ClickHouse/dbms/include/DB/Analyzers/AnalyzeLambdas.h

#pragma once

#include <DB/Parsers/IAST.h>
#include <vector>


namespace DB
{

class WriteBuffer;


/** For every lambda expression, rename its parameters to '_lambda0_arg0' form.
  * Check correctness of lambda expressions.
  * Find functions, that have lambda expressions as arguments (they are called "higher order" functions).
  *
  * This should be done before CollectAliases.
  */
struct AnalyzeLambdas
{
	void process(ASTPtr & ast);

	/// Parameters of lambda expressions.
	using LambdaParameters = std::vector<String>;
	static LambdaParameters extractLambdaParameters(ASTPtr & ast);


	using HigherOrderFunctions = std::vector<ASTPtr>;
	HigherOrderFunctions higher_order_functions;

	/// Debug output
	void dump(WriteBuffer & out) const;
};

}