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