faster csv loading

csvreader.cpp

@@ -2,7 +2,6 @@
 #include "csvreader.h"
 #include "parser.h"
 
-#include <fstream>
 
 namespace usql {
 
@@ -18,7 +17,6 @@ namespace usql {
 
 
 int CsvReader::parseCSV(const std::string &filename, std::vector<ColDefNode> &cols_def, Table &table) {
-
 	std::vector<ColDefNode> cdefs;
 	cdefs.reserve(cols_def.size());
 	for (auto &cd : cols_def) {
@@ -28,22 +26,33 @@ int CsvReader::parseCSV(const std::string &filename, std::vector<ColDefNode> &co
 	int row_cnt = 0;
 	bool inQuote(false);
 	std::string field;
-	std::string csvSource;
 
 	std::vector<std::string> line;
 	line.reserve(32);
 
-	std::fstream data_file;
-	data_file.open(filename, std::ios::in);
-	/// if (newfile.is_open()){   //checking whether the file is open
+	FILE* fp = fopen(filename.c_str(), "r");
+	if (fp == NULL)
+	    exit(EXIT_FAILURE);
 
-	while (getline(data_file, csvSource)) {
+	char* line_str = NULL;
+	size_t len = 0;
+
+
+	int read_chars;
+	while ((read_chars = getline(&line_str, &len, fp)) != -1) {
 		if (skip_header && !header_skiped) {
 			header_skiped = true;
 			continue;
 		}
+		if (read_chars > 0 && line_str[read_chars - 1] == '\n') {
+ 		     line_str[read_chars - 1] = '\0';
+ 		     --read_chars;
+  		}
+		std::string csvSource{line_str};
+		
 		std::string::const_iterator aChar = csvSource.begin();
-		while (aChar != csvSource.end()) {
+		std::string::const_iterator strEnd = csvSource.end();
+		while (aChar != strEnd) {
 			if (*aChar == quote_character) {
 				inQuote = !inQuote;
 			} else if (*aChar == field_separator) {
@@ -57,7 +66,7 @@ int CsvReader::parseCSV(const std::string &filename, std::vector<ColDefNode> &co
 				field.push_back(*aChar);
 			}
 
-			aChar++;
+			++aChar;
 		}
 
 		if (!field.empty())
@@ -73,7 +82,10 @@ int CsvReader::parseCSV(const std::string &filename, std::vector<ColDefNode> &co
 //
 	}
 
-	data_file.close();
+	fclose(fp);
+	if (line_str)
+	    free(line_str);
+
 
 	return row_cnt;
 }