// Mini-VM library (function-based) with a tiny JSON extractor
// Safe MVP: no real JSON parsing; string scan for first int literal only
using selfhost.shared.common.string_helpers as StringHelpers

static box MiniVm {
  // Read consecutive digits starting at pos (delegated)
  read_digits(json, pos) { return StringHelpers.read_digits(json, pos) }

  // Extract the first integer literal from our AST JSON v0 subset
  parse_first_int(json) {
    @key = "\"value\":{\"type\":\"int\",\"value\":"
    @idx = json.lastIndexOf(key)
    if idx < 0 { return "0" }
    @start = idx + key.length()
    return me.read_digits(json, start)
  }

  // Execute a minimal program: print the extracted integer and exit code 0
  run(json) {
    @n = parse_first_int(json)
    print(n)
    return 0
  }
}