move assists to a separate crate

1 files changed, 145 insertions, 0 deletions

diff --git a/crates/ra_assists/src/fill_match_arms.rs b/crates/ra_assists/src/fill_match_arms.rs
new file mode 100644
index 000000000..9aa37d94c
--- /dev/null
+++ b/crates/ra_assists/src/fill_match_arms.rs
@@ -0,0 +1,145 @@
+use std::fmt::Write;
+
+use hir::{
+    AdtDef, Ty, FieldSource, source_binder,
+    db::HirDatabase,
+};
+use ra_syntax::ast::{self, AstNode};
+
+use crate::{AssistCtx, Assist};
+
+pub(crate) fn fill_match_arms(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let match_expr = ctx.node_at_offset::<ast::MatchExpr>()?;
+
+    // We already have some match arms, so we don't provide any assists.
+    match match_expr.match_arm_list() {
+        Some(arm_list) if arm_list.arms().count() > 0 => {
+            return None;
+        }
+        _ => {}
+    }
+
+    let expr = match_expr.expr()?;
+    let function =
+        source_binder::function_from_child_node(ctx.db, ctx.frange.file_id, expr.syntax())?;
+    let infer_result = function.infer(ctx.db);
+    let syntax_mapping = function.body_syntax_mapping(ctx.db);
+    let node_expr = syntax_mapping.node_expr(expr)?;
+    let match_expr_ty = infer_result[node_expr].clone();
+    let enum_def = match match_expr_ty {
+        Ty::Adt {
+            def_id: AdtDef::Enum(e),
+            ..
+        } => e,
+        _ => return None,
+    };
+    let enum_name = enum_def.name(ctx.db)?;
+    let db = ctx.db;
+
+    ctx.build("fill match arms", |edit| {
+        let mut buf = format!("match {} {{\n", expr.syntax().text().to_string());
+        let variants = enum_def.variants(db);
+        for variant in variants {
+            let name = match variant.name(db) {
+                Some(it) => it,
+                None => continue,
+            };
+            write!(&mut buf, "    {}::{}", enum_name, name.to_string()).unwrap();
+
+            let pat = variant
+                .fields(db)
+                .into_iter()
+                .map(|field| {
+                    let name = field.name(db).to_string();
+                    let (_, source) = field.source(db);
+                    match source {
+                        FieldSource::Named(_) => name,
+                        FieldSource::Pos(_) => "_".to_string(),
+                    }
+                })
+                .collect::<Vec<_>>();
+
+            match pat.first().map(|s| s.as_str()) {
+                Some("_") => write!(&mut buf, "({})", pat.join(", ")).unwrap(),
+                Some(_) => write!(&mut buf, "{{{}}}", pat.join(", ")).unwrap(),
+                None => (),
+            };
+
+            buf.push_str(" => (),\n");
+        }
+        buf.push_str("}");
+        edit.set_cursor(expr.syntax().range().start());
+        edit.replace_node_and_indent(match_expr.syntax(), buf);
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::helpers::check_assist;
+
+    use super::fill_match_arms;
+
+    #[test]
+    fn fill_match_arms_empty_body() {
+        check_assist(
+            fill_match_arms,
+            r#"
+            enum A {
+                As,
+                Bs,
+                Cs(String),
+                Ds(String, String),
+                Es{x: usize, y: usize}
+            }
+
+            fn main() {
+                let a = A::As;
+                match a<|> {}
+            }
+            "#,
+            r#"
+            enum A {
+                As,
+                Bs,
+                Cs(String),
+                Ds(String, String),
+                Es{x: usize, y: usize}
+            }
+
+            fn main() {
+                let a = A::As;
+                match <|>a {
+                    A::As => (),
+                    A::Bs => (),
+                    A::Cs(_) => (),
+                    A::Ds(_, _) => (),
+                    A::Es{x, y} => (),
+                }
+            }
+            "#,
+        );
+    }
+    #[test]
+    fn fill_match_arms_no_body() {
+        check_assist(
+            fill_match_arms,
+            r#"
+            enum E { X, Y}
+
+            fn main() {
+                match E::X<|>
+            }
+            "#,
+            r#"
+            enum E { X, Y}
+
+            fn main() {
+                match <|>E::X {
+                    E::X => (),
+                    E::Y => (),
+                }
+            }
+            "#,
+        );
+    }
+}