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# SPDX-License-Identifier: GPL-3.0-or-later
# Copyright (C) 2025-2026 Benjamin Abendroth <braph93@gmx.de>
'''Module for parsing shell-like commands with logical operators.'''
from .string_stream import StringStream
# pylint: disable=too-few-public-methods
class Literal:
'''Represents a literal string.'''
def __init__(self, string):
self.string = string
def __str__(self):
return self.string
def __repr__(self):
return f'Literal({self.string!r})'
class Command:
'''Represents a command.'''
def __init__(self):
self.args = []
def __repr__(self):
return f'Command({self.args!r})'
class Lexer(StringStream):
'''Lexer class.'''
def parse(self):
'''Split string into tokens (e.g. logical operators) and literals.'''
tokens = []
while True:
token = self._parse_token()
if token is not None:
tokens.append(token)
else:
return tokens
def _parse_token(self):
c = self.peek()
if c is None:
return None
if c in ('!', '(', ')'):
self.advance(1)
return c
if c.isspace():
self.advance(1)
return self._parse_token()
if c == '&':
if not self.peek(1) == '&':
raise ValueError('Single `&` found')
self.advance(2)
return '&&'
if c == '|':
if not self.peek(1) == '|':
raise ValueError('Single `|` found')
self.advance(2)
return '||'
return self._parse_literal()
def _parse_literal(self):
literal = ''
while True:
c = self.peek()
if c is None:
return Literal(literal)
if c == '"':
literal += self.parse_shell_double_quote(in_quotes=False)
elif c == "'":
literal += self.parse_shell_single_quote(in_quotes=False)
elif c.isspace() or c in ('&', '|', '!', '(', ')'):
return Literal(literal)
else:
self.advance(1)
literal += c
def make_commands(tokens):
'''Parse tokens.
Input:
[Literal("foo"), Literal("bar"), '&&' Literal("baz")]
Output:
[Command(["foo", "bar"]), '&&', Command(["baz"])]
'''
new_tokens = []
current = Command()
for token in tokens:
if token in ('&&', '||', '!', '(', ')'):
if current.args:
new_tokens.append(current)
current = Command()
new_tokens.append(token)
else:
current.args.append(str(token))
if current.args:
new_tokens.append(current)
return new_tokens
def check_syntax(tokens):
'''Checks tokens for syntax errors.'''
last = None
parentheses = 0
for token in tokens:
if token == '(':
parentheses += 1
if last not in (None, '&&', '||', '!', '('):
raise ValueError("Unexpected `(`")
elif token == ')':
parentheses -= 1
if parentheses < 0 or last in (None, '(', '&&', '||', '!'):
raise ValueError("Unexpected `)`")
elif token in ('&&', '||'):
if last in (None, '(', '&&', '||', '!'):
raise ValueError(f"Unexpected `{token}`")
elif token == '!':
if last not in (None, '(', '&&', '||', '!'):
raise ValueError("Unexpected `!`")
last = token
if parentheses > 0:
raise ValueError("Unclosed `(`")
if last is None:
raise ValueError("No command found")
def parse(string):
'''Parse a string and turn it into And/Or/Not/Command objects.'''
lex_tokens = Lexer(string).parse()
tokens = make_commands(lex_tokens)
check_syntax(tokens)
return tokens
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