Rust: step0_repl and step1_read_print

1 files changed, 76 insertions, 0 deletions

diff --git a/rust/src/readline.rs b/rust/src/readline.rs
new file mode 100644
index 0000000..17d1ed9
--- /dev/null
+++ b/rust/src/readline.rs
@@ -0,0 +1,76 @@
+// Based on: https://github.com/shaleh/rust-readline (MIT)
+extern crate libc;
+
+use std::c_str;
+
+use std::io::{File, Append, Write};
+use std::io::BufferedReader;
+
+mod ext_readline {
+    extern crate libc;
+    use self::libc::c_char;
+    #[link(name = "readline")]
+    extern {
+        pub fn add_history(line: *const c_char);
+        pub fn readline(p: *const c_char) -> *const c_char;
+    }
+}
+
+pub fn add_history(line: &str) {
+    unsafe {
+        ext_readline::add_history(line.to_c_str().as_ptr());
+    }
+}
+
+pub fn readline(prompt: &str) -> Option<String> {
+    let cprmt = prompt.to_c_str();
+    unsafe {
+        let ret = ext_readline::readline(cprmt.as_ptr());
+        if ret.is_null() {  // user pressed Ctrl-D
+            None
+        }
+        else {
+            c_str::CString::new(ret, true).as_str().map(|ret| ret.to_string())
+        }
+    }
+}
+
+// --------------------------------------------
+
+static mut history_loaded : bool = false;
+static HISTORY_FILE : &'static str = "/home/joelm/.mal-history";
+
+fn load_history() {
+    unsafe {
+        if history_loaded { return; }
+        history_loaded = true;
+    }
+
+    let path = Path::new(HISTORY_FILE);
+    let mut file = BufferedReader::new(File::open(&path));
+    for line in file.lines() {
+        let rt: &[_] = &['\r', '\n'];
+        let line2 = line.unwrap();
+        let line3 = line2.as_slice().trim_right_chars(rt);
+        add_history(line3);
+    }
+}
+
+fn append_to_history(line: &str) {
+    let path = Path::new("/home/joelm/.mal-history");
+    let mut file = File::open_mode(&path, Append, Write);
+    let _ = file.write_line(line);
+}
+
+pub fn mal_readline (prompt: &str) -> Option<String> {
+    load_history();
+    let line = readline(prompt);
+    match line {
+        None => None,
+        _ => {
+            add_history(line.clone().unwrap().as_slice());
+            append_to_history(line.clone().unwrap().as_slice());
+            line
+        }
+    }
+}