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