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import re
from mopidy_mpd import exceptions
WORD_RE = re.compile(
r"""
^
(\s*) # Leading whitespace not allowed, capture it to report.
([a-z][a-z0-9_]*) # A command name
(?:\s+|$) # trailing whitespace or EOS
(.*) # Possibly a remainder to be parsed
""",
re.VERBOSE,
)
# Quotes matching is an unrolled version of "(?:[^"\\]|\\.)*"
PARAM_RE = re.compile(
r"""
^ # Leading whitespace is not allowed
(?:
([^%(unprintable)s"']+) # ord(char) < 0x20, not ", not '
| # or
"([^"\\]*(?:\\.[^"\\]*)*)" # anything surrounded by quotes
)
(?:\s+|$) # trailing whitespace or EOS
(.*) # Possibly a remainder to be parsed
"""
% {"unprintable": "".join(map(chr, range(0x21)))},
re.VERBOSE,
)
BAD_QUOTED_PARAM_RE = re.compile(
r"""
^
"[^"\\]*(?:\\.[^"\\]*)* # start of a quoted value
(?: # followed by:
("[^\s]) # non-escaped quote, followed by non-whitespace
| # or
([^"]) # anything that is not a quote
)
""",
re.VERBOSE,
)
UNESCAPE_RE = re.compile(r"\\(.)") # Backslash escapes any following char.
def split(line):
"""Splits a line into tokens using same rules as MPD.
- Lines may not start with whitespace
- Tokens are split by arbitrary amount of spaces or tabs
- First token must match `[a-z][a-z0-9_]*`
- Remaining tokens can be unquoted or quoted tokens.
- Unquoted tokens consist of all printable characters except double quotes,
single quotes, spaces and tabs.
- Quoted tokens are surrounded by a matching pair of double quotes.
- The closing quote must be followed by space, tab or end of line.
- Any value is allowed inside a quoted token. Including double quotes,
assuming it is correctly escaped.
- Backslash inside a quoted token is used to escape the following
character.
For examples see the tests for this function.
"""
if not line.strip():
raise exceptions.MpdNoCommand("No command given")
match = WORD_RE.match(line)
if not match:
raise exceptions.MpdUnknownError("Invalid word character")
whitespace, command, remainder = match.groups()
if whitespace:
raise exceptions.MpdUnknownError("Letter expected")
result = [command]
while remainder:
match = PARAM_RE.match(remainder)
if not match:
msg = _determine_error_message(remainder)
raise exceptions.MpdArgError(msg, command=command)
unquoted, quoted, remainder = match.groups()
result.append(unquoted or UNESCAPE_RE.sub(r"\g<1>", quoted))
return result
def _determine_error_message(remainder):
"""Helper to emulate MPD errors."""
# Following checks are simply to match MPD error messages:
match = BAD_QUOTED_PARAM_RE.match(remainder)
if match:
if match.group(1):
return "Space expected after closing '\"'"
else:
return "Missing closing '\"'"
return "Invalid unquoted character"
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