rb_u_string_squeeze.c

#include "rb_includes.h"
#include "rb_u_string_internal_tr.h"

static long
rb_u_string_squeeze_loop(const struct rb_u_string *string, struct tr_table *table,
                         char *result)
{
        long count = 0;

        const char *p = USTRING_STR(string);
        const char *end = USTRING_END(string);

        uint32_t previous = U_N_CODEPOINTS;
        char *base = result;
        while (p < end) {
                const char *q;
                uint32_t c = u_decode(&q, p, end);
                if (c != previous ||
                    (table != NULL && !tr_table_lookup(table, c))) {
                        long run = q - p;
                        if (base != NULL) {
                                memcpy(base, p, run);
                                base += run;
                        }
                        count += run;
                        previous = c;
                }
                p = q;
        }

        return count;
}

/* @overload squeeze(*sets)
 *
 *   Returns the receiver, replacing any substrings of {#length} > 1 consisting
 *   of the same character _c_ with _c_, where _c_ is a member of the
 *   intersection of the character sets in SETS, inheriting any taint and
 *   untrust.
 *
 *   If SETS is empty, then the set of all Unicode characters is used.
 *
 *   The complement of all Unicode characters and a given set of characters may
 *   be specified by prefixing a non-empty set with ‘`^`’ (U+005E CIRCUMFLEX
 *   ACCENT).
 *
 *   Any sequence of characters _a_-_b_ inside a set will expand to also
 *   include all characters whose code points lay between those of _a_ and _b_.
 *
 *   @param [Array<U::String, #to_str>] sets
 *   @return [U::String] */
VALUE
rb_u_string_squeeze(int argc, VALUE *argv, VALUE self)
{
        const struct rb_u_string *string = RVAL2USTRING(self);

        if (USTRING_LENGTH(string) == 0)
                return Qnil;

        struct tr_table table;
        if (argc > 0)
                tr_table_initialize_from_strings(&table, argc, argv);

        struct tr_table *table_pointer = (argc > 0) ? &table : NULL;

        long count = rb_u_string_squeeze_loop(string, table_pointer, NULL);
        if (count == 0)
                return self;

        char *remaining = ALLOC_N(char, count + 1);
        rb_u_string_squeeze_loop(string, table_pointer, remaining);
        remaining[count] = '\0';

        return rb_u_string_new_c_own(self, remaining, count);
}