From 371a4e8db3aa6fdc0a6d144351e9c0169c13badf Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 22 Apr 2026 11:28:02 +0100
Subject: Parse type level references

---
 .../untyped/UntypedStructFieldDefinitionNode.java  | 10 +++++++++
 .../untyped/UntypedTypeLevelExpressionNode.java    |  4 ++++
 .../ast/untyped/UntypedTypeLevelReferenceNode.java |  9 ++++++++
 .../zwobble/hobgoblin/compiler/parser/Parser.java  | 18 ++++++++++++++++
 .../hobgoblin/compiler/parser/TokenIterator.java   | 11 ++++++++++
 .../parser/ParserTypeLevelReferenceTests.java      | 25 ++++++++++++++++++++++
 6 files changed, 77 insertions(+)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedStructFieldDefinitionNode.java
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelReferenceNode.java
 create mode 100644 src/test/java/org/zwobble/hobgoblin/compiler/parser/ParserTypeLevelReferenceTests.java

(limited to 'src')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedStructFieldDefinitionNode.java b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedStructFieldDefinitionNode.java
new file mode 100644
index 0000000..0e21663
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedStructFieldDefinitionNode.java
@@ -0,0 +1,10 @@
+package org.zwobble.hobgoblin.compiler.ast.untyped;
+
+import org.zwobble.hobgoblin.compiler.sources.Source;
+
+public record UntypedStructFieldDefinitionNode(
+    String name,
+    UntypedTypeLevelExpressionNode type,
+    Source source
+) implements UntypedNode {
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java
new file mode 100644
index 0000000..871393d
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelExpressionNode.java
@@ -0,0 +1,4 @@
+package org.zwobble.hobgoblin.compiler.ast.untyped;
+
+public sealed interface UntypedTypeLevelExpressionNode extends UntypedNode permits UntypedTypeLevelReferenceNode {
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelReferenceNode.java b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelReferenceNode.java
new file mode 100644
index 0000000..018655e
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/ast/untyped/UntypedTypeLevelReferenceNode.java
@@ -0,0 +1,9 @@
+package org.zwobble.hobgoblin.compiler.ast.untyped;
+
+import org.zwobble.hobgoblin.compiler.sources.Source;
+
+public record UntypedTypeLevelReferenceNode(
+    String name,
+    Source source
+) implements UntypedTypeLevelExpressionNode {
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/parser/Parser.java b/src/main/java/org/zwobble/hobgoblin/compiler/parser/Parser.java
index 704f34f..4411306 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/parser/Parser.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/parser/Parser.java
@@ -1,6 +1,8 @@
 package org.zwobble.hobgoblin.compiler.parser;
 
 import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedNamespaceNode;
+import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelExpressionNode;
+import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelReferenceNode;
 import org.zwobble.hobgoblin.compiler.sources.FileFragmentSource;
 import org.zwobble.hobgoblin.compiler.sources.Source;
 import org.zwobble.hobgoblin.compiler.types.NamespaceName;
@@ -28,6 +30,22 @@ public class Parser {
         );
     }
 
+    public static UntypedTypeLevelExpressionNode parseTypeLevelExpression(
+        TokenIterator tokens
+    ) {
+        var start = tokens.startPosition();
+
+        var name = tokens.next(TokenType.IDENTIFIER);
+
+        var end = tokens.endPosition();
+        var source = createSource(start, end);
+
+        return new UntypedTypeLevelReferenceNode(
+            name.charSequence().toString(),
+            source
+        );
+    }
+
     private static Source createSource(SourcePosition start, SourcePosition end) {
         return new FileFragmentSource(start.to(end));
     }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/parser/TokenIterator.java b/src/main/java/org/zwobble/hobgoblin/compiler/parser/TokenIterator.java
index 9e1dd9c..cb59e79 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/parser/TokenIterator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/parser/TokenIterator.java
@@ -19,6 +19,17 @@ class TokenIterator {
         return this.getAbsolute(this.tokenIndex);
     }
 
+    public Token next(TokenType tokenType) {
+        var token = peek();
+        if (token.tokenType().equals(tokenType)) {
+            this.tokenIndex++;
+            return token;
+        } else {
+            // TODO: better expected string
+            throw new UnexpectedTokenError(tokenType.toString(), token);
+        }
+    }
+
     private Token getAbsolute(int index) {
         if (index < this.tokens.size()) {
             return this.tokens.get(index);
diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/parser/ParserTypeLevelReferenceTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/parser/ParserTypeLevelReferenceTests.java
new file mode 100644
index 0000000..4f50199
--- /dev/null
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/parser/ParserTypeLevelReferenceTests.java
@@ -0,0 +1,25 @@
+package org.zwobble.hobgoblin.compiler.parser;
+
+import org.junit.jupiter.api.Test;
+import org.zwobble.hobgoblin.compiler.ast.untyped.UntypedTypeLevelReferenceNode;
+
+import static org.zwobble.hobgoblin.compiler.parser.ParserTesting.parseString;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.*;
+
+public class ParserTypeLevelReferenceTests {
+    @Test
+    public void canParseIdentifierAsTypeLevelReference() {
+        var source = "Point";
+
+        var node = parseString(
+            source,
+            Parser::parseTypeLevelExpression
+        );
+
+        assertThat(node, instanceOf(
+            UntypedTypeLevelReferenceNode.class,
+            has("name", UntypedTypeLevelReferenceNode::name, equalTo("Point"))
+        ));
+    }
+}
-- 
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