schemamanager.java

纯Java的数据库

        if (table.isView()) {
            checkCascadeDropViews((View) table, cascade);
        } else {
            checkCascadeDropReferenced(table, cascade);
            checkCascadeDropViews(table, cascade);
        }

        // get it again as table object might be a different one
        table = (Table) schema.tableList.remove(dropIndex);

        removeExportedKeys(table);
        database.getUserManager().removeDbObject(table.getName());
        schema.triggerNameList.removeOwner(table.tableName);
        schema.indexNameList.removeOwner(table.tableName);
        schema.constraintNameList.removeOwner(table.tableName);
        table.dropTriggers();
        table.drop();
    }

    void setTable(int index, Table table) {

        Schema schema = (Schema) schemaMap.get(table.getSchemaName());

        schema.tableList.set(index, table.getName().name, table);
    }

    void renameTable(Session session, Table table, String newName,
                     boolean isQuoted) throws HsqlException {

        Schema schema = (Schema) schemaMap.get(table.tableName.schema.name);
        int    i      = schema.tableList.getIndex(table.tableName.name);

        checkCascadeDropViews(table, false);
        table.rename(session, newName, isQuoted);
        schema.tableList.setKey(i, newName);
    }

    /**
     * Throws if the table is referenced in a foreign key constraint.
     */
    private void checkCascadeDropReferenced(Table table,
            boolean cascade) throws HsqlException {

        Constraint[] constraints       = table.getConstraints();
        Constraint   currentConstraint = null;
        Table        refTable          = null;
        boolean      isSelfRef         = false;

        for (int i = constraints.length - 1; i >= 0; i--) {
            currentConstraint = constraints[i];

            if (currentConstraint.getType() != Constraint.MAIN) {
                continue;
            }

            refTable  = currentConstraint.getRef();
            isSelfRef = (refTable != null && table.equals(refTable));

            if (isSelfRef) {
                continue;
            }

            if (cascade) {
                Constraint refConst =
                    refTable.getConstraint(currentConstraint.getFkName());
                TableWorks tw = new TableWorks(null, refTable);

                tw.dropFKConstraint(refConst);

                constraints = table.constraintList;
                i           = constraints.length;
            } else {
                throw Trace.error(Trace.TABLE_REFERENCED_CONSTRAINT,
                                  Trace.Database_dropTable, new Object[] {
                    currentConstraint.getName().name, refTable.getName().name
                });
            }
        }
    }

    /**
     * Throws if the view is referenced in a view.
     */
    void checkCascadeDropViews(View view,
                               boolean cascade) throws HsqlException {

        View[] views = getViewsWithView(view);

        if (views != null) {
            if (cascade) {

                // drop from end to avoid repeat drop
                for (int i = views.length - 1; i >= 0; i--) {
                    dropTable(views[i], cascade);
                }
            } else {
                throw Trace.error(Trace.TABLE_REFERENCED_VIEW,
                                  views[0].getName().name);
            }
        }
    }

    /**
     * Throws if the table is referenced in a view.
     */
    void checkCascadeDropViews(Table table,
                               boolean cascade) throws HsqlException {

        View[] views = getViewsWithTable(table, null);

        if (views != null) {
            if (cascade) {

                // drop from end to avoid repeat drop
                for (int i = views.length - 1; i >= 0; i--) {
                    dropTable(views[i], cascade);
                }
            } else {
                throw Trace.error(Trace.TABLE_REFERENCED_VIEW,
                                  views[0].getName().name);
            }
        }
    }

    /**
     * Throws if the sequence is referenced in a view.
     */
    void checkCascadeDropViews(NumberSequence sequence,
                               boolean cascade) throws HsqlException {

        View[] views = getViewsWithSequence(sequence);

        if (views != null) {
            if (cascade) {

                // drop from end to avoid repeat drop
                for (int i = views.length - 1; i >= 0; i--) {
                    dropTable(views[i], cascade);
                }
            } else {
                throw Trace.error(Trace.SEQUENCE_REFERENCED_BY_VIEW,
                                  views[0].getName().name);
            }
        }
    }

    /**
     * Throws if the column is referenced in a view.
     */
    void checkColumnIsInView(Table table,
                             String column) throws HsqlException {

        View[] views = getViewsWithTable(table, column);

        if (views != null) {
            throw Trace.error(Trace.COLUMN_IS_REFERENCED,
                              views[0].getName().name);
        }
    }

    /**
     * Returns an array of views that reference another view.
     */
    private View[] getViewsWithView(View view) {

        HsqlArrayList list   = null;
        Schema        schema = (Schema) schemaMap.get(view.getSchemaName());

        for (int i = 0; i < schema.tableList.size(); i++) {
            Table t = (Table) schema.tableList.get(i);

            if (t.isView()) {
                boolean found = ((View) t).hasView(view);

                if (found) {
                    if (list == null) {
                        list = new HsqlArrayList();
                    }

                    list.add(t);
                }
            }
        }

        return list == null ? null
                            : (View[]) list.toArray(new View[list.size()]);
    }

    /**
     * Returns an array of views that reference the specified table or
     * the specified column if column parameter is not null.
     */
    private View[] getViewsWithTable(Table table, String column) {

        HsqlArrayList list = null;
        Iterator      it   = allTablesIterator();

        while (it.hasNext()) {
            Table t = (Table) it.next();

            if (t.isView()) {
                boolean found = column == null ? ((View) t).hasTable(table)
                                               : ((View) t).hasColumn(table,
                                                   column);

                if (found) {
                    if (list == null) {
                        list = new HsqlArrayList();
                    }

                    list.add(t);
                }
            }
        }

        return list == null ? null
                            : (View[]) list.toArray(new View[list.size()]);
    }

    /**
     * Returns an array of views that reference a sequence.
     */
    View[] getViewsWithSequence(NumberSequence sequence) {

        HsqlArrayList list = null;
        Iterator      it   = allTablesIterator();

        while (it.hasNext()) {
            Table t = (Table) it.next();

            if (t.isView()) {
                boolean found = ((View) t).hasSequence(sequence);

                if (found) {
                    if (list == null) {
                        list = new HsqlArrayList();
                    }

                    list.add(t);
                }
            }
        }

        return list == null ? null
                            : (View[]) list.toArray(new View[list.size()]);
    }

    /**
     * After addition or removal of columns and indexes all views that
     * reference the table should be recompiled.
     */
    void recompileViews(Table table) throws HsqlException {

        View[] viewlist = getViewsWithTable(table, null);

        if (viewlist != null) {
            for (int i = 0; i < viewlist.length; i++) {
                String schema = viewlist[i].compileTimeSchema.name;

                if (!schemaExists(schema)) {
                    schema = null;
                }

                Session session =
                    database.sessionManager.getSysSession(schema, false);

                viewlist[i].compile(session);
            }
        }
    }

    /**
     *  Removes any foreign key Constraint objects (exported keys) held by any
     *  tables referenced by the specified table. <p>
     *
     *  This method is called as the last step of a successful call to
     *  dropTable() in order to ensure that the dropped Table ceases to be
     *  referenced when enforcing referential integrity.
     *
     * @param  toDrop The table to which other tables may be holding keys.
     *      This is a table that is in the process of being dropped.
     */
    void removeExportedKeys(Table toDrop) {

        Schema schema = (Schema) schemaMap.get(toDrop.getSchemaName());

        for (int i = 0; i < schema.tableList.size(); i++) {
            Table table = (Table) schema.tableList.get(i);

            for (int j = table.constraintList.length - 1; j >= 0; j--) {
                Table refTable = table.constraintList[j].getRef();

                if (toDrop == refTable) {
                    table.constraintList =
                        (Constraint[]) ArrayUtil.toAdjustedArray(
                            table.constraintList, null, j, -1);
                }
            }
        }
    }

    /**
     *  Drops a trigger with the specified name in the given context.
     */
    void dropTrigger(Session session, String name,
                     String schemaName) throws HsqlException {

        Schema  schema = (Schema) schemaMap.get(schemaName);
        boolean found  = schema.triggerNameList.containsName(name);

        Trace.check(found, Trace.TRIGGER_NOT_FOUND, name);

        HsqlName tableName =
            (HsqlName) schema.triggerNameList.removeName(name);
        Table t = this.findUserTable(session, tableName.name, schemaName);

        t.dropTrigger(name);
        session.setScripting(true);
    }

    public class Schema {

        HsqlName            name;
        DatabaseObjectNames triggerNameList;
        DatabaseObjectNames constraintNameList;
        DatabaseObjectNames indexNameList;
        SequenceManager     sequenceManager;
        HashMappedList      tableList;

        Schema(String name, boolean isquoted) {

            this.name = database.nameManager.newHsqlName(name, isquoted);
            triggerNameList    = new DatabaseObjectNames();
            indexNameList      = new DatabaseObjectNames();
            constraintNameList = new DatabaseObjectNames();
            sequenceManager    = new SequenceManager();
            tableList          = new HashMappedList();
        }

        boolean isEmpty() {
            return sequenceManager.sequenceMap.isEmpty()
                   && tableList.isEmpty();
        }

        Iterator tablesIterator() {
            return tableList.values().iterator();
        }

        Iterator sequencesIterator() {
            return sequenceManager.sequenceMap.values().iterator();
        }

        void clearStructures() {

            if (tableList != null) {
                for (int i = 0; i < tableList.size(); i++) {
                    Table table = (Table) tableList.get(i);

                    table.dropTriggers();
                }
            }

            triggerNameList    = null;
            indexNameList      = null;
            constraintNameList = null;
            sequenceManager    = null;
            tableList          = null;
        }
    }
}