sjm.examples.query
Class QueryBuilder

java.lang.Object
  |
  +--sjm.examples.query.QueryBuilder

public class QueryBuilder

extends java.lang.Object

implements PubliclyCloneable

This class accepts terms, class names and comparisons, and then builds a query from them. The query this builder creates will have the form:

	
     q(term0, term1, ...), 
     className0, className1, ...,
     comparison0, comparison1, ...
 

The first structure forms a "projection", which is set of terms that should all be valid after the remaining structures prove themselves. To use the query after building it, prove its tail to establish values for its head. For example, consider the select statement:

    select PricePerBag * 0.9 
        from chip 
        where PricePerBag > 10
 

a parser for this statement can pass a QueryBuilder one term, one class name and one comparison; the builder will take these and build the query:

     q(*(PricePerBag, 0.9)), 
     chip(ChipID, ChipName, PricePerBag, Ounces, Oil), 
     >(PricePerBag, 10.0)
 

A program can prove the tail of this query (that is, all the structures after the first). Each proof of the tail will establish a value for the PricePerBag variable. After each proof, the term in the head structure will have a value of .9 times the PricePerBag.

Field Summary

protected java.util.Vector	classNames
protected java.util.Vector	comparisons
protected Speller	speller
protected java.util.Vector	terms

Constructor Summary

QueryBuilder(Speller speller)
Construct a query builder that will use the given speller.

Method Summary

void	addClassName(java.lang.String s) Add the given class name to the query.
void	addComparison(Comparison c) Add a comparison to the query.
void	addTerm(Term t) Add a term that will appear in the head structure of the query.
Query	build(AxiomSource as) Create a query from the terms, class names and variables this object has received so far.
java.lang.Object	clone() Return a copy of this object.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

speller

protected Speller speller

terms

protected java.util.Vector terms

classNames

protected java.util.Vector classNames

comparisons

protected java.util.Vector comparisons

Constructor Detail

QueryBuilder

public QueryBuilder(Speller speller)

Construct a query builder that will use the given speller.

Method Detail

addClassName

public void addClassName(java.lang.String s)

Add the given class name to the query. This method checks that the class name when properly spelled matches a known class name.

addComparison

public void addComparison(Comparison c)

Add a comparison to the query.

addTerm

public void addTerm(Term t)

Add a term that will appear in the head structure of the query.

build

public Query build(AxiomSource as)

Create a query from the terms, class names and variables this object has received so far.

clone

public java.lang.Object clone()

Return a copy of this object.

Specified by:

clone in interface PubliclyCloneable

Overrides:

clone in class java.lang.Object

Returns:

a copy of this object