Introduce completion abstractions to nushell. (#2198)

* Introduce completion abstractions to nushell.

Currently, we rely on rustyline's completion structures. By abstracting this
away, we are more flexible to introduce someone elses completion engine, or our
own.

* Update value_shell.rs

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

crates/nu-cli/src/completion.rs

@@ -0,0 +1,26 @@
+use nu_errors::ShellError;
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct Suggestion {
+    pub display: String,
+    pub replacement: String,
+}
+
+pub struct Context<'a>(pub &'a rustyline::Context<'a>);
+
+impl<'a> AsRef<rustyline::Context<'a>> for Context<'a> {
+    fn as_ref(&self) -> &rustyline::Context<'a> {
+        self.0
+    }
+}
+
+pub trait Completer {
+    fn complete(
+        &self,
+        line: &str,
+        pos: usize,
+        ctx: &Context<'_>,
+    ) -> Result<(usize, Vec<Suggestion>), ShellError>;
+
+    fn hint(&self, line: &str, pos: usize, ctx: &Context<'_>) -> Option<String>;
+}

crates/nu-cli/src/lib.rs

@@ -15,6 +15,7 @@ extern crate quickcheck_macros;
 
 mod cli;
 mod commands;
+mod completion;
 mod context;
 pub mod data;
 mod deserializer;

crates/nu-cli/src/shell/filesystem_shell.rs

@@ -5,6 +5,7 @@ use crate::commands::ls::LsArgs;
 use crate::commands::mkdir::MkdirArgs;
 use crate::commands::move_::mv::Arguments as MvArgs;
 use crate::commands::rm::RemoveArgs;
+use crate::completion;
 use crate::data::dir_entry_dict;
 use crate::path::canonicalize;
 use crate::prelude::*;
@@ -737,13 +738,15 @@ impl Shell for FilesystemShell {
             )),
         }
     }
+}
 
+impl completion::Completer for FilesystemShell {
     fn complete(
         &self,
         line: &str,
         pos: usize,
-        ctx: &rustyline::Context<'_>,
-    ) -> Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError> {
+        ctx: &completion::Context<'_>,
+    ) -> Result<(usize, Vec<completion::Suggestion>), ShellError> {
         let expanded = expand_ndots(&line);
 
         // Find the first not-matching char position, if there is one
@@ -764,11 +767,26 @@ impl Shell for FilesystemShell {
             pos
         };
 
-        requote(self.completer.complete(&expanded, pos, ctx))
+        self.completer
+            .complete(&expanded, pos, ctx.as_ref())
+            .map_err(|e| ShellError::untagged_runtime_error(format!("{}", e)))
+            .map(requote)
+            .map(|(pos, completions)| {
+                (
+                    pos,
+                    completions
+                        .into_iter()
+                        .map(|pair| completion::Suggestion {
+                            display: pair.display,
+                            replacement: pair.replacement,
+                        })
+                        .collect(),
+                )
+            })
     }
 
-    fn hint(&self, line: &str, pos: usize, ctx: &rustyline::Context<'_>) -> Option<String> {
-        self.hinter.hint(line, pos, ctx)
+    fn hint(&self, line: &str, pos: usize, ctx: &completion::Context<'_>) -> Option<String> {
+        self.hinter.hint(line, pos, ctx.as_ref())
     }
 }
 
@@ -860,11 +878,9 @@ fn is_hidden_dir(dir: impl AsRef<Path>) -> bool {
 }
 
 fn requote(
-    completions: Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError>,
-) -> Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError> {
-    match completions {
-        Ok(items) => {
-            let mut new_items = Vec::with_capacity(items.0);
+    items: (usize, Vec<rustyline::completion::Pair>),
+) -> (usize, Vec<rustyline::completion::Pair>) {
+    let mut new_items = Vec::with_capacity(items.1.len());
 
     for item in items.1 {
         let unescaped = rustyline::completion::unescape(&item.replacement, Some('\\'));
@@ -880,8 +896,5 @@ fn requote(
         });
     }
 
-            Ok((items.0, new_items))
-        }
-        Err(err) => Err(err),
-    }
+    (items.0, new_items)
 }

crates/nu-cli/src/shell/help_shell.rs

@@ -5,6 +5,7 @@ use crate::commands::ls::LsArgs;
 use crate::commands::mkdir::MkdirArgs;
 use crate::commands::move_::mv::Arguments as MvArgs;
 use crate::commands::rm::RemoveArgs;
+use crate::completion;
 use crate::data::command_dict;
 use crate::prelude::*;
 use crate::shell::shell::Shell;
@@ -228,15 +229,15 @@ impl Shell for HelpShell {
             "save on help shell is not supported",
         ))
     }
+}
 
+impl completion::Completer for HelpShell {
     fn complete(
         &self,
         line: &str,
         pos: usize,
-        _ctx: &rustyline::Context<'_>,
-    ) -> Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError> {
-        let mut completions = vec![];
-
+        _ctx: &completion::Context<'_>,
+    ) -> Result<(usize, Vec<completion::Suggestion>), ShellError> {
         let mut possible_completion = vec![];
         let commands = self.commands();
         for cmd in commands {
@@ -255,6 +256,7 @@ impl Shell for HelpShell {
             replace_pos -= 1;
         }
 
+        let mut completions = vec![];
         for command in possible_completion.iter() {
             let mut pos = replace_pos;
             let mut matched = true;
@@ -272,7 +274,7 @@ impl Shell for HelpShell {
             }
 
             if matched {
-                completions.push(rustyline::completion::Pair {
+                completions.push(completion::Suggestion {
                     display: command.to_string(),
                     replacement: command.to_string(),
                 });
@@ -281,7 +283,7 @@ impl Shell for HelpShell {
         Ok((replace_pos, completions))
     }
 
-    fn hint(&self, _line: &str, _pos: usize, _ctx: &rustyline::Context<'_>) -> Option<String> {
+    fn hint(&self, _line: &str, _pos: usize, _ctx: &completion::Context<'_>) -> Option<String> {
         None
     }
 }

crates/nu-cli/src/shell/helper.rs

@@ -1,11 +1,12 @@
+use crate::completion::{self, Completer as _};
 use crate::context::Context;
 use crate::shell::palette::{DefaultPalette, Palette};
+
 use ansi_term::{Color, Style};
 use nu_parser::SignatureRegistry;
 use nu_protocol::hir::FlatShape;
 use nu_source::{Spanned, Tag, Tagged};
 use rustyline::completion::Completer;
-use rustyline::error::ReadlineError;
 use rustyline::highlight::Highlighter;
 use rustyline::hint::Hinter;
 use std::borrow::Cow::{self, Owned};
@@ -24,21 +25,37 @@ impl Helper {
     }
 }
 
+impl rustyline::completion::Candidate for completion::Suggestion {
+    fn display(&self) -> &str {
+        &self.display
+    }
+
+    fn replacement(&self) -> &str {
+        &self.replacement
+    }
+}
+
 impl Completer for Helper {
-    type Candidate = rustyline::completion::Pair;
+    type Candidate = completion::Suggestion;
+
     fn complete(
         &self,
         line: &str,
         pos: usize,
         ctx: &rustyline::Context<'_>,
-    ) -> Result<(usize, Vec<rustyline::completion::Pair>), ReadlineError> {
-        self.context.shell_manager.complete(line, pos, ctx)
+    ) -> Result<(usize, Vec<Self::Candidate>), rustyline::error::ReadlineError> {
+        let ctx = completion::Context(ctx);
+        self.context
+            .shell_manager
+            .complete(line, pos, &ctx)
+            .map_err(|_| rustyline::error::ReadlineError::Eof)
     }
 }
 
 impl Hinter for Helper {
     fn hint(&self, line: &str, pos: usize, ctx: &rustyline::Context<'_>) -> Option<String> {
-        self.context.shell_manager.hint(line, pos, ctx)
+        let ctx = completion::Context(ctx);
+        self.context.shell_manager.hint(line, pos, &ctx)
     }
 }
 

crates/nu-cli/src/shell/shell.rs

@@ -6,13 +6,15 @@ use crate::commands::ls::LsArgs;
 use crate::commands::mkdir::MkdirArgs;
 use crate::commands::move_::mv::Arguments as MvArgs;
 use crate::commands::rm::RemoveArgs;
+use crate::completion;
 use crate::prelude::*;
 use crate::stream::OutputStream;
+
 use encoding_rs::Encoding;
 use nu_errors::ShellError;
 use std::path::PathBuf;
 
-pub trait Shell: std::fmt::Debug {
+pub trait Shell: completion::Completer + std::fmt::Debug {
     fn name(&self) -> String;
     fn homedir(&self) -> Option<PathBuf>;
 
@@ -42,13 +44,4 @@ pub trait Shell: std::fmt::Debug {
         contents: &[u8],
         name: Span,
     ) -> Result<OutputStream, ShellError>;
-
-    fn complete(
-        &self,
-        line: &str,
-        pos: usize,
-        ctx: &rustyline::Context<'_>,
-    ) -> Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError>;
-
-    fn hint(&self, _line: &str, _pos: usize, _ctx: &rustyline::Context<'_>) -> Option<String>;
 }

crates/nu-cli/src/shell/shell_manager.rs

@@ -6,10 +6,12 @@ use crate::commands::ls::LsArgs;
 use crate::commands::mkdir::MkdirArgs;
 use crate::commands::move_::mv::Arguments as MvArgs;
 use crate::commands::rm::RemoveArgs;
+use crate::completion::{self, Completer};
 use crate::prelude::*;
 use crate::shell::filesystem_shell::FilesystemShell;
 use crate::shell::shell::Shell;
 use crate::stream::OutputStream;
+
 use encoding_rs::Encoding;
 use nu_errors::ShellError;
 use parking_lot::Mutex;
@@ -102,25 +104,6 @@ impl ShellManager {
         self.shells.lock()[self.current_shell()].save(full_path, save_data, name)
     }
 
-    pub fn complete(
-        &self,
-        line: &str,
-        pos: usize,
-        ctx: &rustyline::Context<'_>,
-    ) -> Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError> {
-        self.shells.lock()[self.current_shell()].complete(line, pos, ctx)
-    }
-
-    pub fn hint(
-        &self,
-        line: &str,
-        pos: usize,
-        ctx: &rustyline::Context<'_>,
-        //context: ExpandContext,
-    ) -> Option<String> {
-        self.shells.lock()[self.current_shell()].hint(line, pos, ctx)
-    }
-
     pub fn next(&mut self) {
         {
             let shell_len = self.shells.lock().len();
@@ -198,3 +181,24 @@ impl ShellManager {
         shells[self.current_shell()].mv(args, name, &path)
     }
 }
+
+impl Completer for ShellManager {
+    fn complete(
+        &self,
+        line: &str,
+        pos: usize,
+        ctx: &completion::Context<'_>,
+    ) -> Result<(usize, Vec<completion::Suggestion>), ShellError> {
+        self.shells.lock()[self.current_shell()].complete(line, pos, ctx)
+    }
+
+    fn hint(
+        &self,
+        line: &str,
+        pos: usize,
+        ctx: &completion::Context<'_>,
+        //context: ExpandContext,
+    ) -> Option<String> {
+        self.shells.lock()[self.current_shell()].hint(line, pos, ctx)
+    }
+}

crates/nu-cli/src/shell/value_shell.rs

@@ -5,6 +5,7 @@ use crate::commands::ls::LsArgs;
 use crate::commands::mkdir::MkdirArgs;
 use crate::commands::move_::mv::Arguments as MvArgs;
 use crate::commands::rm::RemoveArgs;
+use crate::completion;
 use crate::prelude::*;
 use crate::shell::shell::Shell;
 use crate::utils::ValueStructure;
@@ -253,15 +254,15 @@ impl Shell for ValueShell {
             "save on help shell is not supported",
         ))
     }
+}
 
+impl completion::Completer for ValueShell {
     fn complete(
         &self,
         line: &str,
         pos: usize,
-        _ctx: &rustyline::Context<'_>,
-    ) -> Result<(usize, Vec<rustyline::completion::Pair>), rustyline::error::ReadlineError> {
-        let mut completions = vec![];
-
+        _ctx: &completion::Context<'_>,
+    ) -> Result<(usize, Vec<completion::Suggestion>), ShellError> {
         let mut possible_completion = vec![];
         let members = self.members();
         for member in members {
@@ -280,6 +281,7 @@ impl Shell for ValueShell {
             replace_pos -= 1;
         }
 
+        let mut completions = vec![];
         for command in possible_completion.iter() {
             let mut pos = replace_pos;
             let mut matched = true;
@@ -297,7 +299,7 @@ impl Shell for ValueShell {
             }
 
             if matched {
-                completions.push(rustyline::completion::Pair {
+                completions.push(completion::Suggestion {
                     display: command.to_string(),
                     replacement: command.to_string(),
                 });
@@ -306,7 +308,7 @@ impl Shell for ValueShell {
         Ok((replace_pos, completions))
     }
 
-    fn hint(&self, _line: &str, _pos: usize, _ctx: &rustyline::Context<'_>) -> Option<String> {
+    fn hint(&self, _line: &str, _pos: usize, _context: &completion::Context<'_>) -> Option<String> {
         None
     }
 }