35 lines
761 B
Nim
35 lines
761 B
Nim
type
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Encoding* = enum
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ecSingle, ecUtf8
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ByteType* = enum
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btSingle, btContinuation,
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btDouble = 2, btTriple = 3, btQuadruple = 4,
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# btInvalid
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proc byteType*(c: char): ByteType =
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let n = c.uint8
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if n < 0x80:
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return btSingle
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elif n < 0xc0:
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return btContinuation
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elif n >= 0xc2 and n < 0xe0:
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# c0 and c1 are invalid utf8 bytes
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return btDouble
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elif n >= 0xe0 and n < 0xf0:
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return btTriple
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elif n >= 0xf0 and n < 0xf5:
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return btQuadruple
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else:
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raise newException(Exception, "Invalid utf8 sequence")
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#return btInvalid
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proc runeLen*(s: string): int =
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for c in s:
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case c.byteType:
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of btSingle, btDouble, btTriple, btQuadruple:
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result.inc
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of btContinuation:
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discard
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