hex-color.md

Example: <hex-color>

The following example parses hex-colors. It supports the 3- and 4-shorthand as well as the written out 4 and 8 character long version.

entry {
    <hex> = [(\d, a - f)]
    <hex-pair> = [<hex> <hex>]
    
    default [object:
        '\\#'
        
        # RRGGBBAA & RRGGBB
        [
            def r = [<hex-pair>]
            def g = [<hex-pair>]
            def b = [<hex-pair>]
            def a = [<hex-pair>]?
        ] | [
            # RGBA & RGB
            def r = [<hex>]
            def g = [<hex>]
            def b = [<hex>] 
            def a = [<hex>]?
        ]
    ]
}

The definition will return an object with r, g, b and an optional alpha-value (a).

Valid inputs:

Input	Output
parse('#b5d')	{r: 'b', b: '5', g: 'd', a: null}
parse('#cf5c')	{r: 'c', b: 'f', g: '5', a: 'c'}
parse('#4eaecc')	{r: '4e', b: 'ae', g: 'cc', a: null}
parse('#328fffcc')	{r: '32', b: '8f', g: 'ff', a: 'cc'}

Invalid inputs:

Input	Output
parse('fff')	null (missing # prefix)
parse('#c2')	null (invalid length)
parse('#c2g')	null (invalid characters)