From 98e60278cd3e2dfffc4f5202de45518714d9402c Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 7 Jul 2023 18:43:53 +0100
Subject: Type check integer addition

---
 .../ast/untyped/UntypedBinaryOperationNode.java    | 11 ++++++++++
 .../ast/untyped/UntypedBinaryOperator.java         |  5 +++++
 .../ast/untyped/UntypedExpressionNode.java         |  2 +-
 .../shedlang/compiler/typechecker/TypeChecker.java | 23 ++++++++++++++++++++
 .../compiler/ast/typed/TypedNodeMatchers.java      | 12 +++++++++++
 .../org/shedlang/compiler/ast/untyped/Untyped.java | 12 +++++++++++
 .../TypeCheckerBinaryOperationTests.java           | 25 ++++++++++++++++++++++
 7 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperationNode.java
 create mode 100644 src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperator.java
 create mode 100644 src/test/java/org/shedlang/compiler/typechecker/TypeCheckerBinaryOperationTests.java

(limited to 'src')

diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperationNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperationNode.java
new file mode 100644
index 00000000..c9ac56ad
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperationNode.java
@@ -0,0 +1,11 @@
+package org.shedlang.compiler.ast.untyped;
+
+import org.shedlang.compiler.sources.Source;
+
+public record UntypedBinaryOperationNode(
+    UntypedBinaryOperator operator,
+    UntypedExpressionNode left,
+    UntypedExpressionNode right,
+    Source source
+) implements UntypedExpressionNode {
+}
diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperator.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperator.java
new file mode 100644
index 00000000..0a14b547
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedBinaryOperator.java
@@ -0,0 +1,5 @@
+package org.shedlang.compiler.ast.untyped;
+
+public enum UntypedBinaryOperator {
+    ADD
+}
diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedExpressionNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedExpressionNode.java
index 10f3f010..cabf5876 100644
--- a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedExpressionNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedExpressionNode.java
@@ -1,5 +1,5 @@
 package org.shedlang.compiler.ast.untyped;
 
 public sealed interface UntypedExpressionNode extends UntypedNode
-    permits UntypedBoolLiteralNode, UntypedCallNode, UntypedIntLiteralNode, UntypedReferenceNode, UntypedStringLiteralNode {
+    permits UntypedBinaryOperationNode, UntypedBoolLiteralNode, UntypedCallNode, UntypedIntLiteralNode, UntypedReferenceNode, UntypedStringLiteralNode {
 }
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index 9aca796e..d3d0ef81 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -146,6 +146,26 @@ public class TypeChecker {
         return context.toResult(new TypedArgsNode(typedPositionalArgs, typedNamedArgs, args.source()));
     }
 
+    private static TypeCheckerResult<TypedExpressionNode> typeCheckBinaryOperation(
+        UntypedBinaryOperationNode untyped,
+        TypeCheckerContext context
+    ) {
+        var leftResult = typeCheckExpression(untyped.left(), context);
+        var left = leftResult.value();
+        context = leftResult.context();
+
+        var rightResult = typeCheckExpression(untyped.right(), context);
+        var right = rightResult.value();
+        context = rightResult.context();
+
+        return context.toResult(new TypedBinaryOperationNode(
+            TypedBinaryOperator.INT_ADD,
+            left,
+            right,
+            untyped.source()
+        ));
+    }
+
     public static TypeCheckerResult<TypedExpressionNode> typeCheckBoolLiteral(
         UntypedBoolLiteralNode untyped,
         TypeCheckerContext context
@@ -215,6 +235,9 @@ public class TypeChecker {
         TypeCheckerContext context
     ) {
         return switch (untyped) {
+            case UntypedBinaryOperationNode untypedBinaryOperation ->
+                typeCheckBinaryOperation(untypedBinaryOperation, context);
+
             case UntypedBoolLiteralNode untypedBoolLiteral ->
                 typeCheckBoolLiteral(untypedBoolLiteral, context);
 
diff --git a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
index 4143a91a..69acee24 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
@@ -40,6 +40,18 @@ public class TypedNodeMatchers {
         return TypedFunctionDefinitionNodeMatcher.empty();
     }
 
+    public static Matcher<TypedExpressionNode> isTypedIntAddNode(
+        Matcher<TypedExpressionNode> left,
+        Matcher<TypedExpressionNode> right
+    ) {
+        return instanceOf(
+            TypedBinaryOperationNode.class,
+            has("operator", x -> x.operator(), equalTo(TypedBinaryOperator.INT_ADD)),
+            has("left", x -> x.left(), left),
+            has("right", x -> x.right(), right)
+        );
+    }
+
     public static Matcher<TypedExpressionNode> isTypedIntLiteralNode(int value) {
         return isTypedIntLiteralNode(BigInteger.valueOf(value));
     }
diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
index ed78e1d4..a5a61303 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
@@ -10,6 +10,18 @@ public class Untyped {
     private Untyped() {
     }
 
+    public static UntypedBinaryOperationNode add(
+        UntypedExpressionNode left,
+        UntypedExpressionNode right
+    ) {
+        return new UntypedBinaryOperationNode(
+            UntypedBinaryOperator.ADD,
+            left,
+            right,
+            Sources.NULL
+        );
+    }
+
     public static UntypedBoolLiteralNode boolLiteral(boolean value) {
         return new UntypedBoolLiteralNode(value, Sources.NULL);
     }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerBinaryOperationTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerBinaryOperationTests.java
new file mode 100644
index 00000000..017c2d97
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerBinaryOperationTests.java
@@ -0,0 +1,25 @@
+package org.shedlang.compiler.typechecker;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.untyped.Untyped;
+import org.shedlang.compiler.types.Types;
+
+import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.isTypedIntAddNode;
+import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.isTypedIntLiteralNode;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.equalTo;
+
+public class TypeCheckerBinaryOperationTests {
+    @Test
+    public void whenBothOperandsAreIntsAndOperatorIsAddThenIsTypedAsIntAdd() {
+        var untyped = Untyped.add(Untyped.intLiteral(42), Untyped.intLiteral(47));
+
+        var typed = TypeChecker.typeCheckExpression(untyped, TypeCheckerContext.EMPTY);
+
+        assertThat(typed.value(), isTypedIntAddNode(
+            isTypedIntLiteralNode(42),
+            isTypedIntLiteralNode(47)
+        ));
+        assertThat(typed.value().type(), equalTo(Types.INT));
+    }
+}
-- 
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