Should the Parameter class be replaced with Java 5 enums? My only
concern is backward compatibility. I noticed that Parameter is
serializable. Is this used by Lucene? I wasn't able to see any place
that depended on it. The only public method, Parameter.toString()
results in the same value as a Java 5 Enum.
It seems that an advanced form of enums would be helpful, too. I'm
seeing a lot of "switch" statements on their value:
e.g.
In AbstractField:
if (store == Field.Store.YES){
this.isStored = true;
}
else if (store == Field.Store.NO){
this.isStored = false;
}
else
throw new IllegalArgumentException("unknown store parameter " +
store);
if (index == Field.Index.NO) {
this.isIndexed = false;
this.isTokenized = false;
} else if (index == Field.Index.ANALYZED) {
this.isIndexed = true;
this.isTokenized = true;
} else if (index == Field.Index.NOT_ANALYZED) {
this.isIndexed = true;
this.isTokenized = false;
} else if (index == Field.Index.NOT_ANALYZED_NO_NORMS) {
this.isIndexed = true;
this.isTokenized = false;
this.omitNorms = true;
} else if (index == Field.Index.ANALYZED_NO_NORMS) {
this.isIndexed = true;
this.isTokenized = true;
this.omitNorms = true;
} else {
throw new IllegalArgumentException("unknown index parameter " +
index);
}
This could be reduced to:
this.stored = store.isStored();
this.isIndexed = index.isIndexed();
this.isTokenized = index.isTokenized();
this.omitNorms = index.omitNorms();
With the following:
public enum Store {
YES { public boolean isStored() { return true; } },
NO { public boolean isStored() { return false; } };
// Determine whether this is stored or not
abstract boolean isStored();
}
public enum Index {
ANALYZED {
public boolean isIndexed() { return true; }
public boolean isTokenized() { return true; }
public boolean omitNorms() { return false; }
...
},
...
abstract boolean isIndexed();
abstract boolean isTokenized();
abstract boolean omitNorms();
...
}
What I like about this pattern is that it clearly documents what each
member does. As it is it is spread around in the files.
One can add a "picker" method to these to serve as a factory. E.g. given
indexed = true, tokenized = false, ... what is the appropriate value
from the Index enum.
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