1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
/*
* Copyright 2016 Google Inc. All Rights Reserved.
*
* Licensed 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.
*/
package com.google.turbine.parse;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.turbine.diag.SourceFile;
import com.google.turbine.diag.TurbineError;
import com.google.turbine.diag.TurbineError.ErrorKind;
/** Preprocesses Unicode escape characters in Java source code, as described in JLS §3.3. */
public class UnicodeEscapePreprocessor {
public static final char ASCII_SUB = 0x1A;
private final SourceFile source;
private final String input;
private int idx = 0;
private int ch;
private boolean evenLeadingSlashes = true;
public UnicodeEscapePreprocessor(SourceFile source) {
this.source = source;
this.input = source.source();
}
/** Returns the current position in the input. */
public int position() {
return idx - 1;
}
/** Returns true if all input has been read. */
public boolean done() {
return idx >= input.length();
}
/** Returns the next unescaped Unicode input character. */
public int next() {
eat();
if (ch == '\\' && evenLeadingSlashes) {
unicodeEscape();
} else {
evenLeadingSlashes = true;
}
return ch;
}
/** Returns a substring of the raw (escaped) input. */
public String readString(int from, int to) {
return input.substring(from, to);
}
/** Consumes a Unicode escape. */
private void unicodeEscape() {
eat();
if (ch != 'u') {
idx--;
ch = '\\';
evenLeadingSlashes = false;
return;
}
do {
eat();
} while (ch == 'u');
char acc = (char) ((hexDigit(ch) & 0xff) << 12);
eat();
acc |= (char) ((hexDigit(ch) & 0xff) << 8);
eat();
acc |= (char) ((hexDigit(ch) & 0xff) << 4);
eat();
acc |= (char) (hexDigit(ch) & 0xff);
ch = acc;
evenLeadingSlashes = ch != '\\';
}
/** Consumes a hex digit. */
private int hexDigit(int d) {
switch (d) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
return (d - '0');
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
return ((d - 'A') + 10);
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
return ((d - 'a') + 10);
case ASCII_SUB:
throw error(ErrorKind.UNEXPECTED_EOF);
default:
throw error(ErrorKind.INVALID_UNICODE);
}
}
/**
* Consumes a raw input character.
*
* <p>Once the input is exhausted, {@code ch} will always be ASCII SUB (\u001a). JLS §3.5 requires
* ASCII SUB to be ignored if it is the last character in the escaped input stream, and assuming
* it terminates the input avoids some bounds checks in the lexer.
*/
private void eat() {
char hi = done() ? ASCII_SUB : input.charAt(idx);
idx++;
if (!Character.isHighSurrogate(hi)) {
ch = hi;
return;
}
if (done()) {
throw error(ErrorKind.UNPAIRED_SURROGATE, (int) hi);
}
char lo = input.charAt(idx++);
if (!Character.isLowSurrogate(lo)) {
throw error(ErrorKind.UNPAIRED_SURROGATE, (int) hi);
}
ch = Character.toCodePoint(hi, lo);
}
public SourceFile source() {
return source;
}
@CheckReturnValue
private TurbineError error(ErrorKind kind, Object... args) {
throw TurbineError.format(
source(), Math.min(position(), source().source().length() - 1), kind, args);
}
}
|
