Open file from filesystem

src/document.rs

@@ -1,4 +1,5 @@
 use crate::Row;
+use std::fs;
 
 #[derive(Default)]
 pub struct Document {
@@ -6,10 +7,18 @@ pub struct Document {
 }
 
 impl Document {
-    pub fn open() -> Self {
+    pub fn open(filename: &str) -> Result<Self, std::io::Error> {
+        let contents = fs::read_to_string(filename)?;
+
         let mut rows = Vec::new();
-        rows.push(Row::from("Hello, World!"));
+
-        Self { rows }
+        for value in contents.lines() {
+            rows.push(Row::from(value));
+        }
+
+        Ok(Self {
+            rows
+        })
     }
 
     pub fn row(&self, index: usize) -> Option<&Row> {

src/editor.rs

@@ -1,6 +1,7 @@
 use crate::Document;
 use crate::Row;
 use crate::Terminal;
+use std::env;
 use termion::event::Key;
 
 const VERSION: &str = env!("CARGO_PKG_VERSION");
@@ -34,10 +35,18 @@ impl Editor {
     }
 
     pub fn default() -> Self {
+        let args: Vec<String> = env::args().collect();
+        let document = if args.len() > 1 {
+            let file_name = &args[1];
+            Document::open(&file_name).unwrap_or_default()
+        } else {
+            Document::default()
+        };
+
         Self {
             should_quit: false,
             terminal: Terminal::default().expect("Failed to initialize terminal"),
-            document: Document::open(),
+            document,
             cursor_position: Position::default(),
         }
     }