31 lines
1.2 KiB
Plaintext
31 lines
1.2 KiB
Plaintext
// Minimal self-contained eval (no using): collect the first Print(Literal int) and print it
|
|
static box Main {
|
|
// helper: find from position
|
|
index_of_from(hay, needle, pos) {
|
|
if pos < 0 { pos = 0 }
|
|
if pos >= hay.length() { return -1 }
|
|
local tail = hay.substring(pos, hay.length())
|
|
local rel = tail.indexOf(needle)
|
|
if rel < 0 { return -1 } else { return pos + rel }
|
|
}
|
|
main(args) {
|
|
local json = "{\"kind\":\"Program\",\"statements\":[{\"kind\":\"Print\",\"expression\":{\"kind\":\"Literal\",\"value\":{\"type\":\"int\",\"value\":42}}}]}"
|
|
// naive collect: first Print of Literal int
|
|
local ki = "\"expression\":{\"kind\":\"Literal\",\"value\":{\"type\":\"int\",\"value\":"
|
|
local p = json.indexOf(ki)
|
|
if p >= 0 {
|
|
local i = p + ki.length()
|
|
local j = i
|
|
loop (true) {
|
|
local ch = json.substring(j, j+1)
|
|
if ch == "" { break }
|
|
if ch == "0" || ch == "1" || ch == "2" || ch == "3" || ch == "4" || ch == "5" || ch == "6" || ch == "7" || ch == "8" || ch == "9" { j = j + 1 continue }
|
|
break
|
|
}
|
|
local digits = json.substring(i, j)
|
|
if digits { print(digits) }
|
|
}
|
|
return 0
|
|
}
|
|
}
|