java/pig-galago/src/com/yahoo/pig/impl/eval/EvalItem.java

   1 /*
   2  * Copyright (c) 2007 Yahoo! Inc.  All rights reserved.
   3  * See accompanying LICENSE file.
   4  */
   5 package com.yahoo.pig.impl.eval;
   6
   7 import java.io.ByteArrayInputStream;
   8 import java.io.IOException;
   9 import java.util.*;
  10
  11 import com.yahoo.pig.data.*;
  12 import com.yahoo.pig.impl.PigContext;
  13 import com.yahoo.pig.impl.logicalLayer.parser.ParseException;
  14 import com.yahoo.pig.impl.logicalLayer.parser.QueryParser;
  15 import com.yahoo.pig.impl.logicalLayer.schema.SchemaItem;
  16
  17 public abstract class EvalItem {
  18
  19         protected PigContext pigContext;
  20         protected EvalItem(PigContext pigContext) {
  21                 this.pigContext = pigContext;
  22         }
  23
  24         public SchemaItem schema = null;
  25
  26     public abstract void eval(Tuple input, DataCollector output) throws IOException;
  27
  28     public abstract Datum simpleEval(Tuple input) throws IOException;
  29
  30     public abstract List<String> getFuncs();
  31
  32     public abstract boolean isSimple();
  33
  34     public abstract String stringVal(Tuple tup) throws IOException;
  35
  36     public abstract Double doubleVal(Tuple tup) throws IOException;
  37
  38     public abstract SchemaItem mapInputSchema(SchemaItem input);
  39
  40     public void finish(){}
  41
  42     /**
  43      * Creates a copy of this eval item
  44      */
  45     public EvalItem copy() throws ParseException {
  46         EvalItem item;
  47         ByteArrayInputStream in = new ByteArrayInputStream(toString().getBytes());
  48         QueryParser parser = new QueryParser(in, pigContext, null);
  49         item = parser.PEvalItem();
  50         return item;
  51     }
  52
  53
  54 }