Refactor completion trait (#2555)

* Remove completion code from help/value shells

* Tweak the `Completer` trait for nushell.

Previously, this trait was built around rustyline's completion traits, and for
`Shell` instances. Now it is built for individual completers inside of nushell
that will complete a specific location based on a partial string. For example,
for completing a partially typed command in the command position.

crates/nu-cli/src/completion/command.rs

@@ -3,13 +3,13 @@ use std::path::Path;
 
 use indexmap::set::IndexSet;
 
-use crate::completion::{Context, Suggestion};
+use crate::completion::{Completer, Context, Suggestion};
 use crate::context;
 
-pub struct Completer;
+pub struct CommandCompleter;
 
-impl Completer {
+impl Completer for CommandCompleter {
-    pub fn complete(&self, ctx: &Context<'_>, partial: &str) -> Vec<Suggestion> {
+    fn complete(&self, ctx: &Context<'_>, partial: &str) -> Vec<Suggestion> {
         let context: &context::Context = ctx.as_ref();
         let mut commands: IndexSet<String> = IndexSet::from_iter(context.registry.names());
 
@@ -33,8 +33,8 @@ impl Completer {
             .collect();
 
         if partial != "" {
-            let path_completer = crate::completion::path::Completer;
+            let path_completer = crate::completion::path::PathCompleter;
-            let path_results = path_completer.path_suggestions(ctx, partial);
+            let path_results = path_completer.path_suggestions(partial);
             let iter = path_results.into_iter().filter_map(|path_suggestion| {
                 let path = path_suggestion.path;
                 if path.is_dir() || is_executable(&path) {

crates/nu-cli/src/completion/flag.rs

@@ -1,13 +1,15 @@
-use crate::completion::{Context, Suggestion};
+use crate::completion::{Completer, Context, Suggestion};
 use crate::context;
 
-pub struct Completer;
+pub struct FlagCompleter {
+    pub(crate) cmd: String,
+}
 
-impl Completer {
+impl Completer for FlagCompleter {
-    pub fn complete(&self, ctx: &Context<'_>, cmd: String, partial: &str) -> Vec<Suggestion> {
+    fn complete(&self, ctx: &Context<'_>, partial: &str) -> Vec<Suggestion> {
         let context: &context::Context = ctx.as_ref();
 
-        if let Some(cmd) = context.registry.get_command(&cmd) {
+        if let Some(cmd) = context.registry.get_command(&self.cmd) {
             let sig = cmd.signature();
             let mut suggestions = Vec::new();
             for (name, (named_type, _desc)) in sig.named.iter() {

crates/nu-cli/src/completion/mod.rs

@@ -3,8 +3,6 @@ pub(crate) mod engine;
 pub(crate) mod flag;
 pub(crate) mod path;
 
-use nu_errors::ShellError;
-
 use crate::context;
 
 #[derive(Debug, Eq, PartialEq)]
@@ -28,10 +26,5 @@ impl<'a> AsRef<context::Context> for Context<'a> {
 }
 
 pub trait Completer {
-    fn complete(
+    fn complete(&self, ctx: &Context<'_>, partial: &str) -> Vec<Suggestion>;
-        &self,
-        line: &str,
-        pos: usize,
-        ctx: &Context<'_>,
-    ) -> Result<(usize, Vec<Suggestion>), ShellError>;
 }

crates/nu-cli/src/completion/path.rs

@@ -1,18 +1,18 @@
 use std::path::PathBuf;
 
-use crate::completion::{Context, Suggestion};
+use crate::completion::{Completer, Context, Suggestion};
 
 const SEP: char = std::path::MAIN_SEPARATOR;
 
-pub struct Completer;
+pub struct PathCompleter;
 
 pub struct PathSuggestion {
     pub(crate) path: PathBuf,
     pub(crate) suggestion: Suggestion,
 }
 
-impl Completer {
+impl PathCompleter {
-    pub fn path_suggestions(&self, _ctx: &Context<'_>, partial: &str) -> Vec<PathSuggestion> {
+    pub fn path_suggestions(&self, partial: &str) -> Vec<PathSuggestion> {
         let expanded = nu_parser::expand_ndots(partial);
         let expanded = expanded.as_ref();
 
@@ -71,3 +71,12 @@ impl Completer {
         }
     }
 }
+
+impl Completer for PathCompleter {
+    fn complete(&self, _ctx: &Context<'_>, partial: &str) -> Vec<Suggestion> {
+        self.path_suggestions(partial)
+            .into_iter()
+            .map(|ps| ps.suggestion)
+            .collect()
+    }
+}

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

@@ -1,5 +1,7 @@
-use crate::completion::path::PathSuggestion;
+use crate::completion::command::CommandCompleter;
-use crate::completion::{self, Suggestion};
+use crate::completion::flag::FlagCompleter;
+use crate::completion::path::{PathCompleter, PathSuggestion};
+use crate::completion::{self, Completer, Suggestion};
 use crate::context;
 
 pub(crate) struct NuCompleter {}
@@ -13,7 +15,7 @@ impl NuCompleter {
         pos: usize,
         context: &completion::Context,
     ) -> (usize, Vec<Suggestion>) {
-        use crate::completion::engine::LocationType;
+        use completion::engine::LocationType;
 
         let nu_context: &context::Context = context.as_ref();
         let lite_block = match nu_parser::lite_parse(line, 0) {
@@ -23,7 +25,7 @@ impl NuCompleter {
 
         let locations = lite_block
             .map(|block| nu_parser::classify_block(&block, &nu_context.registry))
-            .map(|block| crate::completion::engine::completion_location(line, &block.block, pos))
+            .map(|block| completion::engine::completion_location(line, &block.block, pos))
             .unwrap_or_default();
 
         if locations.is_empty() {
@@ -36,17 +38,17 @@ impl NuCompleter {
                     let partial = location.span.slice(line);
                     match location.item {
                         LocationType::Command => {
-                            let command_completer = crate::completion::command::Completer;
+                            let command_completer = CommandCompleter;
                             command_completer.complete(context, partial)
                         }
 
                         LocationType::Flag(cmd) => {
-                            let flag_completer = crate::completion::flag::Completer;
+                            let flag_completer = FlagCompleter { cmd };
-                            flag_completer.complete(context, cmd, partial)
+                            flag_completer.complete(context, partial)
                         }
 
                         LocationType::Argument(cmd, _arg_name) => {
-                            let path_completer = crate::completion::path::Completer;
+                            let path_completer = PathCompleter;
 
                             const QUOTE_CHARS: &[char] = &['\'', '"', '`'];
 
@@ -71,7 +73,7 @@ impl NuCompleter {
                                 partial
                             };
 
-                            let completed_paths = path_completer.path_suggestions(context, partial);
+                            let completed_paths = path_completer.path_suggestions(partial);
                             match cmd.as_deref().unwrap_or("") {
                                 "cd" => select_directory_suggestions(completed_paths),
                                 _ => completed_paths,

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

@@ -6,7 +6,6 @@ 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;
 
@@ -230,56 +229,3 @@ impl Shell for HelpShell {
         ))
     }
 }
-
-impl completion::Completer for HelpShell {
-    fn complete(
-        &self,
-        line: &str,
-        pos: usize,
-        _ctx: &completion::Context<'_>,
-    ) -> Result<(usize, Vec<completion::Suggestion>), ShellError> {
-        let mut possible_completion = vec![];
-        let commands = self.commands();
-        for cmd in commands {
-            let Value { value, .. } = cmd;
-            for desc in value.data_descriptors() {
-                possible_completion.push(desc);
-            }
-        }
-
-        let line_chars: Vec<_> = line.chars().collect();
-        let mut replace_pos = pos;
-        while replace_pos > 0 {
-            if line_chars[replace_pos - 1] == ' ' {
-                break;
-            }
-            replace_pos -= 1;
-        }
-
-        let mut completions = vec![];
-        for command in possible_completion.iter() {
-            let mut pos = replace_pos;
-            let mut matched = true;
-            if pos < line_chars.len() {
-                for chr in command.chars() {
-                    if line_chars[pos] != chr {
-                        matched = false;
-                        break;
-                    }
-                    pos += 1;
-                    if pos == line_chars.len() {
-                        break;
-                    }
-                }
-            }
-
-            if matched {
-                completions.push(completion::Suggestion {
-                    display: command.to_string(),
-                    replacement: command.to_string(),
-                });
-            }
-        }
-        Ok((replace_pos, completions))
-    }
-}

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

@@ -5,7 +5,6 @@ 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;
@@ -76,6 +75,8 @@ impl ValueShell {
         shell_entries
     }
 
+    // TODO make use of this in the new completion engine
+    #[allow(dead_code)]
     fn members(&self) -> VecDeque<Value> {
         self.members_under(Path::new("."))
     }
@@ -255,56 +256,3 @@ impl Shell for ValueShell {
         ))
     }
 }
-
-impl completion::Completer for ValueShell {
-    fn complete(
-        &self,
-        line: &str,
-        pos: usize,
-        _ctx: &completion::Context<'_>,
-    ) -> Result<(usize, Vec<completion::Suggestion>), ShellError> {
-        let mut possible_completion = vec![];
-        let members = self.members();
-        for member in members {
-            let Value { value, .. } = member;
-            for desc in value.data_descriptors() {
-                possible_completion.push(desc);
-            }
-        }
-
-        let line_chars: Vec<_> = line.chars().collect();
-        let mut replace_pos = pos;
-        while replace_pos > 0 {
-            if line_chars[replace_pos - 1] == ' ' {
-                break;
-            }
-            replace_pos -= 1;
-        }
-
-        let mut completions = vec![];
-        for command in possible_completion.iter() {
-            let mut pos = replace_pos;
-            let mut matched = true;
-            if pos < line_chars.len() {
-                for chr in command.chars() {
-                    if line_chars[pos] != chr {
-                        matched = false;
-                        break;
-                    }
-                    pos += 1;
-                    if pos == line_chars.len() {
-                        break;
-                    }
-                }
-            }
-
-            if matched {
-                completions.push(completion::Suggestion {
-                    display: command.to_string(),
-                    replacement: command.to_string(),
-                });
-            }
-        }
-        Ok((replace_pos, completions))
-    }
-}