1 files changed, 81 insertions, 0 deletions

diff --git a/crates/ra_hir/src/ty/op.rs b/crates/ra_hir/src/ty/op.rs
new file mode 100644
index 000000000..8703cf236
--- /dev/null
+++ b/crates/ra_hir/src/ty/op.rs
@@ -0,0 +1,81 @@
+use crate::expr::BinaryOp;
+use super::{Ty, InferTy};
+
+pub(super) fn binary_op_return_ty(op: BinaryOp, rhs_ty: Ty) -> Ty {
+    match op {
+        BinaryOp::BooleanOr
+        | BinaryOp::BooleanAnd
+        | BinaryOp::EqualityTest
+        | BinaryOp::NegatedEqualityTest
+        | BinaryOp::LesserEqualTest
+        | BinaryOp::GreaterEqualTest
+        | BinaryOp::LesserTest
+        | BinaryOp::GreaterTest => Ty::Bool,
+        BinaryOp::Assignment
+        | BinaryOp::AddAssign
+        | BinaryOp::SubAssign
+        | BinaryOp::DivAssign
+        | BinaryOp::MulAssign
+        | BinaryOp::RemAssign
+        | BinaryOp::ShrAssign
+        | BinaryOp::ShlAssign
+        | BinaryOp::BitAndAssign
+        | BinaryOp::BitOrAssign
+        | BinaryOp::BitXorAssign => Ty::unit(),
+        BinaryOp::Addition
+        | BinaryOp::Subtraction
+        | BinaryOp::Multiplication
+        | BinaryOp::Division
+        | BinaryOp::Remainder
+        | BinaryOp::LeftShift
+        | BinaryOp::RightShift
+        | BinaryOp::BitwiseAnd
+        | BinaryOp::BitwiseOr
+        | BinaryOp::BitwiseXor => match rhs_ty {
+            Ty::Int(..)
+            | Ty::Float(..)
+            | Ty::Infer(InferTy::IntVar(..))
+            | Ty::Infer(InferTy::FloatVar(..)) => rhs_ty,
+            _ => Ty::Unknown,
+        },
+        BinaryOp::RangeRightOpen | BinaryOp::RangeRightClosed => Ty::Unknown,
+    }
+}
+
+pub(super) fn binary_op_rhs_expectation(op: BinaryOp, lhs_ty: Ty) -> Ty {
+    match op {
+        BinaryOp::BooleanAnd | BinaryOp::BooleanOr => Ty::Bool,
+        BinaryOp::Assignment | BinaryOp::EqualityTest => match lhs_ty {
+            Ty::Int(..) | Ty::Float(..) | Ty::Str | Ty::Char | Ty::Bool => lhs_ty,
+            _ => Ty::Unknown,
+        },
+        BinaryOp::LesserEqualTest
+        | BinaryOp::GreaterEqualTest
+        | BinaryOp::LesserTest
+        | BinaryOp::GreaterTest
+        | BinaryOp::AddAssign
+        | BinaryOp::SubAssign
+        | BinaryOp::DivAssign
+        | BinaryOp::MulAssign
+        | BinaryOp::RemAssign
+        | BinaryOp::ShrAssign
+        | BinaryOp::ShlAssign
+        | BinaryOp::BitAndAssign
+        | BinaryOp::BitOrAssign
+        | BinaryOp::BitXorAssign
+        | BinaryOp::Addition
+        | BinaryOp::Subtraction
+        | BinaryOp::Multiplication
+        | BinaryOp::Division
+        | BinaryOp::Remainder
+        | BinaryOp::LeftShift
+        | BinaryOp::RightShift
+        | BinaryOp::BitwiseAnd
+        | BinaryOp::BitwiseOr
+        | BinaryOp::BitwiseXor => match lhs_ty {
+            Ty::Int(..) | Ty::Float(..) => lhs_ty,
+            _ => Ty::Unknown,
+        },
+        _ => Ty::Unknown,
+    }
+}