50 

    51 class PreparedStatement {

    52 private:

    53 	sqlite3_stmt* stmt;

    54 

    55 public:

    56 

    57 	PreparedStatement(sqlite3_stmt* stmt) : stmt(stmt) {

    58 	}

    59 

    60 	virtual ~PreparedStatement() {

    61 		sqlite3_finalize(stmt);

    62 	}

    63 

    64 	void setBoolean(int parameterIndex, relpipe::reader::boolean_t value) {

    65 		int result = sqlite3_bind_int(stmt, parameterIndex, value);

    66 		if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");

    67 	}

    68 

    69 	void setInteger(int parameterIndex, relpipe::reader::integer_t value) {

    70 		int result = sqlite3_bind_int64(stmt, parameterIndex, value);

    71 		if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");

    72 	}

    73 

    74 	void setString(int parameterIndex, std::string value) {

    75 		int result = sqlite3_bind_text(stmt, parameterIndex, value.c_str(), -1, SQLITE_TRANSIENT);

    76 		if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");

    77 	}

    78 

    79 	void setNull(int parameterIndex) {

    80 		int result = sqlite3_bind_null(stmt, parameterIndex);

    81 		if (result != SQLITE_OK) throw SqlException(L"Unable to set SQLite parameter.");

    82 	}

    83 

    84 	bool next() {

    85 		int result = sqlite3_step(stmt);

    86 		if (result == SQLITE_ROW) return true;

    87 		else if (result == SQLITE_DONE) return false;

    88 		else throw SqlException(L"Error while iterating over SQLite result.");

    89 	}

    90 

    91 	void reset() {

    92 		int result = sqlite3_reset(stmt);

    93 		if (result != SQLITE_OK) throw SqlException(L"Unable to reset SQLite prepared statement.");

    94 	}

    95 

    96 	int getColumnCount() {

    97 		return sqlite3_column_count(stmt);

    98 	}

    99 

   100 	std::string getColumName(int columnIndex) {

   101 		const char* name = sqlite3_column_name(stmt, columnIndex);

   102 		if (name) return name;

   103 		else throw SqlException(L"Unable to get SQLite column name.");

   104 	}

   105 

   106 	relpipe::writer::TypeId getColumType(int columnIndex, relpipe::writer::TypeId defaultType = relpipe::writer::TypeId::STRING) {

   107 		const char* type = sqlite3_column_decltype(stmt, columnIndex);

   108 

   109 		// TODO: sqlite3_column_decltype returns value only for columns of existing tables, not for dynamic expressions – SQLite uses dynamic types

   110 		// maybe we could write a function/module that returns result set metadata for given query (before executing it)

   111 		// or use at least explicit casts in SQL and modify sqlite3_column_decltype() function or add some new one to return such casted type

   112 		// 

   113 		// fprintf(stderr, "%d → %s\n", columnIndex, type);

   114 		// SELECT typeof(1+1); == "integer"

   115 		// https://www.sqlite.org/c3ref/column_decltype.html – sqlite3_column_decltype

   116 		// https://www.sqlite.org/c3ref/column_blob.html – sqlite3_column_type

   117 		// https://www.sqlite.org/datatype3.html – Datatypes In SQLite Version 3

   118 		// https://dba.stackexchange.com/questions/203220/sqlite-what-is-the-use-of-specifying-data-types

   119 		// https://www.mail-archive.com/sqlite-users@mailinglists.sqlite.org/msg118093.html

   120 

   121 		if (type == nullptr) return relpipe::writer::TypeId::STRING;

   122 		else if (strcmp(type, "integer") == 0) return relpipe::writer::TypeId::INTEGER;

   123 		else if (strcmp(type, "text") == 0) return relpipe::writer::TypeId::STRING;

   124 		else return defaultType;

   125 		// TODO: support also other data types

   126 	}

   127 

   128 	std::string getString(int columnIndex) {

   129 		const char* value = (const char*) sqlite3_column_text(stmt, columnIndex);

   130 		return value ? value : ""; // TODO: support NULL values (when supported in relpipe format)

   131 	}

   132 

   133 };