hdds_gen Code Generator

hdds_gen (CLI: hddsgen) is a high-performance IDL 4.2 code generator that produces type support code for multiple languages from a single IDL source.

Features

• Full IDL 4.2 compliance - 100% support for basic types, templates, constructs
• 7 target languages - Rust, C++, C, Python, TypeScript, Micro (embedded Rust), C-Micro
• Zero dependencies - Generated code is self-contained
• CDR2 serialization - Automatic encode/decode implementation
• XTypes support - Type evolution and compatibility
• CI/CD ready - JSON diagnostics, deterministic output

Quick Start

# Install
cargo install hdds-gen

# Generate Rust code
hddsgen gen rust MyTypes.idl -o my_types.rs

# Generate C++ with namespace
hddsgen gen cpp MyTypes.idl --namespace-cpp "MyApp::Types" -o my_types.hpp

# Generate TypeScript
hddsgen gen typescript MyTypes.idl -o my_types.ts

# Generate full example project
hddsgen gen rust MyTypes.idl --example --out-dir ./my_project

Subcommands

Command	Purpose
gen	Generate code in target language
parse	Validate IDL and pretty-print AST
check	Validate with structural checks (CI-friendly)
fmt	Reformat IDL to canonical style

Target Languages

Language	Output	Use Case
rust	Idiomatic Rust with derives	Native Rust DDS applications
cpp	Modern C++ headers (.hpp)	C++ DDS applications
c	Header-only C99	Embedded systems, FFI
python	Dataclasses with type hints	Scripting, prototyping
typescript	Interfaces + CDR2 encode/decode	Web apps, Node.js, Deno
micro	no_std Rust	Embedded Rust (ESP32, ARM)
c-micro	Header-only MCU C	STM32, AVR, PIC, ESP32

Feature Support Matrix

Not all backends support all IDL features. Here's the honest breakdown:

Feature	Rust	C++	C	Python	TS	micro	c-micro
Primitives	✅	✅	✅	✅	✅	✅	✅
Struct	✅	✅	✅	✅	✅	✅	✅
@key	✅	✅	✅	✅	✅	✅	✅
@optional	✅	✅	⚠️	✅	✅	❌	❌
Nested structs	✅	✅	✅	✅	✅	✅	✅
Enum	✅	✅	✅	✅	✅	✅	✅
Union	✅	✅	⚠️	✅	✅	✅	✅
Typedef	✅	✅	✅	✅	✅	❌	❌
Sequence	✅	✅	✅	✅	✅	✅	✅
Array	✅	✅	✅	✅	✅	✅	✅
Map	✅	✅	✅	✅	✅	❌	❌
Bitset	✅	✅	✅	⚠️	✅	❌	❌
Bitmask	✅	✅	✅	⚠️	✅	❌	❌
Modules	✅	✅	✅	✅	✅	✅	✅
Inheritance	✅	✅	✅	✅	⚠️	❌	❌
@extensibility	✅	✅	⚠️	✅	✅	❌	❌

Legend: ✅ Full support (def + codec) | ⚠️ Partial | ❌ Not supported

Coverage Score

Backend	Score	Notes
Rust	100%	Full IDL 4.2 compliance
C++	100%	Full IDL 4.2 compliance
TypeScript	97%	Inheritance codec partial
Python	94%	Bitset/Bitmask codec partial
C	88%	Legacy C89 constraints
micro	63%	Embedded constraints (no_std)
c-micro	63%	Embedded constraints (MCU)

Known Gaps by Design

Backend	Missing Features	Reason
C	@optional, Union decode, @extensibility	Legacy C89 compatibility
micro/c-micro	Map, Bitset, Bitmask, Typedef, @optional	no_std/embedded constraints
Python	Bitset/Bitmask codec	Planned improvement
TypeScript	Inheritance codec	Interface extends OK, codec to verify

Example

Input: Temperature.idl

module sensors {
    @topic
    struct Temperature {
        @key string sensor_id;
        float value;
        unsigned long long timestamp;
    };
};

Output: Rust

#[derive(Debug, Clone, Serialize, Deserialize, Topic)]
pub struct Temperature {
    #[key]
    pub sensor_id: String,
    pub value: f32,
    pub timestamp: u64,
}

Output: C

typedef struct {
    char* sensor_id;
    float value;
    uint64_t timestamp;
} sensors_Temperature;

int32_t sensors_Temperature_encode(const sensors_Temperature* p, uint8_t* buf, uint32_t len);
int32_t sensors_Temperature_decode(sensors_Temperature* p, const uint8_t* buf, uint32_t len);

Next Steps

• Installation - Install hdds_gen
• CLI Reference - All command options
• IDL Syntax - Supported IDL features