From 6d9a2f0b07204debf78f70e3d1ed5078ee4e54c0 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Thu, 28 Sep 2023 11:38:44 +0100
Subject: Basic type checking for field access

---
 .../compiler/ast/typed/TypedNodeMatchers.java      | 13 +++++++
 .../org/shedlang/compiler/ast/untyped/Untyped.java |  7 ++++
 .../typechecker/TypeCheckerFieldAccessTests.java   | 44 ++++++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFieldAccessTests.java

(limited to 'src/test/java')

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 259c3215..a21e3375 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
@@ -92,6 +92,19 @@ public class TypedNodeMatchers {
         );
     }
 
+    public static Matcher<TypedExpressionNode> isTypedFieldAccessNode(
+        Matcher<TypedExpressionNode> receiver,
+        String fieldName,
+        Type type
+    ) {
+        return instanceOf(
+            TypedFieldAccessNode.class,
+            has("receiver", x -> x.receiver(), receiver),
+            has("fieldName", x -> x.fieldName(), equalTo(fieldName)),
+            has("type", x -> x.type(), equalTo(type))
+        );
+    }
+
     public static TypedFunctionDefinitionNodeMatcher isTypedFunctionDefinitionNode() {
         return TypedFunctionDefinitionNodeMatcher.empty();
     }
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 dcdb9f46..6480af7b 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
@@ -84,6 +84,13 @@ public class Untyped {
         return new UntypedExpressionStatementNode(expression, Sources.NULL);
     }
 
+    public static UntypedExpressionNode fieldAccess(
+        UntypedExpressionNode receiver,
+        String fieldName
+    ) {
+        return new UntypedFieldAccessNode(receiver, fieldName, Sources.NULL);
+    }
+
     public static UntypedFunctionReturnNode functionReturn(UntypedExpressionNode expression) {
         return new UntypedFunctionReturnNode(expression, Sources.NULL);
     }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFieldAccessTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFieldAccessTests.java
new file mode 100644
index 00000000..f560cfce
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerFieldAccessTests.java
@@ -0,0 +1,44 @@
+package org.shedlang.compiler.typechecker;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.untyped.Untyped;
+import org.shedlang.compiler.ast.untyped.UntypedCallNode;
+import org.shedlang.compiler.typechecker.errors.*;
+import org.shedlang.compiler.typechecker.typesets.TypeSets;
+import org.shedlang.compiler.types.*;
+import org.shedlang.compiler.util.P;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.equalTo;
+import static org.zwobble.precisely.Matchers.isSequence;
+
+public class TypeCheckerFieldAccessTests {
+    @Test
+    public void canAccessFieldOnStructType() {
+        var untyped = Untyped.fieldAccess(
+            Untyped.reference("user"),
+            "name"
+        );
+        var structType = Types.struct(NamespaceName.of("Example"), "User");
+        var structTypeInfo = new StructTypeInfo(P.orderedPMap(Map.entry("name", Types.STRING)));
+        var context = TypeCheckerContext.EMPTY
+            .enterGlobal(P.map(Map.entry("user", structType)))
+            .addStructTypeInfo(structType, structTypeInfo);
+
+        var typed = TypeChecker.typeCheckExpression(untyped, context);
+
+        assertThat(
+            typed.value(),
+            isTypedFieldAccessNode(
+                isTypedReferenceNode("user", structType),
+                "name",
+                Types.STRING
+            )
+        );
+    }
+}
-- 
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