Allow diagnostics to generate multi-edit fixes (#3709)

crates/ruff_diagnostics/src/diagnostic.rs

@@ -6,7 +6,7 @@ use serde::{Deserialize, Serialize};
 
 use ruff_python_ast::types::Range;
 
-use crate::edit::Edit;
+use crate::Fix;
 
 #[derive(Debug, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@@ -27,31 +27,31 @@ pub struct Diagnostic {
     pub kind: DiagnosticKind,
     pub location: Location,
     pub end_location: Location,
-    pub fix: Option<Edit>,
+    pub fix: Fix,
     pub parent: Option<Location>,
 }
 
 impl Diagnostic {
-    pub fn new<K: Into<DiagnosticKind>>(kind: K, range: Range) -> Self {
+    pub fn new<T: Into<DiagnosticKind>>(kind: T, range: Range) -> Self {
         Self {
             kind: kind.into(),
             location: range.location,
             end_location: range.end_location,
-            fix: None,
+            fix: Fix::empty(),
             parent: None,
         }
     }
 
-    /// Set the [`Edit`] used to fix the diagnostic.
-    pub fn set_fix(&mut self, fix: Edit) {
-        self.fix = Some(fix);
+    /// Set the [`Fix`] used to fix the diagnostic.
+    pub fn set_fix<T: Into<Fix>>(&mut self, fix: T) {
+        self.fix = fix.into();
     }
 
-    /// Set the [`Edit`] used to fix the diagnostic, if the provided function returns `Ok`.
+    /// Set the [`Fix`] used to fix the diagnostic, if the provided function returns `Ok`.
     /// Otherwise, log the error.
-    pub fn try_set_fix(&mut self, func: impl FnOnce() -> Result<Edit>) {
+    pub fn try_set_fix<T: Into<Fix>>(&mut self, func: impl FnOnce() -> Result<T>) {
         match func() {
-            Ok(fix) => self.fix = Some(fix),
+            Ok(fix) => self.fix = fix.into(),
             Err(err) => error!("Failed to create fix: {}", err),
         }
     }

crates/ruff_diagnostics/src/edit.rs

@@ -2,6 +2,8 @@ use rustpython_parser::ast::Location;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// A text edit to be applied to a source file. Inserts, deletes, or replaces
+/// content at a given location.
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Edit {

crates/ruff_diagnostics/src/fix.rs

@@ -0,0 +1,58 @@
+use rustpython_parser::ast::Location;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use crate::edit::Edit;
+
+/// A collection of [`Edit`] elements to be applied to a source file.
+#[derive(Default, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct Fix {
+    edits: Vec<Edit>,
+}
+
+impl Fix {
+    /// Create a new [`Fix`] from a vector of [`Edit`] elements.
+    pub fn new(edits: Vec<Edit>) -> Self {
+        Self { edits }
+    }
+
+    /// Create an empty [`Fix`].
+    pub const fn empty() -> Self {
+        Self { edits: Vec::new() }
+    }
+
+    /// Return `true` if the [`Fix`] contains no [`Edit`] elements.
+    pub fn is_empty(&self) -> bool {
+        self.edits.is_empty()
+    }
+
+    /// Return the [`Location`] of the first [`Edit`] in the [`Fix`].
+    pub fn location(&self) -> Option<Location> {
+        self.edits.iter().map(|edit| edit.location).min()
+    }
+
+    /// Return the [`Location`] of the last [`Edit`] in the [`Fix`].
+    pub fn end_location(&self) -> Option<Location> {
+        self.edits.iter().map(|edit| edit.end_location).max()
+    }
+
+    /// Return a slice of the [`Edit`] elements in the [`Fix`].
+    pub fn edits(&self) -> &[Edit] {
+        &self.edits
+    }
+}
+
+impl FromIterator<Edit> for Fix {
+    fn from_iter<T: IntoIterator<Item = Edit>>(iter: T) -> Self {
+        Self {
+            edits: Vec::from_iter(iter),
+        }
+    }
+}
+
+impl From<Edit> for Fix {
+    fn from(edit: Edit) -> Self {
+        Self { edits: vec![edit] }
+    }
+}

crates/ruff_diagnostics/src/lib.rs

@@ -1,7 +1,9 @@
 pub use diagnostic::{Diagnostic, DiagnosticKind};
 pub use edit::Edit;
+pub use fix::Fix;
 pub use violation::{AlwaysAutofixableViolation, AutofixKind, Violation};
 
 mod diagnostic;
 mod edit;
+mod fix;
 mod violation;