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1f0afff48b
* Support for .?[] operator on openArrays * Operator .?[] evaluates openArray expression only once * Fix for Nim 1.2.x --------- Co-authored-by: Mark Spanbroek <mark@spanbroek.net>
33 lines
932 B
Nim
33 lines
932 B
Nim
import std/macros
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import std/options
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proc safeGet[T](expression: seq[T] | openArray[T], index: int): Option[T] =
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if index >= expression.low and index <= expression.high:
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expression[index].some
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else:
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T.none
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proc safeGet(expression: string, index: int): Option[char] =
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if index >= expression.low and index <= expression.high:
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expression[index].some
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else:
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char.none
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macro `.?`*(expression: seq | string | openArray, brackets: untyped{nkBracket}): untyped =
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# chain is of shape: (seq or string or openArray).?[index]
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let index = brackets[0]
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quote do:
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block:
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safeGet(`expression`, `index`)
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macro `.?`*(expression: typed, brackets: untyped{nkBracket}): untyped =
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# chain is of shape: expression.?[index]
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let index = brackets[0]
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quote do:
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block:
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type T = typeof(`expression`[`index`])
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try:
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`expression`[`index`].some
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except KeyError:
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T.none
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