Only run $env.PROMPT_COMMAND once per prompt (#10986)

# Description

If `$env.TRANSIENT_PROMPT_COMMAND` is not set, use the prompt created by
`$env.PROMPT_COMMAND` instead of running the command a second time. As a
side effect, `$env.TRANSIENT_PROMPT_COMMAND` now runs after the hooks
`pre_prompt` and `env_change`, instead of before.

# User-Facing Changes

- `$env.PROMPT_COMMAND` gets run only once per prompt instead of twice
- `$env.TRANSIENT_PROMPT_COMMAND` now sees any environment set in a
`pre_prompt` or `env_change` hook, like `$env.PROMPT_COMMAND` does

crates/nu-cli/src/prompt.rs

@@ -39,35 +39,6 @@ impl NushellPrompt {
         }
     }
 
-    pub fn update_prompt_left(&mut self, prompt_string: Option<String>) {
-        self.left_prompt_string = prompt_string;
-    }
-
-    pub fn update_prompt_right(
-        &mut self,
-        prompt_string: Option<String>,
-        render_right_prompt_on_last_line: bool,
-    ) {
-        self.right_prompt_string = prompt_string;
-        self.render_right_prompt_on_last_line = render_right_prompt_on_last_line;
-    }
-
-    pub fn update_prompt_indicator(&mut self, prompt_indicator_string: Option<String>) {
-        self.default_prompt_indicator = prompt_indicator_string;
-    }
-
-    pub fn update_prompt_vi_insert(&mut self, prompt_vi_insert_string: Option<String>) {
-        self.default_vi_insert_prompt_indicator = prompt_vi_insert_string;
-    }
-
-    pub fn update_prompt_vi_normal(&mut self, prompt_vi_normal_string: Option<String>) {
-        self.default_vi_normal_prompt_indicator = prompt_vi_normal_string;
-    }
-
-    pub fn update_prompt_multiline(&mut self, prompt_multiline_indicator_string: Option<String>) {
-        self.default_multiline_indicator = prompt_multiline_indicator_string;
-    }
-
     pub fn update_all_prompt_strings(
         &mut self,
         left_prompt_string: Option<String>,
@@ -90,6 +61,32 @@ impl NushellPrompt {
         self.render_right_prompt_on_last_line = render_right_prompt_on_last_line;
     }
 
+    pub fn overlay_all_prompt_strings(
+        &mut self,
+        left_prompt_string: Option<String>,
+        right_prompt_string: Option<String>,
+        prompt_indicator_string: Option<String>,
+        prompt_multiline_indicator_string: Option<String>,
+        prompt_vi: (Option<String>, Option<String>),
+        render_right_prompt_on_last_line: bool,
+    ) {
+        let (prompt_vi_insert_string, prompt_vi_normal_string) = prompt_vi;
+
+        self.left_prompt_string = left_prompt_string.or(self.left_prompt_string.take());
+        self.right_prompt_string = right_prompt_string.or(self.right_prompt_string.take());
+        self.default_prompt_indicator =
+            prompt_indicator_string.or(self.default_prompt_indicator.take());
+        self.default_multiline_indicator =
+            prompt_multiline_indicator_string.or(self.default_multiline_indicator.take());
+
+        self.default_vi_insert_prompt_indicator =
+            prompt_vi_insert_string.or(self.default_vi_insert_prompt_indicator.take());
+        self.default_vi_normal_prompt_indicator =
+            prompt_vi_normal_string.or(self.default_vi_normal_prompt_indicator.take());
+
+        self.render_right_prompt_on_last_line = render_right_prompt_on_last_line;
+    }
+
     fn default_wrapped_custom_string(&self, str: String) -> String {
         format!("({str})")
     }

crates/nu-cli/src/prompt_update.rs

@@ -7,8 +7,6 @@ use nu_protocol::{
     Config, PipelineData, Value,
 };
 use reedline::Prompt;
-use std::borrow::Cow;
-use std::sync::Arc;
 
 // Name of environment variable where the prompt could be stored
 pub(crate) const PROMPT_COMMAND: &str = "PROMPT_COMMAND";
@@ -153,118 +151,79 @@ pub(crate) fn update_prompt<'prompt>(
     ret_val
 }
 
-struct TransientPrompt {
+pub(crate) fn make_transient_prompt(
-    engine_state: Arc<EngineState>,
-    stack: Stack,
-}
-
-/// Try getting `$env.TRANSIENT_PROMPT_<X>`, and get `$env.PROMPT_<X>` if that fails
-fn get_transient_prompt_string(
-    transient_prompt: &str,
-    prompt: &str,
     config: &Config,
     engine_state: &EngineState,
-    stack: &mut Stack,
+    stack: &Stack,
-) -> Option<String> {
+    nu_prompt: &NushellPrompt,
-    get_prompt_string(transient_prompt, config, engine_state, stack)
+) -> Box<dyn Prompt> {
-        .or_else(|| get_prompt_string(prompt, config, engine_state, stack))
+    let mut stack = stack.clone();
-}
+    let mut nu_prompt = nu_prompt.clone();
 
-impl Prompt for TransientPrompt {
+    let left_prompt_string =
-    fn render_prompt_left(&self) -> Cow<str> {
+        get_prompt_string(TRANSIENT_PROMPT_COMMAND, config, engine_state, &mut stack);
-        let mut nu_prompt = NushellPrompt::new();
-        let config = &self.engine_state.get_config().clone();
-        let mut stack = self.stack.clone();
-        nu_prompt.update_prompt_left(get_transient_prompt_string(
-            TRANSIENT_PROMPT_COMMAND,
-            PROMPT_COMMAND,
-            config,
-            &self.engine_state,
-            &mut stack,
-        ));
-        nu_prompt.render_prompt_left().to_string().into()
-    }
 
-    fn render_prompt_right(&self) -> Cow<str> {
+    // Now that we have the prompt string lets ansify it.
-        let mut nu_prompt = NushellPrompt::new();
+    // <133 A><prompt><133 B><command><133 C><command output>
-        let config = &self.engine_state.get_config().clone();
+    let left_prompt_string = if config.shell_integration {
-        let mut stack = self.stack.clone();
+        if let Some(prompt_string) = left_prompt_string {
-        nu_prompt.update_prompt_right(
+            Some(format!(
-            get_transient_prompt_string(
+                "{PRE_PROMPT_MARKER}{prompt_string}{POST_PROMPT_MARKER}"
-                TRANSIENT_PROMPT_COMMAND_RIGHT,
+            ))
-                PROMPT_COMMAND_RIGHT,
+        } else {
-                config,
+            left_prompt_string
-                &self.engine_state,
+        }
-                &mut stack,
+    } else {
-            ),
+        left_prompt_string
-            config.render_right_prompt_on_last_line,
+    };
-        );
-        nu_prompt.render_prompt_right().to_string().into()
-    }
 
-    fn render_prompt_indicator(&self, prompt_mode: reedline::PromptEditMode) -> Cow<str> {
+    let right_prompt_string = get_prompt_string(
-        let mut nu_prompt = NushellPrompt::new();
+        TRANSIENT_PROMPT_COMMAND_RIGHT,
-        let config = &self.engine_state.get_config().clone();
+        config,
-        let mut stack = self.stack.clone();
-        nu_prompt.update_prompt_indicator(get_transient_prompt_string(
-            TRANSIENT_PROMPT_INDICATOR,
-            PROMPT_INDICATOR,
-            config,
-            &self.engine_state,
-            &mut stack,
-        ));
-        nu_prompt.update_prompt_vi_insert(get_transient_prompt_string(
-            TRANSIENT_PROMPT_INDICATOR_VI_INSERT,
-            PROMPT_INDICATOR_VI_INSERT,
-            config,
-            &self.engine_state,
-            &mut stack,
-        ));
-        nu_prompt.update_prompt_vi_normal(get_transient_prompt_string(
-            TRANSIENT_PROMPT_INDICATOR_VI_NORMAL,
-            PROMPT_INDICATOR_VI_NORMAL,
-            config,
-            &self.engine_state,
-            &mut stack,
-        ));
-        nu_prompt
-            .render_prompt_indicator(prompt_mode)
-            .to_string()
-            .into()
-    }
-
-    fn render_prompt_multiline_indicator(&self) -> Cow<str> {
-        let mut nu_prompt = NushellPrompt::new();
-        let config = &self.engine_state.get_config().clone();
-        let mut stack = self.stack.clone();
-        nu_prompt.update_prompt_multiline(get_transient_prompt_string(
-            TRANSIENT_PROMPT_MULTILINE_INDICATOR,
-            PROMPT_MULTILINE_INDICATOR,
-            config,
-            &self.engine_state,
-            &mut stack,
-        ));
-        nu_prompt
-            .render_prompt_multiline_indicator()
-            .to_string()
-            .into()
-    }
-
-    fn render_prompt_history_search_indicator(
-        &self,
-        history_search: reedline::PromptHistorySearch,
-    ) -> Cow<str> {
-        NushellPrompt::new()
-            .render_prompt_history_search_indicator(history_search)
-            .to_string()
-            .into()
-    }
-}
-
-/// Construct the transient prompt
-pub(crate) fn transient_prompt(engine_state: Arc<EngineState>, stack: &Stack) -> Box<dyn Prompt> {
-    Box::new(TransientPrompt {
         engine_state,
-        stack: stack.clone(),
+        &mut stack,
-    })
+    );
+
+    let prompt_indicator_string =
+        get_prompt_string(TRANSIENT_PROMPT_INDICATOR, config, engine_state, &mut stack);
+
+    let prompt_multiline_string = get_prompt_string(
+        TRANSIENT_PROMPT_MULTILINE_INDICATOR,
+        config,
+        engine_state,
+        &mut stack,
+    );
+
+    let prompt_vi_insert_string = get_prompt_string(
+        TRANSIENT_PROMPT_INDICATOR_VI_INSERT,
+        config,
+        engine_state,
+        &mut stack,
+    );
+
+    let prompt_vi_normal_string = get_prompt_string(
+        TRANSIENT_PROMPT_INDICATOR_VI_NORMAL,
+        config,
+        engine_state,
+        &mut stack,
+    );
+
+    // apply the other indicators
+    nu_prompt.overlay_all_prompt_strings(
+        left_prompt_string,
+        right_prompt_string,
+        prompt_indicator_string,
+        prompt_multiline_string,
+        (prompt_vi_insert_string, prompt_vi_normal_string),
+        config.render_right_prompt_on_last_line,
+    );
+
+    trace!(
+        "make_transient_prompt {}:{}:{}",
+        file!(),
+        line!(),
+        column!()
+    );
+
+    Box::new(nu_prompt)
 }

crates/nu-cli/src/repl.rs

@@ -267,11 +267,7 @@ pub fn evaluate_repl(
             .with_quick_completions(config.quick_completions)
             .with_partial_completions(config.partial_completions)
             .with_ansi_colors(config.use_ansi_coloring)
-            .with_cursor_config(cursor_config)
+            .with_cursor_config(cursor_config);
-            .with_transient_prompt(prompt_update::transient_prompt(
-                engine_reference.clone(),
-                stack,
-            ));
         perf(
             "reedline builder",
             start_time,
@@ -423,8 +419,11 @@ pub fn evaluate_repl(
         );
 
         start_time = std::time::Instant::now();
+        // Now we compute the prompt after running the hooks
         let config = &engine_state.get_config().clone();
-        let prompt = prompt_update::update_prompt(config, engine_state, stack, &mut nu_prompt);
+        prompt_update::update_prompt(config, engine_state, stack, &mut nu_prompt);
+        let transient_prompt =
+            prompt_update::make_transient_prompt(config, engine_state, stack, &nu_prompt);
         perf(
             "update_prompt",
             start_time,
@@ -437,7 +436,8 @@ pub fn evaluate_repl(
         entry_num += 1;
 
         start_time = std::time::Instant::now();
-        let input = line_editor.read_line(prompt);
+        line_editor = line_editor.with_transient_prompt(transient_prompt);
+        let input = line_editor.read_line(&nu_prompt);
         let shell_integration = config.shell_integration;
 
         match input {