Add simple stdin input command (#754)

* Add simple stdin input command

* Add binary input

* Tweak binary view

crates/nu-command/src/default_context.rs

@@ -166,6 +166,7 @@ pub fn create_default_context(cwd: impl AsRef<Path>) -> EngineState {
             AnsiGradient,
             AnsiStrip,
             Clear,
+            Input,
             Kill,
             Sleep,
         };

crates/nu-command/src/platform/input.rs

@@ -0,0 +1,119 @@
+use nu_engine::CallExt;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{
+    Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
+};
+use std::io::{Read, Write};
+
+#[derive(Clone)]
+pub struct Input;
+
+impl Command for Input {
+    fn name(&self) -> &str {
+        "input"
+    }
+
+    fn usage(&self) -> &str {
+        "Get input from the user."
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("input")
+            .optional("prompt", SyntaxShape::String, "prompt to show the user")
+            .named(
+                "bytes-until",
+                SyntaxShape::String,
+                "read bytes (not text) until a stop byte",
+                Some('u'),
+            )
+            .category(Category::Platform)
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        _input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        let prompt: Option<String> = call.opt(engine_state, stack, 0)?;
+        let bytes_until: Option<String> = call.get_flag(engine_state, stack, "bytes-until")?;
+
+        if let Some(bytes_until) = bytes_until {
+            let _ = crossterm::terminal::enable_raw_mode();
+
+            if let Some(prompt) = prompt {
+                print!("{}", prompt);
+                let _ = std::io::stdout().flush();
+            }
+            if let Some(c) = bytes_until.bytes().next() {
+                let mut buf = [0u8; 1];
+                let mut buffer = vec![];
+
+                let mut stdin = std::io::stdin();
+
+                loop {
+                    if let Err(err) = stdin.read_exact(&mut buf) {
+                        let _ = crossterm::terminal::disable_raw_mode();
+                        return Err(ShellError::IOError(err.to_string()));
+                    }
+                    buffer.push(buf[0]);
+
+                    if buf[0] == c {
+                        let _ = crossterm::terminal::disable_raw_mode();
+                        break;
+                    }
+                }
+
+                Ok(Value::Binary {
+                    val: buffer,
+                    span: call.head,
+                }
+                .into_pipeline_data())
+            } else {
+                let _ = crossterm::terminal::disable_raw_mode();
+                Err(ShellError::IOError(
+                    "input can't stop on this byte".to_string(),
+                ))
+            }
+        } else {
+            if let Some(prompt) = prompt {
+                print!("{}", prompt);
+                let _ = std::io::stdout().flush();
+            }
+
+            // Just read a normal line of text
+            let mut buf = String::new();
+            let input = std::io::stdin().read_line(&mut buf);
+
+            match input {
+                Ok(_) => Ok(Value::String {
+                    val: buf,
+                    span: call.head,
+                }
+                .into_pipeline_data()),
+                Err(err) => Err(ShellError::IOError(err.to_string())),
+            }
+        }
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Get input from the user, and assign to a variable",
+            example: "let user-input = (input)",
+            result: None,
+        }]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Input;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::test_examples;
+        test_examples(Input {})
+    }
+}

crates/nu-command/src/platform/mod.rs

@@ -1,9 +1,11 @@
 mod ansi;
 mod clear;
+mod input;
 mod kill;
 mod sleep;
 
 pub use ansi::{Ansi, AnsiGradient, AnsiStrip};
 pub use clear::Clear;
+pub use input::Input;
 pub use kill::Kill;
 pub use sleep::Sleep;

crates/nu-command/src/viewers/table.rs

@@ -78,11 +78,15 @@ impl Command for Table {
             )),
             PipelineData::Value(Value::Binary { val, .. }, ..) => Ok(PipelineData::StringStream(
                 StringStream::from_stream(
-                    vec![Ok(if val.iter().all(|x| x.is_ascii()) {
-                        format!("{}", String::from_utf8_lossy(&val))
-                    } else {
-                        format!("{}\n", nu_pretty_hex::pretty_hex(&val))
-                    })]
+                    vec![Ok(
+                        if val.iter().all(|x| {
+                            *x < 128 && (*x >= b' ' || *x == b'\t' || *x == b'\r' || *x == b'\n')
+                        }) {
+                            format!("{}", String::from_utf8_lossy(&val))
+                        } else {
+                            format!("{}\n", nu_pretty_hex::pretty_hex(&val))
+                        },
+                    )]
                     .into_iter(),
                     ctrlc,
                 ),