Dart Borsh: Optional Fields, Enum Handling, and Typed Array Serialization

[ERoydev]

What

Optional field handler implemted in templates

reader.readU8() == 1 ? reader.readString() : null;
writer.writeU8(optional_str != null ? 1 : 0);

• if optional_str (or other fields) is null it writes 1 meaning value is present, then writes the string, else it writes 0
• For read try to read the first byte if its 1 it reads and return the value otherwise returns null

Borsh logic for Enums

Variant represents an Optioan in the Enum and this Option can have a Tuple, Struct or be Empty as a value, i treat everything inside like a structFieldType and i extract those fields in a collection.

Loop through variants of the Enum and for each variant:

• I count the fields that this variants has `(StringType, NumberType, ... ) and i take the all the fields that this variants has.
• I use to generate serialization/deserialization methods for every field + checking if Optional using the recursiveBorsh macros.

Added couple of methods in the Shared nunjucks template

• fixed offset of bytes for some of the methods
• I found that in dart i cannot have u8 or u64 types for numbers so we just use int and bigint

Implemented fragment for Dart Typed Arrays conversion

• Maps Rust number formats (u8, i16, etc.) to Dart typed arrays (Uint8List, Int16List, …).
• Handles string arrays → List.
• Handles struct arrays → List.
• Handles number arrays with proper dart:typed_data imports. to have like (Uint32List, Int16List, ...)
• Provides a fallback to generic Dart lists when no mapping is found.