accept multiple files and stdin

1 files changed, 28 insertions, 6 deletions

diff --git a/src/main.rs b/src/main.rs
index 76b2543..767914d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,7 @@
 use std::error::Error;
 use std::process;
 use std::fs;
+use std::io::{self, BufReader, BufRead};
 
 use clap::Parser;
 
@@ -9,12 +10,18 @@ use clap::Parser;
 struct Config {
     /// The pattern to look for
     pattern: String,
-    /// The path to the file to read
-    file: String,
+    /// The path to files to read. A path of "-" stands for standard input.
+    ///
+    /// If no FILE is given, read standard input.
+    files: Vec<String>,
 }
 
 fn main() {
-    let config = Config::parse();
+    let mut config = Config::parse();
+
+    if config.files.is_empty() {
+        config.files.push(String::from("-"));
+    }
 
     if let Err(e) = run(config) {
         eprintln!("Error: {e}");
@@ -23,10 +30,25 @@ fn main() {
 }
 
 fn run(config: Config) -> Result<(), Box<dyn Error>> {
-    let contents = fs::read_to_string(config.file)?;
+    for file in config.files {
+        // On-Stack Dynamic Dispatch
+        let (mut stdin_read, mut file_read);
+
+        // We need to ascribe the type to get dynamic dispatch.
+        let reader: &mut dyn BufRead = if file == "-" {
+            stdin_read = BufReader::new(io::stdin());
+            &mut stdin_read
+        } else {
+            file_read = BufReader::new(fs::File::open(&file)?);
+            &mut file_read
+        };
+
+        let mut contents = String::new();
+        reader.read_to_string(&mut contents)?;
 
-    for line in trgrep::search(&config.pattern, &contents) {
-        println!("{line}");
+        for line in trgrep::search(&config.pattern, &contents) {
+            println!("{line}");
+        }
     }
 
     Ok(())