implemented new in context/builder.rs

Author: DS3a

rclrs/src/context/builder.rs

@@ -1,3 +1,38 @@
-pub struct NodeBuilder {
+use crate::rcl_bindings::*;
+use crate::{Context, RclrsError};
+use std::ffi::CString;
+use std::os::raw::c_char;
+use parking_lot::Mutex;
 
+pub struct ContextBuilder {
+    cstring_args: Vec<CString>,
+    c_args: Option<Vec<*const c_char>>,
+    context_mtx: Mutex<rcl_context_t>,
+    allocator: rcl_allocator_t,
+    init_options_mtx: Mutex<rcl_init_options_t>,
+}
+
+impl ContextBuilder {
+
+    /// Build a new ContextBuilder instance
+    pub fn new(args: impl IntoIterator<Item = String>) -> Result<ContextBuilder, RclrsError> {
+        unsafe {
+            Ok(ContextBuilder {
+                cstring_args: args.into_iter().map(|arg| {
+                    CString::new(arg.as_str()).map_err(|err| RclrsError::StringContainsNul{
+                        err,
+                        s: arg.clone(),
+                    })
+                }).collect::<Result<_, _>>()?,
+                c_args: None, // to be built in the build function
+                context_mtx: Mutex::new(rcl_get_zero_initialized_context()),
+                allocator: rcutils_get_default_allocator(),
+                init_options_mtx: Mutex::new(rcl_get_zero_initialized_init_options())
+            })
+        }
+    }
+
+    pub fn build(&self) -> Result<Context, RclrsError> {
+        todo!("call build here");
+    }
 }