feat: supertab

Implement "supertab", which optionally makes the `insert_tab` command
run a different command when the cursor has non-whitespace to its left,
i.e. you are in the middle of the line's content, and not trying to
indent.

book/src/configuration.md

@@ -57,6 +57,7 @@ on unix operating systems.
 | `rulers` | List of column positions at which to display the rulers. Can be overridden by language specific `rulers` in `languages.toml` file. | `[]` |
 | `bufferline` | Renders a line at the top of the editor displaying open buffers. Can be `always`, `never` or `multiple` (only shown if more than one buffer is in use) | `never` |
 | `color-modes` | Whether to color the mode indicator with different colors depending on the mode itself | `false` |
+| `supertab` | If set to a command name, then when the cursor is in a position with non-whitespace to its left, instead of inserting a tab, it will run the given command. If there is only whitespace to the left, then it inserts a tab as normal. One can emulate a tabout behavior with this with the `move_parent_node_end` command. | `None` |
 
 ### `[editor.statusline]` Section
 

helix-term/src/commands.rs

@@ -2921,6 +2921,8 @@ fn goto_prev_diag(cx: &mut Context) {
 }
 
 pub mod insert {
+    use std::str::FromStr;
+
     use super::*;
     pub type Hook = fn(&Rope, &Selection, char) -> Option<Transaction>;
     pub type PostHook = fn(&mut Context, char);
@@ -3055,16 +3057,44 @@ pub mod insert {
     }
 
     pub fn insert_tab(cx: &mut Context) {
+        let (view, doc) = current_ref!(cx.editor);
+        let view_id = view.id;
+
+        if let Some(ref cmd) = cx.editor.config().supertab {
+            let cursors_after_whitespace = doc.selection(view_id).ranges().iter().all(|range| {
+                let cursor = range.cursor(doc.text().slice(..));
+                let current_line_num = doc.text().char_to_line(cursor);
+                let current_line_start = doc.text().line_to_char(current_line_num);
+                let left = doc.text().slice(current_line_start..cursor);
+                log::debug!("left: {:?}", left);
+                left.chars().all(|c| c.is_whitespace())
+            });
+
+            if !cursors_after_whitespace {
+                let cmd = match MappableCommand::from_str(cmd) {
+                    Err(err) => {
+                        cx.editor.set_error(err.to_string());
+                        return;
+                    }
+                    Ok(cmd) => cmd,
+                };
+
+                cmd.execute(cx);
+                return;
+            }
+        }
+
         let (view, doc) = current!(cx.editor);
+
         // TODO: round out to nearest indentation level (for example a line with 3 spaces should
         // indent by one to reach 4 spaces).
-
         let indent = Tendril::from(doc.indent_style.as_str());
         let transaction = Transaction::insert(
             doc.text(),
-            &doc.selection(view.id).clone().cursors(doc.text().slice(..)),
+            &doc.selection(view_id).clone().cursors(doc.text().slice(..)),
             indent,
         );
+
         apply_transaction(&transaction, doc, view);
     }
 

helix-term/src/ui/menu.rs

@@ -249,6 +249,17 @@ impl<T: Item + 'static> Component for Menu<T> {
             compositor.pop();
         }));
 
+        let config = cx.editor.config();
+
+        // Ignore tab key when supertab is turned on in order not to interfere
+        // with it. (Is there a better way to do this?)
+        if config.supertab.is_some()
+            && config.auto_completion
+            && (event == key!(Tab) || event == shift!(Tab))
+        {
+            return EventResult::Ignored(None);
+        }
+
         match event {
             // esc or ctrl-c aborts the completion and closes the menu
             key!(Esc) | ctrl!('c') => {

helix-term/tests/test/commands/movement.rs

@@ -250,3 +250,249 @@ async fn test_move_parent_node_start() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn test_supertab_move_parent_node_end() -> anyhow::Result<()> {
+    let tests = vec![
+        // single cursor stays single cursor, first goes to end of current
+        // node, then parent
+        (
+            helpers::platform_line(indoc! {r##"
+                fn foo() {
+                    let result = if true {
+                        "yes"
+                    } else {
+                        "no#["|]#
+                    }
+                }
+            "##}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        \"no\"#[|\n]#
+                    }
+                }
+            "}),
+        ),
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        \"no\"#[\n|]#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        \"no\"
+                    }#[|\n]#
+                }
+            "}),
+        ),
+        // appending to the end of a line should still look at the current
+        // line, not the next one
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        \"no#[\"|]#
+                    }
+                }
+            "}),
+            "a<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        \"no\"
+                    }#[\n|]#
+                }
+            "}),
+        ),
+        // before cursor is all whitespace, so insert tab
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        #[\"no\"|]#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                            #[|\"no\"]#
+                    }
+                }
+            "}),
+        ),
+        // if selection spans multiple lines, it should still only look at the
+        // line on which the head is
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        #[\"yes\"
+                    } else {
+                        \"no\"|]#
+                    }
+                }
+            "}),
+            "a<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    } else {
+                        \"no\"
+                    }#[\n|]#
+                }
+            "}),
+        ),
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        #[\"yes\"
+                    } else {
+                        \"no\"|]#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                            #[|\"yes\"
+                    } else {
+                        \"no\"]#
+                    }
+                }
+            "}),
+        ),
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    #[l|]#et result = if true {
+                        #(\"yes\"
+                    } else {
+                        \"no\"|)#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                        #[|l]#et result = if true {
+                            #(|\"yes\"
+                    } else {
+                        \"no\")#
+                    }
+                }
+            "}),
+        ),
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"#[\n|]#
+                    } else {
+                        \"no\"#(\n|)#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    }#[| ]#else {
+                        \"no\"
+                    }#(|\n)#
+                }
+            "}),
+        ),
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        #[\"yes\"|]#
+                    } else {
+                        #(\"no\"|)#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                            #[|\"yes\"]#
+                    } else {
+                            #(|\"no\")#
+                    }
+                }
+            "}),
+        ),
+        // if any cursors are not preceded by all whitespace, then do the
+        // supertab action
+        (
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        #[\"yes\"\n|]#
+                    } else {
+                        \"no#(\"\n|)#
+                    }
+                }
+            "}),
+            "i<tab>",
+            helpers::platform_line(indoc! {"\
+                fn foo() {
+                    let result = if true {
+                        \"yes\"
+                    }#[| ]#else {
+                        \"no\"
+                    }#(|\n)#
+                }
+            "}),
+        ),
+    ];
+
+    for test in tests {
+        test_with_config(
+            Args {
+                files: vec![(PathBuf::from("foo.rs"), Position::default())],
+                ..Default::default()
+            },
+            Config {
+                editor: helix_view::editor::Config {
+                    supertab: Some("move_parent_node_end".into()),
+                    ..helpers::test_editor_config()
+                },
+                ..helpers::test_config()
+            },
+            helpers::test_syntax_conf(None),
+            test,
+        )
+        .await?;
+    }
+
+    Ok(())
+}

helix-term/tests/test/helpers.rs

@@ -232,15 +232,19 @@ pub fn temp_file_with_contents<S: AsRef<str>>(
 /// Generates a config with defaults more suitable for integration tests
 pub fn test_config() -> Config {
     merge_keys(Config {
-        editor: helix_view::editor::Config {
-            lsp: LspConfig {
-                enable: false,
-                ..Default::default()
-            },
+        editor: test_editor_config(),
+        ..Default::default()
+    })
+}
+
+pub fn test_editor_config() -> helix_view::editor::Config {
+    helix_view::editor::Config {
+        lsp: LspConfig {
+            enable: false,
             ..Default::default()
         },
         ..Default::default()
-    })
+    }
 }
 
 /// Replaces all LF chars with the system's appropriate line feed

helix-view/src/editor.rs

@@ -174,6 +174,9 @@ pub struct Config {
     pub indent_guides: IndentGuidesConfig,
     /// Whether to color modes with different colors. Defaults to `false`.
     pub color_modes: bool,
+    /// An alternative command to run when tab is pressed and the cursor has
+    /// text other than whitespace to its left on the current line.
+    pub supertab: Option<String>,
 }
 
 #[derive(Debug, Default, Clone, PartialEq, Eq, Serialize, Deserialize)]
@@ -624,6 +627,7 @@ impl Default for Config {
             bufferline: BufferLine::default(),
             indent_guides: IndentGuidesConfig::default(),
             color_modes: false,
+            supertab: None,
         }
     }
 }