From 35e5a39b044f5916fb528ec1c80d05c05e4389c4 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 26 Jul 2026 00:13:52 +0100
Subject: Add less than operator to Rust AST

---
 .../hobgoblin/compiler/output/lang/rust/RustWriter.java     |  3 +++
 .../compiler/output/lang/rust/ast/RustBinaryOperator.java   |  1 +
 .../compiler/output/lang/rust/RustWriterTests.java          | 13 +++++++++++++
 3 files changed, 17 insertions(+)

(limited to 'src')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java
index 53b9a38..af6c1a7 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriter.java
@@ -443,6 +443,7 @@ public class RustWriter implements AutoCloseable {
         return switch (operator) {
             case ADD -> RustPrecedence.ADDITIVE;
             case EQUAL -> RustPrecedence.COMPARISON;
+            case LESS_THAN -> RustPrecedence.COMPARISON;
             case NOT_EQUAL -> RustPrecedence.COMPARISON;
         };
     }
@@ -478,6 +479,7 @@ public class RustWriter implements AutoCloseable {
         this.writer.write(switch (binaryExpression.operator()) {
             case ADD -> "+";
             case EQUAL -> "==";
+            case LESS_THAN -> "<";
             case NOT_EQUAL -> "!=";
         });
         this.writer.write(" ");
@@ -492,6 +494,7 @@ public class RustWriter implements AutoCloseable {
         return switch (binaryExpression.operator()) {
             case ADD -> RustAssociativity.LEFT;
             case EQUAL -> RustAssociativity.NONE;
+            case LESS_THAN -> RustAssociativity.NONE;
             case NOT_EQUAL -> RustAssociativity.NONE;
         };
     }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustBinaryOperator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustBinaryOperator.java
index 1d9fff7..05eca58 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustBinaryOperator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustBinaryOperator.java
@@ -8,6 +8,7 @@ package org.zwobble.hobgoblin.compiler.output.lang.rust.ast;
 public enum RustBinaryOperator {
     ADD,
     EQUAL,
+    LESS_THAN,
     NOT_EQUAL
 
     // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustBinaryOperator body
diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java
index 55c8f54..b5dd515 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/rust/RustWriterTests.java
@@ -436,6 +436,19 @@ public class RustWriterTests {
         assertThat(string, equalTo("x == y"));
     }
 
+    @Test
+    public void binaryExpressionLessThan() throws IOException {
+        var rust = RustBinaryExpression.arbitrary()
+            .withOperator(RustBinaryOperator.LESS_THAN)
+            .withLeft(RustPath.of("x"))
+            .withRight(RustPath.of("y"))
+            .build();
+
+        var string = write(writer -> writer.writeTopLevelExpression(rust));
+
+        assertThat(string, equalTo("x < y"));
+    }
+
     @Test
     public void binaryExpressionNotEqual() throws IOException {
         var rust = RustBinaryExpression.arbitrary()
-- 
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