DB2ExprParser.java

/*
 * Copyright 1999-2017 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.druid.sql.dialect.db2.parser;

import com.alibaba.druid.sql.ast.SQLExpr;
import com.alibaba.druid.sql.ast.SQLName;
import com.alibaba.druid.sql.ast.expr.SQLIdentifierExpr;
import com.alibaba.druid.sql.ast.expr.SQLSequenceExpr;
import com.alibaba.druid.sql.parser.Lexer;
import com.alibaba.druid.sql.parser.SQLExprParser;
import com.alibaba.druid.sql.parser.Token;

public class DB2ExprParser extends SQLExprParser {

    public final static String[] AGGREGATE_FUNCTIONS = { "AVG", "COUNT", "MAX", "MIN", "STDDEV", "SUM", "ROW_NUMBER",
                                                         "ROWNUMBER" };

    public DB2ExprParser(String sql){
        this(new DB2Lexer(sql));
        this.lexer.nextToken();
    }

    public DB2ExprParser(Lexer lexer){
        super(lexer);
        this.aggregateFunctions = AGGREGATE_FUNCTIONS;
    }

    public SQLExpr primaryRest(SQLExpr expr) {
        if (identifierEquals("VALUE")) {
            if (expr instanceof SQLIdentifierExpr) {
                SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
                String ident = identExpr.getName();
                if (ident.equalsIgnoreCase("NEXT")) {
                    lexer.nextToken();
                    accept(Token.FOR);
                    SQLName seqName = this.name();
                    SQLSequenceExpr seqExpr = new SQLSequenceExpr(seqName, SQLSequenceExpr.Function.NextVal);
                    return seqExpr;
                } else if (ident.equalsIgnoreCase("PREVIOUS")) {
                    lexer.nextToken();
                    accept(Token.FOR);
                    SQLName seqName = this.name();
                    SQLSequenceExpr seqExpr = new SQLSequenceExpr(seqName, SQLSequenceExpr.Function.PrevVal);
                    return seqExpr;
                }
            }
        } else if (identifierEquals("DATE")) {
            if (expr instanceof SQLIdentifierExpr) {
                SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
                String ident = identExpr.getName();
                if (ident.equalsIgnoreCase("CURRENT")) {
                    lexer.nextToken();

                    expr = new SQLIdentifierExpr("CURRENT DATE");
                }
            }
        } else if (identifierEquals("TIMESTAMP")) {
            if (expr instanceof SQLIdentifierExpr) {
                SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
                String ident = identExpr.getName();
                if (ident.equalsIgnoreCase("CURRENT")) {
                    lexer.nextToken();

                    expr = new SQLIdentifierExpr("CURRENT DATE");
                }
            }
        }

        return super.primaryRest(expr);
    }

    protected SQLExpr dotRest(SQLExpr expr) {
        if (identifierEquals("NEXTVAL")) {
            if (expr instanceof SQLIdentifierExpr) {
                SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
                SQLSequenceExpr seqExpr = new SQLSequenceExpr(identExpr, SQLSequenceExpr.Function.NextVal);
                lexer.nextToken();
                return seqExpr;
            }
        } else if (identifierEquals("PREVVAL")) {
            if (expr instanceof SQLIdentifierExpr) {
                SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
                SQLSequenceExpr seqExpr = new SQLSequenceExpr(identExpr, SQLSequenceExpr.Function.PrevVal);
                lexer.nextToken();
                return seqExpr;
            }
        } else if (identifierEquals("CURRVAL")) {
            if (expr instanceof SQLIdentifierExpr) {
                SQLIdentifierExpr identExpr = (SQLIdentifierExpr) expr;
                SQLSequenceExpr seqExpr = new SQLSequenceExpr(identExpr, SQLSequenceExpr.Function.CurrVal);
                lexer.nextToken();
                return seqExpr;
            }
        }

        return super.dotRest(expr);
    }

}