Optimize a, c, i text usage

Avoid the cost of string copies through the use of a reference counted
str.

The benchmark results improve as follows:

access-log-append aci-optimize is 1.07 times faster than rust-f2a2d868

src/uu/sed/src/command.rs

@@ -14,7 +14,6 @@ use crate::named_writer::NamedWriter;
 use crate::script_char_provider::ScriptCharProvider;
 use crate::script_line_provider::ScriptLineProvider;
 
-use std::borrow::Cow;
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::path::PathBuf; // For file descriptors and equivalent
@@ -74,7 +73,7 @@ pub struct ProcessingContext {
 #[derive(Clone, Debug)]
 /// Elements that shall be appended at the end of each command processing cycle
 pub enum AppendElement {
-    Text(String),  // The specified text string
+    Text(Rc<str>), // The specified text string
     Path(PathBuf), // The contents of the specified file path
 }
 
@@ -322,7 +321,7 @@ pub enum CommandData {
     NamedWriter(Rc<RefCell<NamedWriter>>),      // File output for 'w'
     Number(usize),                              // Number for 'l', 'q', 'Q' (GNU)
     Substitution(Box<Substitution>),            // Substitute command 's'
-    Text(Cow<'static, str>),                    // Text for 'a', 'c', 'i'
+    Text(Rc<str>),                              // Text for 'a', 'c', 'i'
     Transliteration(Box<Transliteration>),      // Transliteration command 'y'
 }
 

src/uu/sed/src/compiler.rs

@@ -19,11 +19,11 @@ use crate::named_writer::NamedWriter;
 use crate::script_char_provider::ScriptCharProvider;
 use crate::script_line_provider::{ScriptLineProvider, ScriptValue};
 
-use std::borrow::Cow;
 use std::cell::RefCell;
 use std::mem;
 use std::path::PathBuf;
 use std::rc::Rc;
+
 use terminal_size::{Width, terminal_size};
 use uucore::error::{UResult, USimpleError};
 
@@ -1105,7 +1105,7 @@ fn compile_text_command_gnu(
             line.advance();
         }
     }
-    cmd.data = CommandData::Text(Cow::Owned(text));
+    cmd.data = CommandData::Text(Rc::from(text));
     Ok(CommandHandling::Continue)
 }
 
@@ -1151,7 +1151,7 @@ fn compile_text_command_posix(
             break;
         }
     }
-    cmd.data = CommandData::Text(Cow::Owned(text));
+    cmd.data = CommandData::Text(Rc::from(text));
     Ok(CommandHandling::Continue)
 }
 
@@ -2541,7 +2541,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "line1\n");
+                assert_eq!(text.to_string(), "line1\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2558,7 +2558,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "line1\n");
+                assert_eq!(text.to_string(), "line1\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2574,7 +2574,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "there\n");
+                assert_eq!(text.to_string(), "there\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2590,7 +2590,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "there\n");
+                assert_eq!(text.to_string(), "there\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2606,7 +2606,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "\n");
+                assert_eq!(text.to_string(), "\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2622,7 +2622,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "");
+                assert_eq!(text.to_string(), "");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2638,7 +2638,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "tom\n");
+                assert_eq!(text.to_string(), "tom\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2654,7 +2654,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, ">helll\x08o\nto\nall\x07\n");
+                assert_eq!(text.to_string(), ">helll\x08o\nto\nall\x07\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }
@@ -2670,7 +2670,7 @@ mod tests {
         compile_text_command(&mut lines, &mut chars, &mut cmd, &mut context).unwrap();
         match &cmd.data {
             CommandData::Text(text) => {
-                assert_eq!(text, "line1\nline2\n");
+                assert_eq!(text.to_string(), "line1\nline2\n");
             }
             _ => panic!("Expected CommandData::Text"),
         }

src/uu/sed/src/processor.rs

@@ -355,7 +355,7 @@ fn flush_appends(output: &mut OutputBuffer, context: &mut ProcessingContext) ->
     for elem in &context.append_elements {
         match elem {
             AppendElement::Text(text) => {
-                output.write_str(text.clone())?;
+                output.write_str(&**text)?;
             }
             AppendElement::Path(path) => {
                 output.copy_file(path)?;
@@ -476,7 +476,7 @@ fn process_file(
                     let text = extract_variant!(command, Text);
                     context
                         .append_elements
-                        .push(AppendElement::Text(text.clone().into_owned()));
+                        .push(AppendElement::Text(text.clone()));
                 }
                 'b' => {
                     // Branch to the specified label or end if none is given.

util/benchmark.sh

@@ -81,6 +81,9 @@ bench_run access-log-translit "$PROG y/0123456789/9876543210/ access.log"
 # Multiple substitutions
 bench_run access-log-complex-sub "$PROG -f $SCRIPTS/http-log-redact.sed access.log"
 
+# Text append
+bench_run access-log-append "$PROG athe-line-ends-here access.log"
+
 rm access.log
 
 # Remove \r