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/** -*-C-*-ish
Kaya standard library
Copyright (C) 2004, 2005 Edwin Brady
This file is distributed under the terms of the GNU Lesser General
Public Licence. See COPYING for licence.
*/
module DB;
import Prelude;
// A database independent API
"DBValue represents the possible values returned by a query.
Anything which is not parseable is returned as a DBText."
public data DBValue
= DBText(String text)
| DBInt(Int num)
| DBFloat(Float float)
| DBTime(Int timestamp)
| DBBool(Bool bool);
"DBResult holds data about the result of a query.
<ul>
<li><em>table</em> gives the data returned.
<li><em>rows</em> is the number of rows in the table
<li><em>cols</em> is the number of columns in the table
<li><em>colnames</em> is the name of the columns
<li><em>resptr</em> is an internal pointer kept by the relevant db interface.
</ul>"
public data DBResult = DBRes([[DBValue]] table,
Int rows,
Int cols,
[String] colnames,
Ptr resptr);
"DBIncResult holds a query result for incremental return.
<ul>
<li><em>rows</em> is the number of rows in the table
<li><em>cols</em> is the number of columns in the table
<li><em>colnames</em> is the name of the columns
<li><em>resptr</em> is an internal pointer kept by the relevant db interface.
</ul>"
public data DBIncResult<a> = DBIncRes(DBHandle<a> con,
Int rows,
Int cols,
[String] colnames,
Ptr resptr);
"A database handle.
The parameter is the specific handle type for a db, eg PGConnection.
To create a database handle in supported dbs:
<ul>
<li>Postgres:
<pre>
import PostgresDB;
PGDB db_connect_pg(String info);
</pre>
</ul>"
public data DBHandle<a> = DBh(a handle,
DBResult(a,String) exec,
DBIncResult<a>(a,String,DBHandle<a>) incexec,
[DBValue](DBIncResult<a>) getrow,
Void(DBIncResult<a>) incdiscard,
Void(a) close);
"Execute a query with the given connection handle."
public DBResult exec(DBHandle<a> con, String query) {
// fn = con.exec;
return con.exec(con.handle, query);
}
"Execute a query with the given connection handle for incremental retrieval of results."
public DBIncResult<a> incExec(DBHandle<a> con, String query) {
// fn = con.exec;
return con.incexec(con.handle, query, con);
}
"Retrieve a row from an incremental query"
public [DBValue] getRow(DBIncResult<a> res) {
return res.con.getrow(res);
}
"Discard an incremental query once it is no longer needed"
public Void incDiscard(DBIncResult<a> res) {
fn = res.con.incdiscard;
fn(res);
}
"Close a connection"
public Void close(DBHandle<a> con) {
/// FIXME: Bah. The parser should be fixed to allow this to be done properly.
fn = con.close;
fn(con.handle);
}
"Get a column name from a result."
public String column(DBResult res, Int col) {
return (res.colnames[col]);
}
"Default incremental retrieval function for DBs where it is unsupported"
public [DBValue] defaultGetRow(DBIncResult<a> res) {
throw(NotImplemented);
}
"Default incremental query function for DBs where it is unsupported"
public DBIncResult<a> defaultIncExec(a con, String query, DBHandle<a> cptr) {
throw(NotImplemented);
}
"Default incremental query discard function for DBs where it is unsupported"
public Void defaultIncDiscard(DBIncResult<a> res) {
throw(NotImplemented);
}
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