I am working on an idea with a completion function that generates file
paths, absolute or relative. Below is a simplified version of what I am
trying to do. I have replaced what I'm really using to generate the paths
with a call to "find", just to make it simple to see what I am stumbling on.

Here's how I've set up the function:

_gen-result() {
    local -a hlist
    hlist=("${(@f)$(find /etc/ -type f)}") # This is just a stand-in for my
real function
    compadd -- $hlist
}

zle -C gen-comp menu-complete _gen-result
bindkey '\ee' gen-comp

I works well. Typing "ls <\ee>" I get the files found below /etc.

Here's what I don't know how to solve: I would like to type some string on
the command line, and I want to have that string working as a filter for
the suggestions, matching anywhere in the path. Say I have "/etc/foo",
"/etc/bar" and /etc/baz/foo.txt", and I type "ls foo <\ee>", I only want
"/etc/foo" and "/etc/baz/foo.txt" to be suggested. In other words, I want
the completion to match against the string anywhere in the full path.

In this particular example, I realize I could pass the filter string as a
restriction to the find command, and I could also filter the array "hlist"
after the paths are generated, but that is not so simple in my real
command. Is there a way to specify in a more "zsh like" way that when using
_gen-result, the whole path should be examined for a match?