Package lepl :: Package core :: Module parser

Module parser

Create and evaluate parsers.

Once a consistent set of matchers is constructed (that describes a grammar) they must be evaluated against some input. The code here supports that evaluation (via trampoline()) and allows the graph of matchers to be rewritten beforehand.

Classes

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GeneratorWrapper
Associate basic info about call that created the generator with the generator itself.

Functions

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list

imap(function, sequence, sequence=..., ...)
Return a list of the results of applying the function to the items of the argument sequence(s).

tagged(method)
Decorator for generators to add extra attributes.

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tagged_function(matcher, function)
Decorator for generators to add extra attributes.

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trampoline(main, m_stack=None, m_value=None)
The main parser loop.

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make_raw_parser(matcher, stream_factory, config)
Make a parser.

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make_multiple(raw)
Convert a raw parser to return a generator of results.

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make_single(raw)
Convert a raw parser to return a single result or None.

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Function Details

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imap(function, sequence, sequence=..., ...)

Return a list of the results of applying the function to the items of the argument sequence(s). If more than one sequence is given, the function is called with an argument list consisting of the corresponding item of each sequence, substituting None for missing values when not all sequences have the same length. If the function is None, return a list of the items of the sequence (or a list of tuples if more than one sequence).

Returns: list

trampoline(main, m_stack=None, m_value=None)

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The main parser loop. Evaluates matchers as coroutines.

A dedicated version for when monitor not present increased the speed of the nat_lang performance test by only around 1% (close to noise).

Replacing stack append/pop with a manually allocated non-decreasing array and index made no significant difference (at around 1% level)

make_raw_parser(matcher, stream_factory, config)

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Make a parser. Rewrite the matcher and prepare the input for a parser. This constructs a function that returns a generator that provides a sequence of matches (ie (results, stream) pairs).