From 51e6a77431e2321cf1878752d715cfc4011327b1 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 12 Jun 2026 17:05:13 +0100
Subject: Add Java assignment

---
 .../hobgoblin/compiler/output/lang/java/JavaWriter.java      | 10 ++++++++++
 .../compiler/output/lang/java/ast/JavaAssignment.java        |  7 +++++++
 .../compiler/output/lang/java/ast/JavaExpression.java        |  2 +-
 .../hobgoblin/compiler/output/lang/java/JavaWriterTests.java | 12 ++++++++++++
 4 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaAssignment.java

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
index a7a3775..8fbdacc 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
@@ -37,6 +37,12 @@ public class JavaWriter implements AutoCloseable {
         this.writer.close();
     }
 
+    private void writeAssignment(JavaAssignment assignment) throws IOException {
+        this.writeExpression(assignment.left());
+        this.writer.write(" = ");
+        this.writeExpression(assignment.right());
+    }
+
     public void writeCompilationUnit(JavaCompilationUnit compilationUnit) throws IOException {
         this.writer.writeHeader();
         this.writer.write("package ");
@@ -173,6 +179,10 @@ public class JavaWriter implements AutoCloseable {
 
     void writeExpression(JavaExpression expression) throws IOException {
         switch (expression) {
+            case JavaAssignment assignment -> {
+                writeAssignment(assignment);
+            }
+
             case JavaIntegerLiteral integerLiteral -> {
                 writeIntegerLiteral(integerLiteral);
             }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaAssignment.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaAssignment.java
new file mode 100644
index 0000000..b53e192
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaAssignment.java
@@ -0,0 +1,7 @@
+package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
+
+public record JavaAssignment(
+    JavaExpression left,
+    JavaExpression right
+) implements JavaExpression {
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaExpression.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaExpression.java
index 8bd706f..195441b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaExpression.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaExpression.java
@@ -1,4 +1,4 @@
 package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
 
-public sealed interface JavaExpression permits JavaIntegerLiteral, JavaMethodCall, JavaNewExpression, JavaNullLiteral, JavaRef, JavaStaticFieldAccess, JavaStaticMethodCall, JavaStringLiteral {
+public sealed interface JavaExpression permits JavaAssignment, JavaIntegerLiteral, JavaMethodCall, JavaNewExpression, JavaNullLiteral, JavaRef, JavaStaticFieldAccess, JavaStaticMethodCall, JavaStringLiteral {
 }
diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
index 8966d5e..14feaaa 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
@@ -725,6 +725,18 @@ public class JavaWriterTests {
         assertThat(string, equalTo("\"hello\""));
     }
 
+    @Test
+    public void assignment() throws IOException {
+        var java = new JavaAssignment(
+            new JavaRef("x"),
+            new JavaIntegerLiteral(42)
+        );
+
+        var string = write(writer -> writer.writeExpression(java));
+
+        assertThat(string, equalTo("x = 42"));
+    }
+
     @Test
     public void staticFieldAccess() throws IOException {
         var java = new JavaStaticFieldAccess(
-- 
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