examples/identify_tokens.rs: Overhaul user experience

libconlang/examples/identify_tokens.rs

@@ -1,16 +1,60 @@
 //! This example grabs input from stdin, lexes it, and prints which lexer rules matched
 #![allow(unused_imports)]
 use conlang::lexer::Lexer;
-use std::{error::Error, io::stdin};
+use std::{
+    error::Error,
+    io::{stdin, IsTerminal, Read},
+    path::{Path, PathBuf},
+};
 
 fn main() -> Result<(), Box<dyn Error>> {
-    // get input from stdin
-    for line in stdin().lines() {
-        let line = line?;
-        let mut lexer = Lexer::new(&line);
-        while let Some(token) = lexer.any() {
-            println!("{:#19} │{}│", token.ty(), &line[token.range()])
+    let conf = Config::new();
+    if conf.paths.is_empty() {
+        take_stdin()?;
+    } else {
+        for path in conf.paths.iter().map(PathBuf::as_path) {
+            lex_tokens(&std::fs::read_to_string(path)?, Some(path));
         }
     }
     Ok(())
 }
+
+struct Config {
+    paths: Vec<PathBuf>,
+}
+
+impl Config {
+    fn new() -> Self {
+        Config { paths: std::env::args().skip(1).map(PathBuf::from).collect() }
+    }
+}
+
+fn take_stdin() -> Result<(), Box<dyn Error>> {
+    if stdin().is_terminal() {
+        for line in stdin().lines() {
+            lex_tokens(&line?, None)
+        }
+    } else {
+        lex_tokens(&std::io::read_to_string(stdin())?, None)
+    }
+    Ok(())
+}
+
+fn lex_tokens(file: &str, path: Option<&Path>) {
+    for token in Lexer::new(file) {
+        if let Some(path) = path {
+            print!("{path:?}:")
+        }
+        print_token(file, token);
+    }
+}
+
+fn print_token(line: &str, t: conlang::token::Token) {
+    println!(
+        "{:02}:{:02}: {:#19} │{}│",
+        t.line(),
+        t.col(),
+        t.ty(),
+        &line[t.range()]
+    )
+}