Multiple input completion Ultisnips

global !p
def complete(t, opts):
    if t:
        opts = [opt[len(t):] for opt in opts if opt.startswith(t)]
    if len(opts) == 1:
        return opts[0]
    if len(opts) == 0:
        return ""
    return "(" + "|".join(opts) + ")"

simple_var_types = sorted(["int", "long long", "string", "float", "double", "bool", "char"])
pair_var_types = sorted(["pair<int, int>", "pair<long, long>"])
var_types = simple_var_types + pair_var_types

import re
def read_cin(var_type, names):
    if t:
        opts = [opt for opt in var_types if opt.startswith(var_type)]
        if len(opts) == 1 and opts[0] in simple_var_types + pair_var_types:
            var_type = opts[0]
            result = "cin"
            for name in re.split("\s*,\s*", names):
                if var_type in simple_var_types:
                    result += " >> {}".format(name)
                if var_type in pair_var_types:
                    result += " >> {}.first >> {}.second".format(name, name)
            return result + ";"
    return "cin >> ;"
endglobal

snippet read "read values from stdin" b
${1:i}`!p snip.rv = complete(t[1], var_types)` ${2:n};
`!p snip.rv = read_cin(t[1], t[2])`
$0
endsnippet

snippet readvl "read vector from stdin" b
vector<${1:i}`!p snip.rv = complete(t[1], var_types)`> ${2:v}(${3:n});
for (int i = 0; i < $3; i++) {
    `!p snip.rv = read_cin(t[1], t[2] + "[i]")`
}
$0
endsnippet