From ef9a82582732b91e6f6b65bf2d471250c205830b Mon Sep 17 00:00:00 2001
From: Andrew Gallant <andrew@astral.sh>
Date: Thu, 13 Mar 2025 11:22:28 -0400
Subject: [PATCH] ruff_db: add `context` configuration

Instead of hard-coding a specific context window,
it seemed prudent to make this configurable. That
makes it easier to test different context window
sizes as well.

I am not totally convinced that this is the right
place for this configuration. I could see the context
window size being a property of `Diagnostic` instead,
since we might want to change the context window
size based not just on some end user configuration,
but perhaps also the specific diagnostic.

But for now, I think it's fine for it to live here,
and all of the rendering logic doesn't care where
it lives. So it should be relatively easy to change
in the future.
---
 crates/ruff_db/src/diagnostic/mod.rs | 29 +++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/crates/ruff_db/src/diagnostic/mod.rs b/crates/ruff_db/src/diagnostic/mod.rs
index b0f88df90a..11b70100c1 100644
--- a/crates/ruff_db/src/diagnostic/mod.rs
+++ b/crates/ruff_db/src/diagnostic/mod.rs
@@ -516,7 +516,7 @@ impl Severity {
 }
 
 /// Configuration for rendering diagnostics.
-#[derive(Clone, Debug, Default)]
+#[derive(Clone, Debug)]
 pub struct DisplayDiagnosticConfig {
     /// The format to use for diagnostic rendering.
     ///
@@ -526,6 +526,15 @@ pub struct DisplayDiagnosticConfig {
     ///
     /// Disabled by default.
     color: bool,
+    /// The number of non-empty lines to show around each snippet.
+    ///
+    /// NOTE: It seems like making this a property of rendering *could*
+    /// be wrong. In particular, I have a suspicion that we may want
+    /// more granular control over this, perhaps based on the kind of
+    /// diagnostic or even the snippet itself. But I chose to put this
+    /// here for now as the most "sensible" place for it to live until
+    /// we had more concrete use cases. ---AG
+    context: usize,
 }
 
 impl DisplayDiagnosticConfig {
@@ -538,6 +547,24 @@ impl DisplayDiagnosticConfig {
     pub fn color(self, yes: bool) -> DisplayDiagnosticConfig {
         DisplayDiagnosticConfig { color: yes, ..self }
     }
+
+    /// Set the number of contextual lines to show around each snippet.
+    pub fn context(self, lines: usize) -> DisplayDiagnosticConfig {
+        DisplayDiagnosticConfig {
+            context: lines,
+            ..self
+        }
+    }
+}
+
+impl Default for DisplayDiagnosticConfig {
+    fn default() -> DisplayDiagnosticConfig {
+        DisplayDiagnosticConfig {
+            format: DiagnosticFormat::default(),
+            color: false,
+            context: 2,
+        }
+    }
 }
 
 /// The diagnostic output format.