54 lines
1.3 KiB
Nim
54 lines
1.3 KiB
Nim
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import macros
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proc hasKind(node: NimNode, kind: NimNodeKind): bool =
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for c in node.children:
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if c.kind == kind:
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return true
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return false
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proc `[]`(node: NimNode, kind: NimNodeKind): NimNode =
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for c in node.children:
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if c.kind == kind:
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return c
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return nil
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template fieldPairs*[T: ref object](x: T): untyped =
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x[].fieldPairs
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macro isObjectVariant*(v: typed): bool =
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## Is this an object variant?
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var typ = v.getTypeImpl()
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if typ.kind == nnkSym:
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return ident("false")
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while typ.kind != nnkObjectTy:
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typ = typ[0].getTypeImpl()
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if typ[2].hasKind(nnkRecCase):
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ident("true")
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else:
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ident("false")
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proc discriminator*(v: NimNode): NimNode =
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var typ = v.getTypeImpl()
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while typ.kind != nnkObjectTy:
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typ = typ[0].getTypeImpl()
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return typ[nnkRecList][nnkRecCase][nnkIdentDefs][nnkSym]
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macro discriminatorFieldName*(v: typed): untyped =
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## Turns into the discriminator field.
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return newLit($discriminator(v))
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macro discriminatorField*(v: typed): untyped =
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## Turns into the discriminator field.
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let
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fieldName = discriminator(v)
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return quote do:
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`v`.`fieldName`
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macro new*(v: typed, d: typed): untyped =
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## Creates a new object variant with the discriminator field.
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let
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typ = v.getTypeInst()
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fieldName = discriminator(v)
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return quote do:
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`v` = `typ`(`fieldName`: `d`)
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