Regex: fix lookarounds handling when computing starting chars
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1c95074657
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@ -711,16 +711,19 @@ private:
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return res;
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}
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static constexpr size_t start_chars_count = CompiledRegex::StartChars::count;
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// Fills accepted and rejected according to which chars can start the given node,
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// returns true if the node did not consume the char, hence a following node in
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// sequence would be still relevant for the parent node start chars computation.
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bool compute_start_chars(const ParsedRegex::AstNodePtr& node,
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bool (&accepted)[256], bool (&rejected)[256]) const
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bool (&accepted)[start_chars_count],
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bool (&rejected)[start_chars_count]) const
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{
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switch (node->op)
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{
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case ParsedRegex::Literal:
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if (node->value < 256)
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if (node->value < start_chars_count)
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accepted[node->value] = true;
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return node->quantifier.allows_none();
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case ParsedRegex::AnyChar:
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@ -763,18 +766,28 @@ private:
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case ParsedRegex::ResetStart:
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return true;
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case ParsedRegex::LookAhead:
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if (not node->children.empty())
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compute_start_chars(m_forward ? node->children.front() : node->children.back(),
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accepted, rejected);
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case ParsedRegex::LookBehind:
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if (not node->children.empty() and
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m_forward == (node->op == ParsedRegex::LookAhead))
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{
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auto& child = m_forward ? node->children.front() : node->children.back();
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if (child->op == ParsedRegex::Literal and child->value < start_chars_count)
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{
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// Any other char is rejected
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std::fill(rejected, rejected + child->value, true);
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std::fill(rejected + child->value + 1, rejected + start_chars_count, true);
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}
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}
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return true;
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case ParsedRegex::NegativeLookAhead:
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if (not node->children.empty())
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compute_start_chars(m_forward ? node->children.front() : node->children.back(),
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rejected, accepted);
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return true;
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case ParsedRegex::LookBehind:
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return true;
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case ParsedRegex::NegativeLookBehind:
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if (node->children.size() == 1 and
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m_forward == (node->op == ParsedRegex::NegativeLookAhead))
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{
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auto& child = node->children.front();
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if (child->op == ParsedRegex::Literal and child->value < start_chars_count)
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rejected[child->value] = true;
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}
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return true;
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}
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return false;
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@ -782,8 +795,8 @@ private:
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std::unique_ptr<CompiledRegex::StartChars> compute_start_chars() const
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{
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bool accepted[256] = {};
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bool rejected[256] = {};
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bool accepted[start_chars_count] = {};
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bool rejected[start_chars_count] = {};
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if (compute_start_chars(m_parsed_regex.ast, accepted, rejected))
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return nullptr;
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@ -791,7 +804,7 @@ private:
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return nullptr;
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auto start_chars = std::make_unique<CompiledRegex::StartChars>();
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for (int i = 0; i < 256; ++i)
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for (int i = 0; i < start_chars_count; ++i)
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start_chars->map[i] = accepted[i] and not rejected[i];
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return start_chars;
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@ -1133,6 +1146,12 @@ auto test_regex = UnitTest{[]{
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kak_assert(StringView{vm.captures()[2], vm.captures()[3]} == "ber");
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}
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{
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TestVM<MatchDirection::Backward> vm{R"((baz|boz|foo|qux)(?<!baz)(?<!o))"};
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kak_assert(vm.exec("quxbozfoobaz", RegexExecFlags::Search));
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kak_assert(StringView{vm.captures()[0], vm.captures()[1]} == "boz");
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}
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{
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TestVM<> vm{R"(()*)"};
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kak_assert(not vm.exec(" "));
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@ -67,7 +67,11 @@ struct CompiledRegex : RefCountable
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MatchDirection direction;
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size_t save_count;
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struct StartChars { bool map[256]; };
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struct StartChars
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{
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static constexpr size_t count = 256;
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bool map[count];
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};
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std::unique_ptr<StartChars> start_chars;
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};
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