Commit 2e783842 authored by eckhart's avatar eckhart

parse.py: streamlining: merged return_form_recursion and memoization Flags to suspend_memoization

parent 94739749
......@@ -2918,6 +2918,12 @@ class ContextSensitive(UnaryParser):
starts to move forward again. Only those variable changes should be
rolled back the locations of which have been passed when backtracking.
The rollback location can also be used to block memoizing. Since
the result returned by a variable changing parser (or a parser
that directly or indirectly calls a variable changing parser), should
never be memoized, memoizing is only triggered, when the location of
a returning parser is greater than the last rollback location.
Usually, the rollback location is exactly the location, where the parser
started parsing. However, the rollback-location must lie before the
location where the parser stopped, because otherwise variable changes
......@@ -2925,7 +2931,13 @@ class ContextSensitive(UnaryParser):
zero length data. In order to avoid this, the rollback location is
artificially reduced by one in case the parser did not capture any text
(either of the two equivalent criteria len(text) == len(rest) or
len(node) == 0) identifies this case).
len(node) == 0) identifies this case). This reduction needs to be
compensated for, if blocking of memoization is determined by the
rollback-location as in `Forward.__call__()` where a formula like::
location <= (grammar.last_rb__loc__ + int(text._len == rest._len)
determines whether memoization should be blocked.
"""
L = text._len
rb_loc = self.grammar.document_length__ - L
......
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