some code refactoring

index.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "exception.h"
+#include "parser.h"
 
 #include <iostream>
 #include <utility>
@@ -10,19 +11,19 @@
 
 namespace usql {
 
-enum class IndexedDataType {
-	integer,
-	string
-};
-
 using rowid_t = size_t;   // int is now enough but size_t is correct
 
+static const int k_default_rowids_size = 16;
+
 template<typename K>
 class Index {
 public:
-	Index(std::string index_name, std::string col_name, IndexedDataType type) :
+	Index(std::string index_name, std::string col_name, ColumnType type) :
 			m_index_name(std::move(index_name)), m_column_name(std::move(col_name)),
-			m_data_type(type), m_uniq(false) {}
+			m_data_type(type), m_uniq(false) {
+		if (type != ColumnType::integer_type && type != ColumnType::varchar_type)
+			throw Exception("creating index on unsupported type");
+	}
 
 	void insert(K key, rowid_t rowid) {
 		auto search = m_index.find(key);
@@ -34,7 +35,7 @@ public:
 		} else {
 			std::vector<rowid_t> rowids{rowid};
 			if (!m_uniq)
-				rowids.reserve(8);
+				rowids.reserve(k_default_rowids_size);
 			m_index[key] = rowids;
 		}
 	}
@@ -57,6 +58,16 @@ public:
 		}
 	}
 
+	std::vector<rowid_t> search(ValueNode * key) {
+		if (m_data_type == ColumnType::integer_type)
+			return search(key->getIntegerValue());
+		else if (m_data_type == ColumnType::varchar_type)
+			return search(key->getStringValue());
+		else
+			throw Exception("using index on unsupported type");
+	}
+
+
 	void truncate() {
 		m_index.clear();
 	}
@@ -78,7 +89,7 @@ public:
 		return m_index_name;
 	}
 
-	[[nodiscard]] IndexedDataType get_data_type() const {
+	[[nodiscard]] ColumnType get_data_type() const {
 		return m_data_type;
 	}
 
@@ -86,7 +97,7 @@ private:
 	bool			m_uniq;
 	std::string		m_index_name;
 	std::string		m_column_name;
-	IndexedDataType	m_data_type;
+	ColumnType		m_data_type;
 
 	std::map<K, std::vector<rowid_t> > m_index;
 };