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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *  http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17
    18  package org.apache.any23.extractor.xpath;
    19
    20  import org.eclipse.rdf4j.model.Value;
    21
    22  import java.util.Locale;
    23  import java.util.Map;
    24
    25  /**
    26   * Represents a generic template term.
    27   *
    28   * @author Michele Mostarda (mostarda@fbk.eu)
    29   */
    30  public abstract class Term<T extends Value> {
    31
    32      /**
    33       * Internal value.
    34       */
    35      private final String internalValue;
    36
    37      /**
    38       * if true the #internalValue is a variable name, otherwise is a constant.
    39       */
    40      private final boolean isVar;
    41
    42      /**
    43       * Constructor.
    44       *
    45       * @param internalValue
    46       *            internal term value.
    47       * @param isVar
    48       *            if true the <code>internalValue</code> is a variable name, otherwise is a constant.
    49       */
    50      protected Term(String internalValue, boolean isVar) {
    51          this.internalValue = internalValue;
    52          this.isVar = isVar;
    53      }
    54
    55      /**
    56       * @return the internal value.
    57       */
    58      public String getInternalValue() {
    59          return internalValue;
    60      }
    61
    62      /**
    63       * @return the isVar flag value.
    64       */
    65      public boolean isVar() {
    66          return isVar;
    67      }
    68
    69      /**
    70       * Returns the value represented by this {@link Term} given the <code>varMapping</code>, the #isVar and
    71       * #internalValue parameters.
    72       *
    73       * @param varMapping
    74       *            a map representing values of variables.
    75       *
    76       * @return the value for this term.
    77       */
    78      public T getValue(Map<String, String> varMapping) {
    79          final String value;
    80          if (isVar) {
    81              value = varMapping.get(internalValue);
    82              if (value == null) {
    83                  throw new IllegalStateException(
    84                          String.format(Locale.ROOT, "Cannot find a valid value for variable '%s'", internalValue));
    85              }
    86          } else {
    87              value = internalValue;
    88          }
    89          return getValueInternal(value);
    90      }
    91
    92      protected abstract T getValueInternal(String value);
    93
    94      @Override
    95      public String toString() {
    96          return isVar ? ("?" + internalValue) : internalValue;
    97      }
    98  }