Method: Hash#transform_keys!

Defined in:
hash.c

#transform_keys! {|key| ... } ⇒ Hash #transform_keys! ⇒ Object

Invokes the given block once for each key in hsh, replacing it with the new key returned by the block, and then returns hsh. This method does not change the values.

h = { a: 1, b: 2, c: 3 }
h.transform_keys! {|k| k.to_s }  #=> { "a" => 1, "b" => 2, "c" => 3 }
h.transform_keys!(&:to_sym)      #=> { a: 1, b: 2, c: 3 }
h.transform_keys!.with_index {|k, i| "#{k}.#{i}" }
                                 #=> { "a.0" => 1, "b.1" => 2, "c.2" => 3 }

If no block is given, an enumerator is returned instead.

Overloads:

  • #transform_keys! {|key| ... } ⇒ Hash

    Yields:

    Returns:



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# File 'hash.c', line 3084

static VALUE
rb_hash_transform_keys_bang(VALUE hash)
{
    RETURN_SIZED_ENUMERATOR(hash, 0, 0, hash_enum_size);
    rb_hash_modify_check(hash);
    if (!RHASH_TABLE_EMPTY_P(hash)) {
        long i;
        VALUE pairs = rb_hash_flatten(0, NULL, hash);
        rb_hash_clear(hash);
        for (i = 0; i < RARRAY_LEN(pairs); i += 2) {
            VALUE key = RARRAY_AREF(pairs, i), new_key = rb_yield(key),
                  val = RARRAY_AREF(pairs, i+1);
            rb_hash_aset(hash, new_key, val);
        }
    }
    return hash;
}