examples: Add parse_input REPL for fun!

libconlang/examples/parse_input.rs

@@ -0,0 +1,65 @@
+//! This example grabs input from stdin, lexes it, parses it, and prints the AST
+#![allow(unused_imports)]
+use conlang::{lexer::Lexer, parser::Parser, pretty_printer::PrettyPrintable, token::Token};
+use std::{
+    error::Error,
+    io::{stdin, IsTerminal, Read},
+    path::{Path, PathBuf},
+};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let conf = Config::new();
+    if conf.paths.is_empty() {
+        take_stdin()?;
+    } else {
+        for path in conf.paths.iter().map(PathBuf::as_path) {
+            parse(&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() {
+            parse(&line?, None)
+        }
+    } else {
+        parse(&std::io::read_to_string(stdin())?, None)
+    }
+    Ok(())
+}
+
+fn parse(file: &str, path: Option<&Path>) {
+    match Parser::from(Lexer::new(file)).parse() {
+        Ok(ast) => ast.print(),
+        Err(e) => {
+            println!("{e:?}");
+            if let Some(t) = e.start() {
+                print_token(path, file, t)
+            }
+        }
+    }
+    println!();
+}
+
+fn print_token(path: Option<&Path>, file: &str, t: conlang::token::Token) {
+    let path = path.unwrap_or(Path::new(""));
+    println!(
+        "{path:?}:{:02}:{:02}: {} ({})",
+        t.line(),
+        t.col(),
+        &file[t.range()],
+        t.ty(),
+    )
+}