show port's deps

[Miguel]

Hi, how can i know what the dependencies are for a particular port?
i want to know in advance before install the port, is there something 
like emerge -pv in gentoo?, with this i mean a user friendly command, i 
already know that doing a make search key=xxx and look at the B-DEPS and 
R-DEPS lines you see them, but you have to search for your especific 
port among the multitud of matches, BTW, what the diference between them?
something like this would be great

# cd /usr/ports/lang/php5
# make show_deps (or similar)


thanks