Codegen serializers

[Daquiver1]

No description provided.

[michalgr]

We want to generate serialize and parse methods for all generated structs. Once that happens we will make them subclasses of JDWPStruct. For that we need two methods for each struct:

• def serialize(self, output: JDWPOutputStreamBase)
• static async def parse(input: JDWPInputStreamBase)

In order to generate both methods we need to iterate through fields defined in the spec and read/write them. Example of parse for __ClassPaths_reply:

@staticmethod
async def parse(input: JDWPInputStreamBase) -> ClassPathsReply:
    baseDir: str = await input.read_string()

    classpaths: int = await input.read_int()

    classpathsArray: List[ClassPathsReplyClasspathsArrayElement] = []
    for _ in range(classpaths):
        classpathsArray.append(await ClassPathsReplyClasspathsArrayElement.parse(input))

    bootclasspaths = await input.read_int()
    
    bootclasspathsArray: List[ClassPathsReplyClasspathsArrayElement] = []
    for _ in range(bootclasspaths):
        bootclasspathsArray.append(await ClassPathsReplyBootclasspathsArrayElement.parse(input))

    return ClassPathsReply(
        baseDir=baseDir,
        classpathsArray=classpathsArray,
        bootclasspathsArray=bootclasspathsArray,
    )

Serialize method for the same struct could look like:

def serialize(self, output: JDWPOutputStreamBase):
    output.write_string(self.baseDir)

    output.write_int(len(self.classpathsArray))

    for element in self.classpathsArray:
        element.serialize(output)
        
    output.write_int(len(self.bootclasspathsArray))

    for element in self.bootclasspathsArray:
        element.serialize(output)

Tags of unions and lengths of arrays are interesting: they don't have corresponding fields in generated structs, but those values. Those values are used only to guide the parsing logic and need to be computed when serializing structs.

[michalgr]

We probably want to make generate_deserialization_function and generate_serialization_function methods of StructGenerator so that we can generate parsing and serializing functions as methods of corresponding structs.

[michalgr]

One more thing, JDWPStruct.serialize is an async method, but I will be changing it now. Writing to a stream is not async, so we can keep it simple.

[michalgr]

This should always be the case, the type of element_type is Struct: https://github.com/facebookexperimental/ExtendedAndroidTools/blob/main/projects/jdwp/defs/schema.py#L76

[michalgr]

Please remove this if, type system enforces that this branch is always taken so let's not consider other options.

[michalgr]

Please remove this if, type system enforces that this branch is always taken so let's not consider other options.

[michalgr]

Here we need to parse every field. We want to parse things like array lengths and union tags because they are necessary for parsing actual arrays and unions.

[michalgr]

You need to handle ArrayLength and UnionTag fields here.

[michalgr]

Is write_{field_name} the right method to call here ?

[michalgr]

This we should generate in a function handling ArrayLength type, __generate_serialize_array_length_code or something like that. That function should find the field of the containing struct whose size it is and write the value accordingly.

[michalgr]

Similarly to the array case the tag should be written in a method handling fields of UnionTag type.

[michalgr]

This does not seem to be correctly indented

[michalgr]

You need to handle array length and union tag types too.

[michalgr]

code formatter complains about this, revert to the original state.