#include "strutil.h"
#include "string.h"

uintptr_t strnhash(const char* s, size_t n) {
    static const size_t shift = sizeof(uintptr_t) * 8 - 4;
    uintptr_t hash = 0;
    for(size_t i = 0; i < n; ++i) {
        hash = ((hash << 4) | s[i]) ^ (((uintptr_t)0xF << shift) & hash);
    }
    return hash;
}

uintptr_t strhash(const char* s) {
    return strnhash(s, strlen(s));
}

long strlast(const char* rbegin, const char* rend, char search) {
    const char* itr = rbegin;
    while(itr < rend && *itr != '\0')
        if(*itr == search) return itr - rend;
        else itr--;
    return -1;
}

long strfirst(const char* begin, const char* end, char search) {
    const char* itr = begin;
    while(itr < end && *itr != '\0')
        if(*itr == search) return itr - begin;
        else itr++;
    return -1;
}

long strcount(const char* begin, const char* end, char search) {
    long count = 0;
    for(;begin < end && *begin != '\0'; ++begin)
        if(*begin == search) ++count;
    return count;
}

long strfirst_pred(const char* begin, const char* end, CharPredFn pred) {
    const char* itr = begin;
    while(itr < end && *itr != '\0')
        if(pred(*itr)) return itr - begin;
        else itr++;
    return -1;
}

long strlast_pred(const char* rbegin, const char* rend, CharPredFn pred) {
    const char* itr = rbegin;
    while(itr < rend && *itr != '\0')
        if(pred(*itr)) return itr - rend;
        else itr--;
    return -1;
}