1 // Protocol Buffers - Google's data interchange format
2 // Copyright 2008 Google Inc. All rights reserved.
3 // http://code.google.com/p/protobuf/
5 // Redistribution and use in source and binary forms, with or without
6 // modification, are permitted provided that the following conditions are
9 // * Redistributions of source code must retain the above copyright
10 // notice, this list of conditions and the following disclaimer.
11 // * Redistributions in binary form must reproduce the above
12 // copyright notice, this list of conditions and the following disclaimer
13 // in the documentation and/or other materials provided with the
15 // * Neither the name of Google Inc. nor the names of its
16 // contributors may be used to endorse or promote products derived from
17 // this software without specific prior written permission.
19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 package com.google.protobuf;
33 import java.io.UnsupportedEncodingException;
36 * The classes contained within are used internally by the Protocol Buffer
37 * library and generated message implementations. They are public only because
38 * those generated messages do not reside in the {@code protobuf} package.
39 * Others should not use this class directly.
41 * @author kenton@google.com (Kenton Varda)
43 public class Internal {
45 * Helper called by generated code to construct default values for string
48 * The protocol compiler does not actually contain a UTF-8 decoder -- it
49 * just pushes UTF-8-encoded text around without touching it. The one place
50 * where this presents a problem is when generating Java string literals.
51 * Unicode characters in the string literal would normally need to be encoded
52 * using a Unicode escape sequence, which would require decoding them.
53 * To get around this, protoc instead embeds the UTF-8 bytes into the
54 * generated code and leaves it to the runtime library to decode them.
56 * It gets worse, though. If protoc just generated a byte array, like:
57 * new byte[] {0x12, 0x34, 0x56, 0x78}
58 * Java actually generates *code* which allocates an array and then fills
59 * in each value. This is much less efficient than just embedding the bytes
60 * directly into the bytecode. To get around this, we need another
61 * work-around. String literals are embedded directly, so protoc actually
62 * generates a string literal corresponding to the bytes. The easiest way
63 * to do this is to use the ISO-8859-1 character set, which corresponds to
64 * the first 256 characters of the Unicode range. Protoc can then use
65 * good old CEscape to generate the string.
67 * So we have a string literal which represents a set of bytes which
68 * represents another string. This function -- stringDefaultValue --
69 * converts from the generated string to the string we actually want. The
70 * generated code calls this automatically.
72 public static String stringDefaultValue(String bytes) {
74 return new String(bytes.getBytes("ISO-8859-1"), "UTF-8");
75 } catch (UnsupportedEncodingException e) {
76 // This should never happen since all JVMs are required to implement
77 // both of the above character sets.
78 throw new IllegalStateException(
79 "Java VM does not support a standard character set.", e);
84 * Helper called by generated code to construct default values for bytes
87 * This is a lot like {@link #stringDefaultValue}, but for bytes fields.
88 * In this case we only need the second of the two hacks -- allowing us to
89 * embed raw bytes as a string literal with ISO-8859-1 encoding.
91 public static ByteString bytesDefaultValue(String bytes) {
93 return ByteString.copyFrom(bytes.getBytes("ISO-8859-1"));
94 } catch (UnsupportedEncodingException e) {
95 // This should never happen since all JVMs are required to implement
97 throw new IllegalStateException(
98 "Java VM does not support a standard character set.", e);
103 * Helper called by generated code to determine if a byte array is a valid
104 * UTF-8 encoded string such that the original bytes can be converted to
105 * a String object and then back to a byte array round tripping the bytes
106 * without loss. More precisely, returns {@code true} whenever:
108 * Arrays.equals(byteString.toByteArray(),
109 * new String(byteString.toByteArray(), "UTF-8").getBytes("UTF-8"))
112 * <p>This method rejects "overlong" byte sequences, as well as
113 * 3-byte sequences that would map to a surrogate character, in
114 * accordance with the restricted definition of UTF-8 introduced in
115 * Unicode 3.1. Note that the UTF-8 decoder included in Oracle's
116 * JDK has been modified to also reject "overlong" byte sequences,
117 * but currently (2011) still accepts 3-byte surrogate character
120 * <p>See the Unicode Standard,</br>
121 * Table 3-6. <em>UTF-8 Bit Distribution</em>,</br>
122 * Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>.
124 * <p>As of 2011-02, this method simply returns the result of {@link
125 * ByteString#isValidUtf8()}. Calling that method directly is preferred.
127 * @param byteString the string to check
128 * @return whether the byte array is round trippable
130 public static boolean isValidUtf8(ByteString byteString) {
131 return byteString.isValidUtf8();
135 * Interface for an enum value or value descriptor, to be used in FieldSet.
136 * The lite library stores enum values directly in FieldSets but the full
137 * library stores EnumValueDescriptors in order to better support reflection.
139 public interface EnumLite {
144 * Interface for an object which maps integers to {@link EnumLite}s.
145 * {@link Descriptors.EnumDescriptor} implements this interface by mapping
146 * numbers to {@link Descriptors.EnumValueDescriptor}s. Additionally,
147 * every generated enum type has a static method internalGetValueMap() which
148 * returns an implementation of this type that maps numbers to enum values.
150 public interface EnumLiteMap<T extends EnumLite> {
151 T findValueByNumber(int number);