NAME

       VistaIOdictionary - representation of a keyword/value mapping

SYNPOSIS

       VistaIODictEntry dictionary[] = {
              { "keyword", integer_value },
              { "keyword", 0, string_value },
              ...
              { NULL }
       };

DESCRIPTION

       This manual page documents a data structure, called a dictionary, for describing a mapping
       between keywords and values. Dictionaries are used  by  the  Vista  library  to  interpret
       keywords present in command line options and in data files. Library routines are available
       for locating dictionary entries by keyword and by value.

   Data Structure
       typedef struct {
              VistaIOStringConst keyword;/* keyword string */
              VistaIOLong ivalue;      /* value, if an integer */
              VistaIOStringConst svalue;/* value, if a string */
              VistaIOBoolean icached;  /* whether integer value cached */
              VistaIOBoolean fcached;  /* whether float value cached */
              VistaIODouble fvalue;    /* cached floating-point value */
       } VistaIODictEntry;

       The dictionary data structure is designed to permit any string  or  numeric  value  to  be
       associated with a keyword, and to permit the use of statically-initialized dictionaries.

       A dictionary is an array of VistaIODictEntry structures. The last entry in the array has a
       keyword field of NULL while each preceding entry contains both a keyword and a value. When
       the  dictionary  is  initialized each value can be represented either as an integer in the
       ivalue field (in which case svalue must be NULL) or as a string pointed to by  the  svalue
       field  (in  which  case  the  ivalue  field  is  irrelevant).  A  floating point number is
       incorporated as a string value containing the number in printable form.  The  ``EXAMPLES''
       section, below, shows typical code for establishing dictionaries.

       Other    fields    of   the   VistaIODictEntry   are   only   used   internally   by   the
       VistaIOLookupDictValue routine, which provides one form of  access  to  dictionaries.  The
       fields are used to cache the results of having converted a string value to an integer or a
       floating-point number. When an entry contains a string value (svalue  is  not  NULL)  then
       icached  and  fcached indicate whether or not equivalent integer and floating-point values
       are also cached in ivalue and fvalue. When creating a dictionary, initialize  icached  and
       fcached  to  zero;  this  need  not  be  done  explicitly if the dictionary is initialized
       statically as shown under ``EXAMPLES''.

   Routines
       With the following routines a dictionary entry can be located  either  by  keyword  or  by
       value.  Both routines search a dictionary sequentially from first entry to last, returning
       the first matching entry encountered.

       VistaIODictEntry *VistaIOLookupDictKeyword (VistaIODictEntry *dict,
                 VistaIOStringConst keyword)

            VistaIOLookupDictEntry  searches  the  dictionary  dict for an entry whose keyword is
            keyword. It returns a pointer to the entry, if found, or NULL otherwise.

       VistaIODictEntry *VistaIOLookupDictValue (VistaIODictEntry *dict, VistaIORepnKind repn,
                 type value)

            VistaIOLookupDictValue  searches  the  dictionary  dict  for  an entry whose value is
            value.  The  value  to  be  searched  for  can  be  specified  in  any   of   several
            representations;  that  chosen is indicated by repn.  Then type is one of VistaIOBit,
            VistaIOUByte, VistaIOSByte, VistaIOShort, VistaIOLong,  VistaIOFloat,  VistaIODouble,
            VistaIOBoolean,  or VistaIOString, depending on repn.  VistaIOLookupDictValue returns
            a pointer to the entry, if found, or NULL otherwise.

   Built-in Dictionaries
       The following dictionaries are already included in the library:

       VistaIOBooleanDict
                      maps between the keywords false, true, no, yes, off, and on and the  values
                      FALSE and TRUE

       VistaIONumericRepnDict
                      maps between the keywords bit, ubyte, sbyte, short, long, float, and double
                      and the values VistaIOBitRepn through VistaIODoubleRepn.

EXAMPLES

       This dictionary describes a mapping between keywords and integers:

              VistaIODictEntry VistaIOBooleanDict[] = {
                     { "false", FALSE }, { "true", TRUE },
                     { "no", FALSE }, { "yes", TRUE },
                     { "off", FALSE }, { "on", TRUE },
                     { NULL }
              };

       This dictionary describes a mapping between keywords and floating point numbers:

              VistaIODictEntry ConstantDict[] = {
                     { "zero", 0 }, { "one", 1 },
                     { "pi", 0, "3.14159" }, { "e", 0, "2.7182818" },
                     { NULL }
              };

       This dictionary describes a mapping between keywords and strings:

              VistaIODictEntry TitleDict[] = {
                     { "Clinton", 0, "President of the U.S.A." },
                     { "Major", 0, "Prime Minister of Great Britain" },
                     { "Mulroney", 0, "Prime Minister of Canada" },
                     { NULL }
              };

AUTHOR

       Art Pope <pope@cs.ubc.ca>

       Adaption to vistaio: Gert Wollny <gw.fossdev@gmail.com>