NAME
XrmGetResource, XrmQGetResource, XrmQGetSearchList, XrmQGetSearchResource - retrieve database resources and search lists
SYNTAX
Bool XrmGetResource(XrmDatabase _d_a_t_a_b_a_s_e, char *_s_t_r___n_a_m_e,
char *_s_t_r___c_l_a_s_s, char **_s_t_r___t_y_p_e___r_e_t_u_r_n, XrmValue
*_v_a_l_u_e___r_e_t_u_r_n);
Bool XrmQGetResource(XrmDatabase _d_a_t_a_b_a_s_e, XrmNameList
_q_u_a_r_k___n_a_m_e, XrmClassList _q_u_a_r_k___c_l_a_s_s, XrmRepresentation
*_q_u_a_r_k___t_y_p_e___r_e_t_u_r_n, XrmValue *_v_a_l_u_e___r_e_t_u_r_n);
typedef XrmHashTable *XrmSearchList;
Bool XrmQGetSearchList(XrmDatabase _d_a_t_a_b_a_s_e, XrmNameList
_n_a_m_e_s, XrmClassList _c_l_a_s_s_e_s, XrmSearchList
_l_i_s_t___r_e_t_u_r_n, int _l_i_s_t___l_e_n_g_t_h);
Bool XrmQGetSearchResource(XrmSearchList _l_i_s_t, XrmName
_n_a_m_e, XrmClass _c_l_a_s_s, XrmRepresentation *_t_y_p_e___r_e_t_u_r_n,
XrmValue *_v_a_l_u_e___r_e_t_u_r_n);
ARGUMENTS
-
_c_l_a_s_s
Specifies the resource class.
-
-
_c_l_a_s_s_e_s
Specifies a list of resource classes.
-
-
_d_a_t_a_b_a_s_e
Specifies the database that is to be used.
-
-
_l_i_s_t
Specifies the search list returned by
-
_X_r_m_Q_G_e_t_S_e_a_r_c_h_L_i_s_t.
-
_l_i_s_t___l_e_n_g_t_h
Specifies the number of entries (not the byte size) allocated for list_return.
-
-
_l_i_s_t___r_e_t_u_r_n
Returns a search list for further use.
-
-
_n_a_m_e
Specifies the resource name.
-
-
_n_a_m_e_s
Specifies a list of resource names.
-
-
_q_u_a_r_k___c_l_a_s_s
Specifies the fully qualified class of the value being retrieved (as a quark).
-
-
_q_u_a_r_k___n_a_m_e
Specifies the fully qualified name of the value being retrieved (as a quark).
-
-
_q_u_a_r_k___t_y_p_e___r_e_t_u_r_n
Returns the representation type of the destination (as a quark).
-
-
_s_t_r___c_l_a_s_s
Specifies the fully qualified class of the value being retrieved (as a string).
-
-
_s_t_r___n_a_m_e
Specifies the fully qualified name of the value being retrieved (as a string).
-
-
_s_t_r___t_y_p_e___r_e_t_u_r_n
Returns the representation type of the destination (as a string).
-
-
_t_y_p_e___r_e_t_u_r_n
Returns data representation type.
-
-
_v_a_l_u_e___r_e_t_u_r_n
Returns the value in the database.
-
DESCRIPTION
The
_X_r_m_G_e_t_R_e_s_o_u_r_c_e
and
_X_r_m_Q_G_e_t_R_e_s_o_u_r_c_e
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
_X_r_m_P_u_t_R_e_s_o_u_r_c_e,
_X_r_m_Q_P_u_t_R_e_s_o_u_r_c_e,
or
_X_r_m_M_e_r_g_e_D_a_t_a_b_a_s_e_s.
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
_X_r_m_G_e_t_R_e_s_o_u_r_c_e
and
_X_r_m_Q_G_e_t_R_e_s_o_u_r_c_e
return
_T_r_u_e;
otherwise, they return
_F_a_l_s_e.
The
_X_r_m_Q_G_e_t_S_e_a_r_c_h_L_i_s_t
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
_X_r_m_G_e_t_R_e_s_o_u_r_c_e
for determining precedence.
If list_return was large enough for the search list,
_X_r_m_Q_G_e_t_S_e_a_r_c_h_L_i_s_t
returns
_T_r_u_e;
otherwise, it returns
_F_a_l_s_e.
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
_X_r_m_Q_G_e_t_S_e_a_r_c_h_L_i_s_t
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
_X_r_m_Q_G_e_t_S_e_a_r_c_h_L_i_s_t.
The
_X_r_m_Q_G_e_t_S_e_a_r_c_h_R_e_s_o_u_r_c_e
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.
_X_r_m_Q_G_e_t_S_e_a_r_c_h_R_e_s_o_u_r_c_e
returns
_T_r_u_e
if the resource was found;
otherwise, it returns
_F_a_l_s_e.
A call to
_X_r_m_Q_G_e_t_S_e_a_r_c_h_L_i_s_t
with a name and class list containing all but the last component
of a resource name followed by a call to
_X_r_m_Q_G_e_t_S_e_a_r_c_h_R_e_s_o_u_r_c_e
with the last component name and class returns the same database entry as
_X_r_m_G_e_t_R_e_s_o_u_r_c_e
and
_X_r_m_Q_G_e_t_R_e_s_o_u_r_c_e
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(3X11),
XrmMergeDatabases(3X11),
XrmPutResource(3X11),
XrmUniqueQuark(3X11)
_X_l_i_b _- _C _L_a_n_g_u_a_g_e _X _I_n_t_e_r_f_a_c_e