Sample Operator Function Resolver

OperatorFunctionResolver.java

package org.apache.drill.exec.resolver;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.drill.common.expression.FunctionCall;
import org.apache.drill.common.expression.LogicalExpression;
import org.apache.drill.common.types.TypeProtos.MajorType;
import org.apache.drill.exec.expr.fn.DrillFuncHolder;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

public class OperatorFuncResolver implements FuncResolver{
	
	private static final Map<String, Integer> precedenceMap;
	/** Would be moved to a new class, would be shared by all resolvers **/
	static {
		precedenceMap = new HashMap<String, Integer>();
		precedenceMap.put("TINYINT", 1);
		precedenceMap.put("SMALLINT", 2);
		precedenceMap.put("INT", 3);
		precedenceMap.put("BIGINT", 4);
		precedenceMap.put("FLOAT4", 5);
		precedenceMap.put("FLOAT8", 6);
		precedenceMap.put("VARCHAR", 7);
		
	}

	@Override
	public DrillFuncHolder getBestMatch(List<DrillFuncHolder> methods, FunctionCall call) {
		
		ImmutableList<LogicalExpression> args = call.args;
		
		if(args.size() != 2){
			
		}
		
		LogicalExpression l1 = args.get(0);
		LogicalExpression l2 = args.get(1);
		
		
		
		int t1 = precedenceMap.get(args.get(0).getMajorType()); //BIGINT, REQUIRED
		int t2 = precedenceMap.get(args.get(1).getMajorType()); // FLOAT8, REQUIRED
		
		MajorType commonType = (t1 > t2) ? args.get(0).getMajorType() : args.get(1).getMajorType();
		

                /** Convert arguments to new args and continue search of best match function **/
		/*List<LogicalExpression> newargs = Lists.newArrayList();
	      for (int i = 0; i < call.args.size(); ++i) {
	        LogicalExpression newExpr = // TODO
	        args.add(newExpr);
	      }*/
		
                /** Conversion of call to new argument types **/
		//FunctionCall modifiedCall = new FunctionCall(call.getDefinition(), newargs, call.getPosition());
		 
		
		for(DrillFuncHolder h : methods){
		      if(h.matches(call)){
		        return h;
		      }
		    }
		
		return null;
	}
	
	
	

}