Add file explorer and tree helper

ref: https://github.com/helix-editor/helix/issues/200
ref: https://github.com/helix-editor/helix/pull/2377
ref: https://github.com/helix-editor/helix/pull/5566
ref: https://github.com/helix-editor/helix/pull/5768

Co-authored-by: cossonleo <cossonleo@foxmail.com>
Co-authored-by: wongjiahau <hou32hou@gmail.com>

2 files changed, 67 insertions, 0 deletions

diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index 7af28ccc..f285aa99 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -212,6 +212,30 @@ impl Default for FilePickerConfig {
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
+pub struct ExplorerConfig {
+    pub position: ExplorerPosition,
+    /// explorer column width
+    pub column_width: usize,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub enum ExplorerPosition {
+    Left,
+    Right,
+}
+
+impl Default for ExplorerConfig {
+    fn default() -> Self {
+        Self {
+            position: ExplorerPosition::Left,
+            column_width: 36,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
 pub struct Config {
     /// Padding to keep between the edge of the screen and the cursor when scrolling. Defaults to 5.
     pub scrolloff: usize,
@@ -280,6 +304,8 @@ pub struct Config {
     pub bufferline: BufferLine,
     /// Vertical indent width guides.
     pub indent_guides: IndentGuidesConfig,
+    /// Explorer configuration.
+    pub explorer: ExplorerConfig,
     /// Whether to color modes with different colors. Defaults to `false`.
     pub color_modes: bool,
     pub soft_wrap: SoftWrap,
@@ -835,6 +861,7 @@ impl Default for Config {
             whitespace: WhitespaceConfig::default(),
             bufferline: BufferLine::default(),
             indent_guides: IndentGuidesConfig::default(),
+            explorer: ExplorerConfig::default(),
             color_modes: false,
             soft_wrap: SoftWrap {
                 enable: Some(false),
@@ -1011,6 +1038,18 @@ pub enum CloseError {
     SaveError(anyhow::Error),
 }
 
+impl From<CloseError> for anyhow::Error {
+    fn from(error: CloseError) -> Self {
+        match error {
+            CloseError::DoesNotExist => anyhow::anyhow!("Document doesn't exist"),
+            CloseError::BufferModified(error) => {
+                anyhow::anyhow!(format!("Buffer modified: '{error}'"))
+            }
+            CloseError::SaveError(error) => anyhow::anyhow!(format!("Save error: {error}")),
+        }
+    }
+}
+
 impl Editor {
     pub fn new(
         mut area: Rect,
diff --git a/helix-view/src/graphics.rs b/helix-view/src/graphics.rs
index 046db86a..fbfde635 100644
--- a/helix-view/src/graphics.rs
+++ b/helix-view/src/graphics.rs
@@ -248,6 +248,34 @@ impl Rect {
             && self.y < other.y + other.height
             && self.y + self.height > other.y
     }
+
+    /// Returns a smaller `Rect` with a margin of 5% on each side, and an additional 2 rows at the bottom
+    pub fn overlaid(self) -> Rect {
+        self.clip_bottom(2).clip_relative(90, 90)
+    }
+
+    /// Returns a smaller `Rect` with width and height clipped to the given `percent_horizontal`
+    /// and `percent_vertical`.
+    ///
+    /// Value of `percent_horizontal` and `percent_vertical` is from 0 to 100.
+    pub fn clip_relative(self, percent_horizontal: u8, percent_vertical: u8) -> Rect {
+        fn mul_and_cast(size: u16, factor: u8) -> u16 {
+            ((size as u32) * (factor as u32) / 100).try_into().unwrap()
+        }
+
+        let inner_w = mul_and_cast(self.width, percent_horizontal);
+        let inner_h = mul_and_cast(self.height, percent_vertical);
+
+        let offset_x = self.width.saturating_sub(inner_w) / 2;
+        let offset_y = self.height.saturating_sub(inner_h) / 2;
+
+        Rect {
+            x: self.x + offset_x,
+            y: self.y + offset_y,
+            width: inner_w,
+            height: inner_h,
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]