XrmGetResource(3X11) SDK X11 R4.11MU05 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.
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 destination (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 destination (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 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
3n, 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 "*"
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 "?")
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 "?") 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), XrmPutResource(3X11),
XrmUniqueQuark(3X11)
Xlib - C Language X Interface
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