Make `text-width` optional in editor config

When it was only used for `:reflow` it made sense to have a default
value set to `80`, but now that soft-wrapping uses this setting, keeping
a default set to `80` would make soft-wrapping behave more aggressively.

helix-term/src/commands/typed.rs

@@ -1739,20 +1739,24 @@ fn reflow(
         return Ok(());
     }
 
+    const DEFAULT_MAX_LEN: usize = 79;
+
     let scrolloff = cx.editor.config().scrolloff;
-    let cfg_text_width: usize = cx.editor.config().text_width;
+    let cfg_text_width = cx.editor.config().text_width;
     let (view, doc) = current!(cx.editor);
 
     // Find the text_width by checking the following sources in order:
     //   - The passed argument in `args`
     //   - The configured text-width for this language in languages.toml
-    //   - The configured text-width in the config.toml
+    //   - The configured text-width in config.toml
+    //   - The const default we set above
     let text_width: usize = args
         .get(0)
         .map(|num| num.parse::<usize>())
         .transpose()?
         .or_else(|| doc.language_config().and_then(|config| config.text_width))
-        .unwrap_or(cfg_text_width);
+        .or(cfg_text_width)
+        .unwrap_or(DEFAULT_MAX_LEN);
 
     let rope = doc.text();
 

helix-view/src/document.rs

@@ -1231,7 +1231,12 @@ impl Document {
     }
 
     pub fn text_format(&self, mut viewport_width: u16, theme: Option<&Theme>) -> TextFormat {
-        if let Some(text_width) = self.language_config().and_then(|config| config.text_width) {
+        let config = self.config.load();
+        let text_width = self
+            .language_config()
+            .and_then(|config| config.text_width)
+            .or_else(|| config.text_width);
+        if let Some(text_width) = text_width {
             // We increase max_line_len by 1 because softwrap considers the newline character
             // as part of the line length while the "typical" expectation is that this is not the case.
             // In particular other commands like :reflow do not count the line terminator.
@@ -1239,7 +1244,6 @@ impl Document {
             // but having the last visual line exceed the width by 1 seems like a rare edge case.
             viewport_width = viewport_width.min(text_width as u16 + 1)
         }
-        let config = self.config.load();
         let soft_wrap = &config.soft_wrap;
         let tab_width = self.tab_width() as u16;
         TextFormat {

helix-view/src/editor.rs

@@ -242,7 +242,7 @@ pub struct Config {
     /// Automatic save on focus lost. Defaults to false.
     pub auto_save: bool,
     /// Set a global text_width
-    pub text_width: usize,
+    pub text_width: Option<usize>,
     /// Time in milliseconds since last keypress before idle timers trigger.
     /// Used for autocompletion, set to 0 for instant. Defaults to 400ms.
     #[serde(
@@ -766,7 +766,7 @@ impl Default for Config {
             indent_guides: IndentGuidesConfig::default(),
             color_modes: false,
             soft_wrap: SoftWrap::default(),
-            text_width: 80,
+            text_width: None,
         }
     }
 }