diff --git a/specs/simple-serialize.md b/specs/simple-serialize.md index b695956d2..b85a20656 100644 --- a/specs/simple-serialize.md +++ b/specs/simple-serialize.md @@ -62,6 +62,8 @@ For basic types the `serialize` function is defined as follows. #### `"uintN"` +A byte string of width `N // 8` containing the little-endian encode integer. + ```python assert N in [8, 16, 32, 64, 128, 256] return value.to_bytes(N // 8, "little") @@ -69,6 +71,9 @@ return value.to_bytes(N // 8, "little") #### `"bool"` +* The byte `\x00` **if** the value is `False` +* The byte `\x01` **if** the value is `True` + ```python assert value in (True, False) return b"\x01" if value is True else b"\x00" @@ -87,29 +92,46 @@ The serialized representation of composite types is comprised of two binary segm #### `"vector"`, `"container"` and `"list"` -For conmposite types the `serialize` function is defined as follows. - -> *Note*: The `collate` function combines the serialized *fixed size* values -> and the serialized offsets into a single array correctly ordered with respect -> to the original element types. The implementation of this logic is not -> included in this example for simplicity. - +An implementation of the `serialize` function for `"Vector"`, `"Container"` and +`"List"` types would take the following form. ```python -# section 2 +# The second section is just the concatenation of the serialized *variable size* elements section_2_parts = [serialize(element) for element in value if is_variable_size(element)] section_2_lengths = [len(part) for part in section_2_parts] section_2 ''.join(section_2_parts) -# section 1 +# Serialize the *fixed size* elements section_1_fixed_parts = [serialize(element) for element in value if is_fixed_size(element)] + +# Compute the length of the first section section_1_length = sum(len(part) for part in section_1_fixed_parts) + 4 * len(section_2_parts) + +# Compute the offset values for each part of the second section section_1_offsets = [ section_1_length + sum(section_2_lengths[:index]) for index in range(len(section_2_parts)) ] assert all(offset < 2**32 for offset in section_1_offsets) -section_1_parts = collate(section_1_fixed_parts, section_1_offsets) + +# compute the appropriate indices for *fixed size* elements for the first section +fixed_size_element_indices = [index for index, element in enumerate(value) if is_fixed_size(element)] + +# compute the appropriate indices for the offsets of the *variable size* elements +variable_size_element_indices = [index for index, element in enumerate(value) if is_variable_size(element)] + +# create a list with placeholders for all values +section_1_parts = [None] * len(value) + +# populate all of the serialized *fixed size* elements +for index, data in zip(fixed_size_element_indices, section_1_fixed_parts): + section_1_parts[index] = data + +# populate all of the serialized offsets for the *variable size* elements +for index, offset in zip(variable_size_element_indices, section_1_offsets): + section_1_parts[index] = serialize(offset) + +assert not any(part is None for part in section_1_parts) section_1 = ''.join(section_1_parts) return ''.join([section_1, section_2])