From f3aea758bcab9bbf07cca29d9e705aa112d94bad Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Thu, 2 Nov 2023 19:07:48 +0000
Subject: Allow resume statements without expression

---
 .../compiler/ast/untyped/UntypedResumeNode.java         |  4 +++-
 src/main/java/org/shedlang/compiler/parser/Parser.java  |  4 +++-
 .../compiler/ast/untyped/UntypedNodeMatchers.java       |  2 +-
 .../compiler/parser/ParserFunctionResumeTests.java      | 17 +++++++++++++++--
 4 files changed, 22 insertions(+), 5 deletions(-)

(limited to 'src')

diff --git a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedResumeNode.java b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedResumeNode.java
index a0eb49e6..45a94451 100644
--- a/src/main/java/org/shedlang/compiler/ast/untyped/UntypedResumeNode.java
+++ b/src/main/java/org/shedlang/compiler/ast/untyped/UntypedResumeNode.java
@@ -2,8 +2,10 @@ package org.shedlang.compiler.ast.untyped;
 
 import org.shedlang.compiler.sources.Source;
 
+import java.util.Optional;
+
 public record UntypedResumeNode(
-    UntypedExpressionNode expression,
+    Optional<UntypedExpressionNode> expression,
     Source source
 ) implements UntypedFunctionStatementNode {
     @Override
diff --git a/src/main/java/org/shedlang/compiler/parser/Parser.java b/src/main/java/org/shedlang/compiler/parser/Parser.java
index 5d4599e1..329a5283 100644
--- a/src/main/java/org/shedlang/compiler/parser/Parser.java
+++ b/src/main/java/org/shedlang/compiler/parser/Parser.java
@@ -829,7 +829,9 @@ public class Parser {
 
         tokens.skip(TokenType.KEYWORD_RESUME);
 
-        var expression = parseTopLevelExpression(tokens);
+        var expression = tokens.isNext(TokenType.SYMBOL_SEMICOLON)
+            ? Optional.<UntypedExpressionNode>empty()
+            : Optional.of(parseTopLevelExpression(tokens));
 
         tokens.skip(TokenType.SYMBOL_SEMICOLON);
 
diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
index e08c8198..8fd2ce41 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
@@ -243,7 +243,7 @@ public class UntypedNodeMatchers {
     }
 
     public static Matcher<UntypedFunctionStatementNode> isUntypedResumeNode(
-        Matcher<UntypedExpressionNode> expression
+        Matcher<Optional<? extends UntypedExpressionNode>> expression
     ) {
         return instanceOf(
             UntypedResumeNode.class,
diff --git a/src/test/java/org/shedlang/compiler/parser/ParserFunctionResumeTests.java b/src/test/java/org/shedlang/compiler/parser/ParserFunctionResumeTests.java
index c581a4f9..8e134656 100644
--- a/src/test/java/org/shedlang/compiler/parser/ParserFunctionResumeTests.java
+++ b/src/test/java/org/shedlang/compiler/parser/ParserFunctionResumeTests.java
@@ -5,14 +5,27 @@ import org.junit.jupiter.api.Test;
 import static org.shedlang.compiler.ast.untyped.UntypedNodeMatchers.*;
 import static org.shedlang.compiler.parser.ParserTesting.parseString;
 import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.isOptionalEmpty;
+import static org.zwobble.precisely.Matchers.isOptionalOf;
 
 public class ParserFunctionResumeTests {
     @Test
-    public void canParseResume() {
+    public void canParseResumeWithExpression() {
         var source = "resume x;";
 
         var node = parseString(source, Parser::parseFunctionStatement);
 
-        assertThat(node, isUntypedResumeNode(isUntypedReferenceNode("x")));
+        assertThat(node, isUntypedResumeNode(isOptionalOf(
+            isUntypedReferenceNode("x"))
+        ));
+    }
+
+    @Test
+    public void canParseResumeWithoutExpression() {
+        var source = "resume;";
+
+        var node = parseString(source, Parser::parseFunctionStatement);
+
+        assertThat(node, isUntypedResumeNode(isOptionalEmpty()));
     }
 }
-- 
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