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#pragma once
#include <Parsers/IAST.h>
#include <Parsers/ASTFunction.h>
#include <Interpreters/InDepthNodeVisitor.h>
namespace DB
{
/// It converts if-chain to multiIf.
class OptimizeIfChainsVisitor
{
public:
OptimizeIfChainsVisitor() = default;
void visit(ASTPtr & ast);
private:
ASTs ifChain(const ASTPtr & child);
};
/// Replaces multiIf with one condition to if,
/// because it's more efficient.
class OptimizeMultiIfToIfData
{
public:
using TypeToVisit = ASTFunction;
void visit(ASTFunction & function, ASTPtr &)
{
/// 3 args: condition, then branch, else branch.
if (function.name == "multiIf" && (function.arguments && function.arguments->children.size() == 3))
function.name = "if";
}
};
using OptimizeMultiIfToIfMatcher = OneTypeMatcher<OptimizeMultiIfToIfData>;
using OptimizeMultiIfToIfVisitor = InDepthNodeVisitor<OptimizeMultiIfToIfMatcher, true>;
}
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