java/src/main/com/google/appengine/api/search/checkers/QueryChecker.java

   1 // Copyright 2010 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.search.checkers;
   4
   5 import com.google.appengine.api.search.SearchQueryException;
   6 import com.google.appengine.api.search.SearchServicePb.SearchParams;
   7 import com.google.appengine.api.search.query.QueryTreeBuilder;
   8
   9 import org.antlr.runtime.RecognitionException;
  10
  11 import java.io.UnsupportedEncodingException;
  12
  13 /**
  14  * Checks values of {@link com.google.appengine.api.search.Query}.
  15  *
  16  */
  17 public final class QueryChecker {
  18   /**
  19    * The maximum length of a query string.
  20    */
  21   public static final int MAXIMUM_QUERY_LENGTH = 2000;
  22
  23   /**
  24    * Checks that query is not null and is parsable.
  25    * @param query the query to check
  26    * @return the checked query
  27    * @throws SearchQueryException if the query is not parsable
  28    * @throws IllegalArgumentException if the query is too long
  29    */
  30   public static String checkQuery(String query) {
  31     Preconditions.checkNotNull(query, "query cannot be null");
  32     int length;
  33     try {
  34       length = query.getBytes("UTF-8").length;
  35     } catch (UnsupportedEncodingException e){
  36       throw new IllegalArgumentException("Unsupported encoding UTF-8. Shouldn't  happen, ever!");
  37     }
  38     Preconditions.checkArgument(
  39         length <= MAXIMUM_QUERY_LENGTH,
  40         String.format("query string must not be longer than %d bytes, was %d", MAXIMUM_QUERY_LENGTH,
  41                       length));
  42     try {
  43       new QueryTreeBuilder().parse(query);
  44     } catch (RecognitionException e) {
  45       throw new SearchQueryException("Unable to parse query: " + query);
  46     }
  47     return query;
  48   }
  49
  50   /**
  51    * Checks the search specification is valid, specifically, has a valid
  52    * index specification, a non-null query, a non-null number of documents
  53    * to return specification, a valid cursor if present, valid sort
  54    * specification list, a valid collection of field names for sorting,
  55    * and a valid scorer specification.
  56    *
  57    * @param params the SearchParams to check
  58    * @return this checked SearchParams
  59    * @throws IllegalArgumentException if some part of the specification is
  60    * invalid
  61    * @throws SearchQueryException if the query is unparsable
  62    */
  63   public static SearchParams checkValid(SearchParams params) {
  64     IndexChecker.checkName(params.getIndexSpec().getName());
  65     checkQuery(params.getQuery());
  66     QueryOptionsChecker.checkValid(params);
  67     return params;
  68   }
  69 }