add expected output for chapter 3

Author: rakurame96

cli-book/ch03_catr/Cargo.toml

@@ -5,8 +5,10 @@ edition = "2021"
 
 [dependencies]
 clap = "4.5.23"
+anyhow = "1.0.79"
 
 [dev-dependencies]
 assert_cmd = "2.0.13"
 predicates = "3.0.4"
-rand = "0.8"
+rand = "0.8"
+pretty_assertions = "1.4.0"

cli-book/ch03_catr/src/lib.rs

@@ -1,94 +1,145 @@
-use std::error::Error;
-use clap::{Arg, ArgAction, Command};
-use std::fs::File;
-use std::io::{self, stdin, BufRead, BufReader};
-
-#[allow(unused)]
-#[derive(Debug)]
-pub struct Config {
-    files: Vec<String>,
-    number_lines: bool,
-    number_nonblank_lines: bool,
-}
-
-type MyResult<T> = Result<T, Box<dyn Error>>;
-
-fn open(filename: &str) -> MyResult<Box<dyn BufRead>> {
-    match filename {
-        "-" => Ok(Box::new(BufReader::new(io::stdin()))),
-        _ => Ok(Box::new(BufReader::new(File::open(filename)?))),
-    }
-}
-
-pub fn run(config: Config) -> MyResult<()> {
-    // dbg!(config);
-    for filename in config.files {
-        // println!("{}", filename);
-        match open(&filename) {
-            Err(err) => eprintln!("Failed to open {}: {}", filename, err),
-            Ok(_) => println!("Opened {}", filename),            
-        }
-    }
-    Ok(())
-} 
-
-pub fn get_args() -> MyResult<Config> {
-    let matches = Command::new("ch03_catr")
-        .version("0.1.0")
-        .author("Rakuram <[email protected]>")
-        .about("Rust cat Command")
-        .help_template(
-            "{name} {version} \n\
-             {author} \n\
-             {about} \n\n\
-             USAGE: \n    {usage}\n\n\
-             {all-args}",
-        )
-        .arg(
-            Arg::new("files")
-                .value_name("FILE")
-                .help("Input files")
-                // .required(true)          // reason why required is not used is because we are using default value
-                .num_args(1..)
-                .default_value("-")
-                .action(ArgAction::Append),
-        )
-        .arg(
-            Arg::new("number_lines")
-                .short('n')
-                .long("number")
-                .help("number all output lines")
-                .action(ArgAction::SetTrue)
-                .conflicts_with("number_nonblank"),
-        )
-        .arg(
-            Arg::new("number_nonblank")
-                .short('b')
-                .long("number-nonblank")
-                .help("number nonempty output lines, overrides -n")
-                .action(ArgAction::SetTrue),
-        )
-        .get_matches();
-
-    // let text: Vec<String> = matches
-    //     .get_many("files")
-    //     .expect("filename is required")
-    //     .cloned()
-    //     .collect();
-
-    // println!("{:#?}", text);
-
-    // let number_lines = matches.get_flag("number_lines");
-
-    // let number_nonblank_lines = matches.get_flag("number_nonblank_lines");
-
-    // println!("text: {:#?}", text);
-    // println!("number_lines: {:#?}", number_lines);
-    // println!("number_nonblank_lines: {:#?}", number_nonblank_lines);
-
-    Ok(Config {
-        files: matches.get_many("files").unwrap().cloned().collect(),
-        number_lines: matches.get_flag("number_lines"),
-        number_nonblank_lines: matches.get_flag("number_nonblank"),
-    })
-}
+use clap::{Arg, ArgAction, Command};
+use std::error::Error;
+use std::fs::File;
+use std::io::{self, BufRead, BufReader};
+
+#[allow(unused)]
+#[derive(Debug)]
+pub struct Config {
+    files: Vec<String>,
+    number_lines: bool,
+    number_nonblank_lines: bool,
+}
+
+type MyResult<T> = Result<T, Box<dyn Error>>;
+
+fn open(filename: &str) -> MyResult<Box<dyn BufRead>> {
+    match filename {
+        "-" => Ok(Box::new(BufReader::new(io::stdin()))),
+        _ => Ok(Box::new(BufReader::new(File::open(filename)?))),
+    }
+}
+
+// method 1
+// pub fn run(config: Config) -> MyResult<()> {
+//     // dbg!(config);
+//     for filename in config.files {
+//         // println!("{}", filename);
+//         match open(&filename) {
+//             Err(err) => eprintln!("Failed to open {}: {}", filename, err),
+//             // Ok(_) => println!("Opened {}", filename),
+//             Ok(file) => {
+//                 let mut line_number  = 0;
+//                 for line_result in file.lines() {
+//                     let line = line_result?;
+//                     line_number += 1;
+
+//                     if config.number_lines {
+//                         println!("{:>6}\t{}", line_number, line);
+//                     } else {
+//                         println!("{}", line);
+//                     }
+
+//                     if config.number_nonblank_lines {
+//                         if line.is_empty() {
+//                             line_number -= 1;
+//                             continue;
+//                         } else {
+//                             println!("{:>6}\t{}", line_number, line);
+//                         }
+//                     }
+//                 }
+//             }
+//         }
+//     }
+//     Ok(())
+// }
+
+// method 2 - Idomatic way
+pub fn run(config: Config) -> MyResult<()> {
+    for filename in config.files {
+        match open(&filename) {
+            Err(err) => eprintln!("Failed to open {}: {}", filename, err),
+            Ok(file) => {
+                let mut last_num = 0; 
+                for (line_num, line) in file.lines().enumerate() {
+                    let line = line?;   // unwrapping from Result
+                    if config.number_lines {
+                        println!("{:6}\t{}", line_num + 1, line);
+                    } else if config.number_nonblank_lines {
+                        if !line.is_empty() {
+                            last_num += 1;
+                            println!("{:6}\t{}", last_num, line);
+                        } else {
+                            println!();
+                        }
+                    } else {
+                        println!("{}", line);
+                    }
+                }
+            }
+        }
+    }
+    Ok(())
+}
+
+pub fn get_args() -> MyResult<Config> {
+    let matches = Command::new("ch03_catr")
+        .version("0.1.0")
+        .author("Rakuram <[email protected]>")
+        .about("Rust cat Command")
+        .help_template(
+            "{name} {version} \n\
+             {author} \n\
+             {about} \n\n\
+             USAGE: \n    {usage}\n\n\
+             {all-args}",
+        )
+        .arg(
+            Arg::new("files")
+                .value_name("FILE")
+                .help("Input files")
+                // .required(true)          // reason why required is not used is because we are using default value
+                .num_args(1..)
+                .default_value("-")
+                .action(ArgAction::Append),
+        )
+        .arg(
+            Arg::new("number_lines")
+                .short('n')
+                .long("number")
+                .help("number all output lines")
+                .action(ArgAction::SetTrue)
+                .conflicts_with("number_nonblank"),
+        )
+        .arg(
+            Arg::new("number_nonblank")
+                .short('b')
+                .long("number-nonblank")
+                .help("number nonempty output lines, overrides -n")
+                .action(ArgAction::SetTrue),
+        )
+        .get_matches();
+
+    // let text: Vec<String> = matches
+    //     .get_many("files")
+    //     .expect("filename is required")
+    //     .cloned()
+    //     .collect();
+
+    // println!("{:#?}", text);
+
+    // let number_lines = matches.get_flag("number_lines");
+
+    // let number_nonblank_lines = matches.get_flag("number_nonblank_lines");
+
+    // println!("text: {:#?}", text);
+    // println!("number_lines: {:#?}", number_lines);
+    // println!("number_nonblank_lines: {:#?}", number_nonblank_lines);
+
+    Ok(Config {
+        files: matches.get_many("files").unwrap().cloned().collect(),
+        number_lines: matches.get_flag("number_lines"),
+        number_nonblank_lines: matches.get_flag("number_nonblank"),
+    })
+}