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Change ReadTag and PeekTag to just use 0 as a return value for "end of stream", rather than using an awkward out parameter.

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This simplifies quite a lot of code.

Generated code in next commit.
This commit is contained in:
Jon Skeet 2015-08-05 11:23:38 +01:00
parent 607940321c
commit ff334a60eb
8 changed files with 53 additions and 65 deletions
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3
csharp/src/Google.Protobuf.Test/CodedInputStreamExtensions.cs
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@ -38,8 +38,7 @@ namespace Google.Protobuf
{
public static void AssertNextTag(this CodedInputStream input, uint expectedTag)
{
uint tag;
Assert.IsTrue(input.ReadTag(out tag));
uint tag = input.ReadTag();
Assert.AreEqual(expectedTag, tag);
}

20
csharp/src/Google.Protobuf.Test/CodedInputStreamTest.cs
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@ -279,9 +279,7 @@ namespace Google.Protobuf
ms.Position = 0;
CodedInputStream input = new CodedInputStream(ms);
uint testtag;
Assert.IsTrue(input.ReadTag(out testtag));
Assert.AreEqual(tag, testtag);
Assert.AreEqual(tag, input.ReadTag());
// TODO(jonskeet): Should this be ArgumentNullException instead?
Assert.Throws<InvalidProtocolBufferException>(() => input.ReadBytes());
@ -377,9 +375,7 @@ namespace Google.Protobuf
CodedInputStream input = new CodedInputStream(ms);
uint actualTag;
Assert.IsTrue(input.ReadTag(out actualTag));
Assert.AreEqual(tag, actualTag);
Assert.AreEqual(tag, input.ReadTag());
string text = input.ReadString();
Assert.AreEqual('\ufffd', text[0]);
}
@ -430,15 +426,21 @@ namespace Google.Protobuf
ms.Position = 0;
CodedInputStream input = new CodedInputStream(ms, new byte[ms.Length / 2]);
uint tag;
Assert.IsTrue(input.ReadTag(out tag));
uint tag = input.ReadTag();
Assert.AreEqual(1, WireFormat.GetTagFieldNumber(tag));
Assert.AreEqual(100, input.ReadBytes().Length);
Assert.IsTrue(input.ReadTag(out tag));
tag = input.ReadTag();
Assert.AreEqual(2, WireFormat.GetTagFieldNumber(tag));
Assert.AreEqual(100, input.ReadBytes().Length);
}
}
[Test]
public void Tag0Throws()
{
var input = new CodedInputStream(new byte[] { 0 });
Assert.Throws<InvalidProtocolBufferException>(() => input.ReadTag());
}
}
}

19
csharp/src/Google.Protobuf.Test/CodedOutputStreamTest.cs
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@ -335,15 +335,16 @@ namespace Google.Protobuf
// Now test Input stream:
{
CodedInputStream cin = new CodedInputStream(new MemoryStream(bytes), new byte[50]);
uint tag;
Assert.AreEqual(0, cin.Position);
// Field 1:
Assert.IsTrue(cin.ReadTag(out tag) && tag >> 3 == 1);
uint tag = cin.ReadTag();
Assert.AreEqual(1, tag >> 3);
Assert.AreEqual(1, cin.Position);
Assert.AreEqual(500, cin.ReadInt32());
Assert.AreEqual(3, cin.Position);
//Field 2:
Assert.IsTrue(cin.ReadTag(out tag) && tag >> 3 == 2);
tag = cin.ReadTag();
Assert.AreEqual(2, tag >> 3);
Assert.AreEqual(4, cin.Position);
int childlen = cin.ReadLength();
Assert.AreEqual(120, childlen);
@ -353,19 +354,22 @@ namespace Google.Protobuf
// Now we are reading child message
{
// Field 11: numeric value: 500
Assert.IsTrue(cin.ReadTag(out tag) && tag >> 3 == 11);
tag = cin.ReadTag();
Assert.AreEqual(11, tag >> 3);
Assert.AreEqual(6, cin.Position);
Assert.AreEqual(500, cin.ReadInt32());
Assert.AreEqual(8, cin.Position);
//Field 12: length delimited 120 bytes
Assert.IsTrue(cin.ReadTag(out tag) && tag >> 3 == 12);
tag = cin.ReadTag();
Assert.AreEqual(12, tag >> 3);
Assert.AreEqual(9, cin.Position);
ByteString bstr = cin.ReadBytes();
Assert.AreEqual(110, bstr.Length);
Assert.AreEqual((byte) 109, bstr[109]);
Assert.AreEqual(120, cin.Position);
// Field 13: fixed numeric value: 501
Assert.IsTrue(cin.ReadTag(out tag) && tag >> 3 == 13);
tag = cin.ReadTag();
Assert.AreEqual(13, tag >> 3);
// ROK - Previously broken here, this returned 126 failing to account for bufferSizeAfterLimit
Assert.AreEqual(121, cin.Position);
Assert.AreEqual(501, cin.ReadSFixed32());
@ -375,7 +379,8 @@ namespace Google.Protobuf
cin.PopLimit(oldlimit);
Assert.AreEqual(125, cin.Position);
// Field 3: fixed numeric value: 501
Assert.IsTrue(cin.ReadTag(out tag) && tag >> 3 == 3);
tag = cin.ReadTag();
Assert.AreEqual(3, tag >> 3);
Assert.AreEqual(126, cin.Position);
Assert.AreEqual(501, cin.ReadSFixed32());
Assert.AreEqual(130, cin.Position);

4
csharp/src/Google.Protobuf.Test/Collections/RepeatedFieldTest.cs
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@ -455,7 +455,7 @@ namespace Google.Protobuf.Collections
Assert.AreEqual(0, output.SpaceLeft);
CodedInputStream input = new CodedInputStream(bytes);
Assert.IsTrue(input.ReadTag(out tag));
tag = input.ReadTag();
RepeatedField<SampleEnum> values = new RepeatedField<SampleEnum>();
values.AddEntriesFrom(input, FieldCodec.ForEnum(tag, x => (int)x, x => (SampleEnum)x));
@ -493,7 +493,7 @@ namespace Google.Protobuf.Collections
Assert.AreEqual(0, output.SpaceLeft);
CodedInputStream input = new CodedInputStream(bytes);
Assert.IsTrue(input.ReadTag(out tag));
tag = input.ReadTag();
RepeatedField<SampleEnum> values = new RepeatedField<SampleEnum>();
values.AddEntriesFrom(input, FieldCodec.ForEnum(tag, x => (int)x, x => (SampleEnum)x));

56
csharp/src/Google.Protobuf/CodedInputStream.cs
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@ -254,37 +254,35 @@ namespace Google.Protobuf
#region Reading of tags etc
/// <summary>
/// Attempts to peek at the next field tag.
/// Peeks at the next field tag. This is like calling <see cref="ReadTag"/>, but the
/// tag is not consumed. (So a subsequent call to <see cref="ReadTag"/> will return the
/// same value.)
/// </summary>
public bool PeekNextTag(out uint fieldTag)
public uint PeekTag()
{
if (hasNextTag)
{
fieldTag = nextTag;
return true;
return nextTag;
}
uint savedLast = lastTag;
hasNextTag = ReadTag(out nextTag);
lastTag = savedLast;
fieldTag = nextTag;
return hasNextTag;
nextTag = ReadTag();
hasNextTag = true;
lastTag = savedLast; // Undo the side effect of ReadTag
return nextTag;
}
/// <summary>
/// Attempts to read a field tag, returning false if we have reached the end
/// of the input data.
/// Reads a field tag, returning the tag of 0 for "end of stream".
/// </summary>
/// <param name="fieldTag">The 'tag' of the field (id * 8 + wire-format)</param>
/// <returns>true if the next fieldTag was read</returns>
public bool ReadTag(out uint fieldTag)
/// <returns>The next field tag, or 0 for end of stream. (0 is never a valid tag.)</returns>
public uint ReadTag()
{
if (hasNextTag)
{
fieldTag = nextTag;
lastTag = fieldTag;
lastTag = nextTag;
hasNextTag = false;
return true;
return lastTag;
}
// Optimize for the incredibly common case of having at least two bytes left in the buffer,
@ -294,7 +292,7 @@ namespace Google.Protobuf
int tmp = buffer[bufferPos++];
if (tmp < 128)
{
fieldTag = (uint)tmp;
lastTag = (uint)tmp;
}
else
{
@ -302,13 +300,13 @@ namespace Google.Protobuf
if ((tmp = buffer[bufferPos++]) < 128)
{
result |= tmp << 7;
fieldTag = (uint) result;
lastTag = (uint) result;
}
else
{
// Nope, rewind and go the potentially slow route.
bufferPos -= 2;
fieldTag = ReadRawVarint32();
lastTag = ReadRawVarint32();
}
}
}
@ -316,20 +314,18 @@ namespace Google.Protobuf
{
if (IsAtEnd)
{
fieldTag = 0;
lastTag = fieldTag;
return false;
lastTag = 0;
return 0; // This is the only case in which we return 0.
}
fieldTag = ReadRawVarint32();
lastTag = ReadRawVarint32();
}
lastTag = fieldTag;
if (lastTag == 0)
{
// If we actually read zero, that's not a valid tag.
throw InvalidProtocolBufferException.InvalidTag();
}
return true;
return lastTag;
}
/// <summary>
@ -580,14 +576,10 @@ namespace Google.Protobuf
/// </summary>
public bool MaybeConsumeTag(uint tag)
{
uint next;
if (PeekNextTag(out next))
if (PeekTag() == tag)
{
if (next == tag)
{
hasNextTag = false;
return true;
}
hasNextTag = false;
return true;
}
return false;
}

6
csharp/src/Google.Protobuf/Collections/MapField.cs
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@ -627,12 +627,8 @@ namespace Google.Protobuf.Collections
public void MergeFrom(CodedInputStream input)
{
uint tag;
while (input.ReadTag(out tag))
while ((tag = input.ReadTag()) != 0)
{
if (tag == 0)
{
throw InvalidProtocolBufferException.InvalidTag();
}
if (tag == codec.keyCodec.Tag)
{
Key = codec.keyCodec.Read(input);

6
csharp/src/Google.Protobuf/FieldCodec.cs
View File

@ -298,12 +298,8 @@ namespace Google.Protobuf
uint tag;
T value = codec.DefaultValue;
while (input.ReadTag(out tag))
while ((tag = input.ReadTag()) != 0)
{
if (tag == 0)
{
throw InvalidProtocolBufferException.InvalidTag();
}
if (tag == codec.Tag)
{
value = codec.Read(input);

4
src/google/protobuf/compiler/csharp/csharp_message.cc
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@ -417,13 +417,11 @@ void MessageGenerator::GenerateMergingMethods(io::Printer* printer) {
printer->Indent();
printer->Print(
"uint tag;\n"
"while (input.ReadTag(out tag)) {\n"
"while ((tag = input.ReadTag()) != 0) {\n"
" switch(tag) {\n");
printer->Indent();
printer->Indent();
printer->Print(
"case 0:\n" // 0 signals EOF / limit reached
" throw pb::InvalidProtocolBufferException.InvalidTag();\n"
"default:\n"
" if (pb::WireFormat.IsEndGroupTag(tag)) {\n"
" return;\n"