RewriteAliasFunctionRule.java

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// distributed with this work for additional information
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// to you 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
//
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package org.apache.doris.rewrite;

import org.apache.doris.analysis.Analyzer;
import org.apache.doris.analysis.CastExpr;
import org.apache.doris.analysis.Expr;
import org.apache.doris.analysis.FunctionCallExpr;
import org.apache.doris.catalog.AliasFunction;
import org.apache.doris.catalog.Function;
import org.apache.doris.common.AnalysisException;

/**
 * rewrite alias function to real function
 */
public class RewriteAliasFunctionRule implements ExprRewriteRule {
    public static RewriteAliasFunctionRule INSTANCE = new RewriteAliasFunctionRule();

    @Override
    public Expr apply(Expr expr, Analyzer analyzer, ExprRewriter.ClauseType clauseType) throws AnalysisException {
        if (expr instanceof FunctionCallExpr) {
            Function fn = expr.getFn();
            if (fn instanceof AliasFunction) {
                Expr originFn = ((AliasFunction) fn).getOriginFunction();
                if (originFn instanceof FunctionCallExpr) {
                    return ((FunctionCallExpr) expr).rewriteExpr(analyzer);
                } else if (originFn instanceof CastExpr) {
                    return ((CastExpr) originFn).rewriteExpr(((AliasFunction) fn).getParameters(),
                            ((FunctionCallExpr) expr).getParams().exprs());
                }
            }

        }
        return expr;
    }
}