rename generate_enum_match_method file to match assist name

crates/ide_assists/src/handlers/generate_enum_is_method.rs

@@ -0,0 +1,250 @@
+use stdx::to_lower_snake_case;
+use syntax::ast::VisibilityOwner;
+use syntax::ast::{self, AstNode, NameOwner};
+
+use crate::{
+    utils::{add_method_to_adt, find_struct_impl},
+    AssistContext, AssistId, AssistKind, Assists,
+};
+
+// Assist: generate_enum_is_method
+//
+// Generate an `is_` method for an enum variant.
+//
+// ```
+// enum Version {
+//  Undefined,
+//  Minor$0,
+//  Major,
+// }
+// ```
+// ->
+// ```
+// enum Version {
+//  Undefined,
+//  Minor,
+//  Major,
+// }
+//
+// impl Version {
+//     /// Returns `true` if the version is [`Minor`].
+//     fn is_minor(&self) -> bool {
+//         matches!(self, Self::Minor)
+//     }
+// }
+// ```
+pub(crate) fn generate_enum_is_method(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let variant = ctx.find_node_at_offset::<ast::Variant>()?;
+    let variant_name = variant.name()?;
+    let parent_enum = ast::Adt::Enum(variant.parent_enum());
+    let pattern_suffix = match variant.kind() {
+        ast::StructKind::Record(_) => " { .. }",
+        ast::StructKind::Tuple(_) => "(..)",
+        ast::StructKind::Unit => "",
+    };
+
+    let enum_lowercase_name = to_lower_snake_case(&parent_enum.name()?.to_string());
+    let fn_name = format!("is_{}", &to_lower_snake_case(variant_name.text()));
+
+    // Return early if we've found an existing new fn
+    let impl_def = find_struct_impl(&ctx, &parent_enum, &fn_name)?;
+
+    let target = variant.syntax().text_range();
+    acc.add(
+        AssistId("generate_enum_is_method", AssistKind::Generate),
+        "Generate an `is_` method for an enum variant",
+        target,
+        |builder| {
+            let vis = parent_enum.visibility().map_or(String::new(), |v| format!("{} ", v));
+            let method = format!(
+                "    /// Returns `true` if the {} is [`{}`].
+    {}fn {}(&self) -> bool {{
+        matches!(self, Self::{}{})
+    }}",
+                enum_lowercase_name, variant_name, vis, fn_name, variant_name, pattern_suffix,
+            );
+
+            add_method_to_adt(builder, &parent_enum, impl_def, &method);
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn test_generate_enum_is_from_variant() {
+        check_assist(
+            generate_enum_is_method,
+            r#"
+enum Variant {
+    Undefined,
+    Minor$0,
+    Major,
+}"#,
+            r#"enum Variant {
+    Undefined,
+    Minor,
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor)
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_is_already_implemented() {
+        check_assist_not_applicable(
+            generate_enum_is_method,
+            r#"
+enum Variant {
+    Undefined,
+    Minor$0,
+    Major,
+}
+
+impl Variant {
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor)
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_is_from_tuple_variant() {
+        check_assist(
+            generate_enum_is_method,
+            r#"
+enum Variant {
+    Undefined,
+    Minor(u32)$0,
+    Major,
+}"#,
+            r#"enum Variant {
+    Undefined,
+    Minor(u32),
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor(..))
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_is_from_record_variant() {
+        check_assist(
+            generate_enum_is_method,
+            r#"
+enum Variant {
+    Undefined,
+    Minor { foo: i32 }$0,
+    Major,
+}"#,
+            r#"enum Variant {
+    Undefined,
+    Minor { foo: i32 },
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor { .. })
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_is_from_variant_with_one_variant() {
+        check_assist(
+            generate_enum_is_method,
+            r#"enum Variant { Undefi$0ned }"#,
+            r#"
+enum Variant { Undefined }
+
+impl Variant {
+    /// Returns `true` if the variant is [`Undefined`].
+    fn is_undefined(&self) -> bool {
+        matches!(self, Self::Undefined)
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_enum_is_from_variant_with_visibility_marker() {
+        check_assist(
+            generate_enum_is_method,
+            r#"
+pub(crate) enum Variant {
+    Undefined,
+    Minor$0,
+    Major,
+}"#,
+            r#"pub(crate) enum Variant {
+    Undefined,
+    Minor,
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    pub(crate) fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor)
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_multiple_generate_enum_is_from_variant() {
+        check_assist(
+            generate_enum_is_method,
+            r#"
+enum Variant {
+    Undefined,
+    Minor,
+    Major$0,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor)
+    }
+}"#,
+            r#"enum Variant {
+    Undefined,
+    Minor,
+    Major,
+}
+
+impl Variant {
+    /// Returns `true` if the variant is [`Minor`].
+    fn is_minor(&self) -> bool {
+        matches!(self, Self::Minor)
+    }
+
+    /// Returns `true` if the variant is [`Major`].
+    fn is_major(&self) -> bool {
+        matches!(self, Self::Major)
+    }
+}"#,
+        );
+    }
+}