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// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.document.select;
import com.yahoo.document.DocumentOperation;
import com.yahoo.document.select.parser.ParseException;
import com.yahoo.document.select.parser.SelectInput;
import com.yahoo.document.select.parser.SelectParser;
import com.yahoo.document.select.parser.TokenMgrError;
import com.yahoo.document.select.rule.ExpressionNode;
/**
* <p>A document selector is a filter which accepts or rejects documents
* based on their type and content. A document selector has a textual
* representation which is called the <i>Document Selection Language</i></p>
*
* <p>Document selectors are multithread safe.</p>
*
* @author bratseth
*/
public class DocumentSelector {
private ExpressionNode expression;
/**
* Creates a document selector from a Document Selection Language string
*
* @param selector The string to parse as a selector.
* @throws ParseException Thrown if the string could not be parsed.
*/
public DocumentSelector(String selector) throws ParseException {
SelectInput input = new SelectInput(selector);
try {
SelectParser parser = new SelectParser(input);
expression = parser.expression();
} catch (TokenMgrError e) {
ParseException t = new ParseException("Tokenization error parsing document selector '" + selector + "'");
throw (ParseException)t.initCause(e);
} catch (RuntimeException | ParseException e) {
ParseException t = new ParseException("Exception parsing document selector '" + selector + "'");
throw (ParseException)t.initCause(e instanceof ParseException ?
new ParseException(input.formatException(e.getMessage())) : e);
}
}
/**
* Returns true if the document referenced by this document operation is accepted by this selector
*
* @param op A document operation
* @return True if the document is accepted.
* @throws RuntimeException if the evaluation enters an illegal state
*/
public Result accepts(DocumentOperation op) {
return accepts(new Context(op));
}
/**
* Returns true if the document referenced by this context is accepted by this selector
*
* @param context The context to match in.
* @return True if the document is accepted.
* @throws RuntimeException if the evaluation enters an illegal state
*/
public Result accepts(Context context) {
return Result.toResult(expression.evaluate(context));
}
/**
* Returns the list of different variables resulting in a true state for this
* expression.
*
* @param op The document to evaluate.
* @return True if the document is accepted.
* @throws RuntimeException if the evaluation enters an illegal state
*/
public ResultList getMatchingResultList(DocumentOperation op) {
return getMatchingResultList(new Context(op));
}
/**
* Returns the list of different variables resulting in a true state for this
* expression.
*
* @param context The context to match in.
* @return True if the document is accepted.
* @throws RuntimeException if the evaluation enters an illegal state
*/
public ResultList getMatchingResultList(Context context) {
return ResultList.toResultList(expression.evaluate(context));
}
/**
* Returns this selector as a Document Selection Language string.
*
* @return The selection string.
*/
public String toString() {
return expression.toString();
}
/**
* Returns the ordering specification, if any, implied by this document
* selection expression.
*
* @param order The order of the
*/
public OrderingSpecification getOrdering(int order) {
return expression.getOrdering(order);
}
/**
* Visits the expression tree.
*
* @param visitor The visitor to use.
*/
public void visit(Visitor visitor) {
expression.accept(visitor);
}
}
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