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// Copyright Yahoo. 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.TokenMgrException;
import com.yahoo.document.select.rule.ExpressionNode;
/**
* 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
* <a href="https://docs.vespa.ai/en/reference/document-select-language.html">document selection language</a>.
*
* Document selectors are multithread safe.
*
* @author bratseth
*/
public class DocumentSelector {
private final 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 (TokenMgrException 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
*/
private ResultList getMatchingResultList(Context context) {
return ResultList.toResultList(expression.evaluate(context));
}
/** Returns this selector as a Document Selection Language string */
@Override
public String toString() {
return expression.toString();
}
/** Visits the expression tree */
public void visit(Visitor visitor) {
expression.accept(visitor);
}
}
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