XrmGetResource(3X11) XLIB FUNCTIONS XrmGetResource(3X11)
NAME
XrmGetResource, XrmQGetResource, XrmQGetSearchList,
XrmQGetSearchResource - retrieve database resources and
search lists
SYNTAX
Bool XrmGetResource(database, strname, strclass,
strtypereturn, valuereturn)
XrmDatabase database;
char *strname;
char *strclass;
char **strtypereturn;
XrmValue *valuereturn;
Bool XrmQGetResource(database, quarkname, quarkclass,
quarktypereturn, valuereturn)
XrmDatabase database;
XrmNameList quarkname;
XrmClassList quarkclass;
XrmRepresentation *quarktypereturn;
XrmValue *valuereturn;
typedef XrmHashTable *XrmSearchList;
Bool XrmQGetSearchList(database, names, classes,
listreturn, listlength)
XrmDatabase database;
XrmNameList names;
XrmClassList classes;
XrmSearchList listreturn;
int listlength;
Bool XrmQGetSearchResource(list, name, class, typereturn,
valuereturn)
XrmSearchList list;
XrmName name;
XrmClass class;
XrmRepresentation *typereturn;
XrmValue *valuereturn;
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.
listlength
Specifies the number of entries (not the byte
size) allocated for list_return.
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XrmGetResource(3X11) XLIB FUNCTIONS XrmGetResource(3X11)
listreturn
Returns a search list for further use.
name Specifies the resource name.
names Specifies a list of resource names.
quarkclass
Specifies the fully qualified class of the value
being retrieved (as a quark).
quarkname
Specifies the fully qualified name of the value
being retrieved (as a quark).
quarktypereturn
Returns the representation type of the destina-
tion (as a quark).
strclass Specifies the fully qualified class of the value
being retrieved (as a string).
strname Specifies the fully qualified name of the value
being retrieved (as a string).
strtypereturn
Returns the representation type of the destina-
tion (as a string).
typereturn
Returns data representation type.
valuereturn
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 repre-
sentation, 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 XrmQGetRe-
source return True; otherwise, they return False.
delim %% 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-
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XrmGetResource(3X11) XLIB FUNCTIONS XrmGetResource(3X11)
to-worst order and uses the same algorithm as XrmGetRe-
source 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 qual-
ified 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 "*" 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 sin-
gle component name or class. A database entry cannot end
in a loose binding; the final component (which cannot be
"?") 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 com-
ponent at a time. At each level, the corresponding compo-
nent and/or binding of each matching entry is determined,
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XrmGetResource(3X11) XLIB FUNCTIONS XrmGetResource(3X11)
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 "?") 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 "?". An entry with a matching class
takes precedence over entries that match using "?".
3. An entry preceded by a tight binding takes precedence
over entries preceded by a loose binding.
SEE ALSO
XrmInitialize(3X11), XrmMergeDatabases(3X11), XrmPutRe-
source(3X11), XrmUniqueQuark(3X11)
Xlib - C Language X Interface
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