Optimize stdbuf using OnceCell

TODO.txt

@@ -1,6 +1,5 @@
 0.4
 - Better shell specific examples for `rew x` + cleanup and reorder all `rew x` examples.
-- Refactor and split `x.rs` into multiple files.
 - Add missing unit test to increase code coverage.
 - Prepare changelog for 0.4.0
 - Finish user guide (performance, caveats, global opts propagation in `rew x`, forward compatibility, versioning).

src/commands/x.rs

@@ -201,15 +201,15 @@ fn eval_simple_pattern(context: &Context, pattern: &SimplePattern) -> Result<()>
 }
 
 fn eval_pattern(context: &Context, pattern: &Pattern, shell: &Shell) -> Result<()> {
- let mut env = context.env();
+ let env = context.env();
  let mut children = Vec::new();
  let mut producers = Vec::new();
  let mut consumers = Vec::new();
 
  for item in pattern.items() {
  match &item {
  Item::Constant(value) => producers.push(Producer::Constant(value.clone())),
- Item::Expression(ref expr) => match build_pipeline(&mut env, shell, expr) {
+ Item::Expression(ref expr) => match build_pipeline(&env, shell, expr) {
  Ok(mut pipeline) => {
  pipeline.add_context(ContextItem {
  name: "expression",
@@ -262,7 +262,7 @@ fn eval_pattern(context: &Context, pattern: &Pattern, shell: &Shell) -> Result<(
  }
 }
 
-fn build_pipeline(env: &mut Env, shell: &Shell, expr: &Expression) -> Result<Pipeline> {
+fn build_pipeline(env: &Env, shell: &Shell, expr: &Expression) -> Result<Pipeline> {
  let stdin_mode = if expr.no_stdin {
  StdinMode::Disconnected
  } else {

src/env.rs

@@ -104,7 +104,7 @@ impl Env {
  ]
  }
 
- pub fn external(&mut self) -> Vec<(String, String)> {
+ pub fn external(&self) -> Vec<(String, String)> {
  let mut env = Vec::new();
 
  if self.args.buf_mode.is_line() {

src/process.rs

@@ -90,7 +90,7 @@ impl Command {
  }
  }
 
- pub fn build(&self, env: &mut Env) -> Result<process::Command> {
+ pub fn build(&self, env: &Env) -> Result<process::Command> {
  match self {
  Command::Internal { meta, args } => {
  let mut command = internal_command()?;

src/stdbuf.rs

@@ -1,17 +1,18 @@
 use anyhow::Result;
 use bstr::ByteSlice;
+use std::cell::OnceCell;
 use std::process::Command;
 use std::process::Stdio;
 
 #[derive(Default)]
 pub struct StdBuf {
- line_buf_env: Option<Vec<(String, String)>>,
+ line_buf_env: OnceCell<Vec<(String, String)>>,
 }
 
 impl StdBuf {
- pub fn line_buf_env(&mut self) -> Vec<(String, String)> {
+ pub fn line_buf_env(&self) -> Vec<(String, String)> {
  self.line_buf_env
- .get_or_insert_with(|| Self::detect_env(&["-oL"]).unwrap_or_default())
+ .get_or_init(|| Self::detect_env(&["-oL"]).unwrap_or_default())
  .clone()
  }