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d62f3627aa
* add parseEnumRange * fix runnable example * update changelog * use parseEnumRange in compiler * reorganise code * add changelog, make single normalizer argument
64 lines
2.4 KiB
Nim
64 lines
2.4 KiB
Nim
#
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#
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# Nim's Runtime Library
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# (c) Copyright 2020 Nim contributors
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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import macros
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macro genEnumCaseStmt*(typ: typedesc, argSym: typed, default: typed,
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userMin, userMax: static[int], normalizer: static[proc(s :string): string]): untyped =
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# generates a case stmt, which assigns the correct enum field given
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# a normalized string comparison to the `argSym` input.
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# string normalization is done using passed normalizer.
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# NOTE: for an enum with fields Foo, Bar, ... we cannot generate
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# `of "Foo".nimIdentNormalize: Foo`.
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# This will fail, if the enum is not defined at top level (e.g. in a block).
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# Thus we check for the field value of the (possible holed enum) and convert
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# the integer value to the generic argument `typ`.
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let typ = typ.getTypeInst[1]
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let impl = typ.getImpl[2]
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expectKind impl, nnkEnumTy
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let normalizerNode = quote: `normalizer`
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expectKind normalizerNode, nnkSym
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result = nnkCaseStmt.newTree(newCall(normalizerNode, argSym))
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# stores all processed field strings to give error msg for ambiguous enums
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var foundFields: seq[string] = @[]
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var fStr = "" # string of current field
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var fNum = BiggestInt(0) # int value of current field
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for f in impl:
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case f.kind
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of nnkEmpty: continue # skip first node of `enumTy`
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of nnkSym, nnkIdent: fStr = f.strVal
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of nnkEnumFieldDef:
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case f[1].kind
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of nnkStrLit: fStr = f[1].strVal
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of nnkTupleConstr:
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fStr = f[1][1].strVal
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fNum = f[1][0].intVal
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of nnkIntLit:
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fStr = f[0].strVal
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fNum = f[1].intVal
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else: error("Invalid tuple syntax!", f[1])
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else: error("Invalid node for enum type!", f)
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# add field if string not already added
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if fNum >= userMin and fNum <= userMax:
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fStr = normalizer(fStr)
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if fStr notin foundFields:
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result.add nnkOfBranch.newTree(newLit fStr, nnkCall.newTree(typ, newLit fNum))
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foundFields.add fStr
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else:
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error("Ambiguous enums cannot be parsed, field " & $fStr &
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" appears multiple times!", f)
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inc fNum
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# finally add else branch to raise or use default
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if default == nil:
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let raiseStmt = quote do:
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raise newException(ValueError, "Invalid enum value: " & $`argSym`)
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result.add nnkElse.newTree(raiseStmt)
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else:
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expectKind(default, nnkSym)
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result.add nnkElse.newTree(default) |