XrmGetResource(3X11)X Version 11 (Release 6.6XrmGetResource(3X11)
NAME
XrmGetResource, XrmQGetResource, XrmQGetSearchList,
XrmQGetSearchResource - retrieve database resources and
search lists
SYNTAX
Bool XrmGetResource(database, str_name, str_class,
str_type_return, value_return)
XrmDatabase database;
char *str_name;
char *str_class;
char **str_type_return;
XrmValue *value_return;
Bool XrmQGetResource(database, quark_name, quark_class,
quark_type_return, value_return)
XrmDatabase database;
XrmNameList quark_name;
XrmClassList quark_class;
XrmRepresentation *quark_type_return;
XrmValue *value_return;
typedef XrmHashTable *XrmSearchList;
Bool XrmQGetSearchList(database, names, classes,
list_return, list_length)
XrmDatabase database;
XrmNameList names;
XrmClassList classes;
XrmSearchList list_return;
int list_length;
Bool XrmQGetSearchResource(list, name, class, type_return,
value_return)
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
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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.
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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
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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(3X11), XrmMergeDatabases(3X11),
XrmPutResource(3X11), XrmUniqueQuark(3X11)
Xlib - C Language X Interface
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