Provided by: libx11-doc_1.8.4-2_all 
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