Make functions viewable in the Variables pane

Author: lionel-

crates/ark/src/modules/positron/view.R

@@ -9,9 +9,10 @@
 # These are only passed if we could infer a variable name from the input and if
 # that variable exists in the calling environment. This is used for live
 # updating the objects, if supported (e.g. data frames in the data viewer).
-view <- function(x, title) {
+view <- function(x, title, name = NULL, env = parent.frame()) {
     # Derive the name of the object from the expression passed to View()
-    name <- as_label(substitute(x))
+    name <- name %||% as_label(substitute(x))
+    stopifnot(is_string(name))
 
     # Create a title from the name of the object if one is not provided
     if (missing(title)) {
@@ -25,9 +26,8 @@ view <- function(x, title) {
     # Note that this means that (for example) View(foo) will watch the variable
     # foo in the parent frame, but Viewing temporary variables like
     # View(cbind(foo, bar)) does not create something that can be watched.
-    if (isTRUE(exists(name, envir = parent.frame(), inherits = FALSE))) {
+    if (nzchar(name) && isTRUE(exists(name, envir = env, inherits = FALSE))) {
         var <- name
-        env <- parent.frame()
     } else {
         var <- ""
         env <- NULL

crates/ark/src/variables/r_variables.rs

@@ -29,6 +29,7 @@ use harp::exec::RFunctionExt;
 use harp::get_option;
 use harp::object::RObject;
 use harp::utils::r_assert_type;
+use harp::utils::r_is_function;
 use harp::vector::CharacterVector;
 use harp::vector::Vector;
 use libr::R_GlobalEnv;
@@ -42,6 +43,7 @@ use crate::lsp::events::EVENTS;
 use crate::r_task;
 use crate::thread::RThreadSafe;
 use crate::variables::variable::PositronVariable;
+use crate::view::view;
 
 /// Enumeration of treatments for the .Last.value variable
 pub enum LastValue {
@@ -368,15 +370,25 @@ impl RVariables {
     fn view(&mut self, path: &Vec<String>) -> Result<String, harp::error::Error> {
         r_task(|| {
             let env = self.env.get().clone();
-            let data = PositronVariable::resolve_data_object(env, &path)?;
+            let obj = PositronVariable::resolve_data_object(env.clone(), &path)?;
+
+            if r_is_function(obj.sexp) {
+                harp::as_result(view(&obj, &path, &env))?;
+
+                // Return a falsy `viewerId`. Should ideally be a more explicit `None`.
+                return Ok(String::from(""));
+            }
+
             let name = unsafe { path.get_unchecked(path.len() - 1) };
+
             let binding = DataObjectEnvInfo {
                 name: name.to_string(),
-                env: RThreadSafe::new(self.env.get().clone()),
+                env: RThreadSafe::new(env),
             };
+
             let viewer_id = RDataExplorer::start(
                 name.clone(),
-                data,
+                obj,
                 Some(binding),
                 self.comm_manager_tx.clone(),
             )?;

crates/ark/src/variables/variable.rs

@@ -33,6 +33,7 @@ use harp::utils::r_format_s4;
 use harp::utils::r_inherits;
 use harp::utils::r_is_altrep;
 use harp::utils::r_is_data_frame;
+use harp::utils::r_is_function;
 use harp::utils::r_is_matrix;
 use harp::utils::r_is_null;
 use harp::utils::r_is_s4;
@@ -589,6 +590,10 @@ fn has_children(value: SEXP) -> bool {
 }
 
 fn has_viewer(value: SEXP) -> bool {
+    if r_is_function(value) {
+        return true;
+    }
+
     if !(r_is_data_frame(value) || r_is_matrix(value)) {
         return false;
     }

crates/ark/src/view.rs

@@ -5,7 +5,28 @@
 //
 //
 
-// Tests for `view.R`
+use harp::exec::RFunction;
+use harp::exec::RFunctionExt;
+use harp::RObject;
+
+use crate::modules::ARK_ENVS;
+
+pub(crate) fn view(x: &RObject, path: &Vec<String>, env: &RObject) -> anyhow::Result<()> {
+    // Currently `view()` only supports identifiers
+    let name = if path.len() == 1 {
+        path.last().unwrap().clone()
+    } else {
+        String::from("")
+    };
+
+    RFunction::new("", "view")
+        .add(x.sexp)
+        .param("name", name)
+        .param("env", env.sexp)
+        .call_in(ARK_ENVS.positron_ns)?;
+
+    Ok(())
+}
 
 #[cfg(test)]
 mod tests {

crates/harp/src/lib.rs

@@ -59,6 +59,7 @@ pub use vector::list::*;
 // resolve to the correct symbols
 extern crate self as harp;
 
+pub use harp::error::as_result;
 pub use harp::exec::top_level_exec;
 pub use harp::exec::try_catch;
 pub use harp::exec::try_eval;