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#pragma once
#include <set>
#include <unordered_map>
#include <vector>
#include <Parsers/ASTLiteral.h>
#include <Parsers/IAST_fwd.h>
namespace DB
{
class CNFQuery
{
public:
struct AtomicFormula
{
bool negative = false;
ASTPtr ast;
/// for set
bool operator<(const AtomicFormula & rhs) const
{
return ast->getTreeHash() == rhs.ast->getTreeHash()
? negative < rhs.negative
: ast->getTreeHash() < rhs.ast->getTreeHash();
}
bool operator==(const AtomicFormula & rhs) const
{
return negative == rhs.negative &&
ast->getTreeHash() == rhs.ast->getTreeHash() &&
ast->getColumnName() == rhs.ast->getColumnName();
}
};
using OrGroup = std::set<AtomicFormula>;
using AndGroup = std::set<OrGroup>;
CNFQuery(AndGroup && statements_) : statements(std::move(statements_)) { } /// NOLINT
template <typename P>
CNFQuery & filterAlwaysTrueGroups(P predicate_is_unknown) /// delete always true groups
{
AndGroup filtered;
for (const auto & or_group : statements)
{
if (predicate_is_unknown(or_group))
filtered.insert(or_group);
}
std::swap(statements, filtered);
return *this;
}
template <typename P>
CNFQuery & filterAlwaysFalseAtoms(P predicate_is_unknown) /// delete always false atoms
{
AndGroup filtered;
for (const auto & or_group : statements)
{
OrGroup filtered_group;
for (auto ast : or_group)
{
if (predicate_is_unknown(ast))
filtered_group.insert(ast);
}
if (!filtered_group.empty())
filtered.insert(filtered_group);
else
{
/// all atoms false -> group false -> CNF false
filtered.clear();
filtered_group.clear();
filtered_group.insert(AtomicFormula{false, std::make_shared<ASTLiteral>(static_cast<UInt8>(0))});
filtered.insert(filtered_group);
std::swap(statements, filtered);
return *this;
}
}
std::swap(statements, filtered);
return *this;
}
template <typename F>
const CNFQuery & iterateGroups(F func) const
{
for (const auto & group : statements)
func(group);
return *this;
}
CNFQuery & appendGroup(AndGroup&& and_group)
{
for (auto && or_group : and_group)
statements.emplace(or_group);
return *this;
}
template <typename F>
CNFQuery & transformGroups(F func)
{
AndGroup result;
for (const auto & group : statements)
{
auto new_group = func(group);
if (!new_group.empty())
result.insert(std::move(new_group));
}
std::swap(statements, result);
return *this;
}
template <typename F>
CNFQuery & transformAtoms(F func)
{
transformGroups([func](const OrGroup & group) -> OrGroup
{
OrGroup result;
for (const auto & atom : group)
{
auto new_atom = func(atom);
if (new_atom.ast)
result.insert(std::move(new_atom));
}
return result;
});
return *this;
}
const AndGroup & getStatements() const { return statements; }
std::string dump() const;
/// Converts != -> NOT =; <,>= -> (NOT) <; >,<= -> (NOT) <= for simpler matching
CNFQuery & pullNotOutFunctions();
/// Revert pullNotOutFunctions actions
CNFQuery & pushNotInFunctions();
/// (a OR b OR ...) AND (NOT a OR b OR ...) -> (b OR ...)
CNFQuery & reduce();
private:
AndGroup statements;
};
class TreeCNFConverter
{
public:
static constexpr size_t DEFAULT_MAX_GROWTH_MULTIPLIER = 20;
static constexpr size_t MAX_ATOMS_WITHOUT_CHECK = 200;
/// @max_growth_multiplier means that it's allowed to grow size of formula only
/// in that amount of times. It's needed to avoid exponential explosion of formula.
/// CNF of boolean formula with N clauses can have 2^N clauses.
/// If amount of atomic formulas will be exceeded nullopt will be returned.
/// 0 - means unlimited.
static std::optional<CNFQuery> tryConvertToCNF(
const ASTPtr & query, size_t max_growth_multiplier = DEFAULT_MAX_GROWTH_MULTIPLIER);
static CNFQuery toCNF(
const ASTPtr & query, size_t max_growth_multiplier = DEFAULT_MAX_GROWTH_MULTIPLIER);
static ASTPtr fromCNF(const CNFQuery & cnf);
};
void pushNotIn(CNFQuery::AtomicFormula & atom);
template <typename TAndGroup>
TAndGroup reduceOnceCNFStatements(const TAndGroup & groups)
{
TAndGroup result;
for (const auto & group : groups)
{
using GroupType = std::decay_t<decltype(group)>;
GroupType copy(group);
bool inserted = false;
for (const auto & atom : group)
{
copy.erase(atom);
using AtomType = std::decay_t<decltype(atom)>;
AtomType negative_atom(atom);
negative_atom.negative = !atom.negative;
copy.insert(negative_atom);
if (groups.contains(copy))
{
copy.erase(negative_atom);
result.insert(copy);
inserted = true;
break;
}
copy.erase(negative_atom);
copy.insert(atom);
}
if (!inserted)
result.insert(group);
}
return result;
}
template <typename TOrGroup>
bool isCNFGroupSubset(const TOrGroup & left, const TOrGroup & right)
{
if (left.size() > right.size())
return false;
for (const auto & elem : left)
if (!right.contains(elem))
return false;
return true;
}
template <typename TAndGroup>
TAndGroup filterCNFSubsets(const TAndGroup & groups)
{
TAndGroup result;
for (const auto & group : groups)
{
bool insert = true;
for (const auto & other_group : groups)
{
if (isCNFGroupSubset(other_group, group) && group != other_group)
{
insert = false;
break;
}
}
if (insert)
result.insert(group);
}
return result;
}
}
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