feat: add named parameter support to virtual tables (#250)

* feat: add named parameter support

* safely handle missing parameters

src/vtab/function.rs

@@ -1,12 +1,13 @@
 use super::{
     ffi::{
-        duckdb_bind_add_result_column, duckdb_bind_get_extra_info, duckdb_bind_get_parameter,
-        duckdb_bind_get_parameter_count, duckdb_bind_info, duckdb_bind_set_bind_data, duckdb_bind_set_cardinality,
-        duckdb_bind_set_error, duckdb_create_table_function, duckdb_data_chunk, duckdb_delete_callback_t,
-        duckdb_destroy_table_function, duckdb_table_function, duckdb_table_function_add_parameter,
-        duckdb_table_function_init_t, duckdb_table_function_set_bind, duckdb_table_function_set_extra_info,
-        duckdb_table_function_set_function, duckdb_table_function_set_init, duckdb_table_function_set_local_init,
-        duckdb_table_function_set_name, duckdb_table_function_supports_projection_pushdown, idx_t,
+        duckdb_bind_add_result_column, duckdb_bind_get_extra_info, duckdb_bind_get_named_parameter,
+        duckdb_bind_get_parameter, duckdb_bind_get_parameter_count, duckdb_bind_info, duckdb_bind_set_bind_data,
+        duckdb_bind_set_cardinality, duckdb_bind_set_error, duckdb_create_table_function, duckdb_data_chunk,
+        duckdb_delete_callback_t, duckdb_destroy_table_function, duckdb_table_function,
+        duckdb_table_function_add_named_parameter, duckdb_table_function_add_parameter, duckdb_table_function_init_t,
+        duckdb_table_function_set_bind, duckdb_table_function_set_extra_info, duckdb_table_function_set_function,
+        duckdb_table_function_set_init, duckdb_table_function_set_local_init, duckdb_table_function_set_name,
+        duckdb_table_function_supports_projection_pushdown, idx_t,
     },
     LogicalType, Value,
 };
@@ -64,8 +65,36 @@ impl BindInfo {
     ///  * `index`: The index of the parameter to get
     ///
     /// returns: The value of the parameter
+    ///
+    /// # Panics
+    /// If requested parameter is out of range for function definition
     pub fn get_parameter(&self, param_index: u64) -> Value {
-        unsafe { Value::from(duckdb_bind_get_parameter(self.ptr, param_index)) }
+        unsafe {
+            let ptr = duckdb_bind_get_parameter(self.ptr, param_index);
+            if ptr.is_null() {
+                panic!("{} is out of range for function definition", param_index);
+            } else {
+                Value::from(ptr)
+            }
+        }
+    }
+
+    /// Retrieves the named parameter with the given name.
+    ///
+    /// # Arguments
+    /// * `name`: The name of the parameter to get
+    ///
+    /// returns: The value of the parameter
+    pub fn get_named_parameter(&self, name: &str) -> Option<Value> {
+        unsafe {
+            let name = &CString::new(name).unwrap();
+            let ptr = duckdb_bind_get_named_parameter(self.ptr, name.as_ptr());
+            if ptr.is_null() {
+                None
+            } else {
+                Some(Value::from(ptr))
+            }
+        }
     }
 
     /// Sets the cardinality estimate for the table function, used for optimization.
@@ -204,6 +233,19 @@ impl TableFunction {
         self
     }
 
+    /// Adds a named parameter to the table function.
+    ///
+    /// # Arguments
+    /// * `name`: The name of the parameter to add.
+    /// * `logical_type`: The type of the parameter to add.
+    pub fn add_named_parameter(&self, name: &str, logical_type: &LogicalType) -> &Self {
+        unsafe {
+            let string = CString::new(name).unwrap();
+            duckdb_table_function_add_named_parameter(self.ptr, string.as_ptr(), logical_type.ptr);
+        }
+        self
+    }
+
     /// Sets the main function of the table function
     ///
     /// # Arguments

src/vtab/mod.rs

@@ -81,6 +81,11 @@ pub trait VTab: Sized {
     fn parameters() -> Option<Vec<LogicalType>> {
         None
     }
+    /// The named parameters of the table function
+    /// default is None
+    fn named_parameters() -> Option<Vec<(String, LogicalType)>> {
+        None
+    }
 }
 
 unsafe extern "C" fn func<T>(info: duckdb_function_info, output: duckdb_data_chunk)
@@ -135,6 +140,9 @@ impl Connection {
         for ty in T::parameters().unwrap_or_default() {
             table_function.add_parameter(&ty);
         }
+        for (name, ty) in T::named_parameters().unwrap_or_default() {
+            table_function.add_named_parameter(&name, &ty);
+        }
         self.db.borrow_mut().register_table_function(table_function)
     }
 }
@@ -232,13 +240,55 @@ mod test {
         }
     }
 
+    struct HelloWithNamedVTab {}
+    impl VTab for HelloWithNamedVTab {
+        type InitData = HelloInitData;
+        type BindData = HelloBindData;
+
+        fn bind(bind: &BindInfo, data: *mut HelloBindData) -> Result<(), Box<dyn Error>> {
+            bind.add_result_column("column0", LogicalType::new(LogicalTypeId::Varchar));
+            let param = bind.get_named_parameter("name").unwrap().to_string();
+            assert!(bind.get_named_parameter("unknown_name").is_none());
+            unsafe {
+                (*data).name = CString::new(param).unwrap().into_raw();
+            }
+            Ok(())
+        }
+
+        fn init(init_info: &InitInfo, data: *mut HelloInitData) -> Result<(), Box<dyn Error>> {
+            HelloVTab::init(init_info, data)
+        }
+
+        fn func(func: &FunctionInfo, output: &mut DataChunk) -> Result<(), Box<dyn Error>> {
+            HelloVTab::func(func, output)
+        }
+
+        fn named_parameters() -> Option<Vec<(String, LogicalType)>> {
+            Some(vec![("name".to_string(), LogicalType::new(LogicalTypeId::Varchar))])
+        }
+    }
+
     #[test]
     fn test_table_function() -> Result<(), Box<dyn Error>> {
         let conn = Connection::open_in_memory()?;
         conn.register_table_function::<HelloVTab>("hello")?;
 
         let val = conn.query_row("select * from hello('duckdb')", [], |row| <(String,)>::try_from(row))?;
         assert_eq!(val, ("Hello duckdb".to_string(),));
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_named_table_function() -> Result<(), Box<dyn Error>> {
+        let conn = Connection::open_in_memory()?;
+        conn.register_table_function::<HelloWithNamedVTab>("hello_named")?;
+
+        let val = conn.query_row("select * from hello_named(name = 'duckdb')", [], |row| {
+            <(String,)>::try_from(row)
+        })?;
+        assert_eq!(val, ("Hello duckdb".to_string(),));
+
         Ok(())
     }