perf: assorted performance changes (reubeno#936)

Author: Elsie19

brush-core/src/commands.rs

@@ -564,12 +564,16 @@ pub(crate) fn execute_external_command(
     args: &[CommandArg],
 ) -> Result<ExecutionSpawnResult, error::Error> {
     // Filter out the args; we only want strings.
-    let mut cmd_args = vec![];
-    for arg in args {
-        if let CommandArg::String(s) = arg {
-            cmd_args.push(s);
-        }
-    }
+    let cmd_args = args
+        .iter()
+        .filter_map(|e| {
+            if let CommandArg::String(s) = e {
+                Some(s)
+            } else {
+                None
+            }
+        })
+        .collect::<Vec<_>>();
 
     // Before we lose ownership of the open files, figure out if stdin will be a terminal.
     let child_stdin_is_terminal = context

brush-parser/benches/parser.rs

@@ -18,7 +18,7 @@ mod unix {
             .unwrap()
     }
 
-    fn parse(tokens: &Vec<Token>) -> brush_parser::ast::Program {
+    fn parse(tokens: &[Token]) -> brush_parser::ast::Program {
         parse_tokens(tokens, &brush_parser::ParserOptions::default()).unwrap()
     }
 

brush-parser/src/parser/mod.rs

@@ -184,7 +184,7 @@ impl<R: std::io::BufRead> Parser<R> {
 /// * `tokens` - The tokens to parse.
 /// * `options` - The options to use when parsing.
 pub fn parse_tokens(
-    tokens: &Vec<Token>,
+    tokens: &[Token],
     options: &ParserOptions,
 ) -> Result<ast::Program, crate::error::ParseError> {
     let parse_result = peg::token_parser::program(&Tokens { tokens }, options);
@@ -193,7 +193,7 @@ pub fn parse_tokens(
 
 fn parse_result_to_error<R>(
     parse_result: Result<R, ::peg::error::ParseError<usize>>,
-    tokens: &Vec<Token>,
+    tokens: &[Token],
 ) -> Result<R, crate::error::ParseError>
 where
     R: std::fmt::Debug,
@@ -205,10 +205,7 @@ where
         }
         Err(parse_error) => {
             tracing::debug!(target: "parse", "Parse error: {:?}", parse_error);
-            Err(crate::error::convert_peg_parse_error(
-                &parse_error,
-                tokens.as_slice(),
-            ))
+            Err(crate::error::convert_peg_parse_error(&parse_error, tokens))
         }
     }
 }

brush-parser/src/prompt.rs

@@ -168,7 +168,7 @@ mod tests {
     fn basic_prompt() -> Result<()> {
         assert_eq!(
             parse(r"\u@\h:\w$ ")?,
-            vec![
+            &[
                 PromptPiece::CurrentUser,
                 PromptPiece::Literal("@".to_owned()),
                 PromptPiece::Hostname {
@@ -190,7 +190,7 @@ mod tests {
     fn brackets_and_vars() -> Result<()> {
         assert_eq!(
             parse(r"\[$foo\]\u > ")?,
-            vec![
+            &[
                 PromptPiece::StartNonPrintingSequence,
                 PromptPiece::Literal("$foo".to_owned()),
                 PromptPiece::EndNonPrintingSequence,