Gfdb_diff_tbl.java

/*
XOWA: the XOWA Offline Wiki Application
Copyright (C) 2012-2017 gnosygnu@gmail.com

XOWA is licensed under the terms of the General Public License (GPL) Version 3,
or alternatively under the terms of the Apache License Version 2.0.

You may use XOWA according to either of these licenses as is most appropriate
for your project on a case-by-case basis.

The terms of each license can be found in the source code repository:

GPLv3 License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-GPLv3.txt
Apache License: https://github.com/gnosygnu/xowa/blob/master/LICENSE-APACHE2.txt
*/
package gplx.dbs.diffs; import gplx.*; import gplx.dbs.*;
import gplx.dbs.metas.*;
public class Gfdb_diff_tbl {		
	public Gfdb_diff_tbl(String name, Dbmeta_fld_itm[] flds, Dbmeta_fld_itm[] keys, Dbmeta_fld_itm[] vals) {
		this.Name = name; this.Flds = flds; this.Keys = keys; this.Vals = vals;
	}
	public final String Name;
	public final Dbmeta_fld_itm[] Flds;
	public final Dbmeta_fld_itm[] Keys;
	public final Dbmeta_fld_itm[] Vals;
	public Db_rdr Make_rdr(Db_conn conn) {
		Db_stmt stmt = conn.Stmt_select_order(Name, Dbmeta_fld_itm.To_str_ary(Flds), Dbmeta_fld_itm.Str_ary_empty, Dbmeta_fld_itm.To_str_ary(Keys));
		return stmt.Exec_select__rls_auto();
	}

	public static Gfdb_diff_tbl New(Dbmeta_tbl_itm tbl) {
		Dbmeta_fld_mgr flds = tbl.Flds();
		Dbmeta_fld_mgr keys = Calc_keys(tbl);
		Dbmeta_fld_mgr vals = Calc_vals(tbl.Flds(), keys);
		return new Gfdb_diff_tbl(tbl.Name(), flds.To_ary(), keys.To_ary(), vals.To_ary());
	}
	public static Dbmeta_fld_mgr Calc_keys(Dbmeta_tbl_itm tbl) {
		Dbmeta_fld_mgr rv = new Dbmeta_fld_mgr();
		// try to find primary
		Dbmeta_fld_mgr flds = tbl.Flds();
		int flds_len = flds.Len();
		for (int i = 0; i < flds_len; ++i) {
			Dbmeta_fld_itm fld = flds.Get_at(i);
			if (fld.Primary()) {
				rv.Add(fld);
				return rv;
			}
		}
		// try to find shortest unique index
		Dbmeta_idx_itm unique_idx = null; int unique_idx_len = Int_.Max_value;
		Dbmeta_idx_mgr idxs = tbl.Idxs();
		int idxs_len = idxs.Len();
		for (int i = 0; i < idxs_len; ++i) {
			Dbmeta_idx_itm idx = idxs.Get_at(i);
			if (idx.Unique() && idx.Flds.length < unique_idx_len) {	// get first shortest unique index; note that "<" is "get first" whereas "<=" is "get last"
				unique_idx = idx;
				unique_idx_len = idx.Flds.length;
				break;
			}
		}
		if (unique_idx != null) {
			Dbmeta_idx_fld[] idx_flds = unique_idx.Flds;
			int idx_flds_len = idx_flds.length;
			for (int i = 0; i < idx_flds_len; ++i)
				rv.Add(flds.Get_by(idx_flds[i].Name));
			return rv;
		}
		// just add all
		for (int i = 0; i < flds_len; ++i) {
			Dbmeta_fld_itm fld = flds.Get_at(i);
			rv.Add(fld);					
		}
		return rv;
	}
	private static Dbmeta_fld_mgr Calc_vals(Dbmeta_fld_mgr flds, Dbmeta_fld_mgr keys) {
		Dbmeta_fld_mgr rv = new Dbmeta_fld_mgr();
		int flds_len = flds.Len();
		for (int i = 0; i < flds_len; ++i) {
			Dbmeta_fld_itm fld = flds.Get_at(i);
			if (!keys.Has(fld.Name())) rv.Add(fld);
		}
		return rv;
	}
}