ConfigFileEvent = object
  case kind*: ConfigFileEventKind
  of cekParseExpectedX, cekParseExpectedCloseX, cekParseExpectedIdent,
     cekInvalidDirective, cekWriteConfig, cekProgressPathAdded:
      location*: TLineInfo   ## diagnostic location
    
  of cekInternalError, cekLexerErrorDiag, cekLexerWarningDiag:
      lexerDiag*: LexerDiag

  of cekFlagError:
      flagResult*: ProcSwitchResult
      flagInfo*: TLineInfo

  of cekProgressConfStart:
      nil

  instLoc*: InstantiationInfo ## instantiation in this module's source
  msg*: string

ConfigFileEventKind = enum
  cekInternalError, cekLexerErrorDiag, ## lexer error being forwarded
  cekParseExpectedX,        ## expected some token
  cekParseExpectedCloseX,   ## expected closing ')', ']', etc
  cekParseExpectedIdent,    ## expected an identifier
  cekInvalidDirective, cekFlagError, ## error from flag processing
  cekLexerWarningDiag,      ## warning from the lexer
  cekWriteConfig,           ## write out the config
  cekProgressConfStart = "Conf", cekProgressPathAdded = "Path"

NimConfEvtWriter = proc (config: ConfigRef; evt: ConfigFileEvent;
                         writeFrom: InstantiationInfo): void

proc getSystemConfigPath(conf: ConfigRef; filename: RelativeFile): AbsoluteFile {.
    ...raises: [OSError], tags: [ReadIOEffect, ReadDirEffect].}

proc getUserConfigPath(filename: RelativeFile): AbsoluteFile {.
    ...raises: [OSError], tags: [ReadEnvEffect, ReadIOEffect].}

proc loadConfigs(cfg: RelativeFile; cache: IdentCache; conf: ConfigRef;
                 evtHandler: NimConfEvtWriter; stopOnError: bool = true): bool {.
    inline, ...raises: [OSError, IOError, Exception, KeyError, EOFError,
                     ValueError, ERecoverableError, CancelConfigProcessing], tags: [
    ReadIOEffect, ReadDirEffect, ReadEnvEffect, RootEffect, WriteEnvEffect,
    WriteDirEffect, WriteIOEffect].}

proc readConfigFile(filename: AbsoluteFile; cache: IdentCache; conf: ConfigRef;
                    evtHandler: NimConfEvtWriter): bool {.inline, ...raises: [
    IOError, Exception, KeyError, EOFError, ValueError, OSError,
    ERecoverableError], tags: [ReadIOEffect, RootEffect, ReadDirEffect,
                               ReadEnvEffect, WriteEnvEffect, WriteDirEffect,
                               WriteIOEffect].}