core/org.eclipse.smila.solr/code/src/org/eclipse/smila/solr/util/SolrQueryUtils.java

/*********************************************************************************************************************
 * Copyright (c) 2008, 2012 Attensity Europe GmbH and brox IT Solutions GmbH. All rights reserved. This program and the
 * accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this
 * distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: Andreas Weber (Attensity Europe GmbH), Thomas Menzel (brox IT Solution GmbH) - initial implementation
 **********************************************************************************************************************/
package org.eclipse.smila.solr.util;

import static org.apache.commons.lang.StringUtils.isEmpty;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.List;

import org.apache.commons.lang.StringUtils;
import org.apache.solr.client.solrj.SolrServerException;
import org.apache.solr.client.solrj.response.SolrResponseBase;
import org.eclipse.smila.datamodel.Value;

/** Provide extensions/simplifications for handling SolrQuery. */
public final class SolrQueryUtils {

  /** Lucene/Solr operator for OR query parts. */
  public static final String OR_SEPARATOR = " ";

  /** The query wrapper filter string. */
  public static final String QUERY_WRAPPER_FILTER = "QueryWrapperFilter";

  /** chars, that if part of a term need to be escaped when searching. */
  public static final String ESCAPE_CHARS = "+-&|!(){}[]^~*?:\\\"";

  /** chars, that if part of a term need to be escaped when searching. including space */
  public static final String ESCAPE_CHARS_WS = ESCAPE_CHARS + " ";

  /** avoid instatiiation. */
  private SolrQueryUtils() {
  }

  /**
   * @param q
   *          the query to add the field query part to.
   * @param field
   *          the field name to add the query part for
   * @param values
   *          the field value alternatives to match in the search
   */
  public static void appendFieldQueryPart(final StringBuilder q, final String field, final List<Value> values) {
    if (field != null && values != null && !(values.isEmpty())) {
      if (q.length() > 0) {
        q.append(OR_SEPARATOR);
      }
      q.append(field).append(':');
      if (values.size() > 1) {
        final StringBuilder multiValue = new StringBuilder();
        multiValue.append("(");
        for (final Value v : values) {
          if (multiValue.length() > 1) {
            multiValue.append(OR_SEPARATOR);
          }
          multiValue.append(v);
        }
        multiValue.append(")");
        q.append(multiValue);
      } else {
        q.append(values.get(0));
      }
    }
  }

  /**
   * Encode a query into application/x-www-form-urlencoded format.
   * 
   * @param query
   *          the query.
   * @return the urlencoded query.
   * @throws UnsupportedEncodingException
   *           UnsupportedEncodingException.
   */
  public static String encodeQuery(String query) throws UnsupportedEncodingException {
    return URLEncoder.encode(query, "UTF-8");
  }

  public static String decodeQuery(String query) throws UnsupportedEncodingException {
    return URLDecoder.decode(query, "UTF-8");
  }

  /**
   * Escapes all chars with a special meaning to the lucene query parser. Spaces are not escaped.
   * 
   * @param query
   *          the query.
   * @return the query after escaping.
   * @see SolrQueryUtils#ESCAPE_CHARS
   * @see SolrQueryUtils# toConstQueryOnField(String, String)
   */
  public static String escapeQuery(String query) {
    return escapeQuery(query, ESCAPE_CHARS);
  }

  /**
   * Escapes the given chars in the given query by prepending '\'.
   * 
   * @param query
   *          the query, if empty nothing happens and it is returned as is.
   * @param escapeChars
   *          the chars to escape
   * @return the string
   */
  public static String escapeQuery(String query, final String escapeChars) {
    /* NOTE: this method has been impl'ed in regard to performance | tmenzel @ May 23, 2011 */
    if (isEmpty(query)) {
      return query;
    }

    final int strLength = query.length();
    final StringBuilder buf = new StringBuilder(strLength * 2); // can only get twice as big thru injecting '\'
    for (int i = 0; i < strLength; i++) {
      final char ch = query.charAt(i);
      if (escapeChars.indexOf(ch) >= 0) {
        buf.append('\\');
      }
      buf.append(ch);
    }
    if (buf.length() != query.length()) {
      return buf.toString();
    }
    return query;
  }

  /**
   * returns true if response indicates an error.
   * 
   * @see http://lucene.472066.n3.nabble.com/Response-status-td490876.html
   */
  public static boolean responseStatusIsError(final SolrResponseBase response) throws SolrServerException {
    return response.getStatus() != 0;
  }

  /**
   * Convert a lucene QueryWrapperFilter to a query filter for solr.
   * 
   * @param filter
   *          the filter.
   * @return the solr query filter.
   */
  public static String toSolrQueryFilter(String filter) {
    filter = StringUtils.remove(filter, QUERY_WRAPPER_FILTER);
    filter = StringUtils.replace(filter, "\\", "\\\\");
    return filter;
  }

  /**
   * creates a query string on the given field for a constant which must be searched "as is", i.e. escaping fo chars and
   * wrapping in quotes
   * 
   * @param fieldName
   *          must not contain whitespace, but this is not checked!
   * @param constant
   *          the constant
   * @return the lucen query string
   */
  public static String toConstQueryOnField(String fieldName, String constant) {
    return fieldName + ":\"" + escapeQuery(constant) + '"';
  }

  /**
   * returns an escaped query string of the form {@code (<field>:<token>)}. The given token is fully escaped, i.e.
   * including spaces.
   * 
   * 
   */
  public static String toTokenQueryOnField(String fieldName, String token) {
    return "(" + fieldName + ":" + escapeQuery(token, ESCAPE_CHARS_WS) + ')';
  }
}