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Diffstat (limited to 'abdl')
| -rw-r--r-- | abdl/__init__.py | 528 |
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diff --git a/abdl/__init__.py b/abdl/__init__.py new file mode 100644 index 0000000..8dde742 --- /dev/null +++ b/abdl/__init__.py @@ -0,0 +1,528 @@ +# A Boneless Datastructure Language +# Copyright (C) 2019 Soni L. +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU Affero General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU Affero General Public License for more details. +# +# You should have received a copy of the GNU Affero General Public License +# along with this program. If not, see <https://www.gnu.org/licenses/>. + +"""A Boneless Datastructure Language, version 2.0.1. + +ABDL expressions are regex-like constructs for matching and validating object structures. They can be used +with JSON and similar formats, and even self-referential data structures. + +Language Reference: + + ABDL expressions have the ability to iterate, index, validate and filter data structures. This is + done with the use of the syntax elements listed below. + + Syntax Elements: + + An ABDL expression is a sequence of zero or more sequences starting with arrows followed by zero or + more subvalues. + + An arrow is ``->`` and indicates indexing/iteration (Mappings, Sequences, Sets). It must be followed + by a variable, literal, parameter, regex or key match. + + A variable is a string of alphanumeric characters, not starting with a digit. It may be followed by a + literal, parameter, regex, key match, or one or more type tests. A ``(key, value)`` tuple containing + the corresponding matched element will be identified by this name in the results dict. + + A literal is a string delimited by single quotes (use ``%'`` to escape ``'`` and ``%%`` to escape ``%``). + A literal can be made "non-validating" by appending an ``?`` after it. It may be followed by one or more + type tests. It is exactly equivalent to indexing an object with a string key. + + A parameter is the symbol ``$`` followed by a string of alphanumeric characters, not starting with + a digit. A parameter can be made "non-validating" by appending an ``?`` after it. It may be followed by + one or more type tests. It is exactly equivalent to indexing an object with an arbitrary object key. + + A regex is an RE, as defined by the ``re`` module, delimited by forward slashes (use ``%/`` to escape + ``/`` and ``%%`` to escape ``%``). A regex can be made "non-validating" by appending an ``?`` after it. + It may be followed by one or more type tests. It attempts to match each key in the object. + + A type test is ``:`` followed by a parameter. A type test can be made "non-validating" by appending + an ``?`` after the ``:``. It attempts to match the type of each matched value in the object. + + A key match is an ABDL expression enclosed in ``[`` and ``]``, optionally prefixed with one or more type + tests. This matches keys (including the type tests). + + A subvalue is an ABDL expression enclosed in ``(`` and ``)``. This allows matching multiple values on + the same object. + + Some syntax elements can be validating or non-validating. Validating syntax elements will raise a + :py:exc:`abdl.ValidationError` whenever a non-matching element is encountered, whereas non-validating + ones will skip them. Note that it is possible for a validating syntax element to still yield results + before raising a :py:exc:`abdl.ValidationError`, so one needs to be careful when writing code where such + behaviour could result in a security vulnerability. + + Examples: + + >>> import abdl + >>> for m in abdl.match("->X:?$dict->Y", {"foo": 1, "bar": {"baz": 2}}, {'dict': dict}): + ... print(m['X'][0], m['Y'][0], m['Y'][1]) + bar baz 2 + + >>> pat = abdl.compile('''-> 'projects'? + ... -> commit /[0-9a-fA-F]{40}|[0-9a-fA-F]{64}/? :?$dict + ... -> url :?$dict + ... -> branch :?$dict''', {'dict': dict}) + >>> data = {"projects": { + ... "385e734a52e13949a7a5c71827f6de920dbfea43": { + ... "https://soniex2.autistic.space/git-repos/ganarchy.git": {"HEAD": {"active": True}} + ... } + ... }} + >>> for m in pat.match(data): + ... print(m['commit'][0], m['url'][0], m['branch'][0], m['branch'][1]) + 385e734a52e13949a7a5c71827f6de920dbfea43 https://soniex2.autistic.space/git-repos/ganarchy.git HEAD {'active': True} + + (If ``:?$dict`` wasn't present, a TypeError would be raised when trying to iterate the ``1`` from ``"foo": 1``.) +""" + +import re + +from collections.abc import Mapping, Sequence, Iterator, Set + +class DeprecationError(Exception): + """Raised for deprecated features, if they are disabled. + + This class controls warning/error behaviour of deprecated features.""" + #enable_key_match_compat = False + #warn_key_match_compat = False + + @classmethod + def warn_all(cls): + """Enables all deprecation warnings.""" + pass + +class PatternError(Exception): + """Raised for invalid input or output expressions.""" + # TODO implement formatting + + def __init__(self, msg, pattern, defs, pos, toks): + self.msg = msg + self.pattern = pattern + self.defs = defs + self.pos = pos + self._toks = toks # internal use + + def _normalize(self, pattern, defs): + if pattern is not None: + if self.pattern is not None: + raise ValueError("Attempt to normalize normalized pattern") + else: + self.pattern = pattern + if defs is not None: + if self.defs is not None: + raise ValueError("Attempt to normalize normalized defs") + else: + self.defs = defs + + @classmethod + def _str_escape(cls, s, pos, toks): + raise cls("Error in string escape", None, None, pos, toks) + + @classmethod + def _str_end(cls, s, pos, toks): + raise cls("Unfinished string", None, None, pos, toks) + + @classmethod + def _re_escape(cls, s, pos, toks): + raise cls("Error in regex escape", None, None, pos, toks) + + @classmethod + def _re_end(cls, s, pos, toks): + raise cls("Unfinished regex", None, None, pos, toks) + + @classmethod + def _unexpected_tok(cls, s, pos, toks): + raise cls("Unexpected token", None, None, pos, toks) + +class ValidationError(Exception): + """Raised when the object tree doesn't validate against the given pattern.""" + # FIXME TODO? + +class _PatternElement: + def on_not_in_key(self, frame, path, defs): + raise NotImplementedError + + def on_in_key(self, frame, path, defs): + raise NotImplementedError + + def collect_params(self, res: list): + pass + +class _Arrow(_PatternElement): + def on_not_in_key(self, frame, path, defs): + assert not path[-1].empty + path.append(_Holder(key=None, value=None, name=None, parent=path[-1].value, empty=True)) + return False + +class _StringKey(_PatternElement): + def __init__(self, toks): + self.key = toks[0] + self.skippable = toks[1] == '?' + + def on_in_key(self, frame, path, defs): + return self.on_not_in_key(frame, path, defs) + + def on_not_in_key(self, frame, path, defs): + path[-1].iterator = self.extract(path[-1].parent) + path[-1].empty = False + return True + + def extract(self, obj): + try: + yield (self.key, obj[self.key]) + except (TypeError, IndexError, KeyError): + if not self.skippable: + raise ValidationError + +class _RegexKey(_PatternElement): + def __init__(self, toks): + self.key = toks[0] + self.compiled = re.compile(self.key) + self.skippable = toks[1] == '?' + + def on_in_key(self, frame, path, defs): + return self.on_not_in_key(frame, path, defs) + + def on_not_in_key(self, frame, path, defs): + filtered_iterator = self.filter(path[-1].iterator) + del path[-1].iterator + path[-1].iterator = filtered_iterator + del filtered_iterator + path[-1].empty = False + return True + + def filter(self, it): + for el in it: + try: + if self.compiled.search(el[0]): + yield el + elif not self.skippable: + raise ValidationError + except TypeError: + if not self.skippable: + raise ValidationError + +class _KeySubtree(_PatternElement): + def __init__(self, toks): + self.key = toks[0] + self.skippable = toks[1] == '?' + + def on_not_in_key(self, frame, path, defs): + path[-1].subtree = True + filtered_iterator = self.filter(path[-1].iterator, defs) + del path[-1].iterator + path[-1].iterator = filtered_iterator + del filtered_iterator + path[-1].empty = False + return True + + def filter(self, it, defs): + for x in it: + for y in _match_helper(self.key, defs, x[0]): + yield (y, x[1]) + + def collect_params(self, res: list): + for sub in self.key: + sub.collect_params(res) + +class _ValueSubtree(_PatternElement): + def __init__(self, toks): + self.key = toks[0] + self.skippable = toks[1] == '?' + + def on_not_in_key(self, frame, path, defs): + assert not path[-1].empty + path.append(_Holder(key=None, value=None, name=None, parent=path[-1].value, empty=False, subtree=True)) + path[-1].iterator = self.filter(path[-1].parent, defs) + return True + + def filter(self, parent, defs): + for x in _match_helper(self.key, defs, parent): + yield (x, parent) + + def collect_params(self, res: list): + for sub in self.key: + sub.collect_params(res) + +class _Ident(_PatternElement): + def __init__(self, toks): + self.key = toks[0] + + def on_not_in_key(self, frame, path, defs): + path[-1].name = self.key + path[-1].empty = False + return True + +class _Param(_PatternElement): + def __init__(self, toks): + assert isinstance(toks[1], _Ident) + self.skippable = toks[0] == '?' + self.key = toks[1].key + + def on_in_key(self, frame, path, defs): + return self.on_not_in_key(frame, path, defs) + + def on_not_in_key(self, frame, path, defs): + path[-1].iterator = self.extract(path[-1].parent, defs[self.key]) + path[-1].empty = False + return True + + def extract(self, obj, key): + try: + yield (key, obj[key]) + except (TypeError, IndexError, KeyError): + if not self.skippable: + raise ValidationError + + def collect_params(self, res: list): + res.append(self.key) + + def get_value(self, defs): + return defs[self.key] + +class _Ty(_PatternElement): + def __init__(self, toks): + assert isinstance(toks[1], _Ident) + self.skippable = toks[0] == '?' + self.key = toks[1].key + + def on_in_key(self, frame, path, defs): + filtered_iterator = self.filter(path[-1].iterator, defs[self.key]) + del path[-1].iterator + path[-1].iterator = filtered_iterator + del filtered_iterator + path[-1].empty = False + return True + + def on_not_in_key(self, frame, path, defs): + assert len(path) == 1 + if isinstance(path[-1].value, defs[self.key]): + return False + elif not self.skippable: + raise ValidationError + path.clear() + return False + + def filter(self, it, ty): + for el in it: + # this may TypeError if ty is not a type nor a tuple of types + # but that's actually the programmer's error + if isinstance(el[1], ty): + yield el + elif not self.skippable: + # and this one is for actual validation + raise ValidationError + + def collect_params(self, res: list): + res.append(self.key) + +class _End(_PatternElement): + def on_in_key(self, frame, path, defs): + try: + path[-1].next() + return False + except StopIteration: + path.pop() + while frame.prev() and not isinstance(frame.current_op, _End): + pass + if not frame.prev(): + # FIXME? + path.clear() + return True # FIXME? + +def _build_syntax(): + from pyparsing import Suppress, Literal, Forward, CharsNotIn, StringEnd, Combine, Optional, Group, Word, srange, Empty + # original regex order: arrow, type/parameter/identifier, string, regex, failure + # better syntax: "arrow" changes from "value" to "key" and thus you need at least one key match before an arrow + subtree = Forward() + # where relevant, enforces match behaviour (skippable object tree branch vs required object tree branch) + skippable = Optional("?", default="") + # r"|'(?:%'|%%|%(?P<EES>.|$)|[^%'])*?(?:'|(?P<ES>$))\??" # string literals + str_literal = (Combine(Suppress("'") + + (Suppress("%") + "'" | Suppress("%") + "%" | Literal("%") + (CharsNotIn("") | StringEnd()).setParseAction(PatternError._str_escape) | CharsNotIn("%'"))[...] + + (Suppress("'") | StringEnd().setParseAction(PatternError._str_end))) + skippable).setParseAction(lambda toks: [_StringKey(toks)]) + # r"|/(?:%/|%%|%(?P<EER>.|$)|[^%/])*?(?:/|(?P<ER>$))\??" # regex + re_literal = (Combine(Suppress("/") + + (Suppress("%") + "/" | Suppress("%") + "%" | Literal("%") + (CharsNotIn("") | StringEnd()).setParseAction(PatternError._re_escape) | CharsNotIn("%/"))[...] + + (Suppress("/") | StringEnd().setParseAction(PatternError._re_end))) + skippable).setParseAction(lambda toks: [_RegexKey(toks)]) + arrow = Literal("->").setParseAction(lambda: [_Arrow()]) + # r"|(?::\??)?\$?[A-Za-z][A-Za-z0-9]*" # identifiers, parameters and type matches + identifier = Word(srange("[A-Za-z_]"), srange("[A-Za-z0-9_]")).setParseAction(lambda toks: [_Ident(toks)]) + parameter = (Suppress("$") + skippable + identifier).setParseAction(lambda toks: [_Param(toks)]) + ty = (Suppress(":") + skippable + Suppress("$") + identifier).setParseAction(lambda toks: [_Ty(toks)]) + # support for objects-as-keys + keysubtree = (Suppress("[") + Group(ty[...] + subtree) + (Suppress("]") | CharsNotIn("").setParseAction(PatternError._unexpected_tok) | StringEnd().setParseAction(PatternError._unexpected_tok)) + Optional("?", default="")).setParseAction(lambda toks: [_KeySubtree(toks)]) + # represents key matching - switches from "key" to "value" + tag = (identifier + Optional(parameter | str_literal | re_literal | keysubtree) | parameter | str_literal | re_literal | keysubtree) + ty[...] + Empty().setParseAction(lambda: [_End()]) + # multiple value matching + valuesubtree = (Suppress("(") + Group(subtree) + (Suppress(")") | CharsNotIn("").setParseAction(PatternError._unexpected_tok) | StringEnd().setParseAction(PatternError._unexpected_tok)) + Optional("?", default="")).setParseAction(lambda toks: [_ValueSubtree(toks)]) + # arrow and tag, value subtree + subtree <<= (arrow + tag)[...] + (valuesubtree + Empty().setParseAction(lambda: [_End()]))[...] + return ((subtree | CharsNotIn("").setParseAction(PatternError._unexpected_tok)) + StringEnd()).parseWithTabs() + +_built_syntax = _build_syntax() + +def _pairs(o): + if isinstance(o, Mapping): + return iter(o.items()) + elif isinstance(o, Sequence): + return iter(enumerate(o, 0)) + elif isinstance(o, Set): + return iter(((e, e) for e in o)) + else: + # maybe there's more stuff I can implement later + raise TypeError + +class _Holder: + def __init__(self, key, value, name, parent=None, it=None, empty=False, subtree=False): + self.name = name + self.key = key + self.value = value + self.empty = empty + self._it = it + self.parent = parent + self.subtree = subtree + + @property + def iterator(self): + if self._it is None: + self._it = _pairs(self.parent) + return self._it + + @iterator.setter + def iterator(self, value): + assert self._it is None + self._it = value + + @iterator.deleter + def iterator(self): + self._it = None + + def next(self): + self.key, self.value = next(self.iterator) + +class _Frame: + def __init__(self, ops): + self.ops = ops + self.pc = -1 + + def next(self): + pc = self.pc + 1 + if pc >= len(self.ops): + return False + self.pc = pc + return True + + @property + def current_op(self): + return self.ops[self.pc] + + def prev(self): + pc = self.pc - 1 + if pc < 0: + return False + self.pc = pc + return True + +def _match_helper(ops, defs, tree): + frame = _Frame(ops) + + path = [_Holder(key=None, value=tree, parent=None, it=iter(()), name=None)] + in_key = False + while path: + if not frame.next(): + assert not path[-1].empty + res = {} + for h in path: + if h.subtree: + for name, kv in h.key.items(): + res[name] = kv + elif h.name is not None: + res[h.name] = (h.key, h.value) + yield res + assert len(path) == 1 or isinstance(frame.current_op, _End) + frame.prev() + in_key = True + else: + op = frame.current_op + if in_key: + in_key = op.on_in_key(frame, path, defs) + else: + in_key = op.on_not_in_key(frame, path, defs) + +class Pattern: + """A compiled pattern object. + + Warning: + Do not create instances of this class manually. Use :py:func:`abdl.compile`. + + """ + + def __init__(self, pattern, defs): + try: + self._ops = _built_syntax.parseString(pattern) + except PatternError as e: + e._normalize(pattern, defs) + raise + else: + self._params = [] + for op in self._ops: + op.collect_params(self._params) + self._defs = {param: defs[param] for param in self._params} + + def match(self, obj): + """Matches this compiled pattern against the given object. + + Args: + obj: The object to match against. + + Returns: + An iterator. This iterator yields ``(key, value)`` pairs + wrapped in a dict for each variable in the pattern. + + """ + return _match_helper(self._ops, self._defs, obj) + +def compile(pattern, defs={}): + """Compiles the pattern and returns a compiled :py:class:`abdl.Pattern` object. + + Args: + pattern (str): The pattern. Refer to module-level documentation for + pattern syntax. + defs (dict): The parameter list. Used by parameters in the pattern. + + Returns: + Pattern: A compiled pattern object. + + """ + # TODO caching + return Pattern(pattern, defs) + +def match(pattern, obj, defs={}): + """Matches the pattern against the given obj. + + This method is equivalent to ``abdl.compile(pattern, defs).match(obj)``. + + Args: + pattern (str): The pattern. Refer to module-level documentation for + pattern syntax. + obj: The object to match against. + defs (dict): The parameter list. Used by parameters in the pattern. + + Returns: + An iterator. This iterator yields ``(key, value)`` pairs + wrapped in a dict for each variable in the pattern. + + """ + return compile(pattern, defs).match(obj) |