1 /**

     2  * Relational pipes

     3  * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)

     4  *

     5  * This program is free software: you can redistribute it and/or modify

     6  * it under the terms of the GNU General Public License as published by

     7  * the Free Software Foundation, version 3 of the License.

     8  *

     9  * This program is distributed in the hope that it will be useful,

    10  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

    12  * GNU General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU General Public License

    15  * along with this program. If not, see <http://www.gnu.org/licenses/>.

    16  */

    17 #pragma once

    18 

    19 #include <memory>

    20 #include <string>

    21 #include <vector>

    22 #include <iostream>

    23 #include <sstream>

    24 #include <locale>

    25 #include <codecvt>

    26 

    27 #include <relpipe/reader/typedefs.h>

    28 #include <relpipe/reader/TypeId.h>

    29 #include <relpipe/reader/handlers/RelationalReaderStringHandler.h>

    30 #include <relpipe/reader/handlers/AttributeMetadata.h>

    31 

    32 #include "Configuration.h"

    33 #include "RelpipeSQLWriterException.h"

    34 

    35 namespace relpipe {

    36 namespace out {

    37 namespace sql {

    38 

    39 using namespace relpipe;

    40 using namespace relpipe::reader;

    41 using namespace relpipe::reader::handlers;

    42 

    43 class SQLHandler : public RelationalReaderStringHandler {

    44 private:

    45 	std::ostream& output;

    46 	Configuration& configuration;

    47 	const char QUOTE = '"';

    48 	std::wstring_convert<std::codecvt_utf8<wchar_t>> convertor; // generate SQL always in UTF-8

    49 	std::vector<AttributeMetadata> firstAttributes;

    50 	integer_t valueCount = 0;

    51 

    52 	/**

    53 	 * @param a

    54 	 * @param b

    55 	 * @return true if relations have same number and types of attributes (names may differ)

    56 	 */

    57 	bool matches(const std::vector<AttributeMetadata>& a, const std::vector<AttributeMetadata>& b) {

    58 		if (a.size() != b.size()) return false;

    59 		for (int i = 0, limit = a.size(); i < limit; i++) if (a[i].getTypeId() != b[i].getTypeId()) return false;

    60 		return true;

    61 	}

    62 public:

    63 

    64 	SQLHandler(std::ostream& output, Configuration& configuration) : output(output), configuration(configuration) {

    65 	}

    66 

    67 	void startRelation(string_t name, std::vector<AttributeMetadata> attributes) override {

    68 		// TODO: CREATE TABLE

    69 		// TODO: escape identifiers

    70 		// TODO: ALTER TABLE / add columns on duplicate relation name

    71 		// TODO: custom data type mapping

    72 		// TODO: custom name transformation

    73 		// TODO: custom SQL script before/after stream/relation/record

    74 		// TODO: comments and/or custom comments

    75 		// TODO: optional transactions: BEGIN/COMMIT/ROLLBACK for stream/relation/record

    76 		output << "CREATE TABLE " << convertor.to_bytes(name) << " ( ... );" << std::endl;

    77 		

    78 		if (firstAttributes.empty()) {

    79 			firstAttributes = attributes;

    80 			if (configuration.writeHeader) for (auto attr : attributes) attribute(configuration.writeTypes ? attr.getAttributeName() + L"::" + attr.getTypeName() : attr.getAttributeName());

    81 		} else if (matches(firstAttributes, attributes)) {

    82 			// do UNION ALL – just append the records

    83 		} else {

    84 			// throw RelpipeSQLWriterException(L"To the SQL format we can convert only one relation or multiple relations that have same number of attributes of same types (relation and attribute names may differ – result is named after the first one).");

    85 		}

    86 	}

    87 

    88 	void attribute(const string_t& value) override {

    89 		valueCount++;

    90 		

    91 		if (value.size() > 0) {

    92 			output << QUOTE;

    93 			for (auto ch : convertor.to_bytes(value)) {

    94 				if (ch == QUOTE) output << QUOTE << QUOTE;

    95 				else output << ch;

    96 			}

    97 			output << QUOTE;

    98 		}

    99 

   100 		if (valueCount % firstAttributes.size()) {

   101 			output << ",";

   102 		} else {

   103 			// TODO: INSERT INTO ...

   104 			// TODO: escape identifiers and values

   105 			// TODO: optional use of function/procedure instead of INSERT

   106 			// TODO: optional INSERT of multiple records

   107 			output << std::endl << "INSERT INTO ... VALUES ... ;" << std::endl;;

   108 			valueCount = 0;

   109 		}

   110 	}

   111 

   112 	void endOfPipe() {

   113 		output.flush();

   114 	}

   115 

   116 };

   117 

   118 }

   119 }

   120 }