--- /dev/null
+package org.apache.lucene.queryParser.ext;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import java.util.HashMap;
+import java.util.Map;
+
+import org.apache.lucene.queryParser.QueryParser;
+
+/**
+ * The {@link Extensions} class represents an extension mapping to associate
+ * {@link ParserExtension} instances with extension keys. An extension key is a
+ * string encoded into a Lucene standard query parser field symbol recognized by
+ * {@link ExtendableQueryParser}. The query parser passes each extension field
+ * token to {@link #splitExtensionField(String, String)} to separate the
+ * extension key from the field identifier.
+ * <p>
+ * In addition to the key to extension mapping this class also defines the field
+ * name overloading scheme. {@link ExtendableQueryParser} uses the given
+ * extension to split the actual field name and extension key by calling
+ * {@link #splitExtensionField(String, String)}. To change the order or the key
+ * / field name encoding scheme users can subclass {@link Extensions} to
+ * implement their own.
+ *
+ * @see ExtendableQueryParser
+ * @see ParserExtension
+ */
+public class Extensions {
+ private final Map<String,ParserExtension> extensions = new HashMap<String,ParserExtension>();
+ private final char extensionFieldDelimiter;
+ /**
+ * The default extension field delimiter character. This constant is set to
+ * ':'
+ */
+ public static final char DEFAULT_EXTENSION_FIELD_DELIMITER = ':';
+
+ /**
+ * Creates a new {@link Extensions} instance with the
+ * {@link #DEFAULT_EXTENSION_FIELD_DELIMITER} as a delimiter character.
+ */
+ public Extensions() {
+ this(DEFAULT_EXTENSION_FIELD_DELIMITER);
+ }
+
+ /**
+ * Creates a new {@link Extensions} instance
+ *
+ * @param extensionFieldDelimiter
+ * the extensions field delimiter character
+ */
+ public Extensions(char extensionFieldDelimiter) {
+ this.extensionFieldDelimiter = extensionFieldDelimiter;
+ }
+
+ /**
+ * Adds a new {@link ParserExtension} instance associated with the given key.
+ *
+ * @param key
+ * the parser extension key
+ * @param extension
+ * the parser extension
+ */
+ public void add(String key, ParserExtension extension) {
+ this.extensions.put(key, extension);
+ }
+
+ /**
+ * Returns the {@link ParserExtension} instance for the given key or
+ * <code>null</code> if no extension can be found for the key.
+ *
+ * @param key
+ * the extension key
+ * @return the {@link ParserExtension} instance for the given key or
+ * <code>null</code> if no extension can be found for the key.
+ */
+ public final ParserExtension getExtension(String key) {
+ return this.extensions.get(key);
+ }
+
+ /**
+ * Returns the extension field delimiter
+ *
+ * @return the extension field delimiter
+ */
+ public char getExtensionFieldDelimiter() {
+ return extensionFieldDelimiter;
+ }
+
+ /**
+ * Splits a extension field and returns the field / extension part as a
+ * {@link Pair}. This method tries to split on the first occurrence of the
+ * extension field delimiter, if the delimiter is not present in the string
+ * the result will contain a <code>null</code> value for the extension key and
+ * the given field string as the field value. If the given extension field
+ * string contains no field identifier the result pair will carry the given
+ * default field as the field value.
+ *
+ * @param defaultField
+ * the default query field
+ * @param field
+ * the extension field string
+ * @return a {@link Pair} with the field name as the {@link Pair#cur} and the
+ * extension key as the {@link Pair#cud}
+ */
+ public Pair<String,String> splitExtensionField(String defaultField,
+ String field) {
+ int indexOf = field.indexOf(this.extensionFieldDelimiter);
+ if (indexOf < 0)
+ return new Pair<String,String>(field, null);
+ final String indexField = indexOf == 0 ? defaultField : field.substring(0,
+ indexOf);
+ final String extensionKey = field.substring(indexOf + 1);
+ return new Pair<String,String>(indexField, extensionKey);
+
+ }
+
+ /**
+ * Escapes an extension field. The default implementation is equivalent to
+ * {@link QueryParser#escape(String)}.
+ *
+ * @param extfield
+ * the extension field identifier
+ * @return the extension field identifier with all special chars escaped with
+ * a backslash character.
+ */
+ public String escapeExtensionField(String extfield) {
+ return QueryParser.escape(extfield);
+ }
+
+ /**
+ * Builds an extension field string from a given extension key and the default
+ * query field. The default field and the key are delimited with the extension
+ * field delimiter character. This method makes no assumption about the order
+ * of the extension key and the field. By default the extension key is
+ * appended to the end of the returned string while the field is added to the
+ * beginning. Special Query characters are escaped in the result.
+ * <p>
+ * Note: {@link Extensions} subclasses must maintain the contract between
+ * {@link #buildExtensionField(String)} and
+ * {@link #splitExtensionField(String, String)} where the latter inverts the
+ * former.
+ * </p>
+ */
+ public String buildExtensionField(String extensionKey) {
+ return buildExtensionField(extensionKey, "");
+ }
+
+ /**
+ * Builds an extension field string from a given extension key and the
+ * extensions field. The field and the key are delimited with the extension
+ * field delimiter character. This method makes no assumption about the order
+ * of the extension key and the field. By default the extension key is
+ * appended to the end of the returned string while the field is added to the
+ * beginning. Special Query characters are escaped in the result.
+ * <p>
+ * Note: {@link Extensions} subclasses must maintain the contract between
+ * {@link #buildExtensionField(String, String)} and
+ * {@link #splitExtensionField(String, String)} where the latter inverts the
+ * former.
+ * </p>
+ *
+ * @param extensionKey
+ * the extension key
+ * @param field
+ * the field to apply the extension on.
+ * @return escaped extension field identifier
+ * @see #buildExtensionField(String) to use the default query field
+ */
+ public String buildExtensionField(String extensionKey, String field) {
+ StringBuilder builder = new StringBuilder(field);
+ builder.append(this.extensionFieldDelimiter);
+ builder.append(extensionKey);
+ return escapeExtensionField(builder.toString());
+ }
+
+ /**
+ * This class represents a generic pair.
+ *
+ * @param <Cur>
+ * the pairs first element
+ * @param <Cud>
+ * the pairs last element of the pair.
+ */
+ public static class Pair<Cur,Cud> {
+
+ public final Cur cur;
+ public final Cud cud;
+
+ /**
+ * Creates a new Pair
+ *
+ * @param cur
+ * the pairs first element
+ * @param cud
+ * the pairs last element
+ */
+ public Pair(Cur cur, Cud cud) {
+ this.cur = cur;
+ this.cud = cud;
+ }
+ }
+
+}
fnp / pylucene.git / blobdiff