Generalize the writing of the export section for future improvements

src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java

@@ -74,7 +74,7 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
 
     private Map<String, Global>         globals             = new LinkedHashMap<>();
 
-    private Map<String, String>         exports             = new LinkedHashMap<>();
+    private List<ExportEntry>           exports             = new ArrayList<>();
 
     private Map<String, ImportFunction> imports             = new LinkedHashMap<>();
 
@@ -129,7 +129,7 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         writeMemorySection();
         writeSection( SectionType.Global, globals.values() );
         writeEventSection();
-        writeExportSection();
+        writeSection( SectionType.Export, exports );
         writeElementSection();
         writeCodeSection();
         writeDataSection();
@@ -225,30 +225,6 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         }
     }
 
-    /**
-     * Write the export section to the output. This section contains a mapping from the external index to the type signature index.
-     * 
-     * @throws IOException
-     *             if any I/O error occur
-     */
-    private void writeExportSection() throws IOException {
-        int count = exports.size();
-        if( count > 0 ) {
-            WasmOutputStream stream = new WasmOutputStream();
-            stream.writeVaruint32( count );
-            for( Map.Entry<String,String> entry : exports.entrySet() ) {
-                String exportName = entry.getKey();
-                byte[] bytes = exportName.getBytes( StandardCharsets.UTF_8 );
-                stream.writeVaruint32( bytes.length );
-                stream.write( bytes );
-                stream.writeVaruint32( ExternalKind.Function.ordinal() );
-                int id = functions.get( entry.getValue() ).id;
-                stream.writeVaruint32( id );
-            }
-            wasm.writeSection( SectionType.Export, stream );
-        }
-    }
-
     /**
      * Write element section. This section create a matching between direct and indirect function call IDs.
      * 
@@ -514,7 +490,7 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
      */
     @Override
     protected void writeExport( FunctionName name, String exportName ) throws IOException {
-        exports.put( exportName, name.signatureName );
+        exports.add( new ExportEntry( exportName, ExternalKind.Function, getFunction( name ).id ) );
     }
 
     /**

src/de/inetsoftware/jwebassembly/binary/ExportEntry.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2019 Volker Berlin (i-net software)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package de.inetsoftware.jwebassembly.binary;
+
+import java.io.IOException;
+
+/**
+ * An entry in the function section of the WebAssembly.
+ * 
+ * @author Volker Berlin
+ */
+class ExportEntry extends SectionEntry {
+
+    private String       name;
+
+    private ExternalKind kind;
+
+    private int          id;
+
+    /**
+     * Create an entry for the export section. This section contains a mapping from the external index to the type
+     * signature index.
+     * 
+     * @param name
+     *            the exported name
+     * @param kind
+     *            the type of exported object
+     * @param id
+     *            the id inside the list of the related type
+     */
+    ExportEntry( String name, ExternalKind kind, int id ) {
+        this.name = name;
+        this.kind = kind;
+        this.id = id;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    void writeSectionEntry( WasmOutputStream stream ) throws IOException {
+        stream.writeString( name );
+        stream.writeVaruint32( kind.ordinal() );
+        stream.writeVaruint32( id );
+    }
+}