1 /*
2  * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License version 2 only, as
7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package com.sun.tools.javac.parser;
27 
28 import java.util.HashSet;
29 import java.util.Set;
30 
31 /**
32  * Methods used to support text blocks lint.
33  *
34  *  <p><b>This is NOT part of any supported API.
35  *  If you write code that depends on this, you do so at your own risk.
36  *  This code and its internal interfaces are subject to change or
37  *  deletion without notice.</b>
38  */
39 class TextBlockSupport {
40      enum WhitespaceChecks {
41         INCONSISTENT,
42         TRAILING
43     };
44 
45     /** Check that the use of white space in content is not problematic.
46      */
checkWhitespace(String string)47     static Set<WhitespaceChecks> checkWhitespace(String string) {
48         // Start with empty result set.
49         Set<WhitespaceChecks> checks = new HashSet<>();
50         // No need to check empty strings.
51         if (string.isEmpty()) {
52             return checks;
53         }
54         // Maximum common indentation.
55         int outdent = 0;
56         // No need to check indentation if opting out (last line is empty.)
57         char lastChar = string.charAt(string.length() - 1);
58         boolean optOut = lastChar == '\n' || lastChar == '\r';
59         // Split string based at line terminators.
60         String[] lines = string.split("\\R");
61         int length = lines.length;
62         // Extract last line.
63         String lastLine = length == 0 ? "" : lines[length - 1];
64          if (!optOut) {
65             // Prime with the last line indentation (may be blank.)
66             outdent = indexOfNonWhitespace(lastLine);
67             for (String line : lines) {
68                 // Blanks lines have no influence (last line accounted for.)
69                 if (!line.isBlank()) {
70                     outdent = Integer.min(outdent, indexOfNonWhitespace(line));
71                     if (outdent == 0) {
72                         break;
73                     }
74                 }
75             }
76         }
77         // Last line is representative.
78         String start = lastLine.substring(0, outdent);
79         for (String line : lines) {
80             // Fail if a line does not have the same indentation.
81             if (!line.isBlank() && !line.startsWith(start)) {
82                 // Mix of different white space
83                 checks.add(WhitespaceChecks.INCONSISTENT);
84             }
85             // Line has content even after indent is removed.
86             if (outdent < line.length()) {
87                 // Is the last character a white space.
88                 lastChar = line.charAt(line.length() - 1);
89                 if (Character.isWhitespace(lastChar)) {
90                     // Has trailing white space.
91                     checks.add(WhitespaceChecks.TRAILING);
92                 }
93             }
94         }
95         return checks;
96     }
97 
indexOfNonWhitespace(String string)98    private static int indexOfNonWhitespace(String string) {
99         return string.length() - string.stripLeading().length();
100     }
101 }
102