From 23dc359d91ac4a90b65d3c4927b3cd928b63da3a Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sat, 10 Jun 2023 14:37:28 +0100
Subject: Type check type level references

---
 .../compiler/ast/typed/TypedNodeMatchers.java      | 12 +++++
 .../org/shedlang/compiler/ast/untyped/Untyped.java |  4 ++
 .../TypeCheckerTypeLevelReferenceTests.java        | 58 ++++++++++++++++++++++
 3 files changed, 74 insertions(+)
 create mode 100644 src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTypeLevelReferenceTests.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 e6127108..c3aaa729 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
@@ -1,6 +1,7 @@
 package org.shedlang.compiler.ast.typed;
 
 import org.shedlang.compiler.types.Type;
+import org.shedlang.compiler.types.TypeLevelValue;
 import org.zwobble.precisely.Matcher;
 
 import java.math.BigInteger;
@@ -70,4 +71,15 @@ public class TypedNodeMatchers {
             has("value", x -> x.value(), equalTo(value))
         );
     }
+
+    public static Matcher<TypedTypeLevelExpressionNode> isTypedTypeLevelReferenceNode(
+        String name,
+        TypeLevelValue value
+    ) {
+        return instanceOf(
+            TypedTypeLevelReferenceNode.class,
+            has("name", x -> x.name(), equalTo(name)),
+            has("value", x -> x.value(), equalTo(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 170857b9..ae15b5cc 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
@@ -56,4 +56,8 @@ public class Untyped {
     public static UntypedStringLiteralNode stringLiteral(String value) {
         return new UntypedStringLiteralNode(value, Sources.NULL);
     }
+
+    public static UntypedTypeLevelReferenceNode typeLevelReference(String name) {
+        return new UntypedTypeLevelReferenceNode(name, Sources.NULL);
+    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTypeLevelReferenceTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTypeLevelReferenceTests.java
new file mode 100644
index 00000000..a0597778
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerTypeLevelReferenceTests.java
@@ -0,0 +1,58 @@
+package org.shedlang.compiler.typechecker;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.untyped.Untyped;
+import org.shedlang.compiler.typechecker.errors.UnexpectedTypeError;
+import org.shedlang.compiler.typechecker.errors.UnknownVariableError;
+import org.shedlang.compiler.typechecker.typesets.TypeSets;
+import org.shedlang.compiler.types.Types;
+import org.shedlang.compiler.util.P;
+
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.isTypedTypeLevelReferenceNode;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.equalTo;
+
+public class TypeCheckerTypeLevelReferenceTests {
+    @Test
+    public void whenNameIsBoundInEnvironmentThenTypeIsUsedFromEnvironment() {
+        var untyped = Untyped.typeLevelReference("String");
+        var context = TypeCheckerContext.EMPTY
+            .enter(P.map(Map.entry("String", Types.metaType(Types.STRING))));
+
+        var typed = TypeChecker.typeCheckTypeLevelExpression(untyped, context);
+
+        assertThat(typed, isTypedTypeLevelReferenceNode("String", Types.STRING));
+    }
+
+    @Test
+    public void whenNameRefersToNonTypeLevelValueThenErrorIsThrown() {
+        var untyped = Untyped.typeLevelReference("String");
+        var context = TypeCheckerContext.EMPTY
+            .enter(P.map(Map.entry("String", Types.STRING)));
+
+        var error = assertThrows(
+            UnexpectedTypeError.class,
+            () -> TypeChecker.typeCheckTypeLevelExpression(untyped, context)
+        );
+
+        assertThat(error.expected(), equalTo(TypeSets.TYPE_LEVEL_VALUE));
+        assertThat(error.actual(), equalTo(Types.STRING));
+    }
+
+    @Test
+    public void whenNameIsNotBoundInEnvironmentThenErrorIsThrown() {
+        var untyped = Untyped.typeLevelReference("String");
+        var context = TypeCheckerContext.EMPTY
+            .enter(P.map(Map.entry("Int", Types.metaType(Types.INT))));
+
+        var error = assertThrows(
+            UnknownVariableError.class,
+            () -> TypeChecker.typeCheckTypeLevelExpression(untyped, context)
+        );
+
+        assertThat(error.variableName(), equalTo("String"));
+    }
+}
-- 
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