NAME

       XrmGetResource, XrmQGetResource, XrmQGetSearchList, XrmQGetSearchResource - retrieve
       database resources and search lists

SYNTAX

       #include <X11/Xresource.h>

       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, XrmNameList 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 XrmQGetSearchList.

       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).

       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
       representation, and the address of a value (size/address pair).  The value and returned
       type point into database memory; therefore, you must not modify the data.

       The database only frees or overwrites entries on XrmPutResource, 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;
       otherwise, 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 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 containing all but the last
       component of a resource name followed by a call to XrmQGetSearchResource with the last
       component 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 pattern matching
       constructs.  An asterisk (*) is a loose binding and is used to represent any number of
       intervening components, including none.  A period (.) is a tight binding and is used to
       separate immediately adjacent components.  A question 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 single entry over all
       others.  The rules, in order of precedence, 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).

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