Implement functions to get parameters from global arguments (#176)

Author: nnmm

rclrs/Cargo.toml

@@ -18,6 +18,10 @@ parking_lot = "0.11.2"
 # Needed for the Message trait, among others
 rosidl_runtime_rs = "*"
 
+[dev-dependencies]
+# Needed for e.g. writing yaml files in tests
+tempfile = "3.3.0"
+
 [build-dependencies]
 # Needed for FFI
 bindgen = "0.59.1"

rclrs/build.rs

@@ -92,6 +92,7 @@ fn main() {
     }
 
     println!("cargo:rustc-link-lib=dylib=rcl");
+    println!("cargo:rustc-link-lib=dylib=rcl_yaml_param_parser");
     println!("cargo:rustc-link-lib=dylib=rcutils");
     println!("cargo:rustc-link-lib=dylib=rmw");
     println!("cargo:rustc-link-lib=dylib=rmw_implementation");

rclrs/src/lib.rs

@@ -8,6 +8,7 @@
 mod context;
 mod error;
 mod node;
+mod parameter;
 mod qos;
 mod wait;
 
@@ -16,6 +17,7 @@ mod rcl_bindings;
 pub use context::*;
 pub use error::*;
 pub use node::*;
+pub use parameter::*;
 pub use qos::*;
 pub use wait::*;
 

rclrs/src/node.rs

@@ -6,10 +6,10 @@ pub use self::publisher::*;
 pub use self::subscription::*;
 
 use crate::rcl_bindings::*;
-use crate::{Context, QoSProfile, RclrsError, ToResult};
-use std::ffi::CStr;
+use crate::{Context, ParameterOverrideMap, QoSProfile, RclrsError, ToResult};
 
 use std::cmp::PartialEq;
+use std::ffi::CStr;
 use std::fmt;
 use std::sync::{Arc, Weak};
 use std::vec::Vec;
@@ -69,6 +69,7 @@ pub struct Node {
     rcl_node_mtx: Arc<Mutex<rcl_node_t>>,
     pub(crate) rcl_context_mtx: Arc<Mutex<rcl_context_t>>,
     pub(crate) subscriptions: Vec<Weak<dyn SubscriptionBase>>,
+    _parameter_map: ParameterOverrideMap,
 }
 
 impl Eq for Node {}
@@ -116,7 +117,7 @@ impl Node {
     /// # Ok::<(), RclrsError>(())
     /// ```
     pub fn name(&self) -> String {
-        self.get_string(rcl_node_get_name)
+        self.call_string_getter(rcl_node_get_name)
     }
 
     /// Returns the namespace of the node.
@@ -142,7 +143,7 @@ impl Node {
     /// # Ok::<(), RclrsError>(())
     /// ```
     pub fn namespace(&self) -> String {
-        self.get_string(rcl_node_get_namespace)
+        self.call_string_getter(rcl_node_get_namespace)
     }
 
     /// Returns the fully qualified name of the node.
@@ -162,26 +163,15 @@ impl Node {
     /// # Ok::<(), RclrsError>(())
     /// ```
     pub fn fully_qualified_name(&self) -> String {
-        self.get_string(rcl_node_get_fully_qualified_name)
+        self.call_string_getter(rcl_node_get_fully_qualified_name)
     }
 
     // Helper for name(), namespace(), fully_qualified_name()
-    fn get_string(
+    fn call_string_getter(
         &self,
         getter: unsafe extern "C" fn(*const rcl_node_t) -> *const c_char,
     ) -> String {
-        let char_ptr = unsafe {
-            // SAFETY: The rcl_node is valid.
-            getter(&*self.rcl_node_mtx.lock())
-        };
-        debug_assert!(!char_ptr.is_null());
-        let cstr = unsafe {
-            // SAFETY: The returned CStr is immediately converted to an owned string,
-            // so the lifetime is no issue. The ptr is valid as per the documentation
-            // of rcl_node_get_name.
-            CStr::from_ptr(char_ptr)
-        };
-        cstr.to_string_lossy().into_owned()
+        unsafe { call_string_getter_with_handle(&*self.rcl_node_mtx.lock(), getter) }
     }
 
     /// Creates a [`Publisher`][1].
@@ -279,3 +269,20 @@ impl Node {
         NodeBuilder::new(context, node_name)
     }
 }
+
+// Helper used to implement call_string_getter(), but also used to get the FQN in the Node::new()
+// function, which is why it's not merged into Node::call_string_getter().
+// This function is unsafe since it's possible to pass in an rcl_node_t with dangling
+// pointers etc.
+unsafe fn call_string_getter_with_handle(
+    rcl_node: &rcl_node_t,
+    getter: unsafe extern "C" fn(*const rcl_node_t) -> *const c_char,
+) -> String {
+    let char_ptr = getter(rcl_node);
+    debug_assert!(!char_ptr.is_null());
+    // SAFETY: The returned CStr is immediately converted to an owned string,
+    // so the lifetime is no issue. The ptr is valid as per the documentation
+    // of rcl_node_get_name.
+    let cstr = CStr::from_ptr(char_ptr);
+    cstr.to_string_lossy().into_owned()
+}

rclrs/src/node/builder.rs

@@ -1,10 +1,13 @@
 use crate::rcl_bindings::*;
-use crate::{Context, Node, RclrsError, ToResult};
+use crate::{
+    node::call_string_getter_with_handle, resolve_parameter_overrides, Context, Node, RclrsError,
+    ToResult,
+};
 
 use std::ffi::CString;
+use std::sync::Arc;
 
 use parking_lot::Mutex;
-use std::sync::Arc;
 
 /// A builder for creating a [`Node`][1].
 ///
@@ -261,16 +264,25 @@ impl NodeBuilder {
             .ok()?;
         };
 
+        let _parameter_map = unsafe {
+            let fqn = call_string_getter_with_handle(&rcl_node, rcl_node_get_fully_qualified_name);
+            resolve_parameter_overrides(
+                &fqn,
+                &rcl_node_options.arguments,
+                &rcl_context.global_arguments,
+            )?
+        };
         let rcl_node_mtx = Arc::new(Mutex::new(rcl_node));
 
         Ok(Node {
             rcl_node_mtx,
             rcl_context_mtx: self.context.clone(),
             subscriptions: std::vec![],
+            _parameter_map,
         })
     }
 
-    /// Creates node options.
+    /// Creates a rcl_node_options_t struct from this builder.
     ///
     /// Any fields not present in the builder will have their default value.
     /// For detail about default values, see [`NodeBuilder`][1] docs.

rclrs/src/parameter.rs

@@ -0,0 +1,5 @@
+mod override_map;
+mod value;
+
+pub(crate) use override_map::*;
+pub use value::*;