feat: configure half-page viewport scroll distance

src/ruby.rs

@@ -3,7 +3,7 @@ use crate::editor::{Context, Effect, Feature};
 use crate::plugin::{DocumentEvent, PluginEvent, PluginUpdate, UpdateEffect};
 use serde::{Deserialize, Serialize};
 use std::io::{self, BufRead, BufReader, Write};
-use std::num::NonZeroU8;
+use std::num::{NonZeroU8, NonZeroUsize};
 use std::path::{Path, PathBuf};
 use std::process::{Child, Command, Stdio};
 use std::sync::mpsc::{self, Receiver, RecvTimeoutError, SyncSender};
@@ -46,6 +46,7 @@ pub struct Config {
     pub popup: PopupConfig,
     pub labels: BTreeMap<String, String>,
     pub scroll_distance: Option<usize>,
+    pub scroll_half_page_lines: Option<NonZeroUsize>,
     pub highlight_trailing_whitespace: bool,
     pub whitespace_characters: BTreeMap<char, char>,
     pub whitespace_scope: crate::editor::WhitespaceScope,
@@ -97,6 +98,7 @@ impl Default for Config {
             popup: PopupConfig::default(),
             labels: BTreeMap::new(),
             scroll_distance: Some(0),
+            scroll_half_page_lines: None,
             highlight_trailing_whitespace: false,
             whitespace_characters: BTreeMap::new(),
             whitespace_scope: crate::editor::WhitespaceScope::All,
@@ -135,6 +137,7 @@ pub fn load_config(path: &Path) -> Result<Config, String> {
                 popup,
                 labels,
                 scroll_distance,
+                scroll_half_page_lines,
                 highlight_trailing_whitespace,
                 whitespace_characters,
                 whitespace_scope,
@@ -174,6 +177,7 @@ pub fn load_config(path: &Path) -> Result<Config, String> {
             config.popup = popup;
             config.labels = labels;
             config.scroll_distance = scroll_distance;
+            config.scroll_half_page_lines = scroll_half_page_lines;
             config.highlight_trailing_whitespace = highlight_trailing_whitespace;
             config.whitespace_characters = whitespace_characters;
             config.whitespace_scope = whitespace_scope;
@@ -512,6 +516,7 @@ struct ConfigFrame {
     labels: BTreeMap<String, String>,
     #[serde(deserialize_with = "scroll_distance")]
     scroll_distance: Option<usize>,
+    scroll_half_page_lines: Option<NonZeroUsize>,
     highlight_trailing_whitespace: bool,
     #[serde(deserialize_with = "whitespace_characters")]
     whitespace_characters: BTreeMap<char, char>,
@@ -1929,6 +1934,50 @@ end
         }
     }
 
+    #[test]
+    fn config_scroll_half_page_lines_controls_counted_scrolling_and_rejects_invalid_values() {
+        let fixture = Fixture::new();
+        for (value, expected) in [
+            ("nil", 30),
+            ("1", 3),
+            ("7", 21),
+            ("18446744073709551615", isize::MAX),
+        ] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |config| config.scroll_half_page_lines = {value} }}"),
+            );
+            let mut session =
+                crate::session::EditorSession::open(None, vec![], Some(&path)).unwrap();
+            session.handle(crate::editor::Input::Char('3'));
+            session.handle(crate::editor::Input::Ctrl('d'));
+            assert_eq!(
+                session.editor().take_viewport_scroll(20),
+                expected,
+                "{value}"
+            );
+        }
+        for value in [
+            "0",
+            "-1",
+            "1.5",
+            "\"3\"",
+            "true",
+            "false",
+            "18446744073709551616",
+        ] {
+            let path = fixture.file(
+                "config.rb",
+                &format!("Vamp.configure {{ |config| config.scroll_half_page_lines = {value} }}"),
+            );
+            let error = load_config(&path).unwrap_err();
+            assert!(
+                error.contains("scroll_half_page_lines") && error.contains("must be"),
+                "{value}: {error}"
+            );
+        }
+    }
+
     #[test]
     fn config_scroll_distance_accepts_nil_and_counts_and_rejects_invalid_values() {
         let fixture = Fixture::new();