PROMPT_STRING env variable (#3918)

* prompt string env variable

* cargo clippy

crates/nu-cli/src/cli.rs

@@ -31,9 +31,12 @@ use std::error::Error;
 use std::iter::Iterator;
 use std::path::PathBuf;
 
+// Name of environment variable where the prompt could be stored
+#[cfg(feature = "rustyline-support")]
+const PROMPT_STRING: &str = "PROMPT_STRING";
+
 pub fn search_paths() -> Vec<std::path::PathBuf> {
  use std::env;
-
  let mut search_paths = Vec::new();
 
  // Automatically add path `nu` is in as a search path
@@ -83,6 +86,66 @@ pub fn run_script_file(
  Ok(())
 }
 
+#[cfg(feature = "rustyline-support")]
+fn default_prompt_string(cwd: &str) -> String {
+ format!(
+ "{}{}{}{}{}{}> ",
+ Color::Green.bold().prefix().to_string(),
+ cwd,
+ nu_ansi_term::ansi::RESET,
+ Color::Cyan.bold().prefix().to_string(),
+ current_branch(),
+ nu_ansi_term::ansi::RESET
+ )
+}
+
+#[cfg(feature = "rustyline-support")]
+fn evaluate_prompt_string(prompt_line: &str, context: &EvaluationContext, cwd: &str) -> String {
+ context.scope.enter_scope();
+ let (prompt_block, err) = nu_parser::parse(prompt_line, 0, &context.scope);
+
+ if err.is_some() {
+ context.scope.exit_scope();
+ default_prompt_string(cwd)
+ } else {
+ let run_result = run_block(
+ &prompt_block,
+ context,
+ InputStream::empty(),
+ ExternalRedirection::Stdout,
+ );
+ context.scope.exit_scope();
+
+ match run_result {
+ Ok(result) => match result.collect_string(Tag::unknown()) {
+ Ok(string_result) => {
+ let errors = context.get_errors();
+ maybe_print_errors(context, Text::from(prompt_line));
+ context.clear_errors();
+
+ if !errors.is_empty() {
+ "> ".into()
+ } else {
+ string_result.item
+ }
+ }
+ Err(e) => {
+ context.host().lock().print_err(e, &Text::from(prompt_line));
+ context.clear_errors();
+
+ "> ".into()
+ }
+ },
+ Err(e) => {
+ context.host().lock().print_err(e, &Text::from(prompt_line));
+ context.clear_errors();
+
+ "> ".into()
+ }
+ }
+ }
+}
+
 #[cfg(feature = "rustyline-support")]
 pub fn cli(
  context: EvaluationContext,
@@ -235,72 +298,17 @@ pub fn cli(
 
  let cwd = context.shell_manager().path();
 
- let colored_prompt = {
- if let Some(prompt) = &prompt {
- let prompt_line = prompt.as_string()?;
-
- context.scope.enter_scope();
- let (prompt_block, err) = nu_parser::parse(&prompt_line, 0, &context.scope);
-
- if err.is_some() {
- context.scope.exit_scope();
-
- format!(
- "{}{}{}{}{}{}> ",
- Color::Green.bold().prefix().to_string(),
- cwd,
- nu_ansi_term::ansi::RESET,
- Color::Cyan.bold().prefix().to_string(),
- current_branch(),
- nu_ansi_term::ansi::RESET
- )
+ // Check if the PROMPT_STRING env variable is set. This env variable
+ // contains nu code that is used to overwrite the prompt
+ let colored_prompt = match context.scope.get_env(PROMPT_STRING) {
+ Some(env_prompt) => evaluate_prompt_string(&env_prompt, &context, &cwd),
+ None => {
+ if let Some(prompt) = &prompt {
+ let prompt_line = prompt.as_string()?;
+ evaluate_prompt_string(&prompt_line, &context, &cwd)
  } else {
- let run_result = run_block(
- &prompt_block,
- &context,
- InputStream::empty(),
- ExternalRedirection::Stdout,
- );
- context.scope.exit_scope();
-
- match run_result {
- Ok(result) => match result.collect_string(Tag::unknown()) {
- Ok(string_result) => {
- let errors = context.get_errors();
- maybe_print_errors(&context, Text::from(prompt_line));
- context.clear_errors();
-
- if !errors.is_empty() {
- "> ".to_string()
- } else {
- string_result.item
- }
- }
- Err(e) => {
- context.host().lock().print_err(e, &Text::from(prompt_line));
- context.clear_errors();
-
- "> ".to_string()
- }
- },
- Err(e) => {
- context.host().lock().print_err(e, &Text::from(prompt_line));
- context.clear_errors();
-
- "> ".to_string()
- }
- }
+ default_prompt_string(&cwd)
  }
- } else {
- format!(
- "{}{}{}{}{}{}> ",
- Color::Green.bold().prefix().to_string(),
- cwd,
- nu_ansi_term::ansi::RESET,
- Color::Cyan.bold().prefix().to_string(),
- current_branch(),
- nu_ansi_term::ansi::RESET
- )
  }
  };
 
@@ -432,6 +440,7 @@ pub fn cli(
  Ok(())
 }
 
+#[cfg(feature = "rustyline-support")]
 pub fn load_local_cfg_if_present(context: &EvaluationContext) {
  trace!("Loading local cfg if present");
  match config::loadable_cfg_exists_in_dir(PathBuf::from(context.shell_manager().path())) {