Method: Array#&

Defined in:
array.c

#&(other_array) ⇒ Object

Returns a new array containing the intersection of self and other_array; that is, containing those elements found in both self and other_array:

[0, 1, 2, 3] & [1, 2] # => [1, 2]

Omits duplicates:

[0, 1, 1, 0] & [0, 1] # => [0, 1]

Preserves order from self:

[0, 1, 2] & [3, 2, 1, 0] # => [0, 1, 2]

Identifies common elements using method #eql? (as defined in each element of self).

Related: see Methods for Combining.



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# File 'array.c', line 5646

static VALUE
rb_ary_and(VALUE ary1, VALUE ary2)
{
    VALUE hash, ary3, v;
    st_data_t vv;
    long i;

    ary2 = to_ary(ary2);
    ary3 = rb_ary_new();
    if (RARRAY_LEN(ary1) == 0 || RARRAY_LEN(ary2) == 0) return ary3;

    if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN && RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
        for (i=0; i<RARRAY_LEN(ary1); i++) {
            v = RARRAY_AREF(ary1, i);
            if (!rb_ary_includes_by_eql(ary2, v)) continue;
            if (rb_ary_includes_by_eql(ary3, v)) continue;
            rb_ary_push(ary3, v);
        }
        return ary3;
    }

    hash = ary_make_hash(ary2);

    for (i=0; i<RARRAY_LEN(ary1); i++) {
        v = RARRAY_AREF(ary1, i);
        vv = (st_data_t)v;
        if (rb_hash_stlike_delete(hash, &vv, 0)) {
            rb_ary_push(ary3, v);
        }
    }

    return ary3;
}