48 lines
1.7 KiB
Plaintext
48 lines
1.7 KiB
Plaintext
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using selfhost.vm.scan as MiniVmScan
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static box MiniVmCompare {
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// Compare(lhs int, rhs int) minimal: prints 0/1 and returns next pos or -1
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try_print_compare_at(json, end, print_pos) {
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local scan = new MiniVmScan()
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local k_cp = "\"kind\":\"Compare\""
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local cpos = scan.index_of_from(json, k_cp, print_pos)
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if cpos <= 0 || cpos >= end { return -1 }
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local k_op = "\"operation\":\""
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local opos = scan.index_of_from(json, k_op, cpos)
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if opos <= 0 || opos >= end { return -1 }
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local oi = opos + k_op.length()
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local oj = scan.index_of_from(json, "\"", oi)
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if oj <= 0 || oj > end { return -1 }
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local op = json.substring(oi, oj)
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// lhs value
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local k_lhs = "\"lhs\":{\"kind\":\"Literal\""
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local hl = scan.index_of_from(json, k_lhs, oj)
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if hl <= 0 || hl >= end { return -1 }
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local k_v = "\"value\":"
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local hv = scan.index_of_from(json, k_v, hl)
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if hv <= 0 || hv >= end { return -1 }
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local a = scan.read_digits(json, hv + k_v.length())
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// rhs value
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local k_rhs = "\"rhs\":{\"kind\":\"Literal\""
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local hr = scan.index_of_from(json, k_rhs, hl)
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if hr <= 0 || hr >= end { return -1 }
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local rv = scan.index_of_from(json, k_v, hr)
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if rv <= 0 || rv >= end { return -1 }
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local b = scan.read_digits(json, rv + k_v.length())
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if !a || !b { return -1 }
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local ai = scan._str_to_int(a)
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local bi = scan._str_to_int(b)
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local res = 0
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if op == "<" { if ai < bi { res = 1 } }
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if op == "==" { if ai == bi { res = 1 } }
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if op == "<=" { if ai <= bi { res = 1 } }
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if op == ">" { if ai > bi { res = 1 } }
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if op == ">=" { if ai >= bi { res = 1 } }
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if op == "!=" { if ai != bi { res = 1 } }
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print(res)
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// advance after rhs object (coarsely)
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return rv + 1
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}
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}
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