Irish strlwr

strlwr_irish.c

/*
 * Copyright 2016 Trinity College, Dublin
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>

/*
 * Checks if the string begins with an upper case vowel, for the set
 * of vowels present in Irish; assumes UTF8.
 */
static int begins_with_upper_vowel(char* s)
{
	if(s == NULL) {
		return 0;
	} else if (*s == 'A' || *s == 'E' || *s == 'I' 
			|| *s == 'O' || *s == 'U') {
		return 1;
	} else if (*s == '\xC3' && ((s + 1) != NULL)) {
		if((*(s + 1) == '\x81') || (*(s + 1) == '\x89') 
		|| (*(s + 1) == '\x8D') || (*(s + 1) == '\x93') 
		|| (*(s + 1) == '\x9A')) {
			return 1;
		} else {
			return 0;
		}
	} else {
		return 0;
	}
}

/*
 * converts an Irish uppercase vowel with fada (ÁÉÍÓÚ)
 * to its lowercase equivalent
 */
static int tolower_fada(int ch)
{
	switch(ch) {
		case '\x81':
			return '\xa1';
		case '\x89':
			return '\xa9';
		case '\x8D':
			return '\xad';
		case '\x93':
			return '\xb3';
		case '\x9A':
			return '\xba';
		default:
			return ch;
	}
}

char* strlwr_irish(char* s)
{
	int start = 1;
	int pcount = 0;
	int size = strlen(s);
	char* p = (char *) malloc(((size * 2) + 1) * sizeof(char));
	char* ret = p;
	if(p != NULL) {
		while(*s != '\0') {
			if(start && ((*s == 't') || (*s == 'n')) 
				&& ((s + 1) != NULL) && begins_with_upper_vowel(s + 1)) {
				start = 0;
				*p++ = *s++;
				*p++ = '-';
				pcount++;
			} else if(*s >= 'A' && *s <= 'Z') {
				*p++ = tolower(*s++);
				pcount++;
			} else if(*s == '\xC3') {
				*p++ = (char) *s++;
				pcount++;
				*p++ = (char) tolower_fada(*s++);
				pcount++;
			} else if(*s >= 'a' && *s <= 'z') {
				*p++ = *s++;
				pcount++;
			} else {
				*p++ = *s++;
				pcount++;
				start = 1;
			}
		}
		*p = '\0';
	}
	return ret;
}

int main(int argc, char** argv)
{
	fprintf(stdout, "Starting\n");
	char* test1 = "tATHAIR";
	char* test2 = "nÁÉÍÓÚR tATHAIR tATHAIR";
	char* out1 = strlwr_irish(test1);
	char* out2 = strlwr_irish(test2);
	printf("%s\n%s\n", test1, test2);
	printf("%s\n%s\n", out1, out2);
	printf("%d %d\n", strlen(test2), strlen(out2));
	free(out1);
	free(out2);
	return 0;
}