47 lines
1.5 KiB
Plaintext
47 lines
1.5 KiB
Plaintext
// array_prepend_zero_macro.hako
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// MacroBoxSpec.expand: prepend 0 to every Array elements list in AST JSON v0
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// Contract: expand(json: string) -> string (AST JSON v0)
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static box MacroBoxSpec {
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expand(json) {
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local s, out, i, pat, plen, ins
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s = json
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out = ""
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i = 0
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pat = "\"kind\":\"Array\",\"elements\":["
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plen = pat.length()
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ins = "{\"kind\":\"Literal\",\"value\":{\"type\":\"int\",\"value\":0}}"
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loop(i < s.length()) {
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if i + plen <= s.length() && s.substring(i, i + plen) == pat {
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// Copy the Array header
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out = out + pat
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// Look ahead: if next is ']' it's empty array; otherwise add comma after inserted element
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if i + plen < s.length() && s.substring(i + plen, i + plen + 1) != "]" {
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out = out + ins + ","
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} else {
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out = out + ins
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}
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i = i + plen
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continue
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}
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// Also support reversed key order: ..."elements":[ ... ],"kind":"Array"
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if i + 12 <= s.length() && s.substring(i, i + 12) == "\"elements\":[" {
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// We will inject blindly here assuming this 'elements' belongs to Array (per schema it does)
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out = out + "\"elements\":["
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if i + 12 < s.length() && s.substring(i + 12, i + 13) != "]" {
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out = out + ins + ","
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} else {
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out = out + ins
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}
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i = i + 12
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continue
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}
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// Copy-through
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out = out + s.substring(i, i + 1)
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i = i + 1
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}
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return out
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}
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}
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