dbms: development.

dbms/include/DB/Parsers/formatAST.h

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+#ifndef DBMS_PARSERS_FORMATAST_H
+#define DBMS_PARSERS_FORMATAST_H
+
+#include <ostream>
+
+#include <DB/Parsers/IAST.h>
+#include <DB/Parsers/ASTSelectQuery.h>
+#include <DB/Parsers/ASTExpressionList.h>
+#include <DB/Parsers/ASTFunction.h>
+#include <DB/Parsers/ASTIdentifier.h>
+#include <DB/Parsers/ASTLiteral.h>
+
+
+namespace DB
+{
+
+/** Берёт синтаксическое дерево и превращает его обратно в текст.
+  */
+void formatAST(const IAST 				& ast, std::ostream & s);
+
+void formatAST(const ASTSelectQuery 	& ast, std::ostream & s);
+void formatAST(const ASTExpressionList 	& ast, std::ostream & s);
+void formatAST(const ASTFunction 		& ast, std::ostream & s);
+void formatAST(const ASTIdentifier 		& ast, std::ostream & s);
+void formatAST(const ASTLiteral 		& ast, std::ostream & s);
+
+}
+
+
+#endif

dbms/src/Parsers/formatAST.cpp

@@ -0,0 +1,127 @@
+#include <sstream>
+
+#include <boost/variant/static_visitor.hpp>
+
+#include <Poco/NumberFormatter.h>
+
+#include <strconvert/escape_manip.h>
+
+#include <DB/Core/Exception.h>
+#include <DB/Core/ErrorCodes.h>
+
+#include <DB/Parsers/formatAST.h>
+
+
+namespace DB
+{
+
+/** Выводит текстовое представление типа, как литерала в SQL запросе */
+class FieldVisitorToString : public boost::static_visitor<String>
+{
+public:
+	String operator() (const Null 		& x) const { return "NULL"; }
+	String operator() (const UInt64 	& x) const { return Poco::NumberFormatter::format(x); }
+	String operator() (const Int64 		& x) const { return Poco::NumberFormatter::format(x); }
+	String operator() (const Float64 	& x) const { return Poco::NumberFormatter::format(x); }
+
+	String operator() (const String 	& x) const
+	{
+		std::stringstream s;
+		s << strconvert::quote_fast << x;
+		return s.str();
+	}
+
+	String operator() (const Array 		& x) const
+	{
+		std::stringstream s;
+		FieldVisitorToString visitor;
+		
+		s << "[";
+		for (Array::const_iterator it = x.begin(); it != x.end(); ++it)
+		{
+			if (it != x.begin())
+				s << ", ";
+			s << boost::apply_visitor(FieldVisitorToString(), *it);
+		}
+		s << "]";
+
+		return s.str();
+	}
+};
+
+
+void formatAST(const IAST & ast, std::ostream & s)
+{
+	const ASTSelectQuery * select = dynamic_cast<const ASTSelectQuery *>(&ast);
+	if (select)
+	{
+		formatAST(*select, s);
+		return;
+	}
+	
+	const ASTExpressionList * exp_list = dynamic_cast<const ASTExpressionList *>(&ast);
+	if (exp_list)
+	{
+		formatAST(*exp_list, s);
+		return;
+	}
+
+	const ASTFunction * func = dynamic_cast<const ASTFunction *>(&ast);
+	if (func)
+	{
+		formatAST(*func, s);
+		return;
+	}
+
+	const ASTIdentifier * id = dynamic_cast<const ASTIdentifier *>(&ast);
+	if (id)
+	{
+		formatAST(*id, s);
+		return;
+	}
+
+	const ASTLiteral * lit = dynamic_cast<const ASTLiteral *>(&ast);
+	if (lit)
+	{
+		formatAST(*lit, s);
+		return;
+	}
+
+	throw DB::Exception("Unknown element in AST", ErrorCodes::UNKNOWN_ELEMENT_IN_AST);
+}
+
+void formatAST(const ASTSelectQuery 		& ast, std::ostream & s)
+{
+	s << "SELECT ";
+	formatAST(*ast.select, s);
+}
+
+void formatAST(const ASTExpressionList 	& ast, std::ostream & s)
+{
+	for (ASTs::const_iterator it = ast.children.begin(); it != ast.children.end(); ++it)
+	{
+		if (it != ast.children.begin())
+			s << ", ";
+		formatAST(**it, s);
+	}
+}
+
+void formatAST(const ASTFunction 			& ast, std::ostream & s)
+{
+	s << ast.name << '(';
+	formatAST(*ast.arguments, s);
+	s << ')';
+}
+
+void formatAST(const ASTIdentifier 		& ast, std::ostream & s)
+{
+	s << ast.name;
+}
+
+void formatAST(const ASTLiteral 			& ast, std::ostream & s)
+{
+	s << boost::apply_visitor(FieldVisitorToString(), ast.value);
+}
+
+}
+