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XrmQGetSearchList, XrmQGetSearchResource - retrieve database resources and
Bool XrmGetResource(database, str_name, str_class, retrieve
database resources and search lists str_type_return, value_return)
Bool XrmQGetResource(database, quark_name, quark_class, value_return)
typedef XrmHashTable *XrmSearchList;
names, classes, list_length)
Bool XrmQGetSearchResource(list, name, class, value_return)
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.
- Specifies the resource class.
- Specifies a list of
- Specifies the database that is to be used.
the search list returned by XrmQGetSearchList.
- Specifies the
number of entries (not the byte size) allocated for list_return.
a search list for further use.
- Specifies the resource name.
a list of resource names.
- Specifies the fully qualified class
of the value being retrieved (as a quark).
- Specifies the fully
qualified name of the value being retrieved (as a quark).
the representation type of the destination (as a quark).
the fully qualified class of the value being retrieved (as a string).
the fully qualified name of the value being retrieved (as a string).
the representation type of the destination (as a string).
data representation type.
- Returns the value in the database.
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.
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
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.
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:
- 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
- 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
- An entry preceded by a tight binding takes precedence over
entries preceded by a loose binding.
Xlib - C Language X Interface
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