feat: add pierre-style presentation to diff view

crates/editor/src/utils.rs

@@ -0,0 +1,138 @@
+//! Shared helpers for the editor's views: gutter cells, role colors, change
+//! washes and diff row building.
+
+#[cfg(feature = "diff_view")]
+use std::ops::Range;
+
+use gpui::{App, HighlightStyle, Hsla, IntoElement, ParentElement as _, Styled as _, div};
+use gpui_native_theme::{ActiveTheme as _, ColorTokens, Ramps};
+#[cfg(feature = "diff_view")]
+use similar::{Change, ChangeTag};
+
+#[cfg(feature = "diff_view")]
+use crate::diff_view::{DiffRow, DiffRowKind};
+#[cfg(feature = "diff_view")]
+use crate::highlight::HighlightedCode;
+use crate::highlight::Role;
+
+/// Maps a highlight role to the theme's semantic palette.
+pub(crate) fn role_color(role: Role, colors: ColorTokens, ramps: Ramps) -> Hsla {
+    match role {
+        Role::Text => colors.foreground,
+        Role::Keyword => ramps.primary.base,
+        Role::String | Role::Escape => ramps.success.base,
+        Role::Comment | Role::Punctuation => colors.muted_foreground,
+        Role::Function | Role::Property => ramps.info.base,
+        Role::Type => ramps.warning.base,
+        Role::Number | Role::Constant => ramps.secondary.base,
+        Role::Operator => colors.foreground,
+        Role::Tag => ramps.destructive.base,
+    }
+}
+
+/// Builds the highlight style for one run of a code view row.
+pub(crate) fn run_style(
+    role: Role,
+    selected: bool,
+    colors: ColorTokens,
+    ramps: Ramps,
+) -> HighlightStyle {
+    HighlightStyle {
+        color: Some(role_color(role, colors, ramps)),
+        background_color: selected.then_some(colors.selection),
+        ..Default::default()
+    }
+}
+
+/// A gutter cell sized to the whole row.
+pub(crate) fn gutter_cell<E>(cx: &App, color: Hsla, content: E) -> gpui::Div
+where
+    E: IntoElement,
+{
+    let theme = cx.theme();
+
+    div()
+        .size_10()
+        .flex()
+        .items_center()
+        .justify_center()
+        .flex_none()
+        .font_family(theme.mono_font)
+        .text_size(theme.sizes.small.text_size)
+        .line_height(gpui::relative(1.0))
+        .text_color(color)
+        .child(content)
+}
+
+/// Builds a diff line row from a `similar` change.
+#[cfg(feature = "diff_view")]
+pub(crate) fn line_row(
+    change: &Change<&str>,
+    code: &HighlightedCode,
+    changed_ranges: Vec<Range<usize>>,
+) -> DiffRow {
+    let content = match change.tag() {
+        ChangeTag::Equal => change
+            .new_index()
+            .and_then(|ix| code.lines.get(ix))
+            .cloned()
+            .unwrap_or_default(),
+        ChangeTag::Delete => change
+            .old_index()
+            .and_then(|ix| code.lines.get(ix))
+            .cloned()
+            .unwrap_or_default(),
+        ChangeTag::Insert => change
+            .new_index()
+            .and_then(|ix| code.lines.get(ix))
+            .cloned()
+            .unwrap_or_default(),
+    };
+
+    let (old_number, new_number) = match change.tag() {
+        ChangeTag::Equal => (
+            change.old_index().map(|ix| ix + 1),
+            change.new_index().map(|ix| ix + 1),
+        ),
+        ChangeTag::Delete => (change.old_index().map(|ix| ix + 1), None),
+        ChangeTag::Insert => (None, change.new_index().map(|ix| ix + 1)),
+    };
+
+    DiffRow {
+        kind: match change.tag() {
+            ChangeTag::Equal => DiffRowKind::Context,
+            ChangeTag::Delete => DiffRowKind::Removed,
+            ChangeTag::Insert => DiffRowKind::Added,
+        },
+        content,
+        old_number,
+        new_number,
+        changed_ranges,
+        header: Default::default(),
+        hidden_lines: 0,
+    }
+}
+
+/// A change wash: the ramp color at the alpha rows tint with.
+pub(crate) fn wash(color: Hsla) -> Hsla {
+    Hsla {
+        a: color.a * 0.14,
+        ..color
+    }
+}
+
+/// The stronger wash under number gutters and intra-line word changes.
+pub(crate) fn wash_strong(color: Hsla) -> Hsla {
+    Hsla {
+        a: color.a * 0.34,
+        ..color
+    }
+}
+
+/// The subtle wash that sets the number gutter off from the code.
+pub(crate) fn wash_gutter(colors: &ColorTokens) -> Hsla {
+    Hsla {
+        a: colors.muted.a * 0.18,
+        ..colors.muted
+    }
+}