Fix C runtime parser: register all case-variant sequences in lookahead - #205
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Fix C runtime parser: register all case-variant sequences in lookahead#205martingercke wants to merge 1 commit into
martingercke wants to merge 1 commit into
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pgf_parsing_lookahead is a 'find all prefixes' binary search over concr->sequences that assumes a strict total order: on an exact match it registers exactly one sequence in state->lexicon_idx and recurses with length bounds that exclude any other sequence of the same length. With case-insensitive matching, a capitalized lexical sequence and its lowercase twin (e.g. "Schule"/"schule" in the German WordNet grammar) compare equal and sit adjacently - a tie. Only one of the twins got registered, decided by array-index parity. Lemmas indexed on the unregistered twin were never predicted, making those words unparseable (e.g. parse -cat=N "Schule"/"Brot"/"Stadt" failed with 'Unexpected token' although lookupMorpho finds them), while others (Birne, Haus) worked by luck. Fix: on an exact match, register the entire contiguous run of sequences that are equal under the comparator, then recurse strictly outside that run. No behavior change for unambiguous matches; lookupMorpho and linearization are untouched. Fixes GrammaticalFramework#204
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Fixes #204.
pgf_parsing_lookaheadregistered only one sequence per exact match. With case-insensitive matching, capitalized/lowercase twin sequences (e.g."Schule"/"schule"in the German WordNet grammar) compare equal, so only one of them enteredstate->lexicon_idx— decided by array-index parity. Lemmas indexed on the unregistered twin were unparseable (Schule,Brot,Stadt, … fail with "Unexpected token" althoughlookupMorphofinds them).This patch registers the entire contiguous run of comparator-equal sequences on an exact match (left/right scans via a small helper) and recurses strictly outside that run.
lookupMorphoand linearization untouched.1c086bed2(unmodified build before/after) with the German WordNet grammar compiled by the master-branch compiler: all affected words parse correctly after the fix; a regression battery (Food example grammar, German sentences, morphology lookups) is unchanged.