Using C++11 to split strings without using the boost library

Recently I did the StringCalculator kata in C++.

In order to be able to split a string using several alternative delimiters of one or more characters I used the following function:

	#include <boost/algorithm/string.hpp>
	#include <boost/algorithm/string/join.hpp>
	#include <boost/algorithm/string/regex.hpp>
	#include <boost/regex.hpp>
	std::vector<std::string> StringUtils::split(
	const std::string & str,
	const std::vector<std::string> & delimiters) {
	std::vector<std::string> tokens;
	boost::algorithm::split_regex(
	tokens,
	str,
	boost::regex(
	boost::join(escapeDelimiters(delimiters), "|"))
	);
	return tokens;
	}

view raw splitWithBoost.cpp hosted with ❤ by GitHub

which is using several functions from the boost library: boost::algorithm::split_regex, boost::regex and boost::join.

Yesterday I managed to use some C++11 features to get the same functionality without using the boost library. This is the resulting code which uses C++11 regex and lambdas:

	#include <regex>
	#include <sstream>
	std::vector<std::string> StringUtils::split(
	const std::string & str,
	const std::vector<std::string> & delimiters) {
	std::regex rgx(join(escapeStrings(delimiters), "|"));
	std::sregex_token_iterator
	first{begin(str), end(str), rgx, -1},
	last;
	return{first, last};
	}
	std::vector<std::string> StringUtils::split(const std::string & str,
	const std::string & delimiter) {
	std::vector<std::string> delimiters = {delimiter};
	return split(str, delimiters);
	}
	std::string StringUtils::join(
	const std::vector<std::string> & tokens,
	const std::string & delimiter) {
	std::stringstream stream;
	stream << tokens.front();
	std::for_each(
	begin(tokens) + 1,
	end(tokens),
	[&](const std::string &elem) {
	stream << delimiter << elem;}
	);
	return stream.str();
	}

view raw splitWithoutBoost.cpp hosted with ❤ by GitHub

These are the StringUtils tests where you can see how the split and join functions work:

	#include <gmock/gmock.h>
	#include <vector>
	#include "../code/StringUtils.h"
	using namespace ::testing;
	TEST(StringUtils, CanEscapeOneString) {
	EXPECT_THAT(StringUtils::escapeString("*"), Eq("\\*"));
	EXPECT_THAT(StringUtils::escapeString("\\"), Eq("\\\\"));
	EXPECT_THAT(StringUtils::escapeString("||"), Eq("\\|\\|"));
	EXPECT_THAT(StringUtils::escapeString(","), Eq(","));
	}
	TEST(StringUtils, CanEscapeSeveralStringsEvenThoseUsedInRegularExpressions) {
	EXPECT_THAT(StringUtils::escapeStrings({",", "*", "||", ";", "\\"}),
	ElementsAre(",", "\\*", "\\|\\|", ";", "\\\\"));
	}
	TEST(StringUtils, CanSplitUsingMultipleTokens) {
	std::vector<std::string> delimiters = {",", "*", "??"};
	EXPECT_THAT(StringUtils::split("1*2??3,4", delimiters),
	ElementsAre("1", "2", "3", "4"));
	}
	TEST(StringUtils, CanTellIfAGivenStringRepresentsAnInteger) {
	EXPECT_TRUE(StringUtils::isAnInteger("1"));
	EXPECT_FALSE(StringUtils::isAnInteger("15 7 8"));
	EXPECT_FALSE(StringUtils::isAnInteger("1.5"));
	EXPECT_FALSE(StringUtils::isAnInteger("!15"));
	}
	TEST(StringUtils, CanJoinAVectorOfStrings) {
	EXPECT_THAT(StringUtils::join({"1", "2", "3"}, "|"), Eq("1|2|3"));
	EXPECT_THAT(StringUtils::join({"1", "2", "3"}, " "), Eq("1 2 3"));
	EXPECT_THAT(StringUtils::join({"1", "2", "3"}, ", "), Eq("1, 2, 3"));
	EXPECT_THAT(StringUtils::join({"1", "2", "3"}, ""), Eq("123"));
	}
	TEST(StringUtils, CanSplitStringsAndJoinThemAgain) {
	std::string str = "1|2|3";
	std::string delimiter = "|";
	EXPECT_THAT(StringUtils::join(StringUtils::split(str, delimiter), delimiter),
	Eq(str));
	}

view raw StringUtilsTests.cpp hosted with ❤ by GitHub

You can find all the code in this repository.