The webdevelper presets: type-in keyword subdomains = parts of the forwarded URLs
For example:
subdomain name “toy” = “noun-1” part of the forwarded URLs  
subdomain name ”food”= “noun-2” part of the forwarded URLs  
number of pre defined noun should be unlimited  
any undefined noun = “noun-0”
subdomain name “my” = “whose-1” part of the forwarded URLs
subdomain name “your” = “whose-2”part of the forwarded URLs
subdomain name “his” = “whose-3”part of the forwarded URLs
number of pre defined possessive pronoun should be unlimited
any undefined possessive pronoun = “whose-0”

So that domain names such as “http://toy.website.com” and “http://food.website.com” could be forwarded to some predefined URLs.

http://toy.website.com” could be forwarded to "http://www.myplace.com/noun-1-whose-0" (“noun-1” first, then ”whose-0”) "http://food.website.com" could be forwarded to "http://www.myplace.com/noun-2-whose-0"

If we type in “http://my.toy.website.com”, it could be forwarded to "http://www.myplace.com/noun-1-whose-1"
"http://your.food.website.com" needs to redirect to "http://www.myplace.com/noun-2-whose-2"

http://my.website.com” to "http://www.myplace.com/noun-0-whose-1"
"http://your.website.com" to "http://www.myplace.com/noun-0-whose-2" (“noun-0”should be in place)

If we type in some undefined words, for example, "http://undefined_whose.toy.website.com" should be forwarded to "http://toy.website.com" [just drop undefined words], then forward again to "http://www.myplace.com/noun-1-whose-0" accordingly.

"http://my.undefined_noun.website.com" first to "http://my.website.com" then to "http://www.myplace.com/noun-0-whose-1"

If we only type-in level 2 subdomains without level 3 subdomains, such as "http://undefined_words.website.com" , or type in more than level 4 subdomains, or type in “both undefined level 3 and undefined level 2” ,such as "http://undefined_whose.undefined_noun.website.com" they should be redirected uniformly to "http://www.myplace.com/domain_rule.html"

Could we use html5 JavaScript, get domain names from the browser to a string, use “split()” [ “ . ”as seperator, “howmany” to get number of subdomains] , then apply “if else” or “case” ?
Or php code?

Anyone could offer a lending hand and post all codes that I am able to use directly?