% String manipulation routines for MetaPost
% It is harmless to input this file more than once.
vardef isdigit primary d =
("0"<=d)and(d<="9") enddef;
% Number of initial characters of string s where `c ' is true
vardef cspan(expr s)(text c) =
0
for i=1 upto length s:
exitunless c substring (i-1,i) of s;
+ 1
endfor
enddef;
% String s is composed of items separated by white space. Lop off the first
% item and the surrounding white space and return just the item.
vardef loptok suffix s =
save t, k;
k = cspan(s," ">=);
if k>0: s:=substring(k,infinity) of s; fi
k := cspan(s," "<);
string t;
t = substring (0,k) of s;
s := substring (k,infinity) of s;
s := substring (cspan(s," ">=),infinity) of s;
t
enddef;