1/*
2 * Copyright (C) 2010 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.streamhtmlparser.impl;
18
19import com.google.common.base.Preconditions;
20
21/**
22 * Holds one state transition as derived from a Python configuration
23 * file. A state transition is a triplet as follows:
24 * <ul>
25 * <li>An expression which consists of one or more characters and/or
26 *     one or more range of characters.
27 * <li> A source state.
28 * <li> A destination state.
29 * </ul>
30 *
31 * <p>For example, the triplet ("a-z123", A, B) will cause the
32 * state to go from A to B for any character that is either 1,2,3 or in
33 * the range a-z inclusive.
34 */
35class StateTableTransition {
36
37  private final String expression;
38  private final InternalState from;
39  private final InternalState to;
40
41   /**
42   * Returns the full state of the {@code StateTableTransition} in a
43   * human readable form. The format of the returned {@code String} is not
44   * specified and is subject to change.
45   *
46   * @return full state of the {@code StateTableTransition}
47   */
48  @Override
49  public String toString() {
50    return String.format("Expression: %s; From: %s; To: %s",
51                         expression, from, to);
52  }
53
54  StateTableTransition(String expression, InternalState from,
55                       InternalState to) {
56    // Developer error if any triggers.
57    Preconditions.checkNotNull(expression);
58    Preconditions.checkNotNull(from);
59    Preconditions.checkNotNull(to);
60    this.expression = expression;
61    this.from = from;
62    this.to = to;
63  }
64
65   String getExpression() {
66     return expression;
67   }
68
69   InternalState getFrom() {
70     return from;
71   }
72
73   InternalState getTo() {
74     return to;
75   }
76}
77