7526: Rename crate assists to ide_assists.

1 files changed, 599 insertions, 0 deletions

diff --git a/crates/ide_assists/src/handlers/replace_if_let_with_match.rs b/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
new file mode 100644
index 000000000..aee880625
--- /dev/null
+++ b/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
@@ -0,0 +1,599 @@
+use std::iter;
+
+use ide_db::{ty_filter::TryEnum, RootDatabase};
+use syntax::{
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
+    AstNode,
+};
+
+use crate::{
+    utils::{does_pat_match_variant, unwrap_trivial_block},
+    AssistContext, AssistId, AssistKind, Assists,
+};
+
+// Assist: replace_if_let_with_match
+//
+// Replaces `if let` with an else branch with a `match` expression.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     $0if let Action::Move { distance } = action {
+//         foo(distance)
+//     } else {
+//         bar()
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     match action {
+//         Action::Move { distance } => foo(distance),
+//         _ => bar(),
+//     }
+// }
+// ```
+pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
+    let cond = if_expr.condition()?;
+    let pat = cond.pat()?;
+    let expr = cond.expr()?;
+    let then_block = if_expr.then_branch()?;
+    let else_block = match if_expr.else_branch()? {
+        ast::ElseBranch::Block(it) => it,
+        ast::ElseBranch::IfExpr(_) => return None,
+    };
+
+    let target = if_expr.syntax().text_range();
+    acc.add(
+        AssistId("replace_if_let_with_match", AssistKind::RefactorRewrite),
+        "Replace with match",
+        target,
+        move |edit| {
+            let match_expr = {
+                let then_arm = {
+                    let then_block = then_block.reset_indent().indent(IndentLevel(1));
+                    let then_expr = unwrap_trivial_block(then_block);
+                    make::match_arm(vec![pat.clone()], then_expr)
+                };
+                let else_arm = {
+                    let pattern = ctx
+                        .sema
+                        .type_of_pat(&pat)
+                        .and_then(|ty| TryEnum::from_ty(&ctx.sema, &ty))
+                        .map(|it| {
+                            if does_pat_match_variant(&pat, &it.sad_pattern()) {
+                                it.happy_pattern()
+                            } else {
+                                it.sad_pattern()
+                            }
+                        })
+                        .unwrap_or_else(|| make::wildcard_pat().into());
+                    let else_expr = unwrap_trivial_block(else_block);
+                    make::match_arm(vec![pattern], else_expr)
+                };
+                let match_expr =
+                    make::expr_match(expr, make::match_arm_list(vec![then_arm, else_arm]));
+                match_expr.indent(IndentLevel::from_node(if_expr.syntax()))
+            };
+
+            edit.replace_ast::<ast::Expr>(if_expr.into(), match_expr);
+        },
+    )
+}
+
+// Assist: replace_match_with_if_let
+//
+// Replaces a binary `match` with a wildcard pattern and no guards with an `if let` expression.
+//
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     $0match action {
+//         Action::Move { distance } => foo(distance),
+//         _ => bar(),
+//     }
+// }
+// ```
+// ->
+// ```
+// enum Action { Move { distance: u32 }, Stop }
+//
+// fn handle(action: Action) {
+//     if let Action::Move { distance } = action {
+//         foo(distance)
+//     } else {
+//         bar()
+//     }
+// }
+// ```
+pub(crate) fn replace_match_with_if_let(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let match_expr: ast::MatchExpr = ctx.find_node_at_offset()?;
+    let mut arms = match_expr.match_arm_list()?.arms();
+    let first_arm = arms.next()?;
+    let second_arm = arms.next()?;
+    if arms.next().is_some() || first_arm.guard().is_some() || second_arm.guard().is_some() {
+        return None;
+    }
+    let condition_expr = match_expr.expr()?;
+    let (if_let_pat, then_expr, else_expr) = if is_pat_wildcard_or_sad(&ctx.sema, &first_arm.pat()?)
+    {
+        (second_arm.pat()?, second_arm.expr()?, first_arm.expr()?)
+    } else if is_pat_wildcard_or_sad(&ctx.sema, &second_arm.pat()?) {
+        (first_arm.pat()?, first_arm.expr()?, second_arm.expr()?)
+    } else {
+        return None;
+    };
+
+    let target = match_expr.syntax().text_range();
+    acc.add(
+        AssistId("replace_match_with_if_let", AssistKind::RefactorRewrite),
+        "Replace with if let",
+        target,
+        move |edit| {
+            let condition = make::condition(condition_expr, Some(if_let_pat));
+            let then_block = match then_expr.reset_indent() {
+                ast::Expr::BlockExpr(block) => block,
+                expr => make::block_expr(iter::empty(), Some(expr)),
+            };
+            let else_expr = match else_expr {
+                ast::Expr::BlockExpr(block)
+                    if block.statements().count() == 0 && block.tail_expr().is_none() =>
+                {
+                    None
+                }
+                ast::Expr::TupleExpr(tuple) if tuple.fields().count() == 0 => None,
+                expr => Some(expr),
+            };
+            let if_let_expr = make::expr_if(
+                condition,
+                then_block,
+                else_expr.map(|else_expr| {
+                    ast::ElseBranch::Block(make::block_expr(iter::empty(), Some(else_expr)))
+                }),
+            )
+            .indent(IndentLevel::from_node(match_expr.syntax()));
+
+            edit.replace_ast::<ast::Expr>(match_expr.into(), if_let_expr);
+        },
+    )
+}
+
+fn is_pat_wildcard_or_sad(sema: &hir::Semantics<RootDatabase>, pat: &ast::Pat) -> bool {
+    sema.type_of_pat(&pat)
+        .and_then(|ty| TryEnum::from_ty(sema, &ty))
+        .map(|it| it.sad_pattern().syntax().text() == pat.syntax().text())
+        .unwrap_or_else(|| matches!(pat, ast::Pat::WildcardPat(_)))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::tests::{check_assist, check_assist_target};
+
+    #[test]
+    fn test_replace_if_let_with_match_unwraps_simple_expressions() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        if $0let VariantData::Struct(..) = *self {
+            true
+        } else {
+            false
+        }
+    }
+}           "#,
+            r#"
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        match *self {
+            VariantData::Struct(..) => true,
+            _ => false,
+        }
+    }
+}           "#,
+        )
+    }
+
+    #[test]
+    fn test_replace_if_let_with_match_doesnt_unwrap_multiline_expressions() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+fn foo() {
+    if $0let VariantData::Struct(..) = a {
+        bar(
+            123
+        )
+    } else {
+        false
+    }
+}           "#,
+            r#"
+fn foo() {
+    match a {
+        VariantData::Struct(..) => {
+            bar(
+                123
+            )
+        }
+        _ => false,
+    }
+}           "#,
+        )
+    }
+
+    #[test]
+    fn replace_if_let_with_match_target() {
+        check_assist_target(
+            replace_if_let_with_match,
+            r#"
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        if $0let VariantData::Struct(..) = *self {
+            true
+        } else {
+            false
+        }
+    }
+}           "#,
+            "if let VariantData::Struct(..) = *self {
+            true
+        } else {
+            false
+        }",
+        );
+    }
+
+    #[test]
+    fn special_case_option() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    $0if let Some(x) = x {
+        println!("{}", x)
+    } else {
+        println!("none")
+    }
+}
+           "#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    match x {
+        Some(x) => println!("{}", x),
+        None => println!("none"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn special_case_inverted_option() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    $0if let None = x {
+        println!("none")
+    } else {
+        println!("some")
+    }
+}
+           "#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    match x {
+        None => println!("none"),
+        Some(_) => println!("some"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn special_case_result() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    $0if let Ok(x) = x {
+        println!("{}", x)
+    } else {
+        println!("none")
+    }
+}
+           "#,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    match x {
+        Ok(x) => println!("{}", x),
+        Err(_) => println!("none"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn special_case_inverted_result() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    $0if let Err(x) = x {
+        println!("{}", x)
+    } else {
+        println!("ok")
+    }
+}
+           "#,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    match x {
+        Err(x) => println!("{}", x),
+        Ok(_) => println!("ok"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn nested_indent() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+fn main() {
+    if true {
+        $0if let Ok(rel_path) = path.strip_prefix(root_path) {
+            let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+            Some((*id, rel_path))
+        } else {
+            None
+        }
+    }
+}
+"#,
+            r#"
+fn main() {
+    if true {
+        match path.strip_prefix(root_path) {
+            Ok(rel_path) => {
+                let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+                Some((*id, rel_path))
+            }
+            _ => None,
+        }
+    }
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn test_replace_match_with_if_let_unwraps_simple_expressions() {
+        check_assist(
+            replace_match_with_if_let,
+            r#"
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        $0match *self {
+            VariantData::Struct(..) => true,
+            _ => false,
+        }
+    }
+}           "#,
+            r#"
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        if let VariantData::Struct(..) = *self {
+            true
+        } else {
+            false
+        }
+    }
+}           "#,
+        )
+    }
+
+    #[test]
+    fn test_replace_match_with_if_let_doesnt_unwrap_multiline_expressions() {
+        check_assist(
+            replace_match_with_if_let,
+            r#"
+fn foo() {
+    $0match a {
+        VariantData::Struct(..) => {
+            bar(
+                123
+            )
+        }
+        _ => false,
+    }
+}           "#,
+            r#"
+fn foo() {
+    if let VariantData::Struct(..) = a {
+        bar(
+            123
+        )
+    } else {
+        false
+    }
+}           "#,
+        )
+    }
+
+    #[test]
+    fn replace_match_with_if_let_target() {
+        check_assist_target(
+            replace_match_with_if_let,
+            r#"
+impl VariantData {
+    pub fn is_struct(&self) -> bool {
+        $0match *self {
+            VariantData::Struct(..) => true,
+            _ => false,
+        }
+    }
+}           "#,
+            r#"match *self {
+            VariantData::Struct(..) => true,
+            _ => false,
+        }"#,
+        );
+    }
+
+    #[test]
+    fn special_case_option_match_to_if_let() {
+        check_assist(
+            replace_match_with_if_let,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    $0match x {
+        Some(x) => println!("{}", x),
+        None => println!("none"),
+    }
+}
+           "#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    if let Some(x) = x {
+        println!("{}", x)
+    } else {
+        println!("none")
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn special_case_result_match_to_if_let() {
+        check_assist(
+            replace_match_with_if_let,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    $0match x {
+        Ok(x) => println!("{}", x),
+        Err(_) => println!("none"),
+    }
+}
+           "#,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    if let Ok(x) = x {
+        println!("{}", x)
+    } else {
+        println!("none")
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn nested_indent_match_to_if_let() {
+        check_assist(
+            replace_match_with_if_let,
+            r#"
+fn main() {
+    if true {
+        $0match path.strip_prefix(root_path) {
+            Ok(rel_path) => {
+                let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+                Some((*id, rel_path))
+            }
+            _ => None,
+        }
+    }
+}
+"#,
+            r#"
+fn main() {
+    if true {
+        if let Ok(rel_path) = path.strip_prefix(root_path) {
+            let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+            Some((*id, rel_path))
+        } else {
+            None
+        }
+    }
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_match_with_if_let_empty_wildcard_expr() {
+        check_assist(
+            replace_match_with_if_let,
+            r#"
+fn main() {
+    $0match path.strip_prefix(root_path) {
+        Ok(rel_path) => println!("{}", rel_path),
+        _ => (),
+    }
+}
+"#,
+            r#"
+fn main() {
+    if let Ok(rel_path) = path.strip_prefix(root_path) {
+        println!("{}", rel_path)
+    }
+}
+"#,
+        )
+    }
+}