Word frequency counter.

freqs.cpp

/**
 * Author: reefridge <reefridgerator@gmail.com>
 * Compilation: `clang++ freqs.cpp -o freqs`
 * Synopsis: `freqs <input> <output>`
 */
#include<string>
#include<vector>
#include<cctype>
#include<fstream>
#include<iostream>

using namespace std;

enum Arg {
	INPUT = 1,
	OUTPUT
};

enum ExitCode {
	OK,
	NOT_ENOUGH_ARGS,
	READ_DATA_ERROR
};

struct WordFreq {
	private:
		unsigned int count;
		string token;
	
	public:
		WordFreq(string w) : token(w), count(0) {};

		const string& getWord() {
			return token;
		}

		const unsigned int& getCount() {
			return count;
		}

		void inc() {
			count++;
		}
};

const string alph = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

vector<string> getWordsFromFile(ifstream&);
vector<string> splitPart(string&);
string& toLowerCase(string& str);
vector<WordFreq> wordsToFreqs(vector<string>&);
WordFreq& getFreq(vector<WordFreq>&, string&);
void sortFreqs(vector<WordFreq>&);
void writeFreqsToFile(ofstream&, vector<WordFreq>&);


int main(int argc, char** argv) {	
	if (argc < 3) {
		cout << "Synopsis: freqs <input> <output>" << endl;
	
		return NOT_ENOUGH_ARGS;
	}

	ifstream input(argv[INPUT]);

		vector<string> words;

		if (!input.good()) {
			input.close();

			return READ_DATA_ERROR;
		}

		words = getWordsFromFile(input);
	
	input.close();

	vector<WordFreq> freqs = wordsToFreqs(words);
	sortFreqs(freqs);

	ofstream output(argv[OUTPUT]);
	
		writeFreqsToFile(output, freqs);
	
	output.close();	

	return OK;
}


vector<WordFreq> wordsToFreqs(vector<string>& words) {
	vector<WordFreq> freqs;
	
	for (int i = 0; i < words.size(); i++)
		getFreq(freqs, words[i]).inc();

	return freqs;
}


WordFreq& getFreq(vector<WordFreq>& freqs, string& word) {
	for (int i = 0; i < freqs.size(); i++) {
		if (freqs[i].getWord() == word)
			return freqs[i];
	}
	
	freqs.push_back(WordFreq(word));

	return freqs.back();
}


vector<string> getWordsFromFile(ifstream& file) {
	vector<string> words, split;
	string part, word;

	while (!(file >> ws).eof()) {
		file >> part;

		if (file.fail())
			break;
		
		do {

			split = splitPart(part);
			word = part;

			if (!split.empty()) {
				
				part = split.back();
				split.pop_back();

				word = split.back();
			
			}

			if (word.length() > 1)
				words.push_back(toLowerCase(word));

		} while (!split.empty());

	}

	return words;
}


vector<string> splitPart(string& part) {
	size_t charPos = part.find_first_not_of(alph);
	vector<string> res;

	if (charPos != string::npos) {
		res.push_back(part.substr(0, charPos));
		res.push_back(part.substr(charPos + 1));
	}
	
	return res;
}


string& toLowerCase(string& str) {
	for (int i = 0; i < str.length(); i++)
		str[i] = std::tolower(str[i]);

	return str;
}


void swapFreqs(vector<WordFreq>& freqs, int i, int j) {
	WordFreq temp = freqs[i];
	freqs[i] = freqs[j];
	freqs[j] = temp;
}


void sortFreqs(vector<WordFreq>& freqs) {
	int size = freqs.size();
	for (int i = 0; i < size - 1; i++) {
		for (int j = 0; j < size - 1; j++) {

			unsigned int current = freqs[j].getCount();
			unsigned int next = freqs[j+1].getCount();
			bool needSwap = false;

			if (current < next) {
				needSwap = true;			
			} else if (current == next) {
			
				if (freqs[j].getWord() > freqs[j+1].getWord())
					needSwap = true;			
		
			}

			if (needSwap)
				swapFreqs(freqs, j, j+1);

		}
	}
}


void writeFreqsToFile(ofstream& output, vector<WordFreq>& freqs) {
	for (int i = 0; i < freqs.size(); i++) {
		output << freqs[i].getCount() << ' ' << freqs[i].getWord() << endl;
	}
}