NAME
lSelect, lSelectDestroy, lSplit, lJoinSubList, lJoin, lWhere
(_lWhere), lOrWhere, lAndWhere, lFreeWhere, lWhat, lFree-
What, lWriteWhere, lWriteWhat, lCountWhat
generic list database functions
SYNOPSIS
#include "cull.h"
lList* lSelect(
char *newname,
lList *sourcelist,
lCondition *condition,
lEnumeration *enumeration
);
lList* lSelectDestroy(
lList *sourcelist,
lCondition *condition,
);
int lSplit(
lList **sourcelist,
lList **not_matched_list,
char *not_matched_list_name,
lCondition *condition,
);
lList* lJoinSublist(
char *newname,
int joinfield,
lList *list1,
lCondition *where1,
lEnumeration *what1,
lDescr *subdescr,
lCondition *where2,
lEnumeration *what2
);
lList* lJoin(
char *newname,
int joinfield1,
lList *lp0,
lCondition *where1,
lEnumeration *what1,
int joinfield2,
lList *lp1,
lCondition *where2,
lEnumeration *what2
);
lCondition* lWhere( char *format, ... );
lCondition* _lWhere(char *format, WhereArgList arglist);
lCondition* lOrWhere( lCondition *cp0, lCondition *cp1);
lCondition* lAndWhere( lCondition *cp0, lCondition *cp1);
void lFreeWhere( lCondition *condition );
void lWriteWhere( lCondition *condition );
lEnumeration* lWhat( char *format, ... );
void lFreeWhat( lEnumeration *enumeration );
void lWriteWhat( lEnumeration *enumeration );
int lCountWhat(
lEnumeration *enumeration,
lDescr *descriptor
);
DESCRIPTION
lSelect
creates a new list extracting those elements from the
source list fulfilling the conditions stated in condi-
tion. The new list elements contain only the fields
given by enumeration. The first argument is the name
of the newly created list, the second argument is the
source list, the third argument are the conditions that
the selection requires and the fourth argument chooses
the fields that shall be contained in the result list
elements. Thus the new list is restricted to the
interesting fields contained in the list element. If
there are matching elements a pointer to the result
list is returned, otherwise NULL is returned. For the
construction of conditions and enumerations see lWhere
and lWhat below.
lSelectDestroy
removes the elements not fulfilling the conditions
stated in condition from the source list. The first
argument is the source list, the second argument are
the conditions that the selection requires. Thus the
new list consists only of elements fulfilling the
stated condition (Attention: for further use of the
original list, you have to do a lCopyList before
lSelectDestroy). A pointer to the result list is
returned. If the reduced list contains no elements the
list is completely freed and NULL is returned. For the
construction of conditions see lWhere below.
lSplit
splits the source list into two distinct parts. The
source list contains all elements fulfilling the condi-
tion stated in condition and the elements not fulfil-
ling this condition are contained in the list specified
as second argument. The first argument is the address
of the source list, the second argument is the address
of a list pointer which must be NULL. If you are not
interested in the not matched list set not_matched_list
and not_matched_list_name to NULL. The third argument
is the name of the not_matched list. The fourth argu-
ment is a condition. (Attention: for further use of the
original list, you have to do a lCopyList
before lSplit). The all elements of the source list
match the condition the source list remains unchanged
and the unmatched list is NULL. If no element matches
the condition the not_matched list contains all ele-
ments and the source list is NULL. In case of success
0 is returned, otherwise -1. For the construction of
conditions see lWhere below.
lJoinSublist
joins a list with one of its sub-lists. lJoinSublist
gets as the first argument the name of the newly
created list. The second argument is the join field (of
type lListT), the third argument is the main list, the
following two arguments are the condition and enumera-
tion for the main list, the sixth argument is the sub-
list descriptor and the last two fields are the condi-
tions and field enumerations for the sub-list.
For every main list element fulfilling the condition
where1 there is a join performed with the by joinfield
specified sub-list of the list element. Only those
elements in the sub-list that match the conditions
stated in where2. The joined elements contain the
fields enumerated in what1 and what2.
The joined list is returned when there were matching
elements in the list and the sub-list. Otherwise NULL
is returned.
For the construction of conditions and enumerations see
lWhere and lWhat below.
lJoin
joins two different lists together. The first argument
is the name of the joined list, the second argument
specifies the field over which the join has to be taken
as it is addressed in list1, it follow the conditions
and field selectors where1 and what1 and the same is
repeated for the second list list2.
Every list element of list1 is combined with every ele-
ment of list2 if the contents of the join fields join-
field1 and joinfield2 is equal and if they match the
conditions stated in where1 (list elements of list1)
and where2 (list elements of list2). The combined list
elements contain the fields enumerated in what1 and
what2.
The joined list is returned if matching elements have
been created. Otherwise NULL is returned.
For the construction of conditions and enumerations see
lWhere and lWhat below.
lWhere / _lWhere
build a structure describing a set of conditions which
are used by several list library functions.
lWhere gets as argument a format string expressing the
conditions. It is possible to have cascaded levels of
conditions using brackets, the logical AND (&&), OR
(||) and NOT (!) operator. If NULL is delivered as
condition structure no restrictions on the list are
performed (i.e. all elements match).
The syntax of the format string takes the following
form:
cond: %T ( negsimple [{ && | || } {negsimple |
%I -> cond } ] )
negsimple: {simple | ! ( simple ) }
simple: %I relop valuetype [{&& | ||} simple ...]
relop: { < | > | == | != | <= | >= | m= | c= | p=
}
valuetype: { %d | %s | %u | %f | %g | %o | %c }
For valuetype the specifiers represent in the order as
above
{ int | string | unsigned long | float | double |
long | char }
The relop specifiers have the following meaning:
<
>
<=
>=
==
!= comparison of numeric types as in the
C language
== case sensitive comparison of strings
c= case insensitive comparison of strings
m= bitmask evaluation operator
p= pattern matching string comparison
The following examples will show the usage:
where1 = lWhere( "%T(%I==%s && %I->%T(%I<%d ||
%I>%u || %I m= %u ))",
type1, field1, "Hello", field2, subtype,
subfield1, 12, subfield2, 34,
bitmasksubfield, IDLE | RUNNING );
where2 = lWhere( "%T(!(%I==%s))", type1, field1,
"Hello");
The condition 'where1' says:
field1 of list element with descriptor type1 must con-
tain "Hello" AND the sub-list stored in field2 with
descriptor subtype has a field subfield1 and subfield2
shall fulfill subfield1 < 12 OR subfield2 > 34 OR in
the bitmasksubfield the bits for RUNNING and IDLE are
set. Bitmasks are stored in an unsigned long
(ulong_32).
The condition 'where2' says:
NOT ( field1 == "Hello" ) for field1 of a list with
descriptor type1.
_lWhere is equal to lWhere concerning the format string
describing the condition. The variable argument list of
lWhere is replaced by an array of arguments delivering
the required information.
The WhereArg struct is built as follows:
struct _WhereArg {
lDescr *descriptor;
int field;
lMultitype *value;
};
The translation of the varargs lWhere functionality to
the WhereArgList mechanism is shown below:
where = lWhere("%T( %I == %s && %I ->
%T ( %I < %d ) )",
QueueT, Q_hostname, "durin.q",
Q_ownerlist, OwnerT, O_ownerage, 22);
The corresponding WhereArgList is:
WhereArg whereargs[20];
whereargs[0].descriptor = QueueT;
whereargs[1].field = Q_hostname;
whereargs[1].value.str = "durin.q";
whereargs[2].field = Q_ownerlist;
whereargs[2].descriptor = OwnerT;
whereargs[3].field = O_ownerage;
whereargs[3].value.i = 22;
where = _lWhere("%T( %I == %s && %I ->
%T ( %I < %d ) )",
whereargs);
lOrWhere
build a new condition from two conditions connecting
them with a logical or. If one of the incoming condi-
tions is NULL, NULL is returned.
lAndWhere
build a new condition from two conditions connecting
them with a logical and. If one of the incoming condi-
tions is NULL, NULL is returned.
lFreeWhere
release the memory allocated by lWhere for a condition
structure. If the specified condition structure is
NULL the function simply returns.
lWriteWhere
writes a condition structure to stdout for debugging
purposes. As argument a lCondition pointer is speci-
fied.
lWhat
builds a field enumeration structure to choose a subset
of fields, no fields at all or all fields in a list
element. The function gets as first argument a format
string describing the following variable argument list.
The built field enumeration is type specific, also if
all or no fields are specified (i.e. one needs a what
structure for every descriptor type)
The syntax of the format string is:
what: %T ( { ALL | NONE | {%I [ %I ...] |
! ( %I [%I...] ) } } )
%T specifies the descriptor type for lWhat, the rest
specifies ALL fields, no fields or the fields listed
with %I [%I...].
The following examples shall make things clearer:
all_what = lWhat("%T(ALL)", QueueT);
select all fields in QueueT.
some_what = lWhat("%T(%I %I %I)", QueueT,
Q_load, Q_name, Q_hostname);
select the fields Q_load, Q_name, Q_hostname from
QueueT.
notsome_what = lWhat("%T( !(%I %I %I))",
QueueT, Q_load, Q_name, Q_hostname);
select all the fields of QueueT without QueueT, Q_load,
Q_name, Q_hostname.
none_what = lWhat("%T(NONE)",QueueT);
select no field at all.
lFreeWhat
release the memory allocated for a field enumeration
structure. If the argument is NULL, the function simply
returns.
lWriteWhat
writes a field enumeration structure to stdout for
debugging purposes.
lCountWhat
count the number of fields defined in a field enumera-
tion structure. As argument a pointer to a field
enumeration structure and a list descriptor must be
provided. If one of the arguments is NULL, -1 is
returned. Otherwise the number of fields is returned.
RETURN VALUES
In case of error the return value is -1 or NULL, otherwise 0
or a valid pointer to the corresponding struct is returned.
ERRORS
The following errors may occur. The touched functions are
stated in parentheses.
LELISTNULL
List pointer is NULL. (lSelect)
LEENUMNULL
Field enumeration is NULL. (lSelect, lFreeWhat, lWrite-
What, lCountWhat)
LECOUNTWHAT
lCountWhat failed. (lSelect)
LEMALLOC
Malloc(3) failed. (lSelect, lWhat)
LEPARTIALDESCR
Building a new partial descriptor failed. (lSelect)
LECREATELIST
lCreateList failed. (lSelect, lJoinSublist, lJoin)
LEELEMNULL
List element is NULL. (lSelect)
LECOPYELEMPART
Copying parts of the element failed. (lSelect)
LEAPPENDELEM
lAppendElem failed. (lSelect, lJoinSublist, lJoin)
LEGETNROFELEM
lGetNumberOfElem failed. (lSelect)
LENULLARGS
Unallowed use of NULL arguments. (lJoinSublist, lJoin)
LEDESCRNULL
List descriptor is NULL. (lJoinSublist, lWhere, lCount-
What)
LENAMENOT
Name not contained in descriptor. (lJoinSublist, lJoin,
lWhat)
LEFALSEFIELD
Not a valid field name specified in enumeration.
(lJoinSublist)
LEJOINDESCR
Joining of descriptors failed. (lJoinSublist, lJoin)
LEJOIN
lJoin failed. (lJoinSublist)
LEADDLIST
lAddList failed. (lJoinSublist)
LEDIFFDESCR
List descriptors are unequal. (lJoin)
LEJOINCOPYELEM
lJoinCopyElem failed. (lJoin)
LENOFORMATSTR
No format string specified. (lWhere, lWhat)
LEPARSECOND
Parsing a condition structure failed. (lWhere)
LECONDNULL
lCondition pointer is NULL. (lFreeWhere, lWriteWhere)
LEOPUNKNOWN
Unknown operator found. (lFreeWhere, lWriteWhere)
LESYNTAX
A syntax error occurred. (lWhat)
LECOUNTDESCR
Counting the number of descriptor fields failed.
(lWhat, lCountWhat)
SEE ALSO
sge_intro(1), list_intro(3).
COPYRIGHT
See sge_intro(1) for a full statement of rights and permis-
sions.
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