cstructs 0.2.1

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cstructs

---

Note: This version supercedes the original cstruct package. This is my first attempt at a test driven development cycle, so I apologize in advance if the things that I do don't make sense.

Table of Contents

• Installation
• Usage
• License

Installation

pip install -U cstructs

Usage

For full usage examples, see the files in the tests folder.

Reading

from test_read.py:

    @datastruct(byteorder="big")
    class Test(metaclass=DataStruct):
        a: NativeTypes.uint16
        b: NativeTypes.uint32
        c: NativeTypes.i32
        d: NativeTypes.uint64
        e: Annotated[bytes, NativeTypes.bytestring(4)]
        f: Annotated[str, NativeTypes.char(12)]
        g: Annotated[str, NativeTypes.char(1, encoding="latin1")]

        def on_read(self):
            assert self.f == "Hello World!"

    stream = io.BytesIO()

    stream.write(bytes.fromhex("0001"))
    stream.write(bytes.fromhex("00000002"))
    stream.write(bytes.fromhex("fffffffd"))
    stream.write(bytes.fromhex("0000000000000004"))
    stream.write(bytes.fromhex("01020304"))
    stream.write(b"Hello World!")
    stream.write(bytes.fromhex("BF"))

    stream.seek(0)

    test = Test.read(stream)

    assert test.a == 1
    assert test.b == 2
    assert test.c == -3
    assert test.d == 4
    assert test.e == b"\x01\x02\x03\x04"
    assert test.f == "Hello World!"
    assert test.g == "¿"

Serializing

from test_write.py:

    @datastruct(byteorder="big")
    class Test(metaclass=DataStruct):
        a: NativeTypes.uint32
        b: NativeTypes.i8
        c: NativeTypes.char
        d: Annotated[str, NativeTypes.char(6, enforce_length=True)]
        e: Annotated[bytes, NativeTypes.bytestring(8)]

        def on_write(self, data: bytearray):
            pass

    test = Test.init_empty()

    test.a = 1

    # ensure all None values get properly encoded to 0(null)
    # fmt: off
    assert test.serialize() == bytes.fromhex(
        "00 00 00 01"
        "00"
        "00"
        "00 00 00 00 00 00"
        "00 00 00 00 00 00 00 00"
    )
    # fmt: on

    test.a = 0xFFFFFFFF
    test.b = 0xFF
    test.c = "!"
    test.d = "Anthy!"
    test.e = b"\x00\x01\x02\x03\x04\x05\x06\x07"

    # fmt: off
    assert test.serialize() == bytes.fromhex(
        "FF FF FF FF"
        "FF"
        "21"
        "41 6E 74 68 79 21"
        "00 01 02 03 04 05 06 07"
    )
    # fmt: on

License

cstructs is distributed under the terms of the GNU GPL v3 license.