ide: code action to convert default to = in function syntax

crates/squawk_ide/src/code_actions/mod.rs

@@ -22,6 +22,7 @@ mod rewrite_create_table_as_as_select_into;
 mod rewrite_double_colon_to_cast;
 mod rewrite_extract_as_function_call;
 mod rewrite_from;
+mod rewrite_function_param_default_as_equals;
 mod rewrite_in_as_expression;
 mod rewrite_integer_radix;
 mod rewrite_is_normalized_as_function_call;
@@ -70,6 +71,7 @@ use rewrite_create_table_as_as_select_into::rewrite_create_table_as_as_select_in
 use rewrite_double_colon_to_cast::rewrite_double_colon_to_cast;
 use rewrite_extract_as_function_call::rewrite_extract_as_function_call;
 use rewrite_from::rewrite_from;
+use rewrite_function_param_default_as_equals::rewrite_function_param_default_as_equals;
 use rewrite_in_as_expression::rewrite_in_as_expression;
 use rewrite_integer_radix::rewrite_integer_radix;
 use rewrite_is_normalized_as_function_call::rewrite_is_normalized_as_function_call;
@@ -118,6 +120,7 @@ pub fn code_actions(db: &dyn Db, position: InFile<TextSize>) -> Option<Vec<CodeA
     rewrite_table_as_select(db, position, &mut actions);
     rewrite_select_as_table(db, position, &mut actions);
     rewrite_from(db, position, &mut actions);
+    rewrite_function_param_default_as_equals(db, position, &mut actions);
     rewrite_integer_radix(db, position, &mut actions);
     rewrite_leading_from(db, position, &mut actions);
     rewrite_values_as_select(db, position, &mut actions);

crates/squawk_ide/src/code_actions/rewrite_function_param_default_as_equals.rs

@@ -0,0 +1,88 @@
+use rowan::TextSize;
+use salsa::Database as Db;
+use squawk_linter::Edit;
+use squawk_syntax::ast::{self, AstNode};
+
+use crate::{file::InFile, offsets::token_from_offset};
+
+use super::{ActionKind, CodeAction};
+
+pub(super) fn rewrite_function_param_default_as_equals(
+    db: &dyn Db,
+    position: InFile<TextSize>,
+    actions: &mut Vec<CodeAction>,
+) -> Option<()> {
+    let token = token_from_offset(db, position)?;
+    let param_default = token.parent_ancestors().find_map(ast::ParamDefault::cast)?;
+    param_default
+        .syntax()
+        .ancestors()
+        .find_map(ast::CreateFunction::cast)?;
+    let default_token = param_default.default_token()?;
+
+    actions.push(CodeAction {
+        title: "Rewrite `DEFAULT` as `=`".to_owned(),
+        edits: vec![Edit::replace(default_token.text_range(), "=".to_owned())],
+        kind: ActionKind::RefactorRewrite,
+    });
+
+    Some(())
+}
+
+#[cfg(test)]
+mod test {
+    use insta::assert_snapshot;
+
+    use crate::code_actions::test_utils::{apply_code_action, code_action_not_applicable};
+
+    use super::rewrite_function_param_default_as_equals;
+
+    #[test]
+    fn rewrites_default_as_equals() {
+        assert_snapshot!(
+            apply_code_action(
+                rewrite_function_param_default_as_equals,
+                "create function f(a int def$0ault 1) returns int language sql as $$ select a $$;",
+            ),
+            @"create function f(a int = 1) returns int language sql as $$ select a $$;"
+        );
+    }
+
+    #[test]
+    fn applies_when_cursor_is_on_default_expression() {
+        assert_snapshot!(
+            apply_code_action(
+                rewrite_function_param_default_as_equals,
+                "create function f(a text DEFAULT lower($0'x')) returns text language sql as $$ select a $$;",
+            ),
+            @"create function f(a text = lower('x')) returns text language sql as $$ select a $$;"
+        );
+    }
+
+    #[test]
+    fn preserves_comments() {
+        assert_snapshot!(
+            apply_code_action(
+                rewrite_function_param_default_as_equals,
+                "create function f(a int DEFAULT$0 /* value */ 1) returns int language sql as $$ select a $$;",
+            ),
+            @"create function f(a int = /* value */ 1) returns int language sql as $$ select a $$;"
+        );
+    }
+
+    #[test]
+    fn not_applicable_to_equals() {
+        assert!(code_action_not_applicable(
+            rewrite_function_param_default_as_equals,
+            "create function f(a int =$0 1) returns int language sql as $$ select a $$;"
+        ));
+    }
+
+    #[test]
+    fn not_applicable_to_column_default() {
+        assert!(code_action_not_applicable(
+            rewrite_function_param_default_as_equals,
+            "create table t(a int DEF$0AULT 1);"
+        ));
+    }
+}