// Phase 164: Test trim_leading from JsonParserBox (Pattern3 with if-else PHI + break)
// Simulates: loop(start < end) { if is_whitespace(ch) { start++ } else { break } }

static box Main {
  main(args) {
    // Simulate trimming leading whitespace
    local s = "   \t\nhello world   "
    local start = 0
    local end = s.length()

    // Loop with if-else PHI: start is updated conditionally with break
    loop(start < end) {
      local ch = s.substring(start, start + 1)
      // Check if whitespace
      local is_ws = 0
      if ch == " " {
        is_ws = 1
      } else if ch == "\t" {
        is_ws = 1
      } else if ch == "\n" {
        is_ws = 1
      } else if ch == "\r" {
        is_ws = 1
      }

      if is_ws == 1 {
        start = start + 1
      } else {
        break
      }
    }

    // Output result
    local trimmed = s.substring(start, end)
    print("Trimmed leading whitespace")
    print("Start position: " + ("" + start))
    print("Trimmed string: " + trimmed)
    print("Expected start: 4")
    print("Expected string: hello world   ")
    return 0
  }
}