Application: gvSIG desktop

import static org.gvsig.expressionevaluator.impl.function.dataaccess.SelectAggregateFunction.FUNCTION_SELECT_AGGREGATE;

    private static class SelectAggregateArgsBuilder implements ArgsBuilder {

        public SelectAggregateArgsBuilder() {

        }

        @Override

        public String toString() {

            return "select_aggregate_args()";

        }

        @Override

        public Codes build(StatementContext context) {

            context.trace(this.toString() + ".build");

            CodeBuilder codeBuilder = context.getCodeBuilder();

            BaseCodes args = (BaseCodes) codeBuilder.args();

            Code table = context.getCode("table");

            Code where = context.getCode("where");

            Code aggregateFunction = context.getCode("AGGREGATE_FUNCTION");

            Code aggregateColumn = context.getCode("AGGREGATE_COLUMN");

            args.add(table);

            if (where == null) {

                args.add(codeBuilder.constant(null));

            } else {

                args.add(where);

            }

            args.add(aggregateFunction);

            args.add(aggregateColumn);

            return args;

        }

    }

            theGrammar.addStatement(createSelectAggregateStatement(theGrammar));

    private Statement createSelectAggregateStatement(Grammar theGrammar) {

        Statement stmt;

//

//      SELECT COUNT(*) FROM table_name WHERE expression

//        

        theGrammar.addReservedWord("SELECT");

        theGrammar.addReservedWord("FROM");

        theGrammar.addReservedWord("WHERE");

        stmt = theGrammar.createStatement("SELECT_COUNT");

        stmt.addRule(stmt.require_any_token("SELECT"));

        stmt.addRule(stmt.require_any_token("COUNT","SUM", "MIN","MAX", "AVG").capture_as("AGGREGATE_FUNCTION"));

        stmt.addRule(stmt.require_any_token("("));

        stmt.addRule(stmt.require_identifier().capture_as("AGGREGATE_COLUMN"));

        stmt.addRule(stmt.require_any_token(")"));

        stmt.addRule(stmt.require_any_token("FROM"));

        stmt.addRule(stmt.require_expression().capture_as("TABLE"));

        stmt.addRule(stmt.optional_any_token("WHERE")

                .addRuleOnTrue(stmt.require_expression().capture_as("WHERE"))

        );

        stmt.addRule(stmt.optional_any_token(";"));

        stmt.code(

                FUNCTION_SELECT_AGGREGATE,

                new SelectAggregateArgsBuilder()

        );

        return stmt;

    }