drupol / htmltag

     *

     * @return $this

     */

    public function append($key, $value = null)

    {

        $this->storage += array(

            $key => new Attribute(

                $key,

                $this->ensureString($value)

            )

        );

        $value = $this->normalizeValue($value);

        foreach ($value as $value_item) {

            $this->storage[$key]->append($value_item);

        }

        return $this;

    }

    /**

     * Remove a value from a specific attribute.

     *

     * @return $this

     */

    public function replace($key, $value, $replacement)

    {

        $this->storage += array(

            $key => new Attribute(

                $key,

                $this->ensureString($value)

            )

        );

        $replacement = $this->normalizeValue($replacement);

        foreach ($replacement as $replacement_value) {

            $this->storage[$key]->replace($value, $replacement_value);

        }

        return $this;

    }

    /**

     * Merge attributes.

     *

     * @return $this

     */

    public function merge(array $data = array())

    {

        foreach ($data as $key => $value) {

            $this->storage += array(

                $key => new Attribute(

                    $key,

                    $this->ensureString($value)

                )

            );

            $this->storage[$key]->merge(

                $this->normalizeValue($value)

            );

        }

        return $this;

    }

    /**

     * Check if an attribute exists and if a value if provided check it as well.