Trait EngineHook 

pub trait EngineHook {
    // Required methods
    fn nextval(&self, name: &str) -> Result<i64>;
    fn currval(&self, name: &str) -> Result<i64>;
    fn setval(&self, name: &str, value: i64, is_called: bool) -> Result<i64>;

    // Provided methods
    fn lastval(&self) -> Result<i64> { ... }
    fn call_scalar_function(
        &self,
        _name: &str,
        _args: &[Value],
    ) -> Option<Result<Value>> { ... }
    fn call_bound_builtin_function(
        &self,
        _binding: &FunctionBinding,
        _args: &[(Option<String>, Value)],
    ) -> Option<Result<Value>> { ... }
    fn has_scalar_functions(&self) -> bool { ... }
    fn resolve_type_name(
        &self,
        _name: &str,
    ) -> Result<Option<ColumnType>, String> { ... }
    fn resolve_regclass(&self, _name: &str) -> Result<Option<i64>, String> { ... }
    fn resolve_regclass_input(&self, name: &str) -> Result<Option<i64>> { ... }
    fn resolve_regprocedure(&self, _name: &str) -> Result<Option<i64>, String> { ... }
    fn resolve_regrole(&self, _name: &str) -> Result<Option<i64>> { ... }
    fn resolve_regnamespace(&self, name: &str) -> Result<Option<i64>> { ... }
    fn resolve_regobject(
        &self,
        ty: &ColumnType,
        name: &str,
    ) -> Result<Option<i64>> { ... }
    fn resolve_regtype_output(
        &self,
        _ty: &ColumnType,
        _oid: i64,
    ) -> Result<Option<String>, String> { ... }
    fn current_schema(&self) -> Result<Option<String>, String> { ... }
    fn current_user(&self) -> Result<Option<String>, String> { ... }
    fn session_user(&self) -> Result<Option<String>, String> { ... }
    fn current_schemas(
        &self,
        _include_implicit: bool,
    ) -> Result<Option<Vec<String>>, String> { ... }
    fn random_value(&self) -> Result<Option<f64>, String> { ... }
    fn random_u64(&self) -> Result<Option<u64>, String> { ... }
    fn set_random_seed(&self, _seed: f64) -> Result<bool, String> { ... }
    fn call_user_function(
        &self,
        _name: &str,
        _args: &[(Option<String>, Value)],
    ) -> Option<Result<Value>> { ... }
    fn call_bound_user_function(
        &self,
        _binding: &FunctionBinding,
        _args: &[(Option<String>, Value)],
    ) -> Option<Result<Value>> { ... }
}

Engine-side hook that scalar function evaluation calls for stateful sequence and user-defined functions. Query-valued expressions are not accepted here: lowering assigns them physical query-plan slots executed by uqa-execution::ScalarSubqueryRunner.

Required Methods

fn nextval(&self, name: &str) -> Result<i64>

fn currval(&self, name: &str) -> Result<i64>

fn setval(&self, name: &str, value: i64, is_called: bool) -> Result<i64>

Provided Methods

fn lastval(&self) -> Result<i64>

fn call_scalar_function( &self, _name: &str, _args: &[Value], ) -> Option<Result<Value>>

fn call_bound_builtin_function( &self, _binding: &FunctionBinding, _args: &[(Option<String>, Value)], ) -> Option<Result<Value>>

Invoke an engine-backed built-in after an exact catalog binding has selected it. Unlike call_scalar_function, this path is also available when dynamic dispatch is disabled, so runtime callbacks cannot override the stored built-in identity.

fn has_scalar_functions(&self) -> bool

fn resolve_type_name(&self, _name: &str) -> Result<Option<ColumnType>, String>

Resolve a catalog-owned SQL type name for casts evaluated with an engine context.

fn resolve_regclass(&self, _name: &str) -> Result<Option<i64>, String>

Resolve a relation name to the OID carrier used by regclass.

fn resolve_regclass_input(&self, name: &str) -> Result<Option<i64>>

Resolve regclass input while preserving typed SQL errors. Embedders that implement the historical string-error hook retain its previous behavior; engines with catalog privilege checks override this method directly.

fn resolve_regprocedure(&self, _name: &str) -> Result<Option<i64>, String>

Resolve an exact routine signature to the OID carrier used by regprocedure.

fn resolve_regrole(&self, _name: &str) -> Result<Option<i64>>

Resolve a regrole input while preserving hard input errors for direct casts.

fn resolve_regnamespace(&self, name: &str) -> Result<Option<i64>>

Resolve a regnamespace input while preserving hard input errors for direct casts.

fn resolve_regobject(&self, ty: &ColumnType, name: &str) -> Result<Option<i64>>

Resolve the text argument of one PostgreSQL to_reg* lookup function. The engine override owns catalog visibility and the lookup function’s NULL-versus-error boundary; the default preserves the two historical hooks for embedders that only implement regclass or regprocedure.

fn resolve_regtype_output( &self, _ty: &ColumnType, _oid: i64, ) -> Result<Option<String>, String>

Resolve one OID-backed alias type to its PostgreSQL text output.

fn current_schema(&self) -> Result<Option<String>, String>

Resolve the first existing schema on the logical session’s search path. None lets standalone expression evaluation use its public compatibility default.

fn current_user(&self) -> Result<Option<String>, String>

fn session_user(&self) -> Result<Option<String>, String>

fn current_schemas( &self, _include_implicit: bool, ) -> Result<Option<Vec<String>>, String>

Resolve the existing schemas visible to the logical session.

fn random_value(&self) -> Result<Option<f64>, String>

Draw from an engine-owned logical-session PRNG. None keeps pure, engine-free expression evaluation available for library callers.

fn random_u64(&self) -> Result<Option<u64>, String>

Draw every bit of one engine-owned logical-session PRNG word. Range functions use this instead of a floating-point sample so bigint and arbitrary-precision numeric bounds remain uniform.

fn set_random_seed(&self, _seed: f64) -> Result<bool, String>

Reseed the logical-session PRNG. false means the hook does not own a mutable random stream and the caller must report the unsupported call.

fn call_user_function( &self, _name: &str, _args: &[(Option<String>, Value)], ) -> Option<Result<Value>>

Invoke a user-defined SQL / PL/pgSQL function. Consulted after built-in dispatch misses (and immediately for calls with named arguments, which built-ins never accept). None means no user-defined function with this name exists.

fn call_bound_user_function( &self, _binding: &FunctionBinding, _args: &[(Option<String>, Value)], ) -> Option<Result<Value>>

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors