341 lines
11 KiB
Plaintext
341 lines
11 KiB
Plaintext
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// no external using required for quick json_query (text-slicing)
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static box Main {
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main() {
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// Simple JSON query runner: evaluate a few (json, path) pairs and print results
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// Path grammar (subset):
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// <path> := ('.' <ident> | '[' <digits> ']')*
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// Examples: .a.b[1], .c, [0]
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local cases = new ArrayBox()
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// Case 1
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local j1 = "{\"a\":{\"b\":[1,2,3]},\"c\":\"x\"}"
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cases.push(j1)
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cases.push(".a.b[1]") // -> 2
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cases.push(j1)
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cases.push(".c") // -> "x"
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cases.push(j1)
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cases.push(".a") // -> {"b":[1,2,3]}
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cases.push(j1)
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cases.push(".a.b") // -> [1,2,3]
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cases.push(j1)
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cases.push(".a.b[10]") // -> null
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cases.push(j1)
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cases.push(".x") // -> null
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cases.push(j1)
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cases.push(".a.b[0]") // -> 1
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// Case 2
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local j2 = "[ {\"k\":\"v\"}, 10, null ]"
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cases.push(j2)
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cases.push("[0].k") // -> "v"
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cases.push(j2)
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cases.push("[1]") // -> 10
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cases.push(j2)
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cases.push("[2]") // -> null
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cases.push(j2)
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cases.push("[3]") // -> null (out of range)
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local i = 0
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loop(i < cases.length()) {
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local json_text = cases.get(i)
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local path = cases.get(i + 1)
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// Parser-less path: slice JSON text directly for quick profile stability
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local out_text = this.eval_path_text(json_text, path)
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if out_text == null { print("null") } else { print(out_text) }
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i = i + 2
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}
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return 0
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}
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// Evaluate a simple JSON path by slicing JSON text directly (no full parse)
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// Returns a JSON substring for the value or null if not found
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eval_path_text(json_text, path) {
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local cur_text = json_text
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local i = 0
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loop(i < path.length()) {
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local ch = path.substring(i, i + 1)
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if ch == "." {
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// parse identifier
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i = i + 1
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local start = i
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loop(i < path.length()) {
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local c = path.substring(i, i + 1)
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if this.is_alnum(c) or c == "_" { i = i + 1 } else { break }
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}
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local key = path.substring(start, i)
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if key.length() == 0 { return null }
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// Get value text directly; then reset window to that text
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local next_text = this.object_get_text(cur_text, 0, cur_text.length(), key)
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if next_text == null { return null }
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cur_text = next_text
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} else {
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if ch == "[" {
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// parse index
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i = i + 1
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local start = i
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loop(i < path.length() and this.is_digit(path.substring(i, i + 1))) { i = i + 1 }
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local idx_str = path.substring(start, i)
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if i >= path.length() or path.substring(i, i + 1) != "]" { return null }
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i = i + 1 // skip ']'
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local idx = this.parse_int(idx_str)
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local next_text = this.array_get_text(cur_text, 0, cur_text.length(), idx)
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if next_text == null { return null }
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cur_text = next_text
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} else {
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return null
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}
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}
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}
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return cur_text
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}
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// Local helpers (avoid external using in app)
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is_digit(ch) {
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return ch == "0" or ch == "1" or ch == "2" or ch == "3" or ch == "4" or ch == "5" or ch == "6" or ch == "7" or ch == "8" or ch == "9"
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}
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is_alpha(ch) {
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return (ch >= "a" and ch <= "z") or (ch >= "A" and ch <= "Z")
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}
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is_alnum(ch) {
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return this.is_alpha(ch) or this.is_digit(ch)
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}
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parse_int(s) {
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local i = 0
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local neg = false
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if s.length() > 0 and s.substring(0,1) == "-" {
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neg = true
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i = 1
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}
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local acc = 0
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loop(i < s.length()) {
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local ch = s.substring(i, i + 1)
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if not this.is_digit(ch) { break }
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// ch to digit
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// 0..9
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if ch == "0" { acc = acc * 10 + 0 }
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else { if ch == "1" { acc = acc * 10 + 1 }
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else { if ch == "2" { acc = acc * 10 + 2 }
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else { if ch == "3" { acc = acc * 10 + 3 }
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else { if ch == "4" { acc = acc * 10 + 4 }
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else { if ch == "5" { acc = acc * 10 + 5 }
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else { if ch == "6" { acc = acc * 10 + 6 }
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else { if ch == "7" { acc = acc * 10 + 7 }
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else { if ch == "8" { acc = acc * 10 + 8 }
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else { if ch == "9" { acc = acc * 10 + 9 } }}}}}}}}}
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i = i + 1
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}
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if neg { return 0 - acc } else { return acc }
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}
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// --- Minimal JSON slicing helpers (object/array) ---
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// Find a key's value span within an object JSON slice [start,end)
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object_get_span(s, start, end, key) {
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local i = start
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if i < end and s.substring(i, i+1) == "{" { i = i + 1 } else { return null }
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loop(i < end) {
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i = this.skip_ws(s, i, end)
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if i >= end { return null }
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if s.substring(i, i+1) == "}" { return null }
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if s.substring(i, i+1) != "\"" { return null }
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local key_end = this.read_string_end(s, i, end)
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if key_end == -1 { return null }
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local key_text = s.substring(i+1, key_end-1)
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i = key_end
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i = this.skip_ws(s, i, end)
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if i >= end or s.substring(i, i+1) != ":" { return null }
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i = i + 1
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i = this.skip_ws(s, i, end)
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local vspan = this.read_value_span(s, i, end)
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if vspan == null { return null }
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if key_text == key { return vspan }
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i = vspan.get(1)
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i = this.skip_ws(s, i, end)
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if i < end and s.substring(i, i+1) == "," {
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i = i + 1
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continue
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} else {
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return null
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}
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}
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return null
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}
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// Return the value text for a key within an object slice, or null
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object_get_text(s, start, end, key) {
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local sp = this.object_get_span(s, start, end, key)
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if sp == null { return null }
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// sp is ArrayBox [i, j]; re-scan without using .get to avoid VM instance calls
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// Instead, rebuild by scanning again (small overhead, safer on current VM path)
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// We locate the key again and then extract value via read_value_span
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// Directly extracting indices from sp would require .get; so re-use scanner
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// Start from beginning for simplicity
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local i = start
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if i < end and s.substring(i, i+1) == "{" { i = i + 1 } else { return null }
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loop(i < end) {
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i = this.skip_ws(s, i, end)
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if i >= end { return null }
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if s.substring(i, i+1) == "}" { return null }
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if s.substring(i, i+1) != "\"" { return null }
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local key_end = this.read_string_end(s, i, end)
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if key_end == -1 { return null }
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local key_text = s.substring(i+1, key_end-1)
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i = key_end
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i = this.skip_ws(s, i, end)
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if i >= end or s.substring(i, i+1) != ":" { return null }
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i = i + 1
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i = this.skip_ws(s, i, end)
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local vspan = this.read_value_span(s, i, end)
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if vspan == null { return null }
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if key_text == key { return s.substring(i, vspan.get(1)) }
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i = vspan.get(1)
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i = this.skip_ws(s, i, end)
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if i < end and s.substring(i, i+1) == "," { i = i + 1 continue } else { return null }
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}
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return null
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}
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// Get the span of the idx-th element at top-level of an array slice [start,end)
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array_get_span(s, start, end, idx) {
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local i = start
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if i < end and s.substring(i, i+1) == "[" {
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i = i + 1
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} else {
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return null
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}
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local cur = 0
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loop(i < end) {
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i = this.skip_ws(s, i, end)
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if i >= end { return null }
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if s.substring(i, i+1) == "]" { return null }
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local vspan = this.read_value_span(s, i, end)
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if vspan == null { return null }
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if cur == idx { return vspan }
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i = vspan.get(1)
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i = this.skip_ws(s, i, end)
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if i < end and s.substring(i, i+1) == "," {
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i = i + 1
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cur = cur + 1
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continue
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} else {
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return null
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}
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}
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return null
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}
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// Return the text of idx-th element within an array slice, or null
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array_get_text(s, start, end, idx) {
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local sp = this.array_get_span(s, start, end, idx)
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if sp == null { return null }
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// Re-scan to compute exact [i,j) and return substring without ArrayBox.get
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local i = start
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if i < end and s.substring(i, i+1) == "[" { i = i + 1 } else { return null }
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local cur = 0
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loop(i < end) {
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i = this.skip_ws(s, i, end)
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if i >= end { return null }
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if s.substring(i, i+1) == "]" { return null }
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local vspan = this.read_value_span(s, i, end)
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if vspan == null { return null }
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if cur == idx { return s.substring(i, vspan.get(1)) }
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i = vspan.get(1)
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i = this.skip_ws(s, i, end)
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if i < end and s.substring(i, i+1) == "," { i = i + 1 cur = cur + 1 continue } else { return null }
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}
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return null
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}
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// Read a JSON value span starting at i; returns [start,end)
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read_value_span(s, i, end) {
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if i >= end { return null }
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local ch = s.substring(i, i+1)
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if ch == "\"" {
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local j = this.read_string_end(s, i, end)
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if j == -1 { return null } else {
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local out = new ArrayBox()
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out.push(i)
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out.push(j)
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return out
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}
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}
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if ch == "{" {
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local j = this.matching_brace(s, i, end, "{", "}")
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if j == -1 { return null } else {
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local out = new ArrayBox()
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out.push(i)
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out.push(j)
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return out
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}
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}
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if ch == "[" {
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local j = this.matching_brace(s, i, end, "[", "]")
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if j == -1 { return null } else {
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local out = new ArrayBox()
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out.push(i)
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out.push(j)
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return out
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}
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}
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// number/bool/null: read until comma or closing
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local j = i
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loop(j < end) {
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local c = s.substring(j, j+1)
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if c == "," or c == "}" or c == "]" or this.is_ws_char(c) { break }
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j = j + 1
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}
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local out = new ArrayBox()
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out.push(i)
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out.push(j)
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return out
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}
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// Find end index (exclusive) of a JSON string literal starting at i ('"')
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read_string_end(s, i, end) {
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local j = i + 1
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loop(j < end) {
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local c = s.substring(j, j+1)
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if c == "\\" {
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j = j + 2
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continue
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}
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if c == "\"" { return j + 1 }
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j = j + 1
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}
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return -1
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}
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// Match paired braces/brackets with simple string-awareness; returns end index (exclusive)
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matching_brace(s, i, end, open, close) {
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local depth = 0
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local j = i
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loop(j < end) {
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local c = s.substring(j, j+1)
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if c == "\"" {
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j = this.read_string_end(s, j, end)
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if j == -1 { return -1 }
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continue
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}
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if c == open {
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depth = depth + 1
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} else {
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if c == close {
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depth = depth - 1
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if depth == 0 { return j + 1 }
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}
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}
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j = j + 1
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}
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return -1
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}
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// Whitespace utilities
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skip_ws(s, i, end) {
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local j = i
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loop(j < end and this.is_ws_char(s.substring(j, j+1))) { j = j + 1 }
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return j
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}
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is_ws_char(ch) { return ch == " " or ch == "\t" or ch == "\n" or ch == "\r" }
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// Note: normalization now lives in JsonNode (object_get/array_get)
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}
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