Type check var statements

7 files changed, 131 insertions, 2 deletions

diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java
index 82fc3a8c..b1fcd49b 100644
--- a/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedFunctionStatementNode.java
@@ -1,5 +1,5 @@
 package org.shedlang.compiler.ast.typed;
 
-public sealed interface TypedFunctionStatementNode extends TypedNode permits TypedBlockReturnNode, TypedExpressionStatementNode, TypedFunctionReturnNode, TypedValNode {
+public sealed interface TypedFunctionStatementNode extends TypedNode permits TypedBlockReturnNode, TypedExpressionStatementNode, TypedFunctionReturnNode, TypedValNode, TypedVarNode {
     TypedFunctionStatementBehaviour behaviour();
 }
diff --git a/src/main/java/org/shedlang/compiler/ast/typed/TypedVarNode.java b/src/main/java/org/shedlang/compiler/ast/typed/TypedVarNode.java
new file mode 100644
index 00000000..3c698b52
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/ast/typed/TypedVarNode.java
@@ -0,0 +1,14 @@
+package org.shedlang.compiler.ast.typed;
+
+import org.shedlang.compiler.sources.Source;
+
+public record TypedVarNode(
+    TypedTargetNode target,
+    TypedExpressionNode expression,
+    Source source
+) implements TypedFunctionStatementNode {
+    @Override
+    public TypedFunctionStatementBehaviour behaviour() {
+        return TypedFunctionStatementBehaviour.CONTINUE;
+    }
+}
diff --git a/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java b/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
index 167983bb..2be8480d 100644
--- a/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
+++ b/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
@@ -212,6 +212,9 @@ public class StackCompiler {
 
             case TypedValNode val ->
                 compileVal(val, context);
+
+            case TypedVarNode var ->
+                throw new UnsupportedOperationException();
         };
     }
 
diff --git a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
index e0be25eb..8cf38fc1 100644
--- a/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/shedlang/compiler/typechecker/TypeChecker.java
@@ -541,7 +541,7 @@ public class TypeChecker {
                 typeCheckVal(val).typeCheckAllPhases(context);
 
             case UntypedVarNode var ->
-                throw new UnsupportedOperationException();
+                typeCheckVar(var, context);
         };
     }
 
@@ -802,6 +802,21 @@ public class TypeChecker {
         return context.toResult(new TypedValNode(target, expression, untyped.source()));
     }
 
+    private static TypeCheckerResult<TypedVarNode> typeCheckVar(
+        UntypedVarNode untyped,
+        TypeCheckerContext context
+    ) {
+        var expressionResult = typeCheckExpression(untyped.expression(), context);
+        var expression = expressionResult.value();
+        context = expressionResult.context();
+
+        var targetResult = typeCheckTarget(untyped.target(), expression.type(), context);
+        var target = targetResult.value();
+        context = targetResult.context();
+
+        return context.toResult(new TypedVarNode(target, expression, untyped.source()));
+    }
+
     private static TypeCheckerResult<TypedTargetNode> typeCheckTarget(
         UntypedTargetNode target,
         Type expressionType,
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 3a46fa54..ef2e4686 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
@@ -237,4 +237,15 @@ public class TypedNodeMatchers {
             has("expression", x -> x.expression(), expression)
         );
     }
+
+    public static Matcher<TypedNode> isTypedVarNode(
+        Matcher<? super TypedTargetNode> target,
+        Matcher<? super TypedExpressionNode> expression
+    ) {
+        return instanceOf(
+            TypedVarNode.class,
+            has("target", x -> x.target(), target),
+            has("expression", x -> x.expression(), expression)
+        );
+    }
 }
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 8dddfa58..141212cc 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/Untyped.java
@@ -157,4 +157,11 @@ public class Untyped {
     ) {
         return new UntypedValNode(target, expression, Sources.NULL);
     }
+
+    public static UntypedVarNode var(
+        UntypedTargetNode target,
+        UntypedExpressionNode expression
+    ) {
+        return new UntypedVarNode(target, expression, Sources.NULL);
+    }
 }
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
new file mode 100644
index 00000000..244ddc98
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerVarTests.java
@@ -0,0 +1,79 @@
+package org.shedlang.compiler.typechecker;
+
+import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.typed.TypedFunctionStatementNode;
+import org.shedlang.compiler.ast.typed.TypedNamespaceStatementNode;
+import org.shedlang.compiler.ast.untyped.Untyped;
+import org.shedlang.compiler.ast.untyped.UntypedFunctionDefinitionNode;
+import org.shedlang.compiler.ast.untyped.UntypedFunctionStatementNode;
+import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
+import org.shedlang.compiler.types.Types;
+import org.shedlang.compiler.util.P;
+
+import java.util.Map;
+
+import static org.shedlang.compiler.ast.typed.TypedNodeMatchers.*;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.anything;
+import static org.zwobble.precisely.Matchers.isSequence;
+
+public class TypeCheckerVarTests {
+    @Test
+    public void canTypeCheckAsFunctionStatement() {
+        var untyped = Untyped.var(Untyped.targetVariable("x"), Untyped.stringLiteral("hello"));
+
+        var typed = typeCheckFunctionStatement(untyped, TypeCheckerContext.EMPTY);
+
+        assertThat(typed.value(), isTypedVarNode(
+            isTypedTargetVariable("x"),
+            isTypedStringLiteralNode("hello")
+        ));
+    }
+
+    @Test
+    public void varCanBeReferencedAfterDefinitionInFunction() {
+        var untyped = UntypedFunctionDefinitionNode.builder()
+            .addStatement(Untyped.var(Untyped.targetVariable("x"), Untyped.stringLiteral("hello")))
+            .addStatement(Untyped.expressionStatement(Untyped.reference("x")))
+            .build();
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespaceWithDefinedVariables(P.map(
+                Map.entry("Unit", Types.metaType(Types.UNIT))
+            ));
+
+        var typed = typeCheckNamespaceStatement(untyped, context);
+
+        assertThat(
+            typed.value(),
+            isTypedFunctionDefinitionNode()
+                .withBody(isTypedBlockNode(isSequence(
+                    isTypedVarNode(anything(), anything()),
+                    isTypedExpressionStatementNode(isTypedReferenceNode("x", Types.STRING))
+                )))
+        );
+    }
+
+    private static TypeCheckerResult<? extends TypedFunctionStatementNode> typeCheckFunctionStatement(
+        UntypedFunctionStatementNode untyped,
+        TypeCheckerContext context
+    ) {
+        var declaredVariables = DeclaredVariables.forFunctionStatement(untyped, P.vector());
+        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
+
+        context = context.enterNamespace(environment.build());
+
+        return TypeChecker.typeCheckFunctionStatement(untyped, context);
+    }
+
+    private static TypeCheckerResult<? extends TypedNamespaceStatementNode> typeCheckNamespaceStatement(
+        UntypedNamespaceStatementNode untyped,
+        TypeCheckerContext context
+    ) {
+        var declaredVariables = DeclaredVariables.forNamespaceStatement(untyped, P.vector());
+        var environment = EnvironmentBuilder.EMPTY.addUndefined(declaredVariables);
+
+        context = context.enterNamespace(environment.build());
+
+        return TypeChecker.typeCheckNamespaceStatement(untyped).typeCheckAllPhases(context);
+    }
+}