186 lines
7.0 KiB
Python
186 lines
7.0 KiB
Python
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import re
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import typing as t
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from dataclasses import dataclass
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from dataclasses import field
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from .converters import ValidationError
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from .exceptions import NoMatch
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from .exceptions import RequestAliasRedirect
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from .exceptions import RequestPath
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from .rules import Rule
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from .rules import RulePart
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class SlashRequired(Exception):
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pass
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@dataclass
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class State:
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"""A representation of a rule state.
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This includes the *rules* that correspond to the state and the
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possible *static* and *dynamic* transitions to the next state.
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"""
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dynamic: t.List[t.Tuple[RulePart, "State"]] = field(default_factory=list)
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rules: t.List[Rule] = field(default_factory=list)
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static: t.Dict[str, "State"] = field(default_factory=dict)
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class StateMachineMatcher:
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def __init__(self, merge_slashes: bool) -> None:
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self._root = State()
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self.merge_slashes = merge_slashes
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def add(self, rule: Rule) -> None:
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state = self._root
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for part in rule._parts:
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if part.static:
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state.static.setdefault(part.content, State())
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state = state.static[part.content]
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else:
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for test_part, new_state in state.dynamic:
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if test_part == part:
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state = new_state
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break
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else:
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new_state = State()
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state.dynamic.append((part, new_state))
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state = new_state
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state.rules.append(rule)
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def update(self) -> None:
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# For every state the dynamic transitions should be sorted by
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# the weight of the transition
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state = self._root
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def _update_state(state: State) -> None:
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state.dynamic.sort(key=lambda entry: entry[0].weight)
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for new_state in state.static.values():
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_update_state(new_state)
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for _, new_state in state.dynamic:
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_update_state(new_state)
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_update_state(state)
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def match(
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self, domain: str, path: str, method: str, websocket: bool
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) -> t.Tuple[Rule, t.MutableMapping[str, t.Any]]:
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# To match to a rule we need to start at the root state and
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# try to follow the transitions until we find a match, or find
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# there is no transition to follow.
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have_match_for = set()
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websocket_mismatch = False
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def _match(
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state: State, parts: t.List[str], values: t.List[str]
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) -> t.Optional[t.Tuple[Rule, t.List[str]]]:
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# This function is meant to be called recursively, and will attempt
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# to match the head part to the state's transitions.
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nonlocal have_match_for, websocket_mismatch
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# The base case is when all parts have been matched via
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# transitions. Hence if there is a rule with methods &
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# websocket that work return it and the dynamic values
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# extracted.
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if parts == []:
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for rule in state.rules:
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if rule.methods is not None and method not in rule.methods:
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have_match_for.update(rule.methods)
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elif rule.websocket != websocket:
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websocket_mismatch = True
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else:
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return rule, values
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# Test if there is a match with this path with a
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# trailing slash, if so raise an exception to report
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# that matching is possible with an additional slash
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if "" in state.static:
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for rule in state.static[""].rules:
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if websocket == rule.websocket and (
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rule.methods is None or method in rule.methods
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):
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if rule.strict_slashes:
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raise SlashRequired()
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else:
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return rule, values
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return None
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part = parts[0]
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# To match this part try the static transitions first
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if part in state.static:
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rv = _match(state.static[part], parts[1:], values)
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if rv is not None:
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return rv
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# No match via the static transitions, so try the dynamic
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# ones.
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for test_part, new_state in state.dynamic:
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target = part
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remaining = parts[1:]
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# A final part indicates a transition that always
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# consumes the remaining parts i.e. transitions to a
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# final state.
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if test_part.final:
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target = "/".join(parts)
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remaining = []
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match = re.compile(test_part.content).match(target)
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if match is not None:
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rv = _match(new_state, remaining, values + list(match.groups()))
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if rv is not None:
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return rv
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# If there is no match and the only part left is a
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# trailing slash ("") consider rules that aren't
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# strict-slashes as these should match if there is a final
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# slash part.
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if parts == [""]:
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for rule in state.rules:
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if rule.strict_slashes:
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continue
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if rule.methods is not None and method not in rule.methods:
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have_match_for.update(rule.methods)
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elif rule.websocket != websocket:
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websocket_mismatch = True
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else:
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return rule, values
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return None
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try:
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rv = _match(self._root, [domain, *path.split("/")], [])
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except SlashRequired:
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raise RequestPath(f"{path}/") from None
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if self.merge_slashes and rv is None:
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# Try to match again, but with slashes merged
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path = re.sub("/{2,}?", "/", path)
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try:
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rv = _match(self._root, [domain, *path.split("/")], [])
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except SlashRequired:
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raise RequestPath(f"{path}/") from None
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if rv is None:
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raise NoMatch(have_match_for, websocket_mismatch)
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else:
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raise RequestPath(f"{path}")
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elif rv is not None:
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rule, values = rv
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result = {}
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for name, value in zip(rule._converters.keys(), values):
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try:
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value = rule._converters[name].to_python(value)
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except ValidationError:
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raise NoMatch(have_match_for, websocket_mismatch) from None
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result[str(name)] = value
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if rule.defaults:
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result.update(rule.defaults)
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if rule.alias and rule.map.redirect_defaults:
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raise RequestAliasRedirect(result, rule.endpoint)
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return rule, result
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raise NoMatch(have_match_for, websocket_mismatch)
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