From 20ba12d3bf07b56cba79c0d606648cac2c9e7325 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 21 Jun 2023 23:21:29 +0100
Subject: Extract writeVec()

---
 .../backends/wasm/structure/WasmBinaryFormat.java  | 77 ++++++++++++++++------
 1 file changed, 56 insertions(+), 21 deletions(-)

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/structure/WasmBinaryFormat.java b/src/main/java/org/shedlang/compiler/backends/wasm/structure/WasmBinaryFormat.java
index b472eecd..6acafeac 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/structure/WasmBinaryFormat.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/structure/WasmBinaryFormat.java
@@ -59,10 +59,11 @@ public class WasmBinaryFormat {
     ) throws IOException {
         if (types.size() > 0) {
             writeSection(SectionType.TYPE, writer, () -> {
-                Leb128Encoding.encodeUnsignedInt32(types.size(), writer);
-                for (var type : types) {
-                    writeFuncType(type, writer);
-                }
+                writeVec(
+                    types,
+                    type -> writeFuncType(type, writer),
+                    writer
+                );
             });
         }
     }
@@ -73,16 +74,16 @@ public class WasmBinaryFormat {
     ) throws IOException {
         if (module.imports().size() > 0) {
             writeSection(SectionType.IMPORT, writer, () -> {
-                Leb128Encoding.encodeUnsignedInt32(module.imports().size(), writer);
-                
                 var funcTypeToFuncIndex = new HashMap<WasmFuncType, Integer>();
                 for (var funcIndex = 0; funcIndex < module.types().size(); funcIndex++) {
                     funcTypeToFuncIndex.put(module.types().get(funcIndex), funcIndex);
                 }
-                
-                for (var import_ : module.imports()) {
-                    writeImport(import_, funcTypeToFuncIndex, writer);
-                }
+
+                writeVec(
+                    module.imports(),
+                    import_ -> writeImport(import_, funcTypeToFuncIndex, writer),
+                    writer
+                );
             });
         }
     }
@@ -108,27 +109,31 @@ public class WasmBinaryFormat {
             writeSection(SectionType.CUSTOM, writer, () -> {
                 writeString("name", writer);
                 writeSection((byte) 1, writer, () -> {
-                    Leb128Encoding.encodeUnsignedInt32(module.imports().size(), writer);
-                    for (var importIndex = 0; importIndex < module.imports().size(); importIndex++) {
-                        Leb128Encoding.encodeUnsignedInt32(importIndex, writer);
-                        writeString(module.imports().get(importIndex).identifier(), writer);
-                    };
+                    writeVec(
+                        module.imports(),
+                        (importIndex, import_) -> {
+                            Leb128Encoding.encodeUnsignedInt32(importIndex, writer);
+                            writeString(module.imports().get(importIndex).identifier(), writer);
+                        },
+                        writer
+                    );
                 });
             });
         }
     }
 
-    private static void writeFuncType(WasmFuncType type, BinaryWriter writer) {
+    private static void writeFuncType(WasmFuncType type, BinaryWriter writer) throws IOException {
         writer.writeByte((byte) 0x60);
         writeValueTypeVector(type.params(), writer);
         writeValueTypeVector(type.results(), writer);
     }
 
-    private static void writeValueTypeVector(List<WasmValueType> types, BinaryWriter writer) {
-        Leb128Encoding.encodeUnsignedInt32(types.size(), writer);
-        for (var type : types) {
-            writeValueType(type, writer);
-        }
+    private static void writeValueTypeVector(List<WasmValueType> types, BinaryWriter writer) throws IOException {
+        writeVec(
+            types,
+            type -> writeValueType(type, writer),
+            writer
+        );
     }
 
     private static void writeValueType(WasmValueType type, BinaryWriter writer) {
@@ -179,6 +184,36 @@ public class WasmBinaryFormat {
         writer.seek(contentEndPosition);
     }
 
+    interface WriteElement<T> {
+        void write(T element) throws IOException;
+    }
+
+    interface WriteIndexedElement<T> {
+        void write(int index, T element) throws IOException;
+    }
+
+    private static <T> void writeVec(
+        List<T> vec,
+        WriteElement<T> writeElement,
+        BinaryWriter writer
+    ) throws IOException {
+        Leb128Encoding.encodeUnsignedInt32(vec.size(), writer);
+        for (var element : vec) {
+            writeElement.write(element);
+        }
+    }
+
+    private static <T> void writeVec(
+        List<T> vec,
+        WriteIndexedElement<T> writeElement,
+        BinaryWriter writer
+    ) throws IOException {
+        Leb128Encoding.encodeUnsignedInt32(vec.size(), writer);
+        for (var elementIndex = 0; elementIndex < vec.size(); elementIndex++) {
+            writeElement.write(elementIndex, vec.get(elementIndex));
+        }
+    }
+
     private static void writeString(String value, BinaryWriter writer) {
         var bytes = value.getBytes(StandardCharsets.UTF_8);
         Leb128Encoding.encodeUnsignedInt32(bytes.length, writer);
-- 
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