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added vector mutators

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This commit is contained in:
Maor Itzkovitch
2015-08-15 14:48:47 +03:00
parent b062af4c8c
commit 7bfed4b29a
6 changed files with 130 additions and 26 deletions
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45
docs/source/JavaUsage.md
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@@ -177,3 +177,48 @@ There currently is no support for parsing text (Schema's and JSON) directly
from Java or C#, though you could use the C++ parser through native call
interfaces available to each language. Please see the
C++ documentation for more on text parsing.
### Mutating FlatBuffers
As you saw above, typically once you have created a FlatBuffer, it is
read-only from that moment on. There are however cases where you have just
received a FlatBuffer, and you'd like to modify something about it before
sending it on to another recipient. With the above functionality, you'd have
to generate an entirely new FlatBuffer, while tracking what you modify in your
own data structures. This is inconvenient.
For this reason FlatBuffers can also be mutated in-place. While this is great
for making small fixes to an existing buffer, you generally want to create
buffers from scratch whenever possible, since it is much more efficient and
the API is much more general purpose.
To get non-const accessors, invoke `flatc` with `--gen-mutable`.
You now can:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.java}
Monster monster = Monster.getRootAsMonster(bb);
monster.mutateHp(10); // Set table field.
monster.pos().mutateZ(4); // Set struct field.
monster.mutateInventory(0, 1); // Set vector element.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We use the somewhat verbose term `mutate` instead of `set` to indicate that
this is a special use case, not to be confused with the default way of
constructing FlatBuffer data.
After the above mutations, you can send on the FlatBuffer to a new recipient
without any further work!
Note that any `mutate` functions on tables return a boolean, which is false
if the field we're trying to set isn't present in the buffer. Fields are not
present if they weren't set, or even if they happen to be equal to the
default value. For example, in the creation code above we set the `mana` field
to `150`, which is the default value, so it was never stored in the buffer.
Trying to call mutateMana() on such data will return false, and the value won't
actually be modified!
One way to solve this is to call `forceDefaults()` on a
`FlatBufferBuilder` to force all fields you set to actually be written. This
of course increases the size of the buffer somewhat, but this may be
acceptable for a mutable buffer.

70
src/idl_gen_general.cpp
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@@ -252,7 +252,7 @@ static Type DestinationType(const LanguageParameters &lang, const Type &type,
bool vectorelem) {
if (lang.language != GeneratorOptions::kJava) return type;
switch (type.base_type) {
case BASE_TYPE_UCHAR: return Type(BASE_TYPE_INT);
case BASE_TYPE_UCHAR: return Type(BASE_TYPE_INT); //intentionally returns int to avoid unnecessary casting in Java
case BASE_TYPE_USHORT: return Type(BASE_TYPE_INT);
case BASE_TYPE_UINT: return Type(BASE_TYPE_LONG);
case BASE_TYPE_VECTOR:
@@ -367,21 +367,25 @@ static std::string DestinationValue(const LanguageParameters &lang,
// In C#, one cast directly cast an Enum to its underlying type, which is essential before putting it onto the buffer.
static std::string SourceCast(const LanguageParameters &lang,
const Type &type) {
switch (lang.language) {
case GeneratorOptions::kJava:
if (type.base_type == BASE_TYPE_UINT) return "(int)";
else if (type.base_type == BASE_TYPE_USHORT) return "(short)";
else if (type.base_type == BASE_TYPE_UCHAR) return "(byte)";
break;
case GeneratorOptions::kCSharp:
if (type.enum_def != nullptr &&
type.base_type != BASE_TYPE_UNION)
return "(" + GenTypeGet(lang, type) + ")";
break;
default:
break;
if (type.base_type == BASE_TYPE_VECTOR) {
return SourceCast(lang, type.VectorType());
} else {
switch (lang.language) {
case GeneratorOptions::kJava:
if (type.base_type == BASE_TYPE_UINT) return "(int)";
else if (type.base_type == BASE_TYPE_USHORT) return "(short)";
else if (type.base_type == BASE_TYPE_UCHAR) return "(byte)";
break;
case GeneratorOptions::kCSharp:
if (type.enum_def != nullptr &&
type.base_type != BASE_TYPE_UNION)
return "(" + GenTypeGet(lang, type) + ")";
break;
default:
break;
}
return "";
}
return "";
}
static std::string GenDefaultValue(const LanguageParameters &lang, const Value &value, bool for_buffer) {
@@ -640,6 +644,7 @@ static void GenStruct(const LanguageParameters &lang, const Parser &parser,
std::string src_cast = SourceCast(lang, field.value.type);
std::string method_start = " public " + type_name_dest + " " +
MakeCamel(field.name, lang.first_camel_upper);
// Most field accessors need to retrieve and test the field offset first,
// this is the prefix code for that:
auto offset_prefix = " { int o = __offset(" +
@@ -784,24 +789,37 @@ static void GenStruct(const LanguageParameters &lang, const Parser &parser,
code += "); }\n";
}
// generate mutators for scalar fields
// generate mutators for scalar fields or vectors of scalars
if (opts.mutable_buffer) {
auto underlying_type = field.value.type.base_type == BASE_TYPE_VECTOR
? field.value.type.VectorType()
: field.value.type;
// boolean parameters have to be explicitly converted to byte representation
std::string setter_parameter = field.value.type.base_type == BASE_TYPE_BOOL ? "(byte)(" + field.name + " ? 1 : 0)" : field.name;
std::string mutator_prefix = MakeCamel("mutate", lang.first_camel_upper);
if (IsScalar(field.value.type.base_type)) {
auto setter_parameter = underlying_type.base_type == BASE_TYPE_BOOL ? "(byte)(" + field.name + " ? 1 : 0)" : field.name;
auto mutator_prefix = MakeCamel("mutate", lang.first_camel_upper);
//a vector mutator also needs the index of the vector element it should mutate
auto mutator_params = (field.value.type.base_type == BASE_TYPE_VECTOR ? "(int j, " : "(") +
GenTypeNameDest(lang, underlying_type) + " " +
field.name + ") { ";
auto setter_index = field.value.type.base_type == BASE_TYPE_VECTOR
? "__vector(o) + j * " + NumToString(InlineSize(underlying_type))
: (struct_def.fixed ? "bb_pos + " + NumToString(field.value.offset) : "o + bb_pos");
if (IsScalar(field.value.type.base_type) ||
(field.value.type.base_type == BASE_TYPE_VECTOR &&
IsScalar(field.value.type.VectorType().base_type))) {
code += " public ";
code += struct_def.fixed ? "void " : lang.bool_type;
code += mutator_prefix + MakeCamel(field.name, true) + "(";
code += GenTypeNameDest(lang, field.value.type);
code += " " + field.name + ") { ";
code += mutator_prefix + MakeCamel(field.name, true);
code += mutator_params;
if (struct_def.fixed) {
code += GenSetter(lang, field.value.type) + "(bb_pos + ";
code += NumToString(field.value.offset) + ", " + src_cast + setter_parameter + "); }\n";
code += GenSetter(lang, underlying_type) + "(" + setter_index + ", ";
code += src_cast + setter_parameter + "); }\n";
} else {
code += "int o = __offset(" + NumToString(field.value.offset) + ");";
code += " if (o != 0) { " + GenSetter(lang, field.value.type);
code += "(o + bb_pos, " + src_cast + setter_parameter + "); return true; } else { return false; } }\n";
code += " if (o != 0) { " + GenSetter(lang, underlying_type);
code += "(" + setter_index + ", " + src_cast + setter_parameter + "); return true; } else { return false; } }\n";
}
}
}

19
tests/FlatBuffers.Test/FlatBuffersExampleTests.cs
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@@ -107,6 +107,25 @@ namespace FlatBuffers.Test
Assert.AreEqual(monster.MutateTestType(Any.Monster), true);
Assert.AreEqual(monster.TestType, Any.Monster);
//mutate the inventory vector
Assert.AreEqual(monster.MutateInventory(0, 1), true);
Assert.AreEqual(monster.MutateInventory(1, 2), true);
Assert.AreEqual(monster.MutateInventory(2, 3), true);
Assert.AreEqual(monster.MutateInventory(3, 4), true);
Assert.AreEqual(monster.MutateInventory(4, 5), true);
for (int i = 0; i < monster.InventoryLength; i++)
{
Assert.AreEqual(monster.GetInventory(i), i + 1);
}
//reverse mutation
Assert.AreEqual(monster.MutateInventory(0, 0), true);
Assert.AreEqual(monster.MutateInventory(1, 1), true);
Assert.AreEqual(monster.MutateInventory(2, 2), true);
Assert.AreEqual(monster.MutateInventory(3, 3), true);
Assert.AreEqual(monster.MutateInventory(4, 4), true);
// get a struct field and edit one of its fields
Vec3 pos = monster.Pos;
Assert.AreEqual(pos.X, 1.0f);

18
tests/JavaTest.java
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@@ -127,6 +127,24 @@ class JavaTest {
TestEq(monster.mutateTestType(Any.Monster), true);
TestEq(monster.testType(), (byte)Any.Monster);
//mutate the inventory vector
TestEq(monster.mutateInventory(0, 1), true);
TestEq(monster.mutateInventory(1, 2), true);
TestEq(monster.mutateInventory(2, 3), true);
TestEq(monster.mutateInventory(3, 4), true);
TestEq(monster.mutateInventory(4, 5), true);
for (int i = 0; i < monster.inventoryLength(); i++) {
TestEq(monster.inventory(i), i + 1);
}
//reverse mutation
TestEq(monster.mutateInventory(0, 0), true);
TestEq(monster.mutateInventory(1, 1), true);
TestEq(monster.mutateInventory(2, 2), true);
TestEq(monster.mutateInventory(3, 3), true);
TestEq(monster.mutateInventory(4, 4), true);
// get a struct field and edit one of its fields
Vec3 pos = monster.pos();
TestEq(pos.x(), 1.0f);

2
tests/MyGame/Example/Monster.cs
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@@ -20,6 +20,7 @@ public sealed class Monster : Table {
public string Name { get { int o = __offset(10); return o != 0 ? __string(o + bb_pos) : null; } }
public byte GetInventory(int j) { int o = __offset(14); return o != 0 ? bb.Get(__vector(o) + j * 1) : (byte)0; }
public int InventoryLength { get { int o = __offset(14); return o != 0 ? __vector_len(o) : 0; } }
public bool MutateInventory(int j, byte inventory) { int o = __offset(14); if (o != 0) { bb.Put(__vector(o) + j * 1, inventory); return true; } else { return false; } }
public Color Color { get { int o = __offset(16); return o != 0 ? (Color)bb.GetSbyte(o + bb_pos) : (Color)8; } }
public bool MutateColor(Color color) { int o = __offset(16); if (o != 0) { bb.PutSbyte(o + bb_pos, (sbyte)color); return true; } else { return false; } }
public Any TestType { get { int o = __offset(18); return o != 0 ? (Any)bb.Get(o + bb_pos) : (Any)0; } }
@@ -39,6 +40,7 @@ public sealed class Monster : Table {
public Monster GetEnemy(Monster obj) { int o = __offset(28); return o != 0 ? obj.__init(__indirect(o + bb_pos), bb) : null; }
public byte GetTestnestedflatbuffer(int j) { int o = __offset(30); return o != 0 ? bb.Get(__vector(o) + j * 1) : (byte)0; }
public int TestnestedflatbufferLength { get { int o = __offset(30); return o != 0 ? __vector_len(o) : 0; } }
public bool MutateTestnestedflatbuffer(int j, byte testnestedflatbuffer) { int o = __offset(30); if (o != 0) { bb.Put(__vector(o) + j * 1, testnestedflatbuffer); return true; } else { return false; } }
public Stat Testempty { get { return GetTestempty(new Stat()); } }
public Stat GetTestempty(Stat obj) { int o = __offset(32); return o != 0 ? obj.__init(__indirect(o + bb_pos), bb) : null; }
public bool Testbool { get { int o = __offset(34); return o != 0 ? 0!=bb.Get(o + bb_pos) : (bool)false; } }

2
tests/MyGame/Example/Monster.java
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@@ -24,6 +24,7 @@ public final class Monster extends Table {
public int inventory(int j) { int o = __offset(14); return o != 0 ? bb.get(__vector(o) + j * 1) & 0xFF : 0; }
public int inventoryLength() { int o = __offset(14); return o != 0 ? __vector_len(o) : 0; }
public ByteBuffer inventoryAsByteBuffer() { return __vector_as_bytebuffer(14, 1); }
public boolean mutateInventory(int j, int inventory) { int o = __offset(14); if (o != 0) { bb.put(__vector(o) + j * 1, (byte)inventory); return true; } else { return false; } }
public byte color() { int o = __offset(16); return o != 0 ? bb.get(o + bb_pos) : 8; }
public boolean mutateColor(byte color) { int o = __offset(16); if (o != 0) { bb.put(o + bb_pos, color); return true; } else { return false; } }
public byte testType() { int o = __offset(18); return o != 0 ? bb.get(o + bb_pos) : 0; }
@@ -46,6 +47,7 @@ public final class Monster extends Table {
public int testnestedflatbuffer(int j) { int o = __offset(30); return o != 0 ? bb.get(__vector(o) + j * 1) & 0xFF : 0; }
public int testnestedflatbufferLength() { int o = __offset(30); return o != 0 ? __vector_len(o) : 0; }
public ByteBuffer testnestedflatbufferAsByteBuffer() { return __vector_as_bytebuffer(30, 1); }
public boolean mutateTestnestedflatbuffer(int j, int testnestedflatbuffer) { int o = __offset(30); if (o != 0) { bb.put(__vector(o) + j * 1, (byte)testnestedflatbuffer); return true; } else { return false; } }
public Stat testempty() { return testempty(new Stat()); }
public Stat testempty(Stat obj) { int o = __offset(32); return o != 0 ? obj.__init(__indirect(o + bb_pos), bb) : null; }
public boolean testbool() { int o = __offset(34); return o != 0 ? 0!=bb.get(o + bb_pos) : false; }