[cli] Part 1: Bump linefeed; use linefeed::Interface; add "--no-tty" argument.

I don't really understand why we were using `linefeed::Reader`
directly, but reading is not the full set of linefeed features we want
to access.  I think the `linefeed::Interface` should be owned by the
`Repl`, not the `InputReader`, but it's a little awkward to share
access with that configuration, so I'm not going to lift the ownership
until I have a reason to.

I think the "--no-tty" argument might be useful for running inside
Emacs.  Along the way, I made read_stdin() strip the trailing newline,
which agrees with InputReader::read_line().

tools/cli/Cargo.toml

@@ -24,7 +24,7 @@ failure = "0.1.1"
 failure_derive = "0.1.1"
 getopts = "0.2"
 lazy_static = "0.2"
-linefeed = "0.4"
+linefeed = "0.5"
 log = "0.4"
 tabwriter = "1"
 tempfile = "1.1"

tools/cli/src/mentat_cli/input.rs

@@ -8,11 +8,15 @@
 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
 // specific language governing permissions and limitations under the License.
 
-use std::io::stdin;
+use std::io::{
+    stdin,
+    stdout,
+    Write,
+};
 
 use linefeed::{
     DefaultTerminal,
-    Reader,
+    Interface,
     ReadResult,
     Signal,
 };
@@ -52,7 +56,7 @@ pub enum InputResult {
 /// Reads input from `stdin`
 pub struct InputReader {
     buffer: String,
-    reader: Option<Reader<DefaultTerminal>>,
+    interface: Option<Interface<DefaultTerminal>>,
     in_process_cmd: Option<Command>,
 }
 
@@ -71,27 +75,24 @@ enum UserAction {
 
 impl InputReader {
     /// Constructs a new `InputReader` reading from `stdin`.
-    pub fn new() -> InputReader {
-        let r = match Reader::new("mentat") {
-            Ok(mut r) => {
-                // Handle SIGINT (Ctrl-C)
-                r.set_report_signal(Signal::Interrupt, true);
-                r.set_word_break_chars(" \t\n!\"#$%&'(){}*+,-./:;<=>?@[\\]^`");
-                Some(r)
-            },
-            Err(_) => None,
-        };
+    pub fn new(interface: Option<Interface<DefaultTerminal>>) -> InputReader {
+        if let Some(ref interface) = interface {
+            let mut r = interface.lock_reader();
+            // Handle SIGINT (Ctrl-C)
+            r.set_report_signal(Signal::Interrupt, true);
+            r.set_word_break_chars(" \t\n!\"#$%&'(){}*+,-./:;<=>?@[\\]^`");
+        }
 
         InputReader{
             buffer: String::new(),
-            reader: r,
+            interface,
             in_process_cmd: None,
         }
     }
 
     /// Returns whether the `InputReader` is reading from a TTY.
     pub fn is_tty(&self) -> bool {
-        self.reader.is_some()
+        self.interface.is_some()
     }
 
     /// Reads a single command, item, or statement from `stdin`.
@@ -179,7 +180,7 @@ impl InputReader {
     }
 
     fn read_line(&mut self, prompt: &str) -> UserAction {
-        match self.reader {
+        match self.interface {
             Some(ref mut r) => {
                 r.set_prompt(prompt);
                 r.read_line().ok().map_or(UserAction::Quit, |line|
@@ -191,7 +192,13 @@ impl InputReader {
                     })
 
             },
-            None => self.read_stdin()
+            None => {
+                print!("{}", prompt);
+                if stdout().flush().is_err() {
+                    return UserAction::Quit;
+                }
+                self.read_stdin()
+            },
         }
     }
 
@@ -200,13 +207,19 @@ impl InputReader {
 
         match stdin().read_line(&mut s) {
             Ok(0) | Err(_) => UserAction::Quit,
-            Ok(_) => UserAction::TextInput(s)
+            Ok(_) => {
+                if s.ends_with("\n") {
+                    let len = s.len() - 1;
+                    s.truncate(len);
+                }
+                UserAction::TextInput(s)
+            },
         }
     }
 
-    fn add_history(&mut self, line: String) {
-        if let Some(ref mut r) = self.reader {
-            r.add_history(line);
+    fn add_history(&self, line: String) {
+        if let Some(ref interface) = self.interface {
+            interface.add_history(line);
         }
     }
 }

tools/cli/src/mentat_cli/lib.rs

@@ -64,6 +64,7 @@ pub fn run() -> i32 {
     opts.optmulti("t", "transact", "Execute a transact on startup. Transacts are executed before queries.", "TRANSACT");
     opts.optmulti("i", "import", "Execute an import on startup. Imports are executed before queries.", "PATH");
     opts.optflag("v", "version", "Print version and exit");
+    opts.optflag("", "no-tty", "Don't try to use a TTY for readline-like input processing");
 
     let matches = match opts.parse(&args[1..]) {
         Ok(m) => m,
@@ -121,13 +122,15 @@ pub fn run() -> i32 {
         }
     }).collect();
 
-    let repl = repl::Repl::new();
-    if repl.is_ok() {
-        repl.unwrap().run(Some(cmds));
+    let mut repl = match repl::Repl::new(!matches.opt_present("no-tty")) {
+        Ok(repl) => repl,
+        Err(e) => {
+            println!("{}", e);
+            return 1
+        }
+    };
 
-    } else {
-        println!("{}", repl.err().unwrap());
-    }
+    repl.run(Some(cmds));
 
     0
 }

tools/cli/src/mentat_cli/repl.rs

@@ -16,6 +16,10 @@ use failure::{
     Error,
 };
 
+use linefeed::{
+    Interface,
+};
+
 use tabwriter::TabWriter;
 
 use termion::{
@@ -185,6 +189,7 @@ fn format_time(duration: Duration) {
 
 /// Executes input and maintains state of persistent items.
 pub struct Repl {
+    input_reader: InputReader,
     path: String,
     store: Store,
     timer_on: bool,
@@ -200,19 +205,26 @@ impl Repl {
     }
 
     /// Constructs a new `Repl`.
-    pub fn new() -> Result<Repl, String> {
+    pub fn new(tty: bool) -> Result<Repl, String> {
+        let interface = if tty {
+            Some(Interface::new("mentat").map_err(|_| "failed to create tty interface; try --no-tty")?)
+        } else {
+            None
+        };
+
+        let input_reader = InputReader::new(interface);
+
         let store = Store::open("").map_err(|e| e.to_string())?;
         Ok(Repl {
+            input_reader,
             path: "".to_string(),
-            store: store,
+            store,
             timer_on: false,
         })
     }
 
     /// Runs the REPL interactively.
     pub fn run(&mut self, startup_commands: Option<Vec<Command>>) {
-        let mut input = InputReader::new();
-
         if let Some(cmds) = startup_commands {
             for command in cmds.iter() {
                 println!("{}", command.output());
@@ -221,7 +233,7 @@ impl Repl {
         }
 
         loop {
-            let res = input.read_input();
+            let res = self.input_reader.read_input();
 
             match res {
                 Ok(MetaCommand(cmd)) => {
@@ -231,7 +243,7 @@ impl Repl {
                 Ok(Empty) |
                 Ok(More) => (),
                 Ok(Eof) => {
-                    if input.is_tty() {
+                    if self.input_reader.is_tty() {
                         println!();
                     }
                     break;