Structures

The #[marine] macro can also wrap a struct making it possible to use it as a function argument or return type. Note that

• only macro-wrapped structures can be used as function arguments and return types
• all fields of the wrapped structure must be public and of the mtype
• it is possible to have inner records in the macro-wrapped structure and to import wrapped structs from other crates

Structure passing requirements

• wrap a structure with the #[marine] macro
• all structures fields must be of the mtype
• the structure must be pointed to without preceding package import in a function signature, i.e. StructureName but not package_name::module_name::StructureName
• wrapped structures can be imported from crates

Examples

See the examples below for wrapping struct:

Example 1

rust
#[marine]
pub struct TestRecord0 {
    pub field_0: i32,
}
#[marine]
pub struct TestRecord1 {
    pub field_0: i32,
    pub field_1: String,
    pub field_2: Vec<u8>,
    pub test_record_0: TestRecord0,
}
#[marine]
pub struct TestRecord2 {
    pub test_record_0: TestRecord0,
    pub test_record_1: TestRecord1,
}
#[marine]
fn foo(mut test_record: TestRecord2) -> TestRecord2 { unimplemented!(); }

rust
#[marine]
pub struct TestRecord0 {
    pub field_0: i32,
}
#[marine]
pub struct TestRecord1 {
    pub field_0: i32,
    pub field_1: String,
    pub field_2: Vec<u8>,
    pub test_record_0: TestRecord0,
}
#[marine]
pub struct TestRecord2 {
    pub test_record_0: TestRecord0,
    pub test_record_1: TestRecord1,
}
#[marine]
fn foo(mut test_record: TestRecord2) -> TestRecord2 { unimplemented!(); }

Example 2

rust
#[marine]
pub struct TestRecord0 {
    pub field_0: i32,
}
#[marine]
pub struct TestRecord1 {
    pub field_0: i32,
    pub field_1: String,
    pub field_2: Vec<u8>,
    pub test_record_0: TestRecord0,
}
#[marine]
pub struct TestRecord2 {
    pub test_record_0: TestRecord0,
    pub test_record_1: TestRecord1,
}
#[marine]
#[link(wasm_import_module = "some_module")]
extern "C" {
  fn foo(mut test_record: TestRecord2) -> TestRecord2;
}

rust
#[marine]
pub struct TestRecord0 {
    pub field_0: i32,
}
#[marine]
pub struct TestRecord1 {
    pub field_0: i32,
    pub field_1: String,
    pub field_2: Vec<u8>,
    pub test_record_0: TestRecord0,
}
#[marine]
pub struct TestRecord2 {
    pub test_record_0: TestRecord0,
    pub test_record_1: TestRecord1,
}
#[marine]
#[link(wasm_import_module = "some_module")]
extern "C" {
  fn foo(mut test_record: TestRecord2) -> TestRecord2;
}

Example 3

rust
mod data_crate {
    use fluence::marine;
    #[marine]
    pub struct Data {
        pub name: String,
        pub data: f64,
    }
}
use data_crate::Data;
use fluence::marine;
fn main() {}
#[marine]
fn some_function() -> Data {
    Data {
        name: "example".into(),
        data: 1.0,
    }
}

rust
mod data_crate {
    use fluence::marine;
    #[marine]
    pub struct Data {
        pub name: String,
        pub data: f64,
    }
}
use data_crate::Data;
use fluence::marine;
fn main() {}
#[marine]
fn some_function() -> Data {
    Data {
        name: "example".into(),
        data: 1.0,
    }
}