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Add documentation for Rust FFI and Swift C Header

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Emily Toop 2018-04-24 18:35:31 +01:00
parent 0c758ab6d3
commit 515300e521
2 changed files with 586 additions and 42 deletions
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ffi/src/lib.rs
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@ -8,6 +8,66 @@
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
//! This module exposes an Foreign Function Interface (FFI) that allows Mentat to be
//! called from other languages.
//!
//! Functions that are available to other languages in this module are defined as
//! extern "C" functions which allow them to be layed out correctly for the
//! platform's C ABI. They all have a `#[no_mangle]` decorator to ensure
//! Rust's name mangling is turned off, so that it is easier to link to.
//!
//! Mentat's FFI contains unsafe code. As it is an interface between foreign code
//! and native Rust code, Rust cannot guarentee that the types and data that it is
//! handling that have been passed to it from another language are present and in
//! the format it is expecting.
//! This interface is designed to ensure that nothing unsafe ever leaves this module
//! and enters Mentat proper.
//!
//! Structs defined with `#[repr(C)]` are guaranteed to have a layout that is compatible
//! with the platform's representation in C.
//!
//! This API passes pointers in two ways, depending on the lifetime of the object and
//! what object owns it.
//! Pointers to values that can guarenteed to live beyond the lifetime of the function,
//! are passed over the FFI as a raw pointer.
//! ```
//! value as *const TypedValue
//! ```
//! Pointers to values that cannot be guarenteed to live beyond the lifetime of the function
//! are first Boxed so that they live on the heap, and the raw pointer passed this way.
//! ```
//! Box::into_raw(Box::new(value))
//! ```
//!
//! The memory for values that are moved onto the heap before being passed over the FFI
//! are no longer managed by Rust, but Rust still owns the value. Therefore the pointer
//! must be returned to Rust in order to be released. To this effect a number of `destructor`
//! function are provided for each Rust value type that is passed, and a catch all destructor
//! to destroy memory for `#[repr(C)]` values. The destructors reclaim the memory via `Box`
//! and then drop the reference, causing the memory to be released.
//!
//! A macro has been provided to make defining destructors easier.
//! ```
//! define_destructor!(query_builder_destroy, QueryBuilder);
//! ```
//!
//! Passing a pointer to released memory will cause Mentat to crash, so callers have to be
//! careful to ensure they manage their pointers properly. Failure to call a destructor for a
//! value on the heap will cause a memory leak.
//!
//! Most of the functions exposed in this FFI have a direct mapping to existing Mentat APIs.
//! Application logic has been kept to a minumum in order to provide the greatest flexibility
//! for callers using the interface, however there are a one exception where several steps
//! have been wrapped into a single call in order to make the interface easier to use.
//! `store_register_observer` takes a single native callback function is wrapped inside a
//! Rust closure and added to a `TxObserver` struct that this then used to register the
//! observer with the store.
//!
//! Result and Option Rust types have `repr(C)` structs that mirror them. This is to provide a more
//! native access pattern to callers and to enable easier passing of optional types and error
//! propogation. These types have implemented `From` such that conversion from the Rust type
//! to the C type is as painless as possible.
//!
extern crate libc;
extern crate mentat;
@ -70,6 +130,16 @@ pub use utils::log;
pub type BindingIterator = vec::IntoIter<Binding>;
pub type BindingListIterator = std::slice::Chunks<'static, mentat::Binding>;
/// A C representation of the a change provided by the transaction observers
/// from a single transact.
/// Holds a transaction identifier, the changes as a set of affected attributes
/// and the length of the list of changes.
///
/// #Safety
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[repr(C)]
#[derive(Debug, Clone)]
pub struct TransactionChange {
@ -78,6 +148,14 @@ pub struct TransactionChange {
pub changes: Box<[Entid]>,
}
/// A C representation of the list of changes provided by the transaction observers.
/// Provides the list of changes as the length of the list.
///
/// #Safety
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[repr(C)]
#[derive(Debug)]
pub struct TxChangeList {
@ -85,6 +163,15 @@ pub struct TxChangeList {
pub len: usize,
}
/// A C representation Rust's Option.
/// A value of Some results in `value` containing a raw pointer as a `c_void`.
/// A value of None results in `value` containing a null pointer.
///
/// #Safety
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[repr(C)]
#[derive(Debug)]
pub struct ExternOption {
@ -99,6 +186,16 @@ impl<T> From<Option<T>> for ExternOption {
}
}
/// A C representation Rust's Result.
/// A value of Ok results in `ok` containing a raw pointer as a `c_void`
/// and `err` containing a null pointer.
/// A value of Err results in `value` containing a null pointer and `err` containing an error message.
///
/// #Safety
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[repr(C)]
#[derive(Debug)]
pub struct ExternResult {
@ -125,11 +222,17 @@ impl<T, E> From<Result<T, E>> for ExternResult where E: std::error::Error {
}
}
// A store cannot be opened twice to the same location.
// Once created, the reference to the store is held by the caller and not Rust,
// therefore the caller is responsible for calling `destroy` to release the memory
// used by the Store in order to avoid a memory leak.
// TODO: Start returning `ExternResult`s rather than crashing on error.
/// A store cannot be opened twice to the same location.
/// Once created, the reference to the store is held by the caller and not Rust,
/// therefore the caller is responsible for calling `destroy` to release the memory
/// used by the Store in order to avoid a memory leak.
/// TODO: Start returning `ExternResult`s rather than crashing on error.
///
/// # Safety
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `store_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub extern "C" fn store_open(uri: *const c_char) -> *mut Store {
let uri = c_char_to_string(uri);
@ -147,6 +250,18 @@ pub extern "C" fn store_open(uri: *const c_char) -> *mut Store {
// TODO: begin_transaction
/// Performs a single transaction against the store.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Store` is not dangling and that
/// the C string provided to `transaction` is valid.
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
///
/// TODO: Document the errors that can result from transact
#[no_mangle]
pub unsafe extern "C" fn store_transact(store: *mut Store, transaction: *const c_char) -> *mut ExternResult {
let store = &mut*store;
@ -160,18 +275,35 @@ pub unsafe extern "C" fn store_transact(store: *mut Store, transaction: *const c
Box::into_raw(Box::new(result.into()))
}
/// Fetches the `tx_id` for the given `TxReport`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TxReport` is not dangling.
#[no_mangle]
pub unsafe extern "C" fn tx_report_get_entid(tx_report: *mut TxReport) -> c_longlong {
let tx_report = &*tx_report;
tx_report.tx_id as c_longlong
}
/// Fetches the `tx_instant` for the given `TxReport`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TxReport` is not dangling.
#[no_mangle]
pub unsafe extern "C" fn tx_report_get_tx_instant(tx_report: *mut TxReport) -> c_longlong {
let tx_report = &*tx_report;
tx_report.tx_instant.timestamp() as c_longlong
}
/// Fetches the `Entid` assigned to the `tempid` during the transaction represented
/// by the given `TxReport`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TxReport` is not dangling and that
/// the C string provided to `tempid` is valid.
#[no_mangle]
pub unsafe extern "C" fn tx_report_entity_for_temp_id(tx_report: *mut TxReport, tempid: *const c_char) -> *mut c_longlong {
let tx_report = &*tx_report;
@ -186,6 +318,19 @@ pub unsafe extern "C" fn tx_report_entity_for_temp_id(tx_report: *mut TxReport,
// TODO: cache
// TODO: q_once
/// Creates a `QueryBuilder` from the given store to execute the provided query.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Store` is not dangling and that
/// the C string provided to `query` is valid.
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `query_builder_destroy` is provided for releasing the memory for this
/// pointer type.
///
/// TODO: Update QueryBuilder so it only takes a `Store` pointer on execution
#[no_mangle]
pub unsafe extern "C" fn store_query<'a>(store: *mut Store, query: *const c_char) -> *mut QueryBuilder<'a> {
let query = c_char_to_string(query);
@ -194,6 +339,12 @@ pub unsafe extern "C" fn store_query<'a>(store: *mut Store, query: *const c_char
Box::into_raw(Box::new(query_builder))
}
/// Binds a `TypedValue::Long` to a `Variable` with the given name.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C string provided to `var` is valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_long(query_builder: *mut QueryBuilder, var: *const c_char, value: c_longlong) {
let var = c_char_to_string(var);
@ -201,6 +352,12 @@ pub unsafe extern "C" fn query_builder_bind_long(query_builder: *mut QueryBuilde
query_builder.bind_long(&var, value);
}
/// Binds a `TypedValue::Ref` to a `Variable` with the given name.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C string provided to `var` is valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_ref(query_builder: *mut QueryBuilder, var: *const c_char, value: c_longlong) {
let var = c_char_to_string(var);
@ -208,6 +365,17 @@ pub unsafe extern "C" fn query_builder_bind_ref(query_builder: *mut QueryBuilder
query_builder.bind_ref(&var, value);
}
/// Binds a `TypedValue::Ref` to a `Variable` with the given name. Takes a keyword as a c string in the format
/// `:namespace/name` and converts it into an `NamespacedKeyword`.
///
/// # Panics
///
/// If the provided keyword does not map to a valid keyword in the schema.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C strings provided to `var` and `value` are valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_ref_kw(query_builder: *mut QueryBuilder, var: *const c_char, value: *const c_char) {
let var = c_char_to_string(var);
@ -218,6 +386,13 @@ pub unsafe extern "C" fn query_builder_bind_ref_kw(query_builder: *mut QueryBuil
}
}
/// Binds a `TypedValue::Keyword` to a `Variable` with the given name. Takes a keyword as a c string in the format
/// `:namespace/name` and converts it into an `NamespacedKeyword`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C strings provided to `var` and `value` are valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_kw(query_builder: *mut QueryBuilder, var: *const c_char, value: *const c_char) {
let var = c_char_to_string(var);
@ -226,7 +401,12 @@ pub unsafe extern "C" fn query_builder_bind_kw(query_builder: *mut QueryBuilder,
query_builder.bind_value(&var, kw);
}
// boolean
/// Binds a `TypedValue::Boolean` to a `Variable` with the given name.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C string provided to `var` is valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_boolean(query_builder: *mut QueryBuilder, var: *const c_char, value: bool) {
let var = c_char_to_string(var);
@ -234,7 +414,12 @@ pub unsafe extern "C" fn query_builder_bind_boolean(query_builder: *mut QueryBui
query_builder.bind_value(&var, value);
}
// double
/// Binds a `TypedValue::Double` to a `Variable` with the given name.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C string provided to `var` is valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_double(query_builder: *mut QueryBuilder, var: *const c_char, value: f64) {
let var = c_char_to_string(var);
@ -242,7 +427,13 @@ pub unsafe extern "C" fn query_builder_bind_double(query_builder: *mut QueryBuil
query_builder.bind_value(&var, value);
}
// instant
/// Binds a `TypedValue::Instant` to a `Variable` with the given name.
/// Takes a timestamp in microseconds.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C string provided to `var` is valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_timestamp(query_builder: *mut QueryBuilder, var: *const c_char, value: c_longlong) {
let var = c_char_to_string(var);
@ -250,7 +441,12 @@ pub unsafe extern "C" fn query_builder_bind_timestamp(query_builder: *mut QueryB
query_builder.bind_instant(&var, value);
}
// string
/// Binds a `TypedValue::String` to a `Variable` with the given name.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C strings provided to `var` and `value` are valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_string(query_builder: *mut QueryBuilder, var: *const c_char, value: *const c_char) {
let var = c_char_to_string(var);
@ -259,7 +455,13 @@ pub unsafe extern "C" fn query_builder_bind_string(query_builder: *mut QueryBuil
query_builder.bind_value(&var, value);
}
// uuid
/// Binds a `TypedValue::Uuid` to a `Variable` with the given name.
/// Takes a UUID as a byte slice of length 16. This maps directly to the `uuid_t` C type.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling and that
/// the C string provided to `var` is valid.
#[no_mangle]
pub unsafe extern "C" fn query_builder_bind_uuid(query_builder: *mut QueryBuilder, var: *const c_char, value: *mut [u8; 16]) {
let var = c_char_to_string(var);
@ -269,6 +471,19 @@ pub unsafe extern "C" fn query_builder_bind_uuid(query_builder: *mut QueryBuilde
query_builder.bind_value(&var, value);
}
/// Executes a query and returns the results as a Scalar.
///
/// # Panics
///
/// If the query executed is not structured as Scalar.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling.
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn query_builder_execute_scalar(query_builder: *mut QueryBuilder) -> *mut ExternResult {
let query_builder = &mut*query_builder;
@ -281,6 +496,19 @@ pub unsafe extern "C" fn query_builder_execute_scalar(query_builder: *mut QueryB
Box::into_raw(Box::new(extern_result))
}
/// Executes a query and returns the results as a Coll.
///
/// # Panics
///
/// If the query executed is not structured as Coll.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling.
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn query_builder_execute_coll(query_builder: *mut QueryBuilder) -> *mut ExternResult {
let query_builder = &mut*query_builder;
@ -288,6 +516,19 @@ pub unsafe extern "C" fn query_builder_execute_coll(query_builder: *mut QueryBui
Box::into_raw(Box::new(results.into()))
}
/// Executes a query and returns the results as a Tuple.
///
/// # Panics
///
/// If the query executed is not structured as Tuple.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling.
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn query_builder_execute_tuple(query_builder: *mut QueryBuilder) -> *mut ExternResult {
let query_builder = &mut*query_builder;
@ -300,6 +541,19 @@ pub unsafe extern "C" fn query_builder_execute_tuple(query_builder: *mut QueryBu
Box::into_raw(Box::new(extern_result))
}
/// Executes a query and returns the results as a Rel.
///
/// # Panics
///
/// If the query executed is not structured as Rel.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `QueryBuilder` is not dangling.
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn query_builder_execute(query_builder: *mut QueryBuilder) -> *mut ExternResult {
let query_builder = &mut*query_builder;
@ -314,56 +568,122 @@ fn unwrap_conversion<T>(value: Option<T>, expected_type: ValueType) -> T {
}
}
// as_long
/// Consumes a `TypedValue` and returns the value as a `long`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Long`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_long(typed_value: *mut Binding) -> c_longlong {
let typed_value = Box::from_raw(typed_value);
unwrap_conversion(typed_value.into_long(), ValueType::Long)
}
// as_entid
/// Consumes a `TypedValue` and returns the value as an `Entid`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Ref`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_entid(typed_value: *mut Binding) -> Entid {
let typed_value = Box::from_raw(typed_value);
unwrap_conversion(typed_value.into_entid(), ValueType::Ref)
}
// kw
/// Consumes a `TypedValue` and returns the value as an keyword `String`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Ref`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_kw(typed_value: *mut Binding) -> *const c_char {
let typed_value = Box::from_raw(typed_value);
unwrap_conversion(typed_value.into_kw_c_string(), ValueType::Keyword) as *const c_char
}
//as_boolean
/// Consumes a `TypedValue` and returns the value as a boolean represented as an `i32`.
/// If the value of the boolean is `true` the value returned is 1.
/// If the value of the boolean is `false` the value returned is 0.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Boolean`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_boolean(typed_value: *mut Binding) -> i32 {
let typed_value = Box::from_raw(typed_value);
if unwrap_conversion(typed_value.into_boolean(), ValueType::Boolean) { 1 } else { 0 }
}
//as_double
/// Consumes a `TypedValue` and returns the value as a `f64`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Double`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_double(typed_value: *mut Binding) -> f64 {
let typed_value = Box::from_raw(typed_value);
unwrap_conversion(typed_value.into_double(), ValueType::Double)
}
//as_timestamp
/// Consumes a `TypedValue` and returns the value as a microsecond timestamp.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Instant`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_timestamp(typed_value: *mut Binding) -> c_longlong {
let typed_value = Box::from_raw(typed_value);
unwrap_conversion(typed_value.into_timestamp(), ValueType::Instant)
}
//as_string
/// Consumes a `TypedValue` and returns the value as a `String`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::String`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_string(typed_value: *mut Binding) -> *const c_char {
let typed_value = Box::from_raw(typed_value);
unwrap_conversion(typed_value.into_c_string(), ValueType::String) as *const c_char
}
//as_uuid
/// Consumes a `TypedValue` and returns the value as a UUID byte slice of length 16.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Uuid`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_as_uuid(typed_value: *mut Binding) -> *mut [u8; 16] {
let typed_value = Box::from_raw(typed_value);
@ -371,19 +691,42 @@ pub unsafe extern "C" fn typed_value_as_uuid(typed_value: *mut Binding) -> *mut
Box::into_raw(Box::new(*value.as_bytes()))
}
//value_type
/// Returns the `ValueType` of this `TypedValue`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TypedValue` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn typed_value_value_type(typed_value: *mut Binding) -> ValueType {
let typed_value = &*typed_value;
typed_value.value_type().unwrap_or_else(|| panic!("Binding is not Scalar and has no ValueType"))
}
/// Returns the value at the provided `index` as a `Vec<ValueType>`.
/// If there is no value present at the `index`, a null pointer is returned.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<Vec<TypedValue>>` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_result_set_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn row_at_index(rows: *mut RelResult<Binding>, index: c_int) -> *mut Vec<Binding> {
let result = &*rows;
result.row(index as usize).map_or_else(std::ptr::null_mut, |v| Box::into_raw(Box::new(v.to_vec())))
}
/// Consumes the `Vec<Vec<TypedValue>>` and returns an iterator over the values.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<Vec<TypedValue>>` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_result_set_iter_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn rows_iter(rows: *mut RelResult<Binding>) -> *mut BindingListIterator {
let result = &*rows;
@ -391,38 +734,96 @@ pub unsafe extern "C" fn rows_iter(rows: *mut RelResult<Binding>) -> *mut Bindin
Box::into_raw(Box::new(rows))
}
/// Returns the next value in the `iter` as a `Vec<ValueType>`.
/// If there is no value next value, a null pointer is returned.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<Vec<TypedValue>>` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_list_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn rows_iter_next(iter: *mut BindingListIterator) -> *mut Vec<Binding> {
let iter = &mut *iter;
iter.next().map_or(std::ptr::null_mut(), |v| Box::into_raw(Box::new(v.to_vec())))
}
/// Consumes the `Vec<TypedValue>` and returns an iterator over the values.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_list_iter_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn values_iter(values: *mut Vec<Binding>) -> *mut BindingIterator {
let result = Box::from_raw(values);
Box::into_raw(Box::new(result.into_iter()))
}
/// Returns the next value in the `iter` as a `ValueType`.
/// If there is no value next value, a null pointer is returned.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn values_iter_next(iter: *mut BindingIterator) -> *mut Binding {
let iter = &mut *iter;
iter.next().map_or(std::ptr::null_mut(), |v| Box::into_raw(Box::new(v)))
}
/// Returns the value at the provided `index` as a `ValueType`.
/// If there is no value present at the `index`, a null pointer is returned.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn value_at_index(values: *mut Vec<Binding>, index: c_int) -> *const Binding {
let result = &*values;
result.get(index as usize).expect("No value at index") as *const Binding
}
//as_long
/// Returns the value of the `TypedValue` at `index` as a `long`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Long`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_long(values: *mut Vec<Binding>, index: c_int) -> c_longlong {
let result = &*values;
let value = result.get(index as usize).expect("No value at index");
unwrap_conversion(value.clone().into_long(), ValueType::Long)
}
// as ref
/// Returns the value of the `TypedValue` at `index` as an `Entid`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Ref`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_entid(values: *mut Vec<Binding>, index: c_int) -> Entid {
let result = &*values;
@ -430,7 +831,16 @@ pub unsafe extern "C" fn value_at_index_as_entid(values: *mut Vec<Binding>, inde
unwrap_conversion(value.clone().into_entid(), ValueType::Ref)
}
// as kw
/// Returns the value of the `TypedValue` at `index` as a keyword `String`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Ref`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_kw(values: *mut Vec<Binding>, index: c_int) -> *const c_char {
let result = &*values;
@ -438,7 +848,18 @@ pub unsafe extern "C" fn value_at_index_as_kw(values: *mut Vec<Binding>, index:
unwrap_conversion(value.clone().into_kw_c_string(), ValueType::Keyword) as *const c_char
}
//as_boolean
/// Returns the value of the `TypedValue` at `index` as a boolean represented by a `i32`.
/// If the value of the `boolean` is `true` then the value returned is 1.
/// If the value of the `boolean` is `false` then the value returned is 0.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Long`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_boolean(values: *mut Vec<Binding>, index: c_int) -> i32 {
let result = &*values;
@ -446,7 +867,16 @@ pub unsafe extern "C" fn value_at_index_as_boolean(values: *mut Vec<Binding>, in
if unwrap_conversion(value.clone().into_boolean(), ValueType::Boolean) { 1 } else { 0 }
}
//as_double
/// Returns the value of the `TypedValue` at `index` as an `f64`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Double`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_double(values: *mut Vec<Binding>, index: c_int) -> f64 {
let result = &*values;
@ -454,7 +884,16 @@ pub unsafe extern "C" fn value_at_index_as_double(values: *mut Vec<Binding>, ind
unwrap_conversion(value.clone().into_double(), ValueType::Double)
}
//as_timestamp
/// Returns the value of the `TypedValue` at `index` as a microsecond timestamp.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::instant`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_timestamp(values: *mut Vec<Binding>, index: c_int) -> c_longlong {
let result = &*values;
@ -462,7 +901,16 @@ pub unsafe extern "C" fn value_at_index_as_timestamp(values: *mut Vec<Binding>,
unwrap_conversion(value.clone().into_timestamp(), ValueType::Instant)
}
//as_string
/// Returns the value of the `TypedValue` at `index` as an `String`.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::String`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_string(values: *mut Vec<Binding>, index: c_int) -> *const c_char {
let result = &*values;
@ -470,7 +918,16 @@ pub unsafe extern "C" fn value_at_index_as_string(values: *mut Vec<Binding>, ind
unwrap_conversion(value.clone().into_c_string(), ValueType::String) as *const c_char
}
//as_uuid
/// Returns the value of the `TypedValue` at `index` as a UUID byte slice of length 16.
///
/// # Panics
///
/// If the `ValueType` of the `TypedValue` is not `ValueType::Uuid`.
/// If there is no value at `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Vec<TypedValue>` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn value_at_index_as_uuid(values: *mut Vec<Binding>, index: c_int) -> *mut [u8; 16] {
let result = &*values;
@ -479,6 +936,22 @@ pub unsafe extern "C" fn value_at_index_as_uuid(values: *mut Vec<Binding>, index
Box::into_raw(Box::new(*uuid.as_bytes()))
}
/// Returns an `ExternResult` containing the `TypedValue` associated with the `attribute` as `:namespace/name`
/// for the given `entid`.
/// If there is a value for that `attribute` on the entity with id `entid` then the value is returned in `ok`.
/// If there no value for that `attribute` on the entity with id `entid` but the attribute is value,
/// then a null pointer is returned in `ok`.
/// If there is no `Attribute` in the `Schema` for the given `attribute` then an error is returned in `err`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Store` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `destroy` is provided for releasing the memory for this
/// pointer type.
///
/// TODO: list the types of error that can be caused by this function
#[no_mangle]
pub unsafe extern "C" fn store_value_for_attribute(store: *mut Store, entid: c_longlong, attribute: *const c_char) -> *mut ExternResult {
let store = &*store;
@ -494,6 +967,19 @@ pub unsafe extern "C" fn store_value_for_attribute(store: *mut Store, entid: c_l
Box::into_raw(Box::new(value))
}
/// Registers a `TxObserver` with the `key` to observe changes to `attributes`
/// on this `store`.
/// Calls `callback` is a relevant transaction occurs.
///
/// # Panics
///
/// If there is no `Attribute` in the `Schema` for a given `attribute`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Store` is not dangling, that the
/// C string in `key` is valid and that the function pointer is not dangling.
///
#[no_mangle]
pub unsafe extern "C" fn store_register_observer(store: *mut Store,
key: *const c_char,
@ -525,6 +1011,12 @@ pub unsafe extern "C" fn store_register_observer(store: *mut Store,
store.register_observer(key, tx_observer);
}
/// Unregisters a `TxObserver` with the `key` to observe changes on this `store`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Store` is not dangling, that the
/// C string in `key` is valid.
#[no_mangle]
pub unsafe extern "C" fn store_unregister_observer(store: *mut Store, key: *const c_char) {
let store = &mut*store;
@ -532,6 +1024,16 @@ pub unsafe extern "C" fn store_unregister_observer(store: *mut Store, key: *cons
store.unregister_observer(&key);
}
/// Returns the `Entid` associated with the `attr` as `:namespace/name`.
///
/// # Panics
///
/// If there is no `Attribute` in the `Schema` for `attr`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `Store` is not dangling, that the
/// C string in `attr` is valid.
#[no_mangle]
pub unsafe extern "C" fn store_entid_for_attribute(store: *mut Store, attr: *const c_char) -> Entid {
let store = &mut*store;
@ -542,6 +1044,19 @@ pub unsafe extern "C" fn store_entid_for_attribute(store: *mut Store, attr: *con
current_schema.get_entid(&kw).expect("Unable to find entid for invalid attribute").into()
}
/// Returns the value at the provided `index` as a `TransactionChange`.
///
/// # Panics
///
/// If there is no value present at the `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TxChangeList` is not dangling .
///
/// Callers are responsible for managing the memory for the return value.
/// A destructor `typed_value_destroy` is provided for releasing the memory for this
/// pointer type.
#[no_mangle]
pub unsafe extern "C" fn tx_change_list_entry_at(tx_report_list: *mut TxChangeList, index: c_int) -> *const TransactionChange {
let tx_report_list = &*tx_report_list;
@ -550,6 +1065,15 @@ pub unsafe extern "C" fn tx_change_list_entry_at(tx_report_list: *mut TxChangeLi
Box::into_raw(report)
}
/// Returns the value at the provided `index` as a `Entid`.
///
/// # Panics
///
/// If there is no value present at the `index`.
///
/// # Safety
///
/// Callers must ensure that the pointer to the `TransactionChange` is not dangling .
#[no_mangle]
pub unsafe extern "C" fn changelist_entry_at(tx_report: *mut TransactionChange, index: c_int) -> Entid {
let tx_report = &*tx_report;
@ -557,15 +1081,7 @@ pub unsafe extern "C" fn changelist_entry_at(tx_report: *mut TransactionChange,
tx_report.changes[index].clone()
}
#[no_mangle]
pub unsafe extern "C" fn store_sync(store: *mut Store, user_uuid: *const c_char, server_uri: *const c_char) -> *mut ExternResult {
let store = &mut*store;
let user_uuid = c_char_to_string(user_uuid);
let server_uri = c_char_to_string(server_uri);
let res = store.sync(&server_uri, &user_uuid);
Box::into_raw(Box::new(res.into()))
}
/// destroy function for releasing the memory for `repr(C)` structs.
#[no_mangle]
pub unsafe extern "C" fn destroy(obj: *mut c_void) {
if !obj.is_null() {
@ -573,6 +1089,7 @@ pub unsafe extern "C" fn destroy(obj: *mut c_void) {
}
}
/// Creates a function with a given `$name` that releases the memroy for a type `$t`.
macro_rules! define_destructor (
($name:ident, $t:ty) => (
#[no_mangle]
@ -581,10 +1098,14 @@ macro_rules! define_destructor (
}
)
);
/// Destructor for releasing the memory of `QueryBuilder`.
define_destructor!(query_builder_destroy, QueryBuilder);
/// Destructor for releasing the memory of `Store`.
define_destructor!(store_destroy, Store);
/// Destructor for releasing the memory of `TxReport`.
define_destructor!(tx_report_destroy, TxReport);
define_destructor!(typed_value_destroy, Binding);

35
sdks/swift/Mentat/Mentat/store.h
View file

@ -13,35 +13,56 @@
#include <stdint.h>
#include <Foundation/NSObjCRuntime.h>
/*
* This file contains headers for all of the structs and functions that map directly to the functions
* defined in mentat/ffi/src/lib.rs.
*
* The C in this file is specifically formatted to be used with Objective C and Swift and contains
* macros and flags that will not be recognised by other C based languages.
*/
/*
A mapping of the TxChange repr(C) Rust object.
The memory for this is managed by Swift.
*/
struct TxChange {
int64_t txid;
int64_t*_Nonnull* _Nonnull changes;
uint64_t len;
};
/*
A mapping of the TxChangeList repr(C) Rust object.
The memory for this is managed by Swift.
*/
struct TxChangeList {
struct TxChange*_Nonnull* _Nonnull reports;
uint64_t len;
};
typedef struct TxChangeList TxChangeList;
/*
A mapping of the ExternResult repr(C) Rust object.
The memory for this is managed by Swift.
*/
struct Result {
void* _Nullable ok;
char* _Nullable err;
};
typedef struct Result Result;
/*
A mapping of the ExternOption repr(C) Rust object.
The memory for this is managed by Swift.
*/
struct Option {
void* _Nullable value;
};
typedef struct Option Option;
struct InProgressTransactResult {
struct InProgress*_Nonnull inProgress;
struct Result*_Nonnull result;
};
typedef struct InProgressTransactResult InProgressTransactResult;
/*
A Mapping for the ValueType Rust object.
*/
typedef NS_ENUM(NSInteger, ValueType) {
ValueTypeRef = 1,
ValueTypeBoolean,
@ -53,6 +74,7 @@ typedef NS_ENUM(NSInteger, ValueType) {
ValueTypeUuid
};
// Opaque Structs mapping to Rust types that are passed over the FFI boundary
struct EntityBuilder;
struct InProgress;
struct InProgressBuilder;
@ -68,6 +90,7 @@ struct TypedValue;
// Store
struct Store*_Nonnull store_open(const char*_Nonnull uri);
// Destructors.
void destroy(void* _Nullable obj);
void query_builder_destroy(struct Query* _Nullable obj);
void store_destroy(struct Store* _Nonnull obj);