Switch CLI to clap for a better experience (#33)

Cargo.toml

@@ -2,6 +2,12 @@
 name = "theforce"
 version = "0.1.0"
 edition = "2018"
+description = "A Star Wars inspired programming language."
+homepage = "https://github.com/mirdaki/theforce"
+repository = "https://github.com/mirdaki/theforce"
+license = "MIT"
+keywords = ["star-wars", "programming-language"]
+categories = ["compilers", "command-line-utilities"]
 
 [features]
 llvm = ["inkwell"]
@@ -10,3 +16,4 @@ llvm = ["inkwell"]
 inkwell = { git = "https://github.com/TheDan64/inkwell", branch = "llvm10-0", optional = true }
 pest = "2.1.3"
 pest_derive = "2.1.0"
+clap = "2.33.3"

src/cli.rs

@@ -1,22 +1,28 @@
-use std::fs;
-
-pub struct Args {
-    pub path: std::path::PathBuf,
-}
+extern crate clap;
+use clap::{App, Arg, ArgMatches};
 
-pub fn parse_arguments() -> Result<Args, String> {
-    let path = match std::env::args().nth(1) {
-        Some(path) => path,
-        None => return Err("Args could not be parsed".to_string()),
-    };
+use std::fs;
 
-    Ok(Args {
-        path: std::path::PathBuf::from(path),
-    })
+pub fn parse_arguments() -> ArgMatches<'static> {
+    App::new(env!("CARGO_PKG_NAME"))
+        .version(env!("CARGO_PKG_VERSION"))
+        .author(env!("CARGO_PKG_AUTHORS"))
+        .about(env!("CARGO_PKG_DESCRIPTION"))
+        .after_help(&*format!(
+            "For more information, please visit {}",
+            env!("CARGO_PKG_HOMEPAGE")
+        ))
+        .arg(
+            Arg::with_name("PATH")
+                .help("The path to a `.force` file to run.")
+                .required(true)
+                .index(1),
+        )
+        .get_matches()
 }
 
-pub fn read_source(args: Args) -> Result<String, String> {
-    match fs::read_to_string(args.path) {
+pub fn read_source(args: ArgMatches) -> Result<String, String> {
+    match fs::read_to_string(args.value_of("PATH").unwrap()) {
         Ok(content) => Ok(content),
         Err(_) => Err("File could not be read".to_string()),
     }

src/main.rs

@@ -9,9 +9,9 @@ mod parser;
 mod compiler;
 
 fn main() -> Result<(), String> {
-    let config = cli::parse_arguments()?;
+    let args = cli::parse_arguments();
 
-    let source = cli::read_source(config)?;
+    let source = cli::read_source(args)?;
 
     let ast = parser::parse(source.as_str());
     interpreter::evaluate(ast.unwrap(), io::stdin().lock(), io::stdout())