# helpers.py import html.entities import operator import re import sys import typing from . import __diag__ from .core import * from .util import ( _bslash, _flatten, _escape_regex_range_chars, make_compressed_re, replaced_by_pep8, ) # # global helpers # def counted_array( expr: ParserElement, int_expr: typing.Optional[ParserElement] = None, *, intExpr: typing.Optional[ParserElement] = None, ) -> ParserElement: """Helper to define a counted list of expressions. This helper defines a pattern of the form:: integer expr expr expr... where the leading integer tells how many expr expressions follow. The matched tokens returns the array of expr tokens as a list - the leading count token is suppressed. If ``int_expr`` is specified, it should be a pyparsing expression that produces an integer value. Examples: .. doctest:: >>> counted_array(Word(alphas)).parse_string('2 ab cd ef') ParseResults(['ab', 'cd'], {}) - In this parser, the leading integer value is given in binary, '10' indicating that 2 values are in the array: .. doctest:: >>> binary_constant = Word('01').set_parse_action(lambda t: int(t[0], 2)) >>> counted_array(Word(alphas), int_expr=binary_constant ... ).parse_string('10 ab cd ef') ParseResults(['ab', 'cd'], {}) - If other fields must be parsed after the count but before the list items, give the fields results names and they will be preserved in the returned ParseResults: .. doctest:: >>> ppc = pyparsing.common >>> count_with_metadata = ppc.integer + Word(alphas)("type") >>> typed_array = counted_array(Word(alphanums), ... int_expr=count_with_metadata)("items") >>> result = typed_array.parse_string("3 bool True True False") >>> print(result.dump()) ['True', 'True', 'False'] - items: ['True', 'True', 'False'] - type: 'bool' """ intExpr = intExpr or int_expr array_expr = Forward() def count_field_parse_action(s, l, t): nonlocal array_expr n = t[0] array_expr <<= (expr * n) if n else Empty() # clear list contents, but keep any named results del t[:] if intExpr is None: intExpr = Word(nums).set_parse_action(lambda t: int(t[0])) else: intExpr = intExpr.copy() intExpr.set_name("arrayLen") intExpr.add_parse_action(count_field_parse_action, call_during_try=True) return (intExpr + array_expr).set_name(f"(len) {expr}...") def match_previous_literal(expr: ParserElement) -> ParserElement: """Helper to define an expression that is indirectly defined from the tokens matched in a previous expression, that is, it looks for a 'repeat' of a previous expression. For example:: .. testcode:: first = Word(nums) second = match_previous_literal(first) match_expr = first + ":" + second will match ``"1:1"``, but not ``"1:2"``. Because this matches a previous literal, will also match the leading ``"1:1"`` in ``"1:10"``. If this is not desired, use :class:`match_previous_expr`. Do *not* use with packrat parsing enabled. """ rep = Forward() def copy_token_to_repeater(s, l, t): if not t: rep << Empty() return if len(t) == 1: rep << t[0] return # flatten t tokens tflat = _flatten(t.as_list()) rep << And(Literal(tt) for tt in tflat) expr.add_parse_action(copy_token_to_repeater, callDuringTry=True) rep.set_name("(prev) " + str(expr)) return rep def match_previous_expr(expr: ParserElement) -> ParserElement: """Helper to define an expression that is indirectly defined from the tokens matched in a previous expression, that is, it looks for a 'repeat' of a previous expression. For example: .. testcode:: first = Word(nums) second = match_previous_expr(first) match_expr = first + ":" + second will match ``"1:1"``, but not ``"1:2"``. Because this matches by expressions, will *not* match the leading ``"1:1"`` in ``"1:10"``; the expressions are evaluated first, and then compared, so ``"1"`` is compared with ``"10"``. Do *not* use with packrat parsing enabled. """ rep = Forward() e2 = expr.copy() rep <<= e2 def copy_token_to_repeater(s, l, t): matchTokens = _flatten(t.as_list()) def must_match_these_tokens(s, l, t): theseTokens = _flatten(t.as_list()) if theseTokens != matchTokens: raise ParseException( s, l, f"Expected {matchTokens}, found{theseTokens}" ) rep.set_parse_action(must_match_these_tokens, callDuringTry=True) expr.add_parse_action(copy_token_to_repeater, callDuringTry=True) rep.set_name("(prev) " + str(expr)) return rep def one_of( strs: Union[typing.Iterable[str], str], caseless: bool = False, use_regex: bool = True, as_keyword: bool = False, *, useRegex: bool = True, asKeyword: bool = False, ) -> ParserElement: """Helper to quickly define a set of alternative :class:`Literal` s, and makes sure to do longest-first testing when there is a conflict, regardless of the input order, but returns a :class:`MatchFirst` for best performance. :param strs: a string of space-delimited literals, or a collection of string literals :param caseless: treat all literals as caseless :param use_regex: bool - as an optimization, will generate a :class:`Regex` object; otherwise, will generate a :class:`MatchFirst` object (if ``caseless=True`` or ``as_keyword=True``, or if creating a :class:`Regex` raises an exception) :param as_keyword: bool - enforce :class:`Keyword`-style matching on the generated expressions Parameters ``asKeyword`` and ``useRegex`` are retained for pre-PEP8 compatibility, but will be removed in a future release. Example: .. testcode:: comp_oper = one_of("< = > <= >= !=") var = Word(alphas) number = Word(nums) term = var | number comparison_expr = term + comp_oper + term print(comparison_expr.search_string("B = 12 AA=23 B<=AA AA>12")) prints: .. testoutput:: [['B', '=', '12'], ['AA', '=', '23'], ['B', '<=', 'AA'], ['AA', '>', '12']] """ asKeyword = asKeyword or as_keyword useRegex = useRegex and use_regex if ( isinstance(caseless, str_type) and __diag__.warn_on_multiple_string_args_to_oneof ): warnings.warn( "warn_on_multiple_string_args_to_oneof:" " More than one string argument passed to one_of, pass" " choices as a list or space-delimited string", stacklevel=2, ) if caseless: is_equal = lambda a, b: a.upper() == b.upper() masks = lambda a, b: b.upper().startswith(a.upper()) else: is_equal = operator.eq masks = lambda a, b: b.startswith(a) symbols: list[str] if isinstance(strs, str_type): strs = typing.cast(str, strs) symbols = strs.split() elif isinstance(strs, Iterable): symbols = list(strs) else: raise TypeError("Invalid argument to one_of, expected string or iterable") if not symbols: return NoMatch() # reorder given symbols to take care to avoid masking longer choices with shorter ones # (but only if the given symbols are not just single characters) i = 0 while i < len(symbols) - 1: cur = symbols[i] for j, other in enumerate(symbols[i + 1 :]): if is_equal(other, cur): del symbols[i + j + 1] break if len(other) > len(cur) and masks(cur, other): del symbols[i + j + 1] symbols.insert(i, other) break else: i += 1 if useRegex: re_flags: int = re.IGNORECASE if caseless else 0 try: if all(len(sym) == 1 for sym in symbols): # symbols are just single characters, create range regex pattern patt = f"[{''.join(_escape_regex_range_chars(sym) for sym in symbols)}]" else: patt = "|".join(re.escape(sym) for sym in symbols) # wrap with \b word break markers if defining as keywords if asKeyword: patt = rf"\b(?:{patt})\b" ret = Regex(patt, flags=re_flags) ret.set_name(" | ".join(repr(s) for s in symbols)) if caseless: # add parse action to return symbols as specified, not in random # casing as found in input string symbol_map = {sym.lower(): sym for sym in symbols} ret.add_parse_action(lambda s, l, t: symbol_map[t[0].lower()]) return ret except re.error: warnings.warn( "Exception creating Regex for one_of, building MatchFirst", stacklevel=2 ) # last resort, just use MatchFirst of Token class corresponding to caseless # and asKeyword settings CASELESS = KEYWORD = True parse_element_class = { (CASELESS, KEYWORD): CaselessKeyword, (CASELESS, not KEYWORD): CaselessLiteral, (not CASELESS, KEYWORD): Keyword, (not CASELESS, not KEYWORD): Literal, }[(caseless, asKeyword)] return MatchFirst(parse_element_class(sym) for sym in symbols).set_name( " | ".join(symbols) ) def dict_of(key: ParserElement, value: ParserElement) -> Dict: """Helper to easily and clearly define a dictionary by specifying the respective patterns for the key and value. Takes care of defining the :class:`Dict`, :class:`ZeroOrMore`, and :class:`Group` tokens in the proper order. The key pattern can include delimiting markers or punctuation, as long as they are suppressed, thereby leaving the significant key text. The value pattern can include named results, so that the :class:`Dict` results can include named token fields. Example: .. doctest:: >>> text = "shape: SQUARE posn: upper left color: light blue texture: burlap" >>> data_word = Word(alphas) >>> label = data_word + FollowedBy(':') >>> attr_expr = ( ... label ... + Suppress(':') ... + OneOrMore(data_word, stop_on=label) ... .set_parse_action(' '.join)) >>> print(attr_expr[1, ...].parse_string(text).dump()) ['shape', 'SQUARE', 'posn', 'upper left', 'color', 'light blue', 'texture', 'burlap'] >>> attr_label = label >>> attr_value = Suppress(':') + OneOrMore(data_word, stop_on=label ... ).set_parse_action(' '.join) # similar to Dict, but simpler call format >>> result = dict_of(attr_label, attr_value).parse_string(text) >>> print(result.dump()) [['shape', 'SQUARE'], ['posn', 'upper left'], ['color', 'light blue'], ['texture', 'burlap']] - color: 'light blue' - posn: 'upper left' - shape: 'SQUARE' - texture: 'burlap' [0]: ['shape', 'SQUARE'] [1]: ['posn', 'upper left'] [2]: ['color', 'light blue'] [3]: ['texture', 'burlap'] >>> print(result['shape']) SQUARE >>> print(result.shape) # object attribute access works too SQUARE >>> print(result.as_dict()) {'shape': 'SQUARE', 'posn': 'upper left', 'color': 'light blue', 'texture': 'burlap'} """ return Dict(OneOrMore(Group(key + value))) def original_text_for( expr: ParserElement, as_string: bool = True, *, asString: bool = True ) -> ParserElement: """Helper to return the original, untokenized text for a given expression. Useful to restore the parsed fields of an HTML start tag into the raw tag text itself, or to revert separate tokens with intervening whitespace back to the original matching input text. By default, returns a string containing the original parsed text. If the optional ``as_string`` argument is passed as ``False``, then the return value is a :class:`ParseResults` containing any results names that were originally matched, and a single token containing the original matched text from the input string. So if the expression passed to :class:`original_text_for` contains expressions with defined results names, you must set ``as_string`` to ``False`` if you want to preserve those results name values. The ``asString`` pre-PEP8 argument is retained for compatibility, but will be removed in a future release. Example: .. testcode:: src = "this is test bold text normal text " for tag in ("b", "i"): opener, closer = make_html_tags(tag) patt = original_text_for(opener + ... + closer) print(patt.search_string(src)[0]) prints: .. testoutput:: [' bold text '] ['text'] """ asString = asString and as_string locMarker = Empty().set_parse_action(lambda s, loc, t: loc) endlocMarker = locMarker.copy() endlocMarker.callPreparse = False matchExpr = locMarker("_original_start") + expr + endlocMarker("_original_end") if asString: extractText = lambda s, l, t: s[t._original_start : t._original_end] else: def extractText(s, l, t): t[:] = [s[t.pop("_original_start") : t.pop("_original_end")]] matchExpr.set_parse_action(extractText) matchExpr.ignoreExprs = expr.ignoreExprs matchExpr.suppress_warning(Diagnostics.warn_ungrouped_named_tokens_in_collection) return matchExpr def ungroup(expr: ParserElement) -> ParserElement: """Helper to undo pyparsing's default grouping of And expressions, even if all but one are non-empty. """ return TokenConverter(expr).add_parse_action(lambda t: t[0]) def locatedExpr(expr: ParserElement) -> ParserElement: """ .. deprecated:: 3.0.0 Use the :class:`Located` class instead. Helper to decorate a returned token with its starting and ending locations in the input string. This helper adds the following results names: - ``locn_start`` - location where matched expression begins - ``locn_end`` - location where matched expression ends - ``value`` - the actual parsed results Be careful if the input text contains ```` characters, you may want to call :meth:`ParserElement.parse_with_tabs` Example: .. testcode:: wd = Word(alphas) res = locatedExpr(wd).search_string("ljsdf123lksdjjf123lkkjj1222") for match in res: print(match) prints: .. testoutput:: [[0, 'ljsdf', 5]] [[8, 'lksdjjf', 15]] [[18, 'lkkjj', 23]] """ locator = Empty().set_parse_action(lambda ss, ll, tt: ll) return Group( locator("locn_start") + expr("value") + locator.copy().leaveWhitespace()("locn_end") ) # define special default value to permit None as a significant value for # ignore_expr _NO_IGNORE_EXPR_GIVEN = NoMatch() def nested_expr( opener: Union[str, ParserElement] = "(", closer: Union[str, ParserElement] = ")", content: typing.Optional[ParserElement] = None, ignore_expr: typing.Optional[ParserElement] = _NO_IGNORE_EXPR_GIVEN, *, ignoreExpr: typing.Optional[ParserElement] = _NO_IGNORE_EXPR_GIVEN, ) -> ParserElement: """Helper method for defining nested lists enclosed in opening and closing delimiters (``"("`` and ``")"`` are the default). :param opener: str - opening character for a nested list (default= ``"("``); can also be a pyparsing expression :param closer: str - closing character for a nested list (default= ``")"``); can also be a pyparsing expression :param content: expression for items within the nested lists :param ignore_expr: expression for ignoring opening and closing delimiters (default = :class:`quoted_string`) Parameter ``ignoreExpr`` is retained for compatibility but will be removed in a future release. If an expression is not provided for the content argument, the nested expression will capture all whitespace-delimited content between delimiters as a list of separate values. Use the ``ignore_expr`` argument to define expressions that may contain opening or closing characters that should not be treated as opening or closing characters for nesting, such as quoted_string or a comment expression. Specify multiple expressions using an :class:`Or` or :class:`MatchFirst`. The default is :class:`quoted_string`, but if no expressions are to be ignored, then pass ``None`` for this argument. Example: .. testcode:: data_type = one_of("void int short long char float double") decl_data_type = Combine(data_type + Opt(Word('*'))) ident = Word(alphas+'_', alphanums+'_') number = pyparsing_common.number arg = Group(decl_data_type + ident) LPAR, RPAR = map(Suppress, "()") code_body = nested_expr('{', '}', ignore_expr=(quoted_string | c_style_comment)) c_function = (decl_data_type("type") + ident("name") + LPAR + Opt(DelimitedList(arg), [])("args") + RPAR + code_body("body")) c_function.ignore(c_style_comment) source_code = ''' int is_odd(int x) { return (x%2); } int dec_to_hex(char hchar) { if (hchar >= '0' && hchar <= '9') { return (ord(hchar)-ord('0')); } else { return (10+ord(hchar)-ord('A')); } } ''' for func in c_function.search_string(source_code): print(f"{func.name} ({func.type}) args: {func.args}") prints: .. testoutput:: is_odd (int) args: [['int', 'x']] dec_to_hex (int) args: [['char', 'hchar']] """ if ignoreExpr != ignore_expr: ignoreExpr = ignore_expr if ignoreExpr is _NO_IGNORE_EXPR_GIVEN else ignoreExpr if ignoreExpr is _NO_IGNORE_EXPR_GIVEN: ignoreExpr = quoted_string() if opener == closer: raise ValueError("opening and closing strings cannot be the same") if content is None: if isinstance(opener, str_type) and isinstance(closer, str_type): opener = typing.cast(str, opener) closer = typing.cast(str, closer) if len(opener) == 1 and len(closer) == 1: if ignoreExpr is not None: content = Combine( OneOrMore( ~ignoreExpr + CharsNotIn( opener + closer + ParserElement.DEFAULT_WHITE_CHARS, exact=1, ) ) ) else: content = Combine( Empty() + CharsNotIn( opener + closer + ParserElement.DEFAULT_WHITE_CHARS ) ) else: if ignoreExpr is not None: content = Combine( OneOrMore( ~ignoreExpr + ~Literal(opener) + ~Literal(closer) + CharsNotIn(ParserElement.DEFAULT_WHITE_CHARS, exact=1) ) ) else: content = Combine( OneOrMore( ~Literal(opener) + ~Literal(closer) + CharsNotIn(ParserElement.DEFAULT_WHITE_CHARS, exact=1) ) ) else: raise ValueError( "opening and closing arguments must be strings if no content expression is given" ) # for these internally-created context expressions, simulate whitespace-skipping if ParserElement.DEFAULT_WHITE_CHARS: content.set_parse_action( lambda t: t[0].strip(ParserElement.DEFAULT_WHITE_CHARS) ) ret = Forward() if ignoreExpr is not None: ret <<= Group( Suppress(opener) + ZeroOrMore(ignoreExpr | ret | content) + Suppress(closer) ) else: ret <<= Group(Suppress(opener) + ZeroOrMore(ret | content) + Suppress(closer)) ret.set_name(f"nested {opener}{closer} expression") # don't override error message from content expressions ret.errmsg = None return ret def _makeTags(tagStr, xml, suppress_LT=Suppress("<"), suppress_GT=Suppress(">")): """Internal helper to construct opening and closing tag expressions, given a tag name""" if isinstance(tagStr, str_type): resname = tagStr tagStr = Keyword(tagStr, caseless=not xml) else: resname = tagStr.name tagAttrName = Word(alphas, alphanums + "_-:") if xml: tagAttrValue = dbl_quoted_string.copy().set_parse_action(remove_quotes) openTag = ( suppress_LT + tagStr("tag") + Dict(ZeroOrMore(Group(tagAttrName + Suppress("=") + tagAttrValue))) + Opt("/", default=[False])("empty").set_parse_action( lambda s, l, t: t[0] == "/" ) + suppress_GT ) else: tagAttrValue = quoted_string.copy().set_parse_action(remove_quotes) | Word( printables, exclude_chars=">" ) openTag = ( suppress_LT + tagStr("tag") + Dict( ZeroOrMore( Group( tagAttrName.set_parse_action(lambda t: t[0].lower()) + Opt(Suppress("=") + tagAttrValue) ) ) ) + Opt("/", default=[False])("empty").set_parse_action( lambda s, l, t: t[0] == "/" ) + suppress_GT ) closeTag = Combine(Literal("", adjacent=False) openTag.set_name(f"<{resname}>") # add start results name in parse action now that ungrouped names are not reported at two levels openTag.add_parse_action( lambda t: t.__setitem__( "start" + "".join(resname.replace(":", " ").title().split()), t.copy() ) ) closeTag = closeTag( "end" + "".join(resname.replace(":", " ").title().split()) ).set_name(f"") openTag.tag = resname closeTag.tag = resname openTag.tag_body = SkipTo(closeTag()) return openTag, closeTag def make_html_tags( tag_str: Union[str, ParserElement], ) -> tuple[ParserElement, ParserElement]: """Helper to construct opening and closing tag expressions for HTML, given a tag name. Matches tags in either upper or lower case, attributes with namespaces and with quoted or unquoted values. Example: .. testcode:: text = 'More info at the pyparsing wiki page' # make_html_tags returns pyparsing expressions for the opening and # closing tags as a 2-tuple a, a_end = make_html_tags("A") link_expr = a + SkipTo(a_end)("link_text") + a_end for link in link_expr.search_string(text): # attributes in the tag (like "href" shown here) are # also accessible as named results print(link.link_text, '->', link.href) prints: .. testoutput:: pyparsing -> https://github.com/pyparsing/pyparsing/wiki """ return _makeTags(tag_str, False) def make_xml_tags( tag_str: Union[str, ParserElement], ) -> tuple[ParserElement, ParserElement]: """Helper to construct opening and closing tag expressions for XML, given a tag name. Matches tags only in the given upper/lower case. Example: similar to :class:`make_html_tags` """ return _makeTags(tag_str, True) any_open_tag: ParserElement any_close_tag: ParserElement any_open_tag, any_close_tag = make_html_tags( Word(alphas, alphanums + "_:").set_name("any tag") ) _htmlEntityMap = {k.rstrip(";"): v for k, v in html.entities.html5.items()} _most_common_entities = "nbsp lt gt amp quot apos cent pound euro copy".replace( " ", "|" ) common_html_entity = Regex( lambda: f"&(?P{_most_common_entities}|{make_compressed_re(_htmlEntityMap)});" ).set_name("common HTML entity") def replace_html_entity(s, l, t): """Helper parser action to replace common HTML entities with their special characters""" return _htmlEntityMap.get(t.entity) class OpAssoc(Enum): """Enumeration of operator associativity - used in constructing InfixNotationOperatorSpec for :class:`infix_notation`""" LEFT = 1 RIGHT = 2 InfixNotationOperatorArgType = Union[ ParserElement, str, tuple[Union[ParserElement, str], Union[ParserElement, str]] ] InfixNotationOperatorSpec = Union[ tuple[ InfixNotationOperatorArgType, int, OpAssoc, typing.Optional[ParseAction], ], tuple[ InfixNotationOperatorArgType, int, OpAssoc, ], ] def infix_notation( base_expr: ParserElement, op_list: list[InfixNotationOperatorSpec], lpar: Union[str, ParserElement] = Suppress("("), rpar: Union[str, ParserElement] = Suppress(")"), ) -> Forward: """Helper method for constructing grammars of expressions made up of operators working in a precedence hierarchy. Operators may be unary or binary, left- or right-associative. Parse actions can also be attached to operator expressions. The generated parser will also recognize the use of parentheses to override operator precedences (see example below). Note: if you define a deep operator list, you may see performance issues when using infix_notation. See :class:`ParserElement.enable_packrat` for a mechanism to potentially improve your parser performance. Parameters: :param base_expr: expression representing the most basic operand to be used in the expression :param op_list: list of tuples, one for each operator precedence level in the expression grammar; each tuple is of the form ``(op_expr, num_operands, right_left_assoc, (optional)parse_action)``, where: - ``op_expr`` is the pyparsing expression for the operator; may also be a string, which will be converted to a Literal; if ``num_operands`` is 3, ``op_expr`` is a tuple of two expressions, for the two operators separating the 3 terms - ``num_operands`` is the number of terms for this operator (must be 1, 2, or 3) - ``right_left_assoc`` is the indicator whether the operator is right or left associative, using the pyparsing-defined constants ``OpAssoc.RIGHT`` and ``OpAssoc.LEFT``. - ``parse_action`` is the parse action to be associated with expressions matching this operator expression (the parse action tuple member may be omitted); if the parse action is passed a tuple or list of functions, this is equivalent to calling ``set_parse_action(*fn)`` (:class:`ParserElement.set_parse_action`) :param lpar: expression for matching left-parentheses; if passed as a str, then will be parsed as ``Suppress(lpar)``. If lpar is passed as an expression (such as ``Literal('(')``), then it will be kept in the parsed results, and grouped with them. (default= ``Suppress('(')``) :param rpar: expression for matching right-parentheses; if passed as a str, then will be parsed as ``Suppress(rpar)``. If rpar is passed as an expression (such as ``Literal(')')``), then it will be kept in the parsed results, and grouped with them. (default= ``Suppress(')')``) Example: .. testcode:: # simple example of four-function arithmetic with ints and # variable names integer = pyparsing_common.signed_integer varname = pyparsing_common.identifier arith_expr = infix_notation(integer | varname, [ ('-', 1, OpAssoc.RIGHT), (one_of('* /'), 2, OpAssoc.LEFT), (one_of('+ -'), 2, OpAssoc.LEFT), ]) arith_expr.run_tests(''' 5+3*6 (5+3)*6 (5+x)*y -2--11 ''', full_dump=False) prints: .. testoutput:: :options: +NORMALIZE_WHITESPACE 5+3*6 [[5, '+', [3, '*', 6]]] (5+3)*6 [[[5, '+', 3], '*', 6]] (5+x)*y [[[5, '+', 'x'], '*', 'y']] -2--11 [[['-', 2], '-', ['-', 11]]] """ # captive version of FollowedBy that does not do parse actions or capture results names class _FB(FollowedBy): def parseImpl(self, instring, loc, doActions=True): self.expr.try_parse(instring, loc) return loc, [] _FB.__name__ = "FollowedBy>" ret = Forward() ret.set_name(f"{base_expr.name}_expression") if isinstance(lpar, str): lpar = Suppress(lpar) if isinstance(rpar, str): rpar = Suppress(rpar) nested_expr = (lpar + ret + rpar).set_name(f"nested_{base_expr.name}_expression") # if lpar and rpar are not suppressed, wrap in group if not (isinstance(lpar, Suppress) and isinstance(rpar, Suppress)): lastExpr = base_expr | Group(nested_expr) else: lastExpr = base_expr | nested_expr arity: int rightLeftAssoc: opAssoc pa: typing.Optional[ParseAction] opExpr1: ParserElement opExpr2: ParserElement matchExpr: ParserElement match_lookahead: ParserElement for operDef in op_list: opExpr, arity, rightLeftAssoc, pa = (operDef + (None,))[:4] # type: ignore[assignment] if isinstance(opExpr, str_type): opExpr = ParserElement._literalStringClass(opExpr) opExpr = typing.cast(ParserElement, opExpr) if arity == 3: if not isinstance(opExpr, (tuple, list)) or len(opExpr) != 2: raise ValueError( "if numterms=3, opExpr must be a tuple or list of two expressions" ) opExpr1, opExpr2 = opExpr term_name = f"{opExpr1}{opExpr2} operations" else: term_name = f"{opExpr} operations" if not 1 <= arity <= 3: raise ValueError("operator must be unary (1), binary (2), or ternary (3)") if rightLeftAssoc not in (OpAssoc.LEFT, OpAssoc.RIGHT): raise ValueError("operator must indicate right or left associativity") thisExpr: ParserElement = Forward().set_name(term_name) thisExpr = typing.cast(Forward, thisExpr) match_lookahead = And([]) if rightLeftAssoc is OpAssoc.LEFT: if arity == 1: match_lookahead = _FB(lastExpr + opExpr) matchExpr = Group(lastExpr + opExpr[1, ...]) elif arity == 2: if opExpr is not None: match_lookahead = _FB(lastExpr + opExpr + lastExpr) matchExpr = Group(lastExpr + (opExpr + lastExpr)[1, ...]) else: match_lookahead = _FB(lastExpr + lastExpr) matchExpr = Group(lastExpr[2, ...]) elif arity == 3: match_lookahead = _FB( lastExpr + opExpr1 + lastExpr + opExpr2 + lastExpr ) matchExpr = Group( lastExpr + (opExpr1 + lastExpr + opExpr2 + lastExpr)[1, ...] ) elif rightLeftAssoc is OpAssoc.RIGHT: if arity == 1: # try to avoid LR with this extra test if not isinstance(opExpr, Opt): opExpr = Opt(opExpr) match_lookahead = _FB(opExpr.expr + thisExpr) matchExpr = Group(opExpr + thisExpr) elif arity == 2: if opExpr is not None: match_lookahead = _FB(lastExpr + opExpr + thisExpr) matchExpr = Group(lastExpr + (opExpr + thisExpr)[1, ...]) else: match_lookahead = _FB(lastExpr + thisExpr) matchExpr = Group(lastExpr + thisExpr[1, ...]) elif arity == 3: match_lookahead = _FB( lastExpr + opExpr1 + thisExpr + opExpr2 + thisExpr ) matchExpr = Group(lastExpr + opExpr1 + thisExpr + opExpr2 + thisExpr) # suppress lookahead expr from railroad diagrams match_lookahead.show_in_diagram = False # TODO - determine why this statement can't be included in the following # if pa block matchExpr = match_lookahead + matchExpr if pa: if isinstance(pa, (tuple, list)): matchExpr.set_parse_action(*pa) else: matchExpr.set_parse_action(pa) thisExpr <<= (matchExpr | lastExpr).setName(term_name) lastExpr = thisExpr ret <<= lastExpr return ret def indentedBlock(blockStatementExpr, indentStack, indent=True, backup_stacks=[]): """ .. deprecated:: 3.0.0 Use the :class:`IndentedBlock` class instead. Helper method for defining space-delimited indentation blocks, such as those used to define block statements in Python source code. :param blockStatementExpr: expression defining syntax of statement that is repeated within the indented block :param indentStack: list created by caller to manage indentation stack (multiple ``statementWithIndentedBlock`` expressions within a single grammar should share a common ``indentStack``) :param indent: boolean indicating whether block must be indented beyond the current level; set to ``False`` for block of left-most statements A valid block must contain at least one ``blockStatement``. (Note that indentedBlock uses internal parse actions which make it incompatible with packrat parsing.) Example: .. testcode:: data = ''' def A(z): A1 B = 100 G = A2 A2 A3 B def BB(a,b,c): BB1 def BBA(): bba1 bba2 bba3 C D def spam(x,y): def eggs(z): pass ''' indentStack = [1] stmt = Forward() identifier = Word(alphas, alphanums) funcDecl = ("def" + identifier + Group("(" + Opt(delimitedList(identifier)) + ")") + ":") func_body = indentedBlock(stmt, indentStack) funcDef = Group(funcDecl + func_body) rvalue = Forward() funcCall = Group(identifier + "(" + Opt(delimitedList(rvalue)) + ")") rvalue << (funcCall | identifier | Word(nums)) assignment = Group(identifier + "=" + rvalue) stmt << (funcDef | assignment | identifier) module_body = stmt[1, ...] parseTree = module_body.parseString(data) parseTree.pprint() prints: .. testoutput:: [['def', 'A', ['(', 'z', ')'], ':', [['A1'], [['B', '=', '100']], [['G', '=', 'A2']], ['A2'], ['A3']]], 'B', ['def', 'BB', ['(', 'a', 'b', 'c', ')'], ':', [['BB1'], [['def', 'BBA', ['(', ')'], ':', [['bba1'], ['bba2'], ['bba3']]]]]], 'C', 'D', ['def', 'spam', ['(', 'x', 'y', ')'], ':', [[['def', 'eggs', ['(', 'z', ')'], ':', [['pass']]]]]]] """ backup_stacks.append(indentStack[:]) def reset_stack(): indentStack[:] = backup_stacks[-1] def checkPeerIndent(s, l, t): if l >= len(s): return curCol = col(l, s) if curCol != indentStack[-1]: if curCol > indentStack[-1]: raise ParseException(s, l, "illegal nesting") raise ParseException(s, l, "not a peer entry") def checkSubIndent(s, l, t): curCol = col(l, s) if curCol > indentStack[-1]: indentStack.append(curCol) else: raise ParseException(s, l, "not a subentry") def checkUnindent(s, l, t): if l >= len(s): return curCol = col(l, s) if not (indentStack and curCol in indentStack): raise ParseException(s, l, "not an unindent") if curCol < indentStack[-1]: indentStack.pop() NL = OneOrMore(LineEnd().set_whitespace_chars("\t ").suppress()) INDENT = (Empty() + Empty().set_parse_action(checkSubIndent)).set_name("INDENT") PEER = Empty().set_parse_action(checkPeerIndent).set_name("") UNDENT = Empty().set_parse_action(checkUnindent).set_name("UNINDENT") if indent: smExpr = Group( Opt(NL) + INDENT + OneOrMore(PEER + Group(blockStatementExpr) + Opt(NL)) + UNDENT ) else: smExpr = Group( Opt(NL) + OneOrMore(PEER + Group(blockStatementExpr) + Opt(NL)) + Opt(UNDENT) ) # add a parse action to remove backup_stack from list of backups smExpr.add_parse_action( lambda: backup_stacks.pop(-1) and None if backup_stacks else None ) smExpr.set_fail_action(lambda a, b, c, d: reset_stack()) blockStatementExpr.ignore(_bslash + LineEnd()) return smExpr.set_name("indented block") # it's easy to get these comment structures wrong - they're very common, # so may as well make them available c_style_comment = Regex(r"/\*(?:[^*]|\*(?!/))*\*\/").set_name("C style comment") "Comment of the form ``/* ... */``" html_comment = Regex(r"").set_name("HTML comment") "Comment of the form ````" rest_of_line = Regex(r".*").leave_whitespace().set_name("rest of line") dbl_slash_comment = Regex(r"//(?:\\\n|[^\n])*").set_name("// comment") "Comment of the form ``// ... (to end of line)``" cpp_style_comment = Regex( r"(?:/\*(?:[^*]|\*(?!/))*\*\/)|(?://(?:\\\n|[^\n])*)" ).set_name("C++ style comment") "Comment of either form :class:`c_style_comment` or :class:`dbl_slash_comment`" java_style_comment = cpp_style_comment "Same as :class:`cpp_style_comment`" python_style_comment = Regex(r"#.*").set_name("Python style comment") "Comment of the form ``# ... (to end of line)``" # build list of built-in expressions, for future reference if a global default value # gets updated _builtin_exprs: list[ParserElement] = [ v for v in vars().values() if isinstance(v, ParserElement) ] # compatibility function, superseded by DelimitedList class def delimited_list( expr: Union[str, ParserElement], delim: Union[str, ParserElement] = ",", combine: bool = False, min: typing.Optional[int] = None, max: typing.Optional[int] = None, *, allow_trailing_delim: bool = False, ) -> ParserElement: """ .. deprecated:: 3.1.0 Use the :class:`DelimitedList` class instead. """ return DelimitedList( expr, delim, combine, min, max, allow_trailing_delim=allow_trailing_delim ) # Compatibility synonyms # fmt: off opAssoc = OpAssoc anyOpenTag = any_open_tag anyCloseTag = any_close_tag commonHTMLEntity = common_html_entity cStyleComment = c_style_comment htmlComment = html_comment restOfLine = rest_of_line dblSlashComment = dbl_slash_comment cppStyleComment = cpp_style_comment javaStyleComment = java_style_comment pythonStyleComment = python_style_comment delimitedList = replaced_by_pep8("delimitedList", DelimitedList) delimited_list = replaced_by_pep8("delimited_list", DelimitedList) countedArray = replaced_by_pep8("countedArray", counted_array) matchPreviousLiteral = replaced_by_pep8("matchPreviousLiteral", match_previous_literal) matchPreviousExpr = replaced_by_pep8("matchPreviousExpr", match_previous_expr) oneOf = replaced_by_pep8("oneOf", one_of) dictOf = replaced_by_pep8("dictOf", dict_of) originalTextFor = replaced_by_pep8("originalTextFor", original_text_for) nestedExpr = replaced_by_pep8("nestedExpr", nested_expr) makeHTMLTags = replaced_by_pep8("makeHTMLTags", make_html_tags) makeXMLTags = replaced_by_pep8("makeXMLTags", make_xml_tags) replaceHTMLEntity = replaced_by_pep8("replaceHTMLEntity", replace_html_entity) infixNotation = replaced_by_pep8("infixNotation", infix_notation) # fmt: on