Add :update that will write the changes if the file has been modified. (helix-editor#4426)

* add command update that will write the changes if file hasn been modified

* add docs

* update the docs

Author: grv07

book/src/generated/typable-cmd.md

@@ -44,6 +44,7 @@
 | `:show-directory`, `:pwd` | Show the current working directory. |
 | `:encoding` | Set encoding. Based on `https://encoding.spec.whatwg.org`. |
 | `:reload` | Discard changes and reload from the source file. |
+| `:update` | Write changes only if the file has been modified. |
 | `:lsp-restart` | Restarts the Language Server that is in use by the current doc |
 | `:tree-sitter-scopes` | Display tree sitter scopes, primarily for theming and development. |
 | `:debug-start`, `:dbg` | Start a debug session from a given template with given parameters. |

helix-term/src/commands/typed.rs

@@ -1029,6 +1029,24 @@ fn reload(
     })
 }
 
+/// Update the [`Document`] if it has been modified.
+fn update(
+    cx: &mut compositor::Context,
+    args: &[Cow<str>],
+    event: PromptEvent,
+) -> anyhow::Result<()> {
+    if event != PromptEvent::Validate {
+        return Ok(());
+    }
+
+    let (_view, doc) = current!(cx.editor);
+    if doc.is_modified() {
+        write(cx, args, event)
+    } else {
+        Ok(())
+    }
+}
+
 fn lsp_restart(
     cx: &mut compositor::Context,
     _args: &[Cow<str>],
@@ -1957,6 +1975,13 @@ pub const TYPABLE_COMMAND_LIST: &[TypableCommand] = &[
             fun: reload,
             completer: None,
         },
+        TypableCommand {
+            name: "update",
+            aliases: &[],
+            doc: "Write changes only if the file has been modified.",
+            fun: update,
+            completer: None,
+        },
         TypableCommand {
             name: "lsp-restart",
             aliases: &[],