Package rxpy :: Package parser :: Module pattern

Module pattern

An ad-hoc parser for regular expressions. I think it's best to consider this as recursive descent with hand-written trampolining, but you can also consider the matchers as states in a state machine. Whatever it is, it works quite nicely, and exploits inheritance well. I call the matchers/states "builders".

Builders have references to their callers and construct the graph through those references (ultimately accumulating the graph nodes in the root SequenceBuilder).

Classes

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SequenceBuilder
Parse a sequence (this is the main entry point for parsing, but users will normally call parse_pattern).

RepeatBuilder
Parse simple repetition expressions (*, + and ?).

GroupEscapeBuilder
Parse "group escapes" - expressions of the form (?X...).

ParserStateBuilder
Parse embedded flags - expressions of the form (?i), (?m) etc.

BaseGroupBuilder
Support for parsing groups.

GroupBuilder
Parse groups - expressions of the form (...) containing sub-expressions, like (ab[c-e]*).

LookbackBuilder
Parse lookback expressions of the form (?<...).

LookaheadBuilder
Parse lookahead expressions of the form (?=...) and (?!...), along with lookback expressions (via LookbackBuilder).

GroupConditionalBuilder
Parse (?(id/name)yes-pattern|no-pattern) expressions.

YesNoBuilder
A helper for GroupConditionBuilder that parses the sub-expressions.

NamedGroupBuilder
Parse '(?P<name>pattern)' and '(?P=name)' by creating either a matching group (and associating the name with the group number) or a group reference (for the group number).

CommentGroupBuilder
Parse comments - expressions of the form (#...).

CharacterBuilder
Parse a character range - expressions of the form [...].

SimpleEscapeBuilder
Parse the standard escaped characters, character codes (x, u and U, by delegating to CharacterCodeBuilder), and octal codes (000 etc, by delegating to OctalEscapeBuilder)

IntermediateEscapeBuilder
Extend SimpleEscapeBuilder to also handle group references (1 etc).

ComplexEscapeBuilder
Extend IntermediateEscapeBuilder to handle character classes (b, s etc).

CharacterCodeBuilder
Parse character code escapes - expressions of the form x..., u..., and U....

OctalEscapeBuilder
Parse octal character code escapes - expressions of the form 000.

GroupReferenceBuilder
Parse group references - expressions of the form 1.

CountBuilder
Parse explicit counted repeats - expressions of the form ...{n,m}.

Functions

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parse_pattern(text, flags=0, alphabet=None, hint_alphabet=None)
Parse a standard regular expression.

source code

parse_groups(texts, flags=0, alphabet=None)
Parse set of expressions, used to define groups for Scanner.

source code