From b4711985b3c8d88e02e7d39cf1653165185867df Mon Sep 17 00:00:00 2001
From: VaclavT <vaclavt@gmail.com>
Date: Sun, 4 Jul 2021 15:03:13 +0200
Subject: [PATCH] another ugly basic implementation

---
 CMakeLists.txt |   2 +-
 Readme.md      |  10 +++++
 executor.cpp   |  79 ++++++++++++++++++++++++--------
 lexer.cpp      |  14 ++++--
 lexer.h        |   7 ++-
 main.cpp       |   5 ++-
 parser.cpp     |  79 +++++++++++++++++++++++---------
 parser.h       |  70 +++++++++++++++++++++++++++--
 row.cpp        |  48 ++++++++++++++++++++
 row.h          | 119 +++++++++++++++++++++++++++++++++++++++++++++++++
 table.cpp      |  28 +++++++++---
 table.h        |  16 +++++--
 12 files changed, 417 insertions(+), 60 deletions(-)
 create mode 100644 Readme.md
 create mode 100644 row.cpp
 create mode 100644 row.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e09d4c5..30407fc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,7 +12,7 @@ project(msql)
 set(PROJECT_NAME msql)
 
 set(SOURCE
-	exception.cpp lexer.cpp parser.cpp executor.cpp main.cpp table.cpp table.h)
+	exception.cpp lexer.cpp parser.cpp executor.cpp main.cpp table.cpp table.h row.cpp row.h)
 
 add_executable(${PROJECT_NAME} ${SOURCE})
 
diff --git a/Readme.md b/Readme.md
new file mode 100644
index 0000000..09d4834
--- /dev/null
+++ b/Readme.md
@@ -0,0 +1,10 @@
+
+### TODO
+- rename it to usql
+- rename Exception to UException, Table to UTable, Row to URow etc
+- unify using of float and double keywords  
+- add constructors  
+- add exceptions  
+- class members should have prefix m_O
+- add pipe | token  
+- add logging
\ No newline at end of file
diff --git a/executor.cpp b/executor.cpp
index c0356dc..fe09c46 100644
--- a/executor.cpp
+++ b/executor.cpp
@@ -14,7 +14,7 @@ Table* Executor::find_table(const std::string name) {
     if (table_def != std::end(m_tables)) {
         return table_def.operator->();
     } else {
-        // TODO throw exception
+        throw Exception("table not found (" + name + ")");
     }
 }
 
@@ -50,25 +50,28 @@ bool Executor::execute_insert_into_table(InsertIntoTableNode& node) {
     Table* table_def = find_table(node.table_name);
 
     // prepare empty new_row
-    std::vector<std::string> new_row;
-    new_row.reserve(table_def->columns_count());
-    for(size_t i=0; i<table_def->columns_count(); i++) {
-        new_row.push_back(std::string {""});
-    }
+    Row new_row = table_def->createEmptyRow();
 
     // copy values
     for(size_t i=0; i<node.cols_names.size(); i++) {
         auto colNameNode = node.cols_names[i];
         ColDefNode col_def = table_def->get_column_def(colNameNode.name);
 
-        // TODO validate
-        new_row[col_def.order] = node.cols_values[i].value;
+        // TODO validate value
+        
+        if (col_def.type == ColumnType::integer_type) {
+            new_row.setColumnValue(col_def.order, std::stoi(node.cols_values[i].value));
+        } else if (col_def.type == ColumnType::float_type) {
+            new_row.setColumnValue(col_def.order, std::stof(node.cols_values[i].value));
+        } else {
+            new_row.setColumnValue(col_def.order, node.cols_values[i].value);
+        }
     }
 
     // TODO check not null columns
 
     // append new_row
-    table_def->m_rows.push_back(new_row);
+    table_def->addRow(new_row);
 
     return true;
 }
@@ -99,18 +102,56 @@ bool Executor::execute_select(SelectFromTableNode& node) {
 
 
     for (auto row = begin (table->m_rows); row != end (table->m_rows); ++row) {
-            // eval there for row
-            bool where_true = true;
-
-            if (where_true) {
-                // prepare empty row
-                std::vector<std::string> new_row;
-                new_row.reserve(result.columns_count());
-                for(auto i=0; i<result.columns_count(); i++) {
-                    new_row.push_back(row->at(source_table_col_index[i]));
+        // eval where for row
+        bool where_true = true;
+        if (node.where->node_type == NodeType::true_node) {    // no where clause
+            where_true = true;
+        } else {    // evaluate where
+            RelationalOperatorNode& filter = static_cast<RelationalOperatorNode &>(*node.where);
+            if (filter.op == RelationalOperatorType::greater) {
+                std::unique_ptr<Node> left_value;
+                if ((*filter.left).node_type == NodeType::database_value) {
+                    DatabaseValueNode *dvl = static_cast<DatabaseValueNode*>(filter.left.get());
+                    ColDefNode col_def = table->get_column_def(dvl->col_name); // TODO optimize it to just get this def once
+                    auto db_value = row->ithColum(col_def.order);
+                    if (col_def.type == ColumnType::integer_type) {
+                        left_value = std::make_unique<IntValueNode>(db_value->integerValue());
+                    }
+                    // TODO other cases
                 }
-                result.m_rows.push_back(new_row);
+
+                std::unique_ptr<Node> right_value;
+                if ((*filter.right).node_type == NodeType::int_value) {
+                    IntValueNode *ivl = static_cast<IntValueNode*>(filter.right.get());
+                    right_value = std::make_unique<IntValueNode>(ivl->value);
+                }
+
+                IntValueNode* left_int_value = static_cast<IntValueNode *>(left_value.get());
+                IntValueNode* right_int_value = static_cast<IntValueNode *>(right_value.get());
+
+                where_true = left_int_value->value > right_int_value->value;
             }
+        }
+
+        if (where_true) {
+            // prepare empty row
+            Row new_row = result.createEmptyRow();
+
+            // copy column values
+            for(auto idx=0; idx<result.columns_count(); idx++) {
+                auto row_col_index = source_table_col_index[idx];
+                ColValue *col_value = row->ithColum(row_col_index);
+                if (result_tbl_col_defs[idx].type == ColumnType::integer_type)
+                    new_row.setColumnValue(idx, ((ColIntegerValue*)col_value)->integerValue());
+                if (result_tbl_col_defs[idx].type == ColumnType::float_type)
+                    new_row.setColumnValue(idx, col_value->floatValue());
+                if (result_tbl_col_defs[idx].type == ColumnType::varchar_type)
+                    new_row.setColumnValue(idx, col_value->stringValue());
+            }
+
+            // add row to result
+            result.m_rows.push_back(new_row);
+        }
     }
 
     result.print();
diff --git a/lexer.cpp b/lexer.cpp
index e95e847..a9dbec3 100644
--- a/lexer.cpp
+++ b/lexer.cpp
@@ -24,7 +24,7 @@ void Lexer::parse(const std::string &code) {
 
 	// TODO make it constant
 	std::regex words_regex("[0-9]+\\.[0-9]+|[0-9][0-9_]+[0-9]|[0-9]+|[A-Za-z]+[A-Za-z0-9_#]*|[\\(\\)\\[\\]\\{\\}]|[-\\+\\*/"
-			       ",;:\?]|==|>=|<=|~=|>|<|=|;|~|\\|\\||&&|\n|\r|\r\n|'([^']|'')*'|\".*?\"|%.*?\n");
+			       ",;:\?]|==|>=|<=|~=|>|<|=|;|~|\\||or|and|\n|\r|\r\n|'([^']|'')*'|\".*?\"|%.*?\n");
 	
 	auto words_begin = std::sregex_iterator(m_code_str.begin(), m_code_str.end(), words_regex);
 	auto words_end = std::sregex_iterator();
@@ -55,6 +55,12 @@ void Lexer::debugTokens() {
 
 Token Lexer::currentToken() { return m_tokens[m_index]; }
 
+Token Lexer::consumeCurrentToken() {
+    int i = m_index;
+    nextToken();
+    return m_tokens[i];
+}
+
 void Lexer::nextToken() {
 	if (m_index < m_tokens.size()) {
 		m_index++;
@@ -65,7 +71,7 @@ void Lexer::skipToken(TokenType type) {
 	if (tokenType() == type) {
 		nextToken();
 	} else {
-		throw Exception("ERROR unexpected token " + currentToken().token_string + ", instead of " + typeToString(type));
+		throw Exception("ERROR unexpected token " + consumeCurrentToken().token_string + ", instead of " + typeToString(type));
 	}
 }
 
@@ -177,10 +183,10 @@ TokenType Lexer::type(const std::string &token) {
 	if (token == "varchar")
 		return TokenType::keyword_varchar;
 
-	if (token == "||")
+	if (token == "or")
 		return TokenType::logical_or;
 
-	if (token == "&&")
+	if (token == "and")
 		return TokenType::logical_and;
 
 	if (token == ",")
diff --git a/lexer.h b/lexer.h
index 16fbe39..4098266 100644
--- a/lexer.h
+++ b/lexer.h
@@ -40,6 +40,7 @@ enum class TokenType {
 	close_paren,
 	logical_and,
 	logical_or,
+	pipe,
 	semicolon,
 	comma,
 	newline,
@@ -61,7 +62,8 @@ public:
 
 	void debugTokens();
 
-	Token currentToken();
+    Token currentToken();
+	Token consumeCurrentToken();
 
 	void nextToken();
 
@@ -72,7 +74,8 @@ public:
 	TokenType nextTokenType();
 	TokenType prevTokenType();
 
-	static bool isRelationalOperator(TokenType token_type);
+    static bool isRelationalOperator(TokenType token_type);
+	static bool isLogicalOperator(TokenType token_type);
 
 private:
 	TokenType type(const std::string &token);
diff --git a/main.cpp b/main.cpp
index 2c2c328..685f397 100644
--- a/main.cpp
+++ b/main.cpp
@@ -16,7 +16,8 @@ int main(int argc, char *argv[]) {
             "insert into a (i, s) values(1, 'one')",
             "insert into a (i, s) values(2, 'two')",
             "insert into a (i, s) values(3, 'two')",
-            "select i, s from a where i > 0"
+            "insert into a (i, s) values(4, 'four')",
+            "select i, s from a where i > 2"
 //            "update a set s = 'three' where i = 3"
 //            "delete from a where i = 3"
 //            "select i, s from a where i > 0"
@@ -25,7 +26,7 @@ int main(int argc, char *argv[]) {
 
     for(auto command : sql_commands) {
         auto node = parser.parse(command);
-        executor.execute(*node.get());
+        executor.execute(*node);
     }
 
 	return 0;
diff --git a/parser.cpp b/parser.cpp
index a3cf028..61a5ba8 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -19,6 +19,7 @@ std::unique_ptr<Node> Parser::parse(const std::string &code) {
 		return parse_select_from_table();
 	}
 
+	std::cout << "ERROR, token:" << lexer.currentToken().token_string << std::endl;
 	return std::make_unique<Node>(NodeType::error);
 }
 
@@ -29,9 +30,8 @@ std::unique_ptr<Node> Parser::parse_create_table() {
 	lexer.skipToken(TokenType::keyword_table);
 
 	if (lexer.tokenType() != TokenType::identifier)	{ /* TODO handle error */ }
-	std::string table_name = lexer.currentToken().token_string;
-	lexer.nextToken();
-	
+	std::string table_name = lexer.consumeCurrentToken().token_string;
+
 	lexer.skipToken(TokenType::open_paren);
 	int column_order = 0;
 	do {
@@ -42,8 +42,7 @@ std::unique_ptr<Node> Parser::parse_create_table() {
 
 		// column name
 		if (lexer.tokenType() != TokenType::identifier)	{ /* TODO handle error */ }
-		column_name = lexer.currentToken().token_string;
-		lexer.nextToken();
+		column_name = lexer.consumeCurrentToken().token_string;
 
 		// column type and optionaly len
 		if (lexer.tokenType() == TokenType::keyword_int) {
@@ -57,8 +56,7 @@ std::unique_ptr<Node> Parser::parse_create_table() {
 			lexer.nextToken();
 			lexer.skipToken(TokenType::open_paren);
 			if (lexer.tokenType() == TokenType::int_number) {
-				column_len = std::stoi(lexer.currentToken().token_string);
-				lexer.nextToken();
+				column_len = std::stoi(lexer.consumeCurrentToken().token_string);
 			} else { /* TODO handle error */ }
 			lexer.skipToken(TokenType::close_paren);
 		} else { /* TODO handle error */ }
@@ -94,15 +92,13 @@ std::unique_ptr<Node> Parser::parse_insert_into_table() {
 
     // table name
     if (lexer.tokenType() != TokenType::identifier)	{ /* TODO handle error */ }
-    std::string table_name = lexer.currentToken().token_string;
-    lexer.nextToken();
+    std::string table_name = lexer.consumeCurrentToken().token_string;
 
     // column names
     lexer.skipToken(TokenType::open_paren);
     do {
         if (lexer.tokenType() != TokenType::identifier)	{ /* TODO handle error */ }
-        cols_names.push_back(lexer.currentToken().token_string);
-        lexer.nextToken();
+        cols_names.push_back(lexer.consumeCurrentToken().token_string);
 
         lexer.skipTokenOptional(TokenType::comma);
     } while (lexer.tokenType() != TokenType::close_paren);
@@ -113,8 +109,7 @@ std::unique_ptr<Node> Parser::parse_insert_into_table() {
     // column values
     lexer.skipToken(TokenType::open_paren);
     do {
-        cols_values.push_back(lexer.currentToken().token_string);
-        lexer.nextToken();
+        cols_values.push_back(lexer.consumeCurrentToken().token_string);
 
         lexer.skipTokenOptional(TokenType::comma);
     } while (lexer.tokenType() != TokenType::close_paren);
@@ -124,25 +119,69 @@ std::unique_ptr<Node> Parser::parse_insert_into_table() {
 }
 
 std::unique_ptr<Node> Parser::parse_select_from_table() {
-    std::vector<Node> where {};
     std::vector<ColNameNode> cols_names {};
+    std::unique_ptr<Node> where_node;
 
     lexer.skipToken(TokenType::keyword_select);
     // TODO support also numbers and expressions
     while (lexer.tokenType() != TokenType::keyword_from) {
 	// TODO add consumeToken() which returns token and advances to next token
-        cols_names.push_back(lexer.currentToken().token_string);
-        lexer.nextToken();
+        cols_names.push_back(lexer.consumeCurrentToken().token_string);
         lexer.skipTokenOptional(TokenType::comma);
     }
     lexer.skipToken(TokenType::keyword_from);
-    std::string table_name = lexer.currentToken().token_string;
-    lexer.nextToken();
+    std::string table_name = lexer.consumeCurrentToken().token_string;
 
-    if (lexer.tokenType() == TokenType::keyword_where) {}
+    if (lexer.tokenType() == TokenType::keyword_where) {
+        lexer.skipToken(TokenType::keyword_where);
+        where_node = parse_where_clause();
+    } else {
+        where_node = std::make_unique<TrueNode>();
+    }
 //    if (lexer.tokenType() == TokenType::keyword_order_by) {}
 //    if (lexer.tokenType() == TokenType::keyword_offset) {}
 //    if (lexer.tokenType() == TokenType::keyword_limit) {}
 
-	return std::make_unique<SelectFromTableNode>(table_name, cols_names, where);
+	return std::make_unique<SelectFromTableNode>(table_name, cols_names, std::move(where_node));
+}
+
+std::unique_ptr<Node> Parser::parse_where_clause() {
+    // TODO add support for multiple filters
+    // TODO add support for parenthises
+
+    auto left = parse_operand_node();
+    auto operation = parse_operator();
+    auto right = parse_operand_node();
+
+    return std::make_unique<RelationalOperatorNode>(operation, std::move(left), std::move(right));
+}
+
+std::unique_ptr<Node> Parser::parse_operand_node() {
+    // while not end or order or limit
+    auto token_type = lexer.tokenType();
+    std::string tokenString = lexer.consumeCurrentToken().token_string;
+    switch (token_type) {
+        case TokenType::int_number:
+            return std::make_unique<IntValueNode>(std::stoi(tokenString));
+        case TokenType::double_number:
+            return std::make_unique<FloatValueNode>(std::stod(tokenString));
+        case TokenType::string_literal:
+            return std::make_unique<StringValueNode>(tokenString);
+        case TokenType::identifier:
+            return std::make_unique<DatabaseValueNode>(tokenString);
+        default: ;
+            // Throw exception
+    }
+}
+
+RelationalOperatorType Parser::parse_operator() {
+    auto op = lexer.consumeCurrentToken();
+    switch (op.type) {
+        case TokenType::equal:
+            return RelationalOperatorType::equal;
+        case TokenType::greater:
+            return RelationalOperatorType::greater;
+        default: ;
+            // Throw exception
+    }
 }
\ No newline at end of file
diff --git a/parser.h b/parser.h
index 535a928..bedca1e 100644
--- a/parser.h
+++ b/parser.h
@@ -14,6 +14,13 @@ enum class ColumnType {
 };
 
 enum class NodeType {
+    true_node,
+    int_value,
+    float_value,
+    string_value,
+    database_value,
+    logical_operator,
+    relational_operator,
 	create_table,
 	insert_into,
 	select_from,
@@ -56,6 +63,59 @@ struct ColDefNode : Node {
 		Node(NodeType::column_def), name(col_name), type(col_type), order(col_order), length(col_len), null(nullable) {}
 };
 
+struct  TrueNode : Node {
+    TrueNode() : Node(NodeType::true_node) {}
+};
+
+struct  IntValueNode : Node {
+    int    value;
+
+    IntValueNode(int value) : Node(NodeType::int_value), value(value) {}
+};
+
+struct  FloatValueNode : Node {
+    double    value;
+
+    FloatValueNode(double value) : Node(NodeType::float_value), value(value) {}
+};
+
+struct  StringValueNode : Node {
+    std::string     value;
+
+    StringValueNode(std::string value) : Node(NodeType::string_value), value(value) {}
+};
+
+struct  DatabaseValueNode : Node {
+    std::string     col_name;
+
+    DatabaseValueNode(std::string name) : Node(NodeType::database_value), col_name(name) {}
+};
+
+struct LogicalOperatorNode : Node {
+//    and_operator,
+//    or_operator,
+//    not_operator,
+    // and / or / not
+    std::unique_ptr<Node> left;
+    std::unique_ptr<Node> right;
+};
+
+enum class RelationalOperatorType {
+    equal,
+    greater
+    // =, !=, >, >=, <, <=, like
+};
+
+struct RelationalOperatorNode : Node {
+    RelationalOperatorType  op;
+
+    std::unique_ptr<Node> left;
+    std::unique_ptr<Node> right;
+
+    RelationalOperatorNode(RelationalOperatorType op, std::unique_ptr<Node> left, std::unique_ptr<Node> right) :
+        Node(NodeType::relational_operator), op(op), left(std::move(left)), right(std::move(right)) {};
+};
+
 struct CreateTableNode : Node {
 	std::string table_name;
 	std::vector<ColDefNode> cols_defs;
@@ -76,10 +136,10 @@ struct InsertIntoTableNode : Node {
 struct SelectFromTableNode : Node {
     std::string table_name;
     std::vector<ColNameNode> cols_names;
-    std::vector<Node> where;
+    std::unique_ptr<Node> where;
 
-    SelectFromTableNode(const std::string name, std::vector<ColNameNode> names, std::vector<Node> where_clause) :
-            Node(NodeType::select_from), table_name(name), cols_names(names), where(where_clause) {}
+    SelectFromTableNode(const std::string name, std::vector<ColNameNode> names, std::unique_ptr<Node> where_clause) :
+            Node(NodeType::select_from), table_name(name), cols_names(names), where(std::move(where_clause)) {}
 };
 
 struct UpdateTableNode : Node { };
@@ -101,6 +161,10 @@ private:
     std::unique_ptr<Node> parse_insert_into_table();
     std::unique_ptr<Node> parse_select_from_table();
 
+    std::unique_ptr<Node> parse_where_clause();
+    std::unique_ptr<Node> parse_operand_node();
+    RelationalOperatorType parse_operator();
+
 private:
 	Lexer lexer;
 };
diff --git a/row.cpp b/row.cpp
new file mode 100644
index 0000000..ee4ec59
--- /dev/null
+++ b/row.cpp
@@ -0,0 +1,48 @@
+
+#include "row.h"
+
+
+Row::Row(int cols_count) {
+    m_columns.reserve(cols_count);
+    for (int i = 0; i < cols_count; i++) {
+        m_columns.push_back(std::make_unique<ColValue>());
+    }
+}
+
+Row::Row(const Row &other) {
+    m_columns.reserve(other.m_columns.size());
+    // TODO fixme this is nonsense
+    for (int i = 0; i < other.m_columns.size(); i++) {
+        m_columns.push_back(std::make_unique<ColNullValue>());
+    }
+
+    for (int i = 0; i < other.m_columns.size(); i++) {
+        if (ColIntegerValue* other_v = dynamic_cast<ColIntegerValue*>(other.m_columns[i].get())) {
+            setColumnValue(i, other_v->integerValue());
+        }
+        if (ColFloatValue* other_v = dynamic_cast<ColFloatValue*>(other.m_columns[i].get())) {
+            setColumnValue(i, other_v->floatValue());
+        }
+        if (ColStringValue* other_v = dynamic_cast<ColStringValue*>(other.m_columns[i].get())) {
+            setColumnValue(i, other_v->stringValue());
+        }
+    }
+}
+
+void Row::setColumnValue(int col_index, int value) {
+    m_columns[col_index] = std::make_unique<ColIntegerValue>(value);
+}
+
+void Row::setColumnValue(int col_index, double value) {
+    m_columns[col_index] = std::make_unique<ColFloatValue>(value);
+}
+
+void Row::setColumnValue(int col_index, std::string value) {
+    m_columns[col_index] = std::make_unique<ColStringValue>(value);
+};
+
+void Row::print() {
+    for(int i=0; i<m_columns.size(); i++) {
+        m_columns[i].get()->print();
+    }
+}
diff --git a/row.h b/row.h
new file mode 100644
index 0000000..474cb6e
--- /dev/null
+++ b/row.h
@@ -0,0 +1,119 @@
+#pragma once
+
+#include "exception.h"
+#include "parser.h"
+
+#include <vector>
+
+class ColumnValue {
+
+
+private:
+    ColumnType  m_type;
+    union {
+        int     int_value;
+        double  float_value;
+
+    };
+};
+
+
+
+struct ColValue {
+
+    virtual bool isNull() { return false; };
+    virtual bool isInteger() { return false; };
+    virtual bool isFloat() { return false; };
+    virtual bool isString() { return false; };
+
+    virtual int integerValue() { throw Exception("Not supported"); };
+    virtual double floatValue() { throw Exception("Not supported"); };
+    virtual std::string stringValue() { throw Exception("Not supported"); };
+
+    virtual void print() {std::cout << "ColValue:" << std::endl; };
+};
+
+
+struct ColNullValue : ColValue {
+
+    virtual bool isNull() { return true; };
+
+    virtual void print() {std::cout << "ColNullValue:" << std::endl; };
+};
+
+
+struct ColIntegerValue : ColValue {
+
+    ColIntegerValue(int value) : m_integer(value) {};
+    ColIntegerValue(const ColIntegerValue &other) : m_integer(other.m_integer) {}
+
+    virtual bool isInteger() { return true; };
+
+    virtual int integerValue() { return m_integer; };
+    virtual double floatValue() { return (double) m_integer; };
+    virtual std::string stringValue() { return std::to_string(m_integer); };
+
+    virtual void print() {std::cout << "ColIntegerValue: " << m_integer <<std::endl; };
+
+    int m_integer;
+};
+
+
+struct ColFloatValue : ColValue {
+
+    ColFloatValue(double value) : m_float(value) {};
+    ColFloatValue(const ColFloatValue &other) : m_float(other.m_float) {}
+
+    virtual bool isFloat() { return true; }
+
+    virtual int integerValue() { return (int) m_float; };
+    virtual double floatValue() { return m_float; };
+    virtual std::string stringValue() { return std::to_string(m_float); };
+
+    virtual void print() {std::cout << "ColFloatValue: " << m_float <<std::endl; };
+
+    double m_float;
+};
+
+
+struct ColStringValue : ColValue {
+
+    ColStringValue(const std::string value) : m_string(value) {};
+    ColStringValue(const ColStringValue &other) : m_string(other.m_string) {};
+
+    virtual bool isString() { return true; }
+
+    virtual int integerValue() { return std::stoi(m_string); };
+    virtual double floatValue() { return std::stod(m_string); };
+    virtual std::string stringValue() { return m_string; };
+
+    virtual void print() {std::cout << "ColStringValue: " << m_string <<std::endl; };
+
+    std::string m_string;
+};
+
+
+
+class Row {
+
+public:
+    Row(int cols_count);
+    Row(const Row &other);
+
+    void setColumnValue(int col_index, int value);
+    void setColumnValue(int col_index, double value);
+    void setColumnValue(int col_index, std::string value);
+
+    ColValue& operator[](int i) {
+        return *m_columns[i];
+    }
+
+    ColValue* ithColum(int i) {
+        return m_columns[i].get();
+    }
+
+    void print();
+
+private:
+    std::vector<std::unique_ptr<ColValue>> m_columns;
+};
diff --git a/table.cpp b/table.cpp
index 0c4b984..577ae7b 100644
--- a/table.cpp
+++ b/table.cpp
@@ -7,22 +7,40 @@ Table::Table(const std::string name, const std::vector<ColDefNode> columns) {
     m_rows.clear();
 }
 
-ColDefNode Table::get_column_def(const std::string col_name) {
+ColDefNode Table::get_column_def(const std::string& col_name) {
     auto name_cmp = [col_name](ColDefNode cd){ return cd.name == col_name; };
     auto col_def = std::find_if(begin(m_col_defs), end(m_col_defs), name_cmp );
     if (col_def != std::end(m_col_defs)) {
         return *col_def;
     } else {
-        // TODO throw exception
+        throw Exception("column not exists (" + col_name + ")");
     }
 }
 
+
+Row Table::createEmptyRow() {
+    return Row(columns_count());
+}
+
+
 void Table::print() {
     std::cout << "** " << m_name << " **" << std::endl;
     for(auto row : m_rows) {
-        for( auto col : row) {
-            std::cout << col <<  ",";
+        for(int ci = 0; ci < columns_count(); ci++) {
+            auto v = row[ci].stringValue();
+            std::cout << v <<  ",";
         }
         std::cout << std::endl;
     }
-}
\ No newline at end of file
+}
+
+Table::Table(const Table& other) {
+   m_name = other.m_name;
+   m_col_defs = other.m_col_defs;
+   m_rows.clear();  // row not copied now
+}
+
+void Table::addRow(const Row &row) {
+    m_rows.push_back(row);
+}
+
diff --git a/table.h b/table.h
index d2415f0..afa8d97 100644
--- a/table.h
+++ b/table.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "parser.h"
+#include "row.h"
 
 #include <vector>
 
@@ -8,14 +9,21 @@
 struct Table {
 
 // public:
+    Table(const Table& other);
+
     Table(const std::string name, const std::vector<ColDefNode> columns);
 
-    ColDefNode get_column_def(const std::string col_name);
+    ColDefNode get_column_def(const std::string& col_name);
     int columns_count() { return m_col_defs.size(); };
+
+    Row createEmptyRow();   // TODO this means unnecessary copying
+    void addRow(const Row &row);
+
     void print();
 
+
 // private:
-    std::string                              m_name;
-    std::vector<ColDefNode>                  m_col_defs;
-    std::vector<std::vector<std::string>>    m_rows;
+    std::string                   m_name;
+    std::vector<ColDefNode>       m_col_defs;
+    std::vector<Row>              m_rows;
 };