001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks.sizes;
021
022import com.puppycrawl.tools.checkstyle.FileStatefulCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026
027/**
028 * <p>
029 * Checks for the number of types declared at the <i>outer</i> (or <i>root</i>) level in a file.
030 * </p>
031 * <p>
032 * Rationale: It is considered good practice to only define one outer type per file.
033 * </p>
034 * <ul>
035 * <li>
036 * Property {@code max} - Specify the maximum number of outer types allowed.
037 * Type is {@code int}.
038 * Default value is {@code 1}.
039 * </li>
040 * </ul>
041 * <p>
042 * To configure the check to accept 1 outer type per file:
043 * </p>
044 * <pre>
045 * &lt;module name="OuterTypeNumber"/&gt;
046 * </pre>
047 * <p>
048 * To configure the check to accept 2 outer types per file:
049 * </p>
050 * <pre>
051 * &lt;module name="OuterTypeNumber"&gt;
052 *   &lt;property name="max" value="2"/&gt;
053 * &lt;/module&gt;
054 * </pre>
055 * <p>
056 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
057 * </p>
058 * <p>
059 * Violation Message Keys:
060 * </p>
061 * <ul>
062 * <li>
063 * {@code maxOuterTypes}
064 * </li>
065 * </ul>
066 *
067 * @since 5.0
068 */
069@FileStatefulCheck
070public class OuterTypeNumberCheck extends AbstractCheck {
071
072    /**
073     * A key is pointing to the warning message text in "messages.properties"
074     * file.
075     */
076    public static final String MSG_KEY = "maxOuterTypes";
077
078    /** Specify the maximum number of outer types allowed. */
079    private int max = 1;
080    /** Tracks the current depth in types. */
081    private int currentDepth;
082    /** Tracks the number of outer types found. */
083    private int outerNum;
084
085    @Override
086    public int[] getDefaultTokens() {
087        return getRequiredTokens();
088    }
089
090    @Override
091    public int[] getAcceptableTokens() {
092        return getRequiredTokens();
093    }
094
095    @Override
096    public int[] getRequiredTokens() {
097        return new int[] {
098            TokenTypes.CLASS_DEF,
099            TokenTypes.INTERFACE_DEF,
100            TokenTypes.ENUM_DEF,
101            TokenTypes.ANNOTATION_DEF,
102            TokenTypes.RECORD_DEF,
103        };
104    }
105
106    @Override
107    public void beginTree(DetailAST ast) {
108        currentDepth = 0;
109        outerNum = 0;
110    }
111
112    @Override
113    public void finishTree(DetailAST ast) {
114        if (max < outerNum) {
115            log(ast, MSG_KEY, outerNum, max);
116        }
117    }
118
119    @Override
120    public void visitToken(DetailAST ast) {
121        if (currentDepth == 0) {
122            outerNum++;
123        }
124        currentDepth++;
125    }
126
127    @Override
128    public void leaveToken(DetailAST ast) {
129        currentDepth--;
130    }
131
132    /**
133     * Setter to specify the maximum number of outer types allowed.
134     *
135     * @param max the new number.
136     */
137    public void setMax(int max) {
138        this.max = max;
139    }
140
141}