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15f33f458d
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: Margus Veanes <margus@microsoft.com> Co-authored-by: Margus Veanes <veanes@users.noreply.github.com>
71 lines
2.7 KiB
C++
71 lines
2.7 KiB
C++
/*++
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Copyright (c) 2026 Microsoft Corporation
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Module Name:
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seq_range_collapse.h
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Abstract:
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Recognize regexes that are boolean combinations of character-class
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primitives (re.empty, re.full_char, re.range with concrete chars,
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and re.union/inter/comp/diff over translatable arguments), and
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materialize a seq::range_predicate back into a canonical regex AST.
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Together with seq_rewriter integration, this lets any boolean
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combination of character-class regexes collapse to a canonical
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multi-range form, so that equivalent character classes share AST
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identity, and downstream consumers (derivative, OneStep, caching)
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can short-circuit them as pure range predicates.
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Authors:
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Margus Veanes (veanes) 2026
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--*/
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#pragma once
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#include "ast/rewriter/seq_range_predicate.h"
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#include "ast/seq_decl_plugin.h"
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namespace seq {
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/**
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* If r is a boolean combination of character-class regex primitives
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* over the unsigned character domain [0, max_char], compute the
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* equivalent range_predicate and return true. Otherwise return false
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* with out untouched.
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*
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* Recognized fragment (all character-class-preserving operations):
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* re.empty -> empty
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* re.full_char_set -> top
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* re.range "c_lo" "c_hi" (concrete) -> [c_lo, c_hi]
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* re.union r1 r2 -> p1 | p2
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* re.intersection r1 r2 -> p1 & p2
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* re.diff r1 r2 -> p1 - p2
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*
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* Notably re.complement is NOT recognized: it is a SEQUENCE-level
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* complement (over all of Σ*), not a character-class complement, so
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* collapsing it would change semantics whenever the result is used
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* in any non-character-class context. Sequence-level rewrites for
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* re.complement (double-comp, deMorgan, etc.) are handled directly
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* in seq_rewriter::mk_re_complement.
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*/
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bool regex_to_range_predicate(seq_util& u, expr* r, range_predicate& out);
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/**
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* Canonical materialization of p as a regex AST over the given
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* sequence sort. Two range_predicates with equal canonical
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* representations produce structurally identical regex ASTs:
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*
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* empty -> re.empty
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* top -> re.full_char_set
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* single range [lo, hi] -> re.range "lo" "hi"
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* multiple ranges -> right-associated re.union of single
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* ranges, in increasing order of lo
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* (matching the canonical range order
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* held by range_predicate).
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*/
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expr_ref range_predicate_to_regex(seq_util& u, range_predicate const& p, sort* seq_sort);
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}
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