Lot of if conditions in Mata

[econwang]

Dear statalist

I wonder whether can code a large set of if conditions in Mata, for example:

void function tmp(string scalar vname, string scalar nvname)
{
string matrix s, ns
real scalar i
st_sview(s,.,vname)
st_sview(s,.,nvname)
for (i=1;i<=row(s);i++) {
   if (s[i,.] == "a") ns[i,.] = "b"
   if (s[i,.] == "e") ns[i,.] = "d"
   if ...
   if ...
   if ...
   ...
}
}

Maybe there are 5000 or more if conditions, I know this can be down by "merge" in stata, just want to know how to code this via mata without a data file, a simple test shows the error message "too may string literals".