From e467fb1ce8b601c11a20e029c9b941cf4d6ba121 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 19 Jul 2026 17:22:43 +0100
Subject: Add wildcard patterns to Rust AST

---
 .../compiler/output/lang/rust/RustWriter.java      | 12 ++++++++++-
 .../compiler/output/lang/rust/ast/RustPattern.java |  2 +-
 .../output/lang/rust/ast/RustWildcardPattern.java  | 24 ++++++++++++++++++++++
 3 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustWildcardPattern.java

(limited to 'src/main/java/org')

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 ef73933..e3991c8 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
@@ -616,11 +616,15 @@ public class RustWriter implements AutoCloseable {
 
     // == Patterns ==
 
-    private void writePattern(RustPattern pattern) throws IOException {
+    void writePattern(RustPattern pattern) throws IOException {
         switch (pattern) {
             case RustIdentifierPattern identifierPattern -> {
                 this.writeIdentifierPattern(identifierPattern);
             }
+
+            case RustWildcardPattern wildcardPattern -> {
+                this.writeWildcardPattern(wildcardPattern);
+            }
         }
     }
 
@@ -630,6 +634,12 @@ public class RustWriter implements AutoCloseable {
         this.writeIdentifier(identifierPattern.variableName());
     }
 
+    private void writeWildcardPattern(
+        RustWildcardPattern wildcardPattern
+    ) throws IOException {
+        this.writer.write("_");
+    }
+
     // == Types ==
 
     void writeType(RustType type) throws IOException {
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustPattern.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustPattern.java
index 47e7237..50ee8eb 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustPattern.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustPattern.java
@@ -5,7 +5,7 @@ package org.zwobble.hobgoblin.compiler.output.lang.rust.ast;
 // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPattern imports
 // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPattern imports
 
-public sealed interface RustPattern permits org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustIdentifierPattern {
+public sealed interface RustPattern permits org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustIdentifierPattern, org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern {
     public interface Builder {
         public org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPattern build();
 
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustWildcardPattern.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustWildcardPattern.java
new file mode 100644
index 0000000..7bc3ce7
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/rust/ast/RustWildcardPattern.java
@@ -0,0 +1,24 @@
+// Generated by hobgoblin.
+
+package org.zwobble.hobgoblin.compiler.output.lang.rust.ast;
+
+// Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern imports
+// Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern imports
+
+public record RustWildcardPattern() implements org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPattern {
+    public static org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern.Builder arbitrary() {
+        return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern.Builder();
+    }
+
+    public record Builder() implements org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustPattern.Builder {
+        public org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern build() {
+            return new org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern();
+        }
+
+        // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern.Builder body
+        // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern.Builder body
+    }
+
+    // Custom area start: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern body
+    // Custom area end: org.zwobble.hobgoblin.compiler.output.lang.rust.ast.RustWildcardPattern body
+}
-- 
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