Revert "base parseEnum on a case statement, fixes #14030 (#14046)"

This reverts commit d42c5a5.
nim-lang · Aug 28, 2020 · 2484311 · 2484311
1 parent fb58066
commit 2484311
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Showing 3 changed files with 11 additions and 171 deletions.
diff --git a/lib/pure/json.nim b/lib/pure/json.nim
@@ -163,7 +163,7 @@ export
 export
   parsejson.JsonEventKind, parsejson.JsonError, JsonParser, JsonKindError,
   open, close, str, getInt, getFloat, kind, getColumn, getLine, getFilename,
-  errorMsg, errorMsgExpected, next, JsonParsingError, raiseParseErr, nimIdentNormalize
+  errorMsg, errorMsgExpected, next, JsonParsingError, raiseParseErr
 
 type
   JsonNodeKind* = enum ## possible JSON node types

diff --git a/lib/pure/strutils.nim b/lib/pure/strutils.nim
@@ -75,7 +75,6 @@
 import parseutils
 from math import pow, floor, log10
 from algorithm import reverse
-import macros # for `parseEnum`
 
 when defined(nimVmExportFixed):
   from unicode import toLower, toUpper
@@ -279,26 +278,6 @@ proc capitalizeAscii*(s: string): string {.noSideEffect,
   if s.len == 0: result = ""
   else: result = toUpperAscii(s[0]) & substr(s, 1)
 
-proc nimIdentNormalize*(s: string): string =
-  ## Normalizes the string `s` as a Nim identifier.
-  ##
-  ## That means to convert to lower case and remove any '_' on all characters
-  ## except first one.
-  runnableExamples:
-    doAssert nimIdentNormalize("Foo_bar") == "Foobar"
-  result = newString(s.len)
-  if s.len > 0:
-    result[0] = s[0]
-  var j = 1
-  for i in 1..len(s) - 1:
-    if s[i] in {'A'..'Z'}:
-      result[j] = chr(ord(s[i]) + (ord('a') - ord('A')))
-      inc j
-    elif s[i] != '_':
-      result[j] = s[i]
-      inc j
-  if j != s.len: setLen(result, j)
-
 proc normalize*(s: string): string {.noSideEffect,
   rtl, extern: "nsuNormalize".} =
   ## Normalizes the string `s`.
@@ -1258,65 +1237,8 @@ proc parseBool*(s: string): bool =
   of "n", "no", "false", "0", "off": result = false
   else: raise newException(ValueError, "cannot interpret as a bool: " & s)
 
-proc addOfBranch(s: string, field, enumType: NimNode): NimNode =
-  result = nnkOfBranch.newTree(
-    newLit s,
-    nnkCall.newTree(enumType, field) # `T(<fieldValue>)`
-  )
-
-macro genEnumStmt(typ: typedesc, argSym: typed, default: typed): untyped =
-  # generates a case stmt, which assigns the correct enum field given
-  # a normalized string comparison to the `argSym` input.
-  # NOTE: for an enum with fields Foo, Bar, ... we cannot generate
-  # `of "Foo".nimIdentNormalize: Foo`.
-  # This will fail, if the enum is not defined at top level (e.g. in a block).
-  # Thus we check for the field value of the (possible holed enum) and convert
-  # the integer value to the generic argument `typ`.
-  let typ = typ.getTypeInst[1]
-  let impl = typ.getImpl[2]
-  expectKind impl, nnkEnumTy
-  result = nnkCaseStmt.newTree(nnkDotExpr.newTree(argSym,
-                                                  bindSym"nimIdentNormalize"))
-  # stores all processed field strings to give error msg for ambiguous enums
-  var foundFields: seq[string] = @[]
-  var fStr = "" # string of current field
-  var fNum = BiggestInt(0) # int value of current field
-  for f in impl:
-    case f.kind
-    of nnkEmpty: continue # skip first node of `enumTy`
-    of nnkSym, nnkIdent: fStr = f.strVal
-    of nnkEnumFieldDef:
-      case f[1].kind
-      of nnkStrLit: fStr = f[1].strVal
-      of nnkTupleConstr:
-        fStr = f[1][1].strVal
-        fNum = f[1][0].intVal
-      of nnkIntLit:
-        fStr = f[0].strVal
-        fNum = f[1].intVal
-      else: error("Invalid tuple syntax!", f[1])
-    else: error("Invalid node for enum type!", f)
-    # add field if string not already added
-    fStr = nimIdentNormalize(fStr)
-    if fStr notin foundFields:
-      result.add addOfBranch(fStr, newLit fNum, typ)
-      foundFields.add fStr
-    else:
-      error("Ambiguous enums cannot be parsed, field " & $fStr &
-        " appears multiple times!", f)
-    inc fNum
-  # finally add else branch to raise or use default
-  if default == nil:
-    let raiseStmt = quote do:
-      raise newException(ValueError, "Invalid enum value: " & $`argSym`)
-    result.add nnkElse.newTree(raiseStmt)
-  else:
-    expectKind(default, nnkSym)
-    result.add nnkElse.newTree(default)
-
 proc parseEnum*[T: enum](s: string): T =
-  ## Parses an enum ``T``. This errors at compile time, if the given enum
-  ## type contains multiple fields with the same string value.
+  ## Parses an enum ``T``.
   ##
   ## Raises ``ValueError`` for an invalid value in `s`. The comparison is
   ## done in a style insensitive way.
@@ -1332,11 +1254,13 @@ proc parseEnum*[T: enum](s: string): T =
     doAssertRaises(ValueError):
       echo parseEnum[MyEnum]("third")
 
-  genEnumStmt(T, s, default = nil)
+  for e in low(T)..high(T):
+    if cmpIgnoreStyle(s, $e) == 0:
+      return e
+  raise newException(ValueError, "invalid enum value: " & s)
 
 proc parseEnum*[T: enum](s: string, default: T): T =
-  ## Parses an enum ``T``. This errors at compile time, if the given enum
-  ## type contains multiple fields with the same string value.
+  ## Parses an enum ``T``.
   ##
   ## Uses `default` for an invalid value in `s`. The comparison is done in a
   ## style insensitive way.
@@ -1351,7 +1275,10 @@ proc parseEnum*[T: enum](s: string, default: T): T =
     doAssert parseEnum[MyEnum]("second") == second
     doAssert parseEnum[MyEnum]("last", third) == third
 
-  genEnumStmt(T, s, default)
+  for e in low(T)..high(T):
+    if cmpIgnoreStyle(s, $e) == 0:
+      return e
+  result = default
 
 proc repeat*(c: char, count: Natural): string {.noSideEffect,
   rtl, extern: "nsuRepeatChar".} =

diff --git a/tests/stdlib/tstrutil.nim b/tests/stdlib/tstrutil.nim
@@ -346,90 +346,3 @@ when true:
 
 main()
 #OUT ha/home/a1xyz/usr/bin
-
-
-# `parseEnum`, ref issue #14030
-# check enum defined at top level
-type
-  Foo = enum
-    A = -10
-    B = "bb"
-    C = (-5, "ccc")
-    D = 15
-    E = "ee" # check that we count enum fields correctly
-
-block:
-  let a = parseEnum[Foo]("A")
-  let b = parseEnum[Foo]("bb")
-  let c = parseEnum[Foo]("ccc")
-  let d = parseEnum[Foo]("D")
-  let e = parseEnum[Foo]("ee")
-  doAssert a == A
-  doAssert b == B
-  doAssert c == C
-  doAssert d == D
-  doAssert e == E
-  try:
-    let f = parseEnum[Foo]("Bar")
-    doAssert false
-  except ValueError:
-    discard
-
-  # finally using default
-  let g = parseEnum[Foo]("Bar", A)
-  doAssert g == A
-
-block:
-  # check enum defined in block
-  type
-    Bar = enum
-      V
-      W = "ww"
-      X = (3, "xx")
-      Y = 10
-      Z = "zz" # check that we count enum fields correctly
-
-  let a = parseEnum[Bar]("V")
-  let b = parseEnum[Bar]("ww")
-  let c = parseEnum[Bar]("xx")
-  let d = parseEnum[Bar]("Y")
-  let e = parseEnum[Bar]("zz")
-  doAssert a == V
-  doAssert b == W
-  doAssert c == X
-  doAssert d == Y
-  doAssert e == Z
-  try:
-    let f = parseEnum[Bar]("Baz")
-    doAssert false
-  except ValueError:
-    discard
-
-  # finally using default
-  let g = parseEnum[Bar]("Baz", V)
-  doAssert g == V
-
-block:
-  # check ambiguous enum fails to parse
-  type
-    Ambig = enum
-      f1 = "A"
-      f2 = "B"
-      f3 = "A"
-
-  doAssert not compiles((let a = parseEnum[Ambig]("A")))
-
-block:
-  # check almost ambiguous enum
-  type
-    AlmostAmbig = enum
-      f1 = "someA"
-      f2 = "someB"
-      f3 = "SomeA"
-
-  let a = parseEnum[AlmostAmbig]("someA")
-  let b = parseEnum[AlmostAmbig]("someB")
-  let c = parseEnum[AlmostAmbig]("SomeA")
-  doAssert a == f1
-  doAssert b == f2
-  doAssert c == f3