ATTRDB(2) ATTRDB(2)
NAME
attrdb - database of attribute-value pairs
SYNOPSIS
include "bufio.m";
include "attrdb.m";
attrdb := load Attrdb Attrdb->PATH;
Attr: adt {
attr: string;
val: string;
tag: int; # application-defined data, initially 0
};
Tuples: adt {
n: int;
pairs: list of ref Attr;
hasattr: fn(t: self ref Tuples, attr: string): int;
haspair: fn(t: self ref Tuples,
attr: string, value: string): int;
find: fn(t: self ref Tuples, attr: string): list of ref Attr;
findbyattr: fn(t: self ref Tuples,
attr: string, value: string, rattr: string):
list of ref Attr;
};
Dbentry: adt {
n: int;
lines: list of ref Tuples;
find: fn(e: self ref Dbentry, attr: string):
list of (ref Tuples, list of ref Attr);
findfirst: fn(e: self ref Dbentry, attr: string): string;
findpair: fn(e: self ref Dbentry,
attr: string, value: string):
list of ref Tuples;
findbyattr: fn(e: self ref Dbentry,
attr: string, value: string, rattr: string):
list of (ref Tuples, list of ref Attr);
};
Db: adt {
open: fn(path: string): ref Db;
sopen: fn(data: string): ref Db;
changed: fn(db: self ref Db): int;
reopen: fn(db: self ref Db): int;
append: fn(db1: self ref Db, db2: ref Db): ref Db;
find: fn(db: self ref Db, start: ref Dbptr,
ATTRDB(2) ATTRDB(2)
attr: string): (ref Dbentry, ref Dbptr);
findpair: fn(db: self ref Db, start: ref Dbptr,
attr: string, value: string):
(ref Dbentry, ref Dbptr);
findbyattr: fn(db: self ref Db, start: ref Dbptr,
attr: string, value: string, rattr: string):
(ref Dbentry, ref Dbptr);
};
init: fn(): string;
parseentry: fn(s: string, lno: int): (ref Dbentry, int, string);
parseline: fn(s: string, lno: int): (ref Tuples, string);
DESCRIPTION
Attrdb fetches data from textual databases that contain
groups of attribute-value pairs. The format is defined by
attrdb(6).
Init must be called before any other function in the module.
Each logical database is represented by a Db value. It can
span several physical files, named in the body of a database
attribute in the primary file of the database. (If no such
attribute appears, there is just the one physical file in
the database.)
Db.open(path)
Opens path as a database, and returns a (reference to
a) Db value that represents it. On an error, it
returns nil and the system error string contains a
diagnostic. If path contains a database attribute with
associated attributes of the form file=filename, the
logical database is formed by (logically) concatenating
the contents of each filename in the order listed. See
attrdb(6) for details.
Db.sopen(data)
Treat the contents of the string data as a database,
and return a Db value representing it.
db1.append(db2)
Return a Db value that represents the result of logi-
cally appending the contents of database db2 to db1.
db.changed()
Return true iff one or more of the underlying files
have changed since they were last read.
db.reopen()
Discard any cached data, and reopen the database files.
Return 0 on success but -1 if any file could not be
ATTRDB(2) ATTRDB(2)
reopened.
db.find(ptr,attr)
Starting at ptr, look in db for the next entry that
contains an attribute attr and return a tuple (e,ptr)
where e is a Dbentry value representing the whole
entry, and ptr is a database pointer for the next
entry. If attr cannot be found, e is nil.
db.findpair(ptr, attr, value)
Starting at ptr, look in db for the next entry that
contains the pair attr=value, and return a tuple
(e,ptr) where e is a Dbentry value representing the
whole entry, and ptr is a database pointer for the next
entry. If the given pair cannot be found, e is nil.
db.findbyattr(ptr, attr, value, rattr)
Starting at ptr in db, look for the next entry contain-
ing both the pair attr=value and a pair with attribute
rattr; return a tuple (e,ptr) where e is a Dbentry
value representing the whole entry, and ptr is a data-
base pointer for the next entry. If no such entry can
be found, e is nil.
Parseline takes a line containing a set of space-separated
attribute=value pairs, and returns a tuple (ts,err). If the
line's syntax is correct, ts is a Tuples value that repre-
sents the pairs as a list of Attr values. If the syntax is
wrong (eg, unmatched quote), ts is nil and err contains a
diagnostic.
SOURCE
/appl/lib/attrdb.b
SEE ALSO
cfg(2), attrdb(6), ndb(6)