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