plucky (3) VistaIOdictionary.3.gz

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>