added strutils.parseEnum; fixes #95

lib/pure/strutils.nim

@@ -378,6 +378,22 @@ proc parseBool*(s: string): bool =
   of "y", "yes", "true", "1", "on": result = true
   of "n", "no", "false", "0", "off": result = false
   else: raise newException(EInvalidValue, "cannot interpret as a bool: " & s)
+
+proc parseEnum*[T: enum](s: string): T =
+  ## parses an enum ``T``. Raises ``EInvalidValue`` for an invalid value in 
+  ## `s`. The comparison is done in a style insensitive way.
+  for e in low(T)..high(T):
+    if cmpIgnoreStyle(s, $e) == 0:
+      return e
+  raise newException(EInvalidValue, "invalid enum value: " & s)
+
+proc parseEnum*[T: enum](s: string, default: T): T =
+  ## parses an enum ``T``. Uses `default` for an invalid value in 
+  ## `s`. The comparison is done in a style insensitive way.
+  for e in low(T)..high(T):
+    if cmpIgnoreStyle(s, $e) == 0:
+      return e
+  result = default
 
 proc repeatChar*(count: int, c: Char = ' '): string {.noSideEffect,
   rtl, extern: "nsuRepeatChar".} =
@@ -1105,5 +1121,8 @@ when isMainModule:
 
   doAssert "-ld a-ldz -ld".replaceWord("-ld") == " a-ldz "
   doAssert "-lda-ldz -ld abc".replaceWord("-ld") == "-lda-ldz  abc"
-  
-  
+  
+  type TMyEnum = enum enA, enB, enC, enuD, enE
+  doAssert parseEnum[TMyEnum]("enu_D") == enuD
+
+  doAssert parseEnum("invalid enum value", enC) == enC