Parse a shortcode differently based on on what it's nested in

Question

Suppose we have two different sets of nested shortcodes, like this:

Apple version

• [wrapper snack="apple"] Today I had a [flavor] snack... [/wrapper]
• Desired output: My snack was quite HEALTHY today...

Donut Version

• [wrapper snack="donut"] Today I had a [flavor] snack... [/wrapper]
• Desired output: My snack was quite FATTY today...

My question is: how can I parse the nested shortcode ([flavor]) differently depending on the shortcode it's nested in (i.e., based on [wrapper]'s snack attribute)? Please accept for the sake of the question that it's impossible/impractical to add an attribute to [flavor].

In pseudo-code, it might work something like this:

function flavor_shortcode_handler ( $atts, $content ) {
    $wrapper = ??? // The value of the shortcode this is nested inside

    if ( $wrapper == 'apple' ) return 'HEALTHY';
    if ( $wrapper == 'donut' ) return 'FATTY';
}

I imagine there are a variety of ways to get the same effect by how we write wrapper's handler function.

Idea 1: Use a global variable

function wrapper_shortcode_handler ( $atts, $content ) {
     // After extracting the snack attribute...
     $GLOBALS['wrapper_value'] = $snack;
     return do_shortcode( $content );
}

Idea 2: Find/replace the nested shortcode before processing it

function wrapper_shortcode_handler ( $atts, $content ) {
     // After extracting the snack attribute...
     $new_content = str_replace( '[flavor]', '[flavor wrapper="'.$snack.'"]', $content );
     return do_shortcode( $new_content );
}

Obviously the examples and solutions are oversimplified, but is there an alternative that would work better?

Answer 1

Register a new shortcode handler depending on the attribute value:

function wrapper_shortcode_handler ( $atts, $content ) {

    if ( "apple" === $atts["snack"] )
        add_shortcode( "flavor", "healthy_callback" );

    if ( "donut" === $atts["snack"] )
        add_shortcode( "flavor", "fatty_callback" );

    return do_shortcode( $content );
}

See also Execute shortcode only in another shortcode