Fish-like completions for nested directories (#10543)

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# Description
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This PR allows tab completion for nested directories while only
specifying a part of the directory names. To illustrate this, if I type
`tar/de/inc` and hit tab, it autocompletes to
`./target/debug/incremental`.



# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->
Nested paths can be tab completed by typing lesser characters.

# Tests + Formatting
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Tests cases are added.

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Cargo.lock

@@ -2741,6 +2741,7 @@ dependencies = [
  "nu-test-support",
  "nu-utils",
  "once_cell",
+ "pathdiff",
  "percent-encoding",
  "reedline",
  "rstest",

crates/nu-cli/Cargo.toml

@@ -36,6 +36,7 @@ log = "0.4"
 miette = { version = "5.10", features = ["fancy-no-backtrace"] }
 once_cell = "1.18"
 percent-encoding = "2"
+pathdiff = "0.2"
 sysinfo = "0.29"
 unicode-segmentation = "1.10"
 uuid = { version = "1.4.1", features = ["v4"] }

crates/nu-cli/src/completions/completion_common.rs

@@ -0,0 +1,136 @@
+use crate::completions::{matches, CompletionOptions};
+use nu_path::home_dir;
+use std::path::{is_separator, Component, Path, PathBuf, MAIN_SEPARATOR as SEP};
+
+fn complete_rec(
+    partial: &[String],
+    cwd: &Path,
+    options: &CompletionOptions,
+    dir: bool,
+    isdir: bool,
+) -> Vec<PathBuf> {
+    let mut completions = vec![];
+
+    if let Ok(result) = cwd.read_dir() {
+        for entry in result.filter_map(|e| e.ok()) {
+            let entry_name = entry.file_name().to_string_lossy().into_owned();
+            let path = entry.path();
+
+            if !dir || path.is_dir() {
+                match partial.first() {
+                    Some(base) if matches(base, &entry_name, options) => {
+                        let partial = &partial[1..];
+                        if !partial.is_empty() || isdir {
+                            completions.extend(complete_rec(partial, &path, options, dir, isdir))
+                        } else {
+                            completions.push(path)
+                        }
+                    }
+                    None => completions.push(path),
+                    _ => {}
+                }
+            }
+        }
+    }
+    completions
+}
+
+enum OriginalCwd {
+    None,
+    Home(PathBuf),
+    Some(PathBuf),
+}
+
+impl OriginalCwd {
+    fn apply(&self, p: &Path) -> String {
+        let mut ret = match self {
+            Self::None => p.to_string_lossy().into_owned(),
+            Self::Some(base) => pathdiff::diff_paths(p, base)
+                .unwrap_or(p.to_path_buf())
+                .to_string_lossy()
+                .into_owned(),
+            Self::Home(home) => match p.strip_prefix(home) {
+                Ok(suffix) => format!("~{}{}", SEP, suffix.to_string_lossy()),
+                _ => p.to_string_lossy().into_owned(),
+            },
+        };
+
+        if p.is_dir() {
+            ret.push(SEP);
+        }
+        ret
+    }
+}
+
+pub fn complete_item(
+    want_directory: bool,
+    span: nu_protocol::Span,
+    partial: &str,
+    cwd: &str,
+    options: &CompletionOptions,
+) -> Vec<(nu_protocol::Span, String)> {
+    let isdir = partial.ends_with(is_separator);
+    let cwd_pathbuf = Path::new(cwd).to_path_buf();
+    let mut original_cwd = OriginalCwd::None;
+    let mut components = Path::new(partial).components().peekable();
+    let mut cwd = match components.peek().cloned() {
+        Some(c @ Component::Prefix(..)) => {
+            // windows only by definition
+            components.next();
+            if let Some(Component::RootDir) = components.peek().cloned() {
+                components.next();
+            };
+            [c, Component::RootDir].iter().collect()
+        }
+        Some(c @ Component::RootDir) => {
+            components.next();
+            PathBuf::from(c.as_os_str())
+        }
+        Some(Component::Normal(home)) if home.to_string_lossy() == "~" => {
+            components.next();
+            original_cwd = OriginalCwd::Home(home_dir().unwrap_or(cwd_pathbuf.clone()));
+            home_dir().unwrap_or(cwd_pathbuf)
+        }
+        _ => {
+            original_cwd = OriginalCwd::Some(cwd_pathbuf.clone());
+            cwd_pathbuf
+        }
+    };
+
+    let mut partial = vec![];
+
+    for component in components {
+        match component {
+            Component::Prefix(..) => unreachable!(),
+            Component::RootDir => unreachable!(),
+            Component::CurDir => {}
+            Component::ParentDir => {
+                if partial.pop().is_none() {
+                    cwd.pop();
+                }
+            }
+            Component::Normal(c) => {
+                partial.push(c.to_string_lossy().into_owned());
+            }
+        }
+    }
+
+    complete_rec(partial.as_slice(), &cwd, options, want_directory, isdir)
+        .into_iter()
+        .map(|p| (span, escape_path(original_cwd.apply(&p), want_directory)))
+        .collect()
+}
+
+// Fix files or folders with quotes or hashes
+pub fn escape_path(path: String, dir: bool) -> String {
+    let filename_contaminated = !dir
+        && path.contains([
+            '\'', '"', ' ', '#', '(', ')', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+        ]);
+    let dirname_contaminated = dir && path.contains(['\'', '"', ' ', '#']);
+    if filename_contaminated || dirname_contaminated {
+        format!("`{path}`")
+    } else {
+        path
+    }
+}

crates/nu-cli/src/completions/directory_completions.rs

@@ -1,14 +1,13 @@
-use crate::completions::{matches, Completer, CompletionOptions};
+use crate::completions::{completion_common::complete_item, Completer, CompletionOptions};
 use nu_protocol::{
     engine::{EngineState, StateWorkingSet},
     levenshtein_distance, Span,
 };
 use reedline::Suggestion;
-use std::fs;
 use std::path::Path;
 use std::sync::Arc;
 
-use super::{partial_from, prepend_base_dir, SortBy};
+use super::SortBy;
 
 const SEP: char = std::path::MAIN_SEPARATOR;
 
@@ -33,11 +32,15 @@ impl Completer for DirectoryCompletion {
         _: usize,
         options: &CompletionOptions,
     ) -> Vec<Suggestion> {
-        let cwd = self.engine_state.current_work_dir();
         let partial = String::from_utf8_lossy(&prefix).to_string();
 
         // Filter only the folders
-        let output: Vec<_> = directory_completion(span, &partial, &cwd, options)
+        let output: Vec<_> = directory_completion(
+            span,
+            &partial,
+            &self.engine_state.current_work_dir(),
+            options,
+        )
         .into_iter()
         .map(move |x| Suggestion {
             value: x.1,
@@ -111,60 +114,5 @@ pub fn directory_completion(
     cwd: &str,
     options: &CompletionOptions,
 ) -> Vec<(nu_protocol::Span, String)> {
-    let original_input = partial;
-
-    let (base_dir_name, partial) = partial_from(partial);
-
-    let base_dir = nu_path::expand_path_with(&base_dir_name, cwd);
-
-    // This check is here as base_dir.read_dir() with base_dir == "" will open the current dir
-    // which we don't want in this case (if we did, base_dir would already be ".")
-    if base_dir == Path::new("") {
-        return Vec::new();
-    }
-
-    if let Ok(result) = base_dir.read_dir() {
-        return result
-            .filter_map(|entry| {
-                entry.ok().and_then(|entry| {
-                    if let Ok(metadata) = fs::metadata(entry.path()) {
-                        if metadata.is_dir() {
-                            let mut file_name = entry.file_name().to_string_lossy().into_owned();
-                            if matches(&partial, &file_name, options) {
-                                let mut path = if prepend_base_dir(original_input, &base_dir_name) {
-                                    format!("{base_dir_name}{file_name}")
-                                } else {
-                                    file_name.to_string()
-                                };
-
-                                if entry.path().is_dir() {
-                                    path.push(SEP);
-                                    file_name.push(SEP);
-                                }
-
-                                // Fix files or folders with quotes or hash
-                                if path.contains('\'')
-                                    || path.contains('"')
-                                    || path.contains(' ')
-                                    || path.contains('#')
-                                {
-                                    path = format!("`{path}`");
-                                }
-
-                                Some((span, path))
-                            } else {
-                                None
-                            }
-                        } else {
-                            None
-                        }
-                    } else {
-                        None
-                    }
-                })
-            })
-            .collect();
-    }
-
-    Vec::new()
+    complete_item(true, span, partial, cwd, options)
 }

crates/nu-cli/src/completions/file_completions.rs

@@ -1,4 +1,4 @@
-use crate::completions::{Completer, CompletionOptions};
+use crate::completions::{completion_common::complete_item, Completer, CompletionOptions};
 use nu_protocol::{
     engine::{EngineState, StateWorkingSet},
     levenshtein_distance, Span,
@@ -32,9 +32,13 @@ impl Completer for FileCompletion {
         _: usize,
         options: &CompletionOptions,
     ) -> Vec<Suggestion> {
-        let cwd = self.engine_state.current_work_dir();
         let prefix = String::from_utf8_lossy(&prefix).to_string();
-        let output: Vec<_> = file_path_completion(span, &prefix, &cwd, options)
+        let output: Vec<_> = file_path_completion(
+            span,
+            &prefix,
+            &self.engine_state.current_work_dir(),
+            options,
+        )
         .into_iter()
         .map(move |x| Suggestion {
             value: x.1,
@@ -122,64 +126,7 @@ pub fn file_path_completion(
     cwd: &str,
     options: &CompletionOptions,
 ) -> Vec<(nu_protocol::Span, String)> {
-    let original_input = partial;
-    let (base_dir_name, partial) = partial_from(partial);
-
-    let base_dir = nu_path::expand_path_with(&base_dir_name, cwd);
-    // This check is here as base_dir.read_dir() with base_dir == "" will open the current dir
-    // which we don't want in this case (if we did, base_dir would already be ".")
-    if base_dir == Path::new("") {
-        return Vec::new();
-    }
-
-    if let Ok(result) = base_dir.read_dir() {
-        return result
-            .filter_map(|entry| {
-                entry.ok().and_then(|entry| {
-                    let mut file_name = entry.file_name().to_string_lossy().into_owned();
-                    if matches(&partial, &file_name, options) {
-                        let mut path = if prepend_base_dir(original_input, &base_dir_name) {
-                            format!("{base_dir_name}{file_name}")
-                        } else {
-                            file_name.to_string()
-                        };
-
-                        if entry.path().is_dir() {
-                            path.push(SEP);
-                            file_name.push(SEP);
-                        }
-
-                        // Fix files or folders with quotes or hashes
-                        if path.contains('\'')
-                            || path.contains('"')
-                            || path.contains(' ')
-                            || path.contains('#')
-                            || path.contains('(')
-                            || path.contains(')')
-                            || path.starts_with('0')
-                            || path.starts_with('1')
-                            || path.starts_with('2')
-                            || path.starts_with('3')
-                            || path.starts_with('4')
-                            || path.starts_with('5')
-                            || path.starts_with('6')
-                            || path.starts_with('7')
-                            || path.starts_with('8')
-                            || path.starts_with('9')
-                        {
-                            path = format!("`{path}`");
-                        }
-
-                        Some((span, path))
-                    } else {
-                        None
-                    }
-                })
-            })
-            .collect();
-    }
-
-    Vec::new()
+    complete_item(false, span, partial, cwd, options)
 }
 
 pub fn matches(partial: &str, from: &str, options: &CompletionOptions) -> bool {
@@ -192,23 +139,3 @@ pub fn matches(partial: &str, from: &str, options: &CompletionOptions) -> bool {
 
     options.match_algorithm.matches_str(from, partial)
 }
-
-/// Returns whether the base_dir should be prepended to the file path
-pub fn prepend_base_dir(input: &str, base_dir: &str) -> bool {
-    if base_dir == format!(".{SEP}") {
-        // if the current base_dir path is the local folder we only add a "./" prefix if the user
-        // input already includes a local folder prefix.
-        let manually_entered = {
-            let mut chars = input.chars();
-            let first_char = chars.next();
-            let second_char = chars.next();
-
-            first_char == Some('.') && second_char.map(is_separator).unwrap_or(false)
-        };
-
-        manually_entered
-    } else {
-        // always prepend the base dir if it is a subfolder
-        true
-    }
-}

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

@@ -1,6 +1,7 @@
 mod base;
 mod command_completions;
 mod completer;
+mod completion_common;
 mod completion_options;
 mod custom_completions;
 mod directory_completions;
@@ -16,8 +17,6 @@ pub use completion_options::{CompletionOptions, MatchAlgorithm, SortBy};
 pub use custom_completions::CustomCompletion;
 pub use directory_completions::DirectoryCompletion;
 pub use dotnu_completions::DotNuCompletion;
-pub use file_completions::{
-    file_path_completion, matches, partial_from, prepend_base_dir, FileCompletion,
-};
+pub use file_completions::{file_path_completion, matches, partial_from, FileCompletion};
 pub use flag_completions::FlagCompletion;
 pub use variable_completions::VariableCompletion;

crates/nu-cli/tests/completions.rs

@@ -5,7 +5,10 @@ use nu_parser::parse;
 use nu_protocol::engine::StateWorkingSet;
 use reedline::{Completer, Suggestion};
 use rstest::{fixture, rstest};
-use support::{completions_helpers::new_quote_engine, file, folder, match_suggestions, new_engine};
+use support::{
+    completions_helpers::{new_partial_engine, new_quote_engine},
+    file, folder, match_suggestions, new_engine,
+};
 
 #[fixture]
 fn completer() -> NuCompleter {
@@ -201,6 +204,87 @@ fn file_completions() {
     match_suggestions(expected_paths, suggestions);
 }
 
+#[test]
+fn partial_completions() {
+    // Create a new engine
+    let (dir, _, engine, stack) = new_partial_engine();
+
+    // Instantiate a new completer
+    let mut completer = NuCompleter::new(std::sync::Arc::new(engine), stack);
+
+    // Test completions for a folder's name
+    let target_dir = format!("cd {}", file(dir.join("pa")));
+    let suggestions = completer.complete(&target_dir, target_dir.len());
+
+    // Create the expected values
+    let expected_paths: Vec<String> = vec![
+        folder(dir.join("partial_a")),
+        folder(dir.join("partial_b")),
+        folder(dir.join("partial_c")),
+    ];
+
+    // Match the results
+    match_suggestions(expected_paths, suggestions);
+
+    // Test completions for the files whose name begin with "h"
+    // and are present under directories whose names begin with "pa"
+    let dir_str = file(dir.join("pa").join("h"));
+    let target_dir = format!("cp {dir_str}");
+    let suggestions = completer.complete(&target_dir, target_dir.len());
+
+    // Create the expected values
+    let expected_paths: Vec<String> = vec![
+        file(dir.join("partial_a").join("hello")),
+        file(dir.join("partial_a").join("hola")),
+        file(dir.join("partial_b").join("hello_b")),
+        file(dir.join("partial_b").join("hi_b")),
+        file(dir.join("partial_c").join("hello_c")),
+    ];
+
+    // Match the results
+    match_suggestions(expected_paths, suggestions);
+
+    // Test completion for all files under directories whose names begin with "pa"
+    let dir_str = folder(dir.join("pa"));
+    let target_dir = format!("ls {dir_str}");
+    let suggestions = completer.complete(&target_dir, target_dir.len());
+
+    // Create the expected values
+    let expected_paths: Vec<String> = vec![
+        file(dir.join("partial_a").join("anotherfile")),
+        file(dir.join("partial_a").join("hello")),
+        file(dir.join("partial_a").join("hola")),
+        file(dir.join("partial_b").join("hello_b")),
+        file(dir.join("partial_b").join("hi_b")),
+        file(dir.join("partial_c").join("hello_c")),
+    ];
+
+    // Match the results
+    match_suggestions(expected_paths, suggestions);
+
+    // Test completion for a single file
+    let dir_str = file(dir.join("fi").join("so"));
+    let target_dir = format!("rm {dir_str}");
+    let suggestions = completer.complete(&target_dir, target_dir.len());
+
+    // Create the expected values
+    let expected_paths: Vec<String> = vec![file(dir.join("final_partial").join("somefile"))];
+
+    // Match the results
+    match_suggestions(expected_paths, suggestions);
+
+    // Test completion where there is a sneaky `..` in the path
+    let dir_str = file(dir.join("par").join("..").join("fi").join("so"));
+    let target_dir = format!("rm {dir_str}");
+    let suggestions = completer.complete(&target_dir, target_dir.len());
+
+    // Create the expected values
+    let expected_paths: Vec<String> = vec![file(dir.join("final_partial").join("somefile"))];
+
+    // Match the results
+    match_suggestions(expected_paths, suggestions);
+}
+
 #[test]
 fn command_ls_with_filecompletion() {
     let (_, _, engine, stack) = new_engine();

crates/nu-cli/tests/support/completions_helpers.rs

@@ -109,6 +109,42 @@ pub fn new_quote_engine() -> (PathBuf, String, EngineState, Stack) {
     (dir, dir_str, engine_state, stack)
 }
 
+pub fn new_partial_engine() -> (PathBuf, String, EngineState, Stack) {
+    // Target folder inside assets
+    let dir = fs::fixtures().join("partial_completions");
+    let mut dir_str = dir
+        .clone()
+        .into_os_string()
+        .into_string()
+        .unwrap_or_default();
+    dir_str.push(SEP);
+
+    // Create a new engine with default context
+    let mut engine_state = create_default_context();
+
+    // New stack
+    let mut stack = Stack::new();
+
+    // Add pwd as env var
+    stack.add_env_var(
+        "PWD".to_string(),
+        Value::string(dir_str.clone(), nu_protocol::Span::new(0, dir_str.len())),
+    );
+    stack.add_env_var(
+        "TEST".to_string(),
+        Value::string(
+            "NUSHELL".to_string(),
+            nu_protocol::Span::new(0, dir_str.len()),
+        ),
+    );
+
+    // Merge environment into the permanent state
+    let merge_result = engine_state.merge_env(&mut stack, &dir);
+    assert!(merge_result.is_ok());
+
+    (dir, dir_str, engine_state, stack)
+}
+
 // match a list of suggestions with the expected values
 pub fn match_suggestions(expected: Vec<String>, suggestions: Vec<Suggestion>) {
     let expected_len = expected.len();