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[C#] Add GetBytes methods for fixed arrays (#8633)

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* [C#] Add GetBytes methods for fixed arrays

I wanted to direct access to fixed array bytes. I made some changes to the idl generator to create GetBytes functions following the same naming conventions used for vectors of scalar types. There was not a 'Length' field present to bound the existing index accessor so I added that too.

+ Add generic GetBytes for fixed length arrays of scalar types
+ Implement conditional compilation for ENABLE_SPAN_T:
  - ENABLE_SPAN_T: Returns `Span<T>` using `MemoryMarshal.Cast<byte, T>()` as needed.
  - Else: Returns `ArraySegment<byte>?` for raw byte access
+ Added tests reusing arrays_test.fbs definitions
+ Added const int Length field to support existing index based accessors

* [C#] Sync generated code for after adding GetBytes methods for fixed arrays

---------

Co-authored-by: Björn Harrtell <bjornharrtell@users.noreply.github.com>
This commit is contained in:
bigjt
2026-02-04 18:13:32 -05:00
committed by GitHub
parent 3c1bb67ae1
commit 1a7495a6dd
4 changed files with 331 additions and 0 deletions
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52
src/idl_gen_csharp.cpp
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@@ -1243,6 +1243,58 @@ class CSharpGenerator : public BaseGenerator {
}
code += " }\n";
}
// Generate Length property and ByteBuffer accessor for arrays in structs.
if (IsArray(field.value.type) && struct_def.fixed &&
IsScalar(field.value.type.VectorType().base_type)) {
auto camel_name = Name(field);
if (camel_name == struct_def.name) { camel_name += "_"; }
// Generate Length constant
code += " public const int " + camel_name;
code += "Length = ";
code += NumToString(field.value.type.fixed_length);
code += ";\n";
// Generate GetBytes methods for scalar arrays (similar to vector pattern)
code += "#if ENABLE_SPAN_T\n";
code += " public Span<" + GenTypeBasic(field.value.type.VectorType()) +
"> Get";
code += camel_name;
code += "Bytes() { return ";
// For byte arrays, we can return the span directly
if (field.value.type.VectorType().base_type == BASE_TYPE_UCHAR) {
code += "__p.bb.ToSpan(__p.bb_pos + ";
code += NumToString(field.value.offset);
code += ", ";
code += NumToString(field.value.type.fixed_length *
SizeOf(field.value.type.VectorType().base_type));
code += ")";
} else {
// For other types, we need to cast the byte span
code += "System.Runtime.InteropServices.MemoryMarshal.Cast<byte, " +
GenTypeBasic(field.value.type.VectorType()) + ">(__p.bb.ToSpan(__p.bb_pos + ";
code += NumToString(field.value.offset);
code += ", ";
code += NumToString(field.value.type.fixed_length *
SizeOf(field.value.type.VectorType().base_type));
code += "))";
}
code += "; }\n";
code += "#else\n";
code += " public ArraySegment<byte>? Get";
code += camel_name;
code += "Bytes() { return ";
code += "__p.bb.ToArraySegment(__p.bb_pos + ";
code += NumToString(field.value.offset);
code += ", ";
code += NumToString(field.value.type.fixed_length *
SizeOf(field.value.type.VectorType().base_type));
code += ");}\n";
code += "#endif\n";
}
// generate object accessors if is nested_flatbuffer
if (field.nested_flatbuffer) {
auto nested_type_name = NamespacedName(*field.nested_flatbuffer);