Use slices directly instead of &Vec (#10328)

Simplifies the signature, makes it more flexible.
Detected a few unnecessary allocations in the process.

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

@@ -263,7 +263,7 @@ mod command_completions_tests {
             ("	hello sud", 1),
         ];
         for (idx, ele) in commands.iter().enumerate() {
-            let index = find_non_whitespace_index(&Vec::from(ele.0.as_bytes()), 0);
+            let index = find_non_whitespace_index(ele.0.as_bytes(), 0);
             assert_eq!(index, ele.1, "Failed on index {}", idx);
         }
     }

crates/nu-cli/src/syntax_highlight.rs

@@ -144,7 +144,7 @@ impl Highlighter for NuHighlighter {
 fn split_span_by_highlight_positions(
     line: &str,
     span: Span,
-    highlight_positions: &Vec<usize>,
+    highlight_positions: &[usize],
     global_span_offset: usize,
 ) -> Vec<(Span, bool)> {
     let mut start = span.start;

crates/nu-cmd-extra/src/extra/platform/ansi/link.rs

@@ -111,7 +111,7 @@ fn operate(
 
 fn process_each_path(
     mut value: Value,
-    column_paths: &Vec<CellPath>,
+    column_paths: &[CellPath],
     text: &Option<String>,
     command_span: Span,
 ) -> Value {

crates/nu-cmd-lang/src/example_support.rs

@@ -10,7 +10,7 @@ pub fn check_example_input_and_output_types_match_command_signature(
     example: &Example,
     cwd: &std::path::Path,
     engine_state: &mut Box<EngineState>,
-    signature_input_output_types: &Vec<(Type, Type)>,
+    signature_input_output_types: &[(Type, Type)],
     signature_operates_on_cell_paths: bool,
 ) -> HashSet<(Type, Type)> {
     let mut witnessed_type_transformations = HashSet::<(Type, Type)>::new();

crates/nu-command/src/debug/inspect_table.rs

@@ -235,7 +235,7 @@ mod util {
         }
     }
 
-    fn convert_records_to_dataset(cols: &Vec<String>, records: Vec<Value>) -> Vec<Vec<String>> {
+    fn convert_records_to_dataset(cols: &[String], records: Vec<Value>) -> Vec<Vec<String>> {
         if !cols.is_empty() {
             create_table_for_record(cols, &records)
         } else if cols.is_empty() && records.is_empty() {

crates/nu-command/src/filters/find.rs

@@ -294,7 +294,7 @@ fn record_matches_regex(values: &[Value], re: &Regex, config: &Config) -> bool {
 
 #[allow(clippy::too_many_arguments)]
 fn highlight_terms_in_record_with_search_columns(
-    search_cols: &Vec<String>,
+    search_cols: &[String],
     record: &Record,
     span: Span,
     config: &Config,
@@ -507,7 +507,7 @@ fn value_should_be_printed(
     filter_config: &Config,
     lower_terms: &[Value],
     span: Span,
-    columns_to_search: &Vec<String>,
+    columns_to_search: &[String],
     invert: bool,
 ) -> bool {
     let lower_value = Value::string(value.into_string("", filter_config).to_lowercase(), span);
@@ -561,7 +561,7 @@ fn term_equals_value(term: &Value, value: &Value, span: Span) -> bool {
 
 fn record_matches_term(
     record: &Record,
-    columns_to_search: &Vec<String>,
+    columns_to_search: &[String],
     filter_config: &Config,
     term: &Value,
     span: Span,

crates/nu-command/src/filters/group_by.rs

@@ -210,7 +210,7 @@ pub fn group_no_grouper(values: Vec<Value>, span: Span) -> Result<Value, ShellEr
 
 // TODO: refactor this, it's a bit of a mess
 fn group_closure(
-    values: &Vec<Value>,
+    values: &[Value],
     span: Span,
     block: Option<Closure>,
     stack: &mut Stack,
@@ -219,7 +219,7 @@ fn group_closure(
 ) -> Result<Value, ShellError> {
     let error_key = "error";
     let mut keys: Vec<Result<String, ShellError>> = vec![];
-    let value_list = Value::list(values.clone(), span);
+    let value_list = Value::list(values.to_vec(), span);
 
     for value in values {
         if let Some(capture_block) = &block {

crates/nu-command/src/filters/join.rs

@@ -23,8 +23,6 @@ enum IncludeInner {
     Yes,
 }
 
-const EMPTY_COL_NAMES: &Vec<String> = &vec![];
-
 impl Command for Join {
     fn name(&self) -> &str {
         "join"
@@ -142,8 +140,8 @@ fn join_type(call: &Call) -> Result<JoinType, nu_protocol::ShellError> {
 }
 
 fn join(
-    left: &Vec<Value>,
-    right: &Vec<Value>,
+    left: &[Value],
+    right: &[Value],
     left_join_key: &str,
     right_join_key: &str,
     join_type: JoinType,
@@ -248,7 +246,7 @@ fn join(
 #[allow(clippy::too_many_arguments)]
 fn join_rows(
     result: &mut Vec<Value>,
-    this: &Vec<Value>,
+    this: &[Value],
     this_join_key: &str,
     other: HashMap<String, Vec<&Record>>,
     other_keys: &[String],
@@ -323,20 +321,20 @@ fn join_rows(
 
 // Return column names (i.e. ordered keys from the first row; we assume that
 // these are the same for all rows).
-fn column_names(table: &[Value]) -> &Vec<String> {
+fn column_names(table: &[Value]) -> &[String] {
     table
         .iter()
         .find_map(|val| match val {
-            Value::Record { val, .. } => Some(&val.cols),
+            Value::Record { val, .. } => Some(&*val.cols),
             _ => None,
         })
-        .unwrap_or(EMPTY_COL_NAMES)
+        .unwrap_or_default()
 }
 
 // Create a map from value in `on` column to a list of the rows having that
 // value.
 fn lookup_table<'a>(
-    rows: &'a Vec<Value>,
+    rows: &'a [Value],
     on: &str,
     sep: &str,
     cap: usize,

crates/nu-command/src/filters/uniq_by.rs

@@ -76,7 +76,7 @@ impl Command for UniqBy {
         let metadata = input.metadata();
 
         let vec: Vec<_> = input.into_iter().collect();
-        match validate(vec.clone(), &columns, call.head) {
+        match validate(&vec, &columns, call.head) {
             Ok(_) => {}
             Err(err) => {
                 return Err(err);
@@ -113,7 +113,7 @@ impl Command for UniqBy {
     }
 }
 
-fn validate(vec: Vec<Value>, columns: &Vec<String>, span: Span) -> Result<(), ShellError> {
+fn validate(vec: &[Value], columns: &[String], span: Span) -> Result<(), ShellError> {
     let first = vec.first();
     if let Some(v) = first {
         let val_span = v.span();
@@ -129,7 +129,7 @@ fn validate(vec: Vec<Value>, columns: &Vec<String>, span: Span) -> Result<(), Sh
                 ));
             }
 
-            if let Some(nonexistent) = nonexistent_column(columns.clone(), record.cols.clone()) {
+            if let Some(nonexistent) = nonexistent_column(columns, &record.cols) {
                 return Err(ShellError::CantFindColumn {
                     col_name: nonexistent,
                     span,

crates/nu-command/src/formats/to/delimited.rs

@@ -46,7 +46,7 @@ fn record_to_delimited(
 }
 
 fn table_to_delimited(
-    vals: &Vec<Value>,
+    vals: &[Value],
     span: Span,
     separator: char,
     config: &Config,

crates/nu-command/src/sort_utils.rs

@@ -77,8 +77,7 @@ pub fn sort(
                 ));
             }
 
-            if let Some(nonexistent) = nonexistent_column(sort_columns.clone(), record.cols.clone())
-            {
+            if let Some(nonexistent) = nonexistent_column(&sort_columns, &record.cols) {
                 return Err(ShellError::CantFindColumn {
                     col_name: nonexistent,
                     span,

crates/nu-engine/src/column.rs

@@ -19,10 +19,10 @@ pub fn get_columns(input: &[Value]) -> Vec<String> {
 }
 
 // If a column doesn't exist in the input, return it.
-pub fn nonexistent_column(inputs: Vec<String>, columns: Vec<String>) -> Option<String> {
+pub fn nonexistent_column(inputs: &[String], columns: &[String]) -> Option<String> {
     let set: HashSet<String> = HashSet::from_iter(columns.iter().cloned());
 
-    for input in &inputs {
+    for input in inputs {
         if set.contains(input) {
             continue;
         }

crates/nu-explore/src/nu_common/value.rs

@@ -122,7 +122,7 @@ pub fn collect_input(value: Value) -> (Vec<String>, Vec<Vec<Value>>) {
     }
 }
 
-fn convert_records_to_dataset(cols: &Vec<String>, records: Vec<Value>) -> Vec<Vec<Value>> {
+fn convert_records_to_dataset(cols: &[String], records: Vec<Value>) -> Vec<Vec<Value>> {
     if !cols.is_empty() {
         create_table_for_record(cols, &records)
     } else if cols.is_empty() && records.is_empty() {

crates/nu-json/src/value.rs

@@ -182,7 +182,7 @@ impl Value {
 
     /// If the `Value` is an Array, returns the associated vector.
     /// Returns None otherwise.
-    pub fn as_array(&self) -> Option<&Vec<Value>> {
+    pub fn as_array(&self) -> Option<&[Value]> {
         match self {
             Value::Array(array) => Some(array),
             _ => None,

crates/nu-parser/src/parse_keywords.rs

@@ -2887,7 +2887,7 @@ pub fn parse_overlay_hide(working_set: &mut StateWorkingSet, call: Box<Call>) ->
 
     if !working_set
         .unique_overlay_names()
-        .contains(&overlay_name.as_bytes().to_vec())
+        .contains(&overlay_name.as_bytes())
     {
         working_set.error(ParseError::ActiveOverlayNotFound(overlay_name_span));
         return pipeline;

crates/nu-protocol/src/engine/engine_state.rs

@@ -343,10 +343,11 @@ impl EngineState {
     where
         'b: 'a,
     {
-        self.scope
-            .active_overlays
-            .iter()
-            .filter(|id| !removed_overlays.contains(self.get_overlay_name(**id)))
+        self.scope.active_overlays.iter().filter(|id| {
+            !removed_overlays
+                .iter()
+                .any(|name| name == self.get_overlay_name(**id))
+        })
     }
 
     pub fn active_overlays<'a, 'b>(
@@ -363,7 +364,7 @@ impl EngineState {
     pub fn active_overlay_names<'a, 'b>(
         &'b self,
         removed_overlays: &'a [Vec<u8>],
-    ) -> impl DoubleEndedIterator<Item = &Vec<u8>> + 'a
+    ) -> impl DoubleEndedIterator<Item = &[u8]> + 'a
     where
         'b: 'a,
     {
@@ -389,7 +390,7 @@ impl EngineState {
             .collect()
     }
 
-    pub fn last_overlay_name(&self, removed_overlays: &[Vec<u8>]) -> &Vec<u8> {
+    pub fn last_overlay_name(&self, removed_overlays: &[Vec<u8>]) -> &[u8] {
         self.active_overlay_names(removed_overlays)
             .last()
             .expect("internal error: no active overlays")
@@ -402,7 +403,7 @@ impl EngineState {
             .expect("internal error: no active overlays")
     }
 
-    pub fn get_overlay_name(&self, overlay_id: OverlayId) -> &Vec<u8> {
+    pub fn get_overlay_name(&self, overlay_id: OverlayId) -> &[u8] {
         &self
             .scope
             .overlays
@@ -931,7 +932,7 @@ impl EngineState {
             .unwrap_or_default()
     }
 
-    pub fn get_file_contents(&self) -> &Vec<(Vec<u8>, usize, usize)> {
+    pub fn get_file_contents(&self) -> &[(Vec<u8>, usize, usize)] {
         &self.file_contents
     }
 
@@ -1081,7 +1082,7 @@ impl StateDelta {
         self.scope.pop();
     }
 
-    pub fn get_file_contents(&self) -> &Vec<(Vec<u8>, usize, usize)> {
+    pub fn get_file_contents(&self) -> &[(Vec<u8>, usize, usize)] {
         &self.file_contents
     }
 }
@@ -1127,8 +1128,8 @@ impl<'a> StateWorkingSet<'a> {
         self.delta.num_modules() + self.permanent_state.num_modules()
     }
 
-    pub fn unique_overlay_names(&self) -> HashSet<&Vec<u8>> {
-        let mut names: HashSet<&Vec<u8>> = self.permanent_state.active_overlay_names(&[]).collect();
+    pub fn unique_overlay_names(&self) -> HashSet<&[u8]> {
+        let mut names: HashSet<&[u8]> = self.permanent_state.active_overlay_names(&[]).collect();
 
         for scope_frame in self.delta.scope.iter().rev() {
             for overlay_id in scope_frame.active_overlays.iter().rev() {
@@ -1138,7 +1139,7 @@ impl<'a> StateWorkingSet<'a> {
                     .expect("internal error: missing overlay");
 
                 names.insert(overlay_name);
-                names.retain(|n| !scope_frame.removed_overlays.contains(n));
+                names.retain(|n| !scope_frame.removed_overlays.iter().any(|m| n == m));
             }
         }
 
@@ -1820,7 +1821,7 @@ impl<'a> StateWorkingSet<'a> {
             .map(|id| self.permanent_state.get_overlay(id))
     }
 
-    pub fn last_overlay_name(&self) -> &Vec<u8> {
+    pub fn last_overlay_name(&self) -> &[u8] {
         let mut removed_overlays = vec![];
 
         for scope_frame in self.delta.scope.iter().rev() {

crates/nu-protocol/src/engine/overlay.rs

@@ -108,7 +108,11 @@ impl ScopeFrame {
 
         self.active_overlays
             .iter()
-            .filter(|id| !removed_overlays.contains(self.get_overlay_name(**id)))
+            .filter(|id| {
+                !removed_overlays
+                    .iter()
+                    .any(|name| name == self.get_overlay_name(**id))
+            })
             .copied()
             .collect()
     }
@@ -125,14 +129,14 @@ impl ScopeFrame {
             .map(|id| self.get_overlay(id))
     }
 
-    pub fn active_overlay_names(&self, removed_overlays: &mut Vec<Vec<u8>>) -> Vec<&Vec<u8>> {
+    pub fn active_overlay_names(&self, removed_overlays: &mut Vec<Vec<u8>>) -> Vec<&[u8]> {
         self.active_overlay_ids(removed_overlays)
             .iter()
             .map(|id| self.get_overlay_name(*id))
             .collect()
     }
 
-    pub fn get_overlay_name(&self, overlay_id: OverlayId) -> &Vec<u8> {
+    pub fn get_overlay_name(&self, overlay_id: OverlayId) -> &[u8] {
         &self
             .overlays
             .get(overlay_id)