineno + nnl
c = len(token.value.rpartition(nl)[-1])
return elements
#
# All the tokens recognized by the lexer
#
@property
def tokens(self):
if self._tokens is None:
kwlist = kwmod.kwlist[:]
if (3, 9, 0) <= PYTHON_VERSION_INFO < (3, 10):
kwlist.remove("__peg_parser__")
t = (
tuple(token_map.values())
+ (
"NAME", # name tokens
"BANG", # ! tokens
"WS", # whitespace in subprocess mode
"LPAREN",
"RPAREN", # ( )
"LBRACKET",
"RBRACKET", # [ ]
"LBRACE",
"RBRACE", # { }
"AT_LPAREN", # @(
"BANG_LPAREN", # !(
"BANG_LBRACKET", # ![
"DOLLAR_LPAREN", # $(
"DOLLAR_LBRACE", # ${
"DOLLAR_LBRACKET", # $[
"ATDOLLAR_LPAREN", # @$(
"ERRORTOKEN", # whoops!
)
+ tuple(i.upper() for i in kwlist)
)
self._tokens = t
return self._tokens