MirOS Manual: XrmGetResource(3), XrmQGetResource(3), XrmQGetSearchList(3), XrmQGetSearchResource(3)


XrmGetResource(3X11)     XLIB FUNCTIONS      XrmGetResource(3X11)

NAME

     XrmGetResource, XrmQGetResource, XrmQGetSearchList, XrmQGet-
     SearchResource - retrieve database resources and search
     lists

SYNTAX

     Bool XrmGetResource(XrmDatabase database, char *str_name,
          char *str_class, char **str_type_return, XrmValue
          *value_return);

     Bool XrmQGetResource(XrmDatabase database, XrmNameList
          quark_name, XrmClassList quark_class, XrmRepresentation
          *quark_type_return, XrmValue *value_return);

     typedef XrmHashTable *XrmSearchList;

          Bool XrmQGetSearchList(XrmDatabase database, XrmNameL-
          ist names, XrmClassList classes, XrmSearchList
          list_return, int list_length);

     Bool XrmQGetSearchResource(XrmSearchList list, XrmName name,
          XrmClass class, XrmRepresentation *type_return,
          XrmValue *value_return);

ARGUMENTS

     class     Specifies the resource class.

     classes   Specifies a list of resource classes.

     database  Specifies the database that is to be used.

     list      Specifies the search list returned by XrmQGetSear-
               chList.

     list_length
               Specifies the number of entries (not the byte
               size) allocated for list_return.

     list_return
               Returns a search list for further use.

     name      Specifies the resource name.

     names     Specifies a list of resource names.

     quark_class
               Specifies the fully qualified class of the value
               being retrieved (as a quark).

     quark_name
               Specifies the fully qualified name of the value
               being retrieved (as a quark).

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XrmGetResource(3X11)     XLIB FUNCTIONS      XrmGetResource(3X11)

     quark_type_return
               Returns the representation type of the destination
               (as a quark).

     str_class Specifies the fully qualified class of the value
               being retrieved (as a string).

     str_name  Specifies the fully qualified name of the value
               being retrieved (as a string).

     str_type_return
               Returns the representation type of the destination
               (as a string).

     type_return
               Returns data representation type.

     value_return
               Returns the value in the database.

DESCRIPTION

     The XrmGetResource and XrmQGetResource functions retrieve a
     resource from the specified database. Both take a fully
     qualified name/class pair, a destination resource represen-
     tation, and the address of a value (size/address pair). The
     value and returned type point into database memory; there-
     fore, you must not modify the data.

     The database only frees or overwrites entries on XrmPu-
     tResource, XrmQPutResource, or XrmMergeDatabases. A client
     that is not storing new values into the database or is not
     merging the database should be safe using the address passed
     back at any time until it exits. If a resource was found,
     both XrmGetResource and XrmQGetResource return True; other-
     wise, they return False.

     The XrmQGetSearchList function takes a list of names and
     classes and returns a list of database levels where a match
     might occur. The returned list is in best-to-worst order and
     uses the same algorithm as XrmGetResource for determining
     precedence. If list_return was large enough for the search
     list, XrmQGetSearchList returns True; otherwise, it returns
     False.

     The size of the search list that the caller must allocate is
     dependent upon the number of levels and wildcards in the
     resource specifiers that are stored in the database. The
     worst case length is %3 sup n%, where n is the number of
     name or class components in names or classes.

     When using XrmQGetSearchList followed by multiple probes for
     resources with a common name and class prefix, only the

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XrmGetResource(3X11)     XLIB FUNCTIONS      XrmGetResource(3X11)

     common prefix should be specified in the name and class list
     to XrmQGetSearchList.

     The XrmQGetSearchResource function searches the specified
     database levels for the resource that is fully identified by
     the specified name and class. The search stops with the
     first match. XrmQGetSearchResource returns True if the
     resource was found; otherwise, it returns False.

     A call to XrmQGetSearchList with a name and class list con-
     taining all but the last component of a resource name fol-
     lowed by a call to XrmQGetSearchResource with the last com-
     ponent name and class returns the same database entry as
     XrmGetResource and XrmQGetResource with the fully qualified
     name and class.

MATCHING RULES

     The algorithm for determining which resource database entry
     matches a given query is the heart of the resource manager.
     All queries must fully specify the name and class of the
     desired resource (use of the characters ``*'' and ``?'' are
     not permitted). The library supports up to 100 components in
     a full name or class. Resources are stored in the database
     with only partially specified names and classes, using pat-
     tern matching constructs. An asterisk (*) is a loose binding
     and is used to represent any number of intervening com-
     ponents, including none. A period (.) is a tight binding and
     is used to separate immediately adjacent components. A ques-
     tion mark (?) is used to match any single component name or
     class. A database entry cannot end in a loose binding; the
     final component (which cannot be the character ``?'') must
     be specified. The lookup algorithm searches the database for
     the entry that most closely matches (is most specific for)
     the full name and class being queried. When more than one
     database entry matches the full name and class, precedence
     rules are used to select just one.

     The full name and class are scanned from left to right (from
     highest level in the hierarchy to lowest), one component at
     a time. At each level, the corresponding component and/or
     binding of each matching entry is determined, and these
     matching components and bindings are compared according to
     precedence rules. Each of the rules is applied at each level
     before moving to the next level, until a rule selects a sin-
     gle entry over all others. The rules, in order of pre-
     cedence, are:

     1.   An entry that contains a matching component (whether
          name, class, or the character ``?'') takes precedence
          over entries that elide the level (that is, entries
          that match the level in a loose binding).

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XrmGetResource(3X11)     XLIB FUNCTIONS      XrmGetResource(3X11)

     2.   An entry with a matching name takes precedence over
          both entries with a matching class and entries that
          match using the character ``?''. An entry with a match-
          ing class takes precedence over entries that match
          using the character ``?''.

     3.   An entry preceded by a tight binding takes precedence
          over entries preceded by a loose binding.

SEE ALSO

     XrmInitialize(3X11), XrmMergeDatabases(3X11),
     XrmPutResource(3X11), XrmUniqueQuark(3X11)
     Xlib - C Language X Interface

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