Support accessing array element using an expression (#219)

micronaut-projects · Jan 9, 2025 · 0162733 · 0162733
1 parent 29ebe1a
commit 0162733
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Showing 3 changed files with 131 additions and 5 deletions.
diff --git a/...rc/main/java/io/micronaut/sourcegen/bytecode/expression/ArrayElementExpressionWriter.java b/...rc/main/java/io/micronaut/sourcegen/bytecode/expression/ArrayElementExpressionWriter.java
@@ -30,7 +30,7 @@ public ArrayElementExpressionWriter(ExpressionDef.ArrayElement arrayElement) {
     @Override
     public void write(GeneratorAdapter generatorAdapter, MethodContext context) {
         ExpressionWriter.writeExpression(generatorAdapter, context, arrayElement.expression());
-        generatorAdapter.push(arrayElement.index());
+        ExpressionWriter.writeExpression(generatorAdapter, context, arrayElement.indexExpression());
         generatorAdapter.arrayLoad(TypeUtils.getType(arrayElement.type(), context.objectDef()));
     }
 }
diff --git a/...gen-bytecode-writer/src/test/java/io/micronaut/sourcegen/bytecode/ByteCodeWriterTest.java b/...gen-bytecode-writer/src/test/java/io/micronaut/sourcegen/bytecode/ByteCodeWriterTest.java
@@ -32,6 +32,107 @@
 
 class ByteCodeWriterTest {
 
+    @Test
+    void arrayElement() {
+        ClassDef def = ClassDef.builder("example.Example")
+            .addModifiers(Modifier.PUBLIC)
+            .addMethod(MethodDef.builder("myMethod")
+                .addParameters(String[].class)
+                .build((aThis, methodParameters) -> methodParameters.get(0).arrayElement(1).returning()))
+            .build();
+
+        StringWriter bytecodeWriter = new StringWriter();
+        byte[] bytes = generateFile(def, bytecodeWriter);
+
+        String bytecode = bytecodeWriter.toString();
+        Assertions.assertEquals("""
+// class version 61.0 (61)
+// access flags 0x1
+// signature Ljava/lang/Object;
+// declaration: example/Example
+public class example/Example {
+
+
+  // access flags 0x1
+  public <init>()V
+    ALOAD 0
+    INVOKESPECIAL java/lang/Object.<init> ()V
+    RETURN
+
+  // access flags 0x0
+  myMethod([Ljava/lang/String;)Ljava/lang/String;
+   L0
+    ALOAD 1
+    ICONST_1
+    AALOAD
+    ARETURN
+   L1
+    LOCALVARIABLE arg1 [Ljava/lang/String; L0 L1 1
+}
+""", bytecode);
+
+        Assertions.assertEquals("""
+package example;
+
+public class Example {
+   String myMethod(String[] arg1) {
+      return arg1[1];
+   }
+}
+""", decompileToJava(bytes));
+    }
+
+    @Test
+    void arrayElement2() {
+        ClassDef def = ClassDef.builder("example.Example")
+            .addModifiers(Modifier.PUBLIC)
+            .addMethod(MethodDef.builder("myMethod")
+                .addParameters(String[].class, int.class)
+                .build((aThis, methodParameters) -> methodParameters.get(0).arrayElement(methodParameters.get(1)).returning()))
+            .build();
+
+        StringWriter bytecodeWriter = new StringWriter();
+        byte[] bytes = generateFile(def, bytecodeWriter);
+
+        String bytecode = bytecodeWriter.toString();
+        Assertions.assertEquals("""
+// class version 61.0 (61)
+// access flags 0x1
+// signature Ljava/lang/Object;
+// declaration: example/Example
+public class example/Example {
+
+
+  // access flags 0x1
+  public <init>()V
+    ALOAD 0
+    INVOKESPECIAL java/lang/Object.<init> ()V
+    RETURN
+
+  // access flags 0x0
+  myMethod([Ljava/lang/String;I)Ljava/lang/String;
+   L0
+    ALOAD 1
+    ILOAD 2
+    AALOAD
+    ARETURN
+   L1
+    LOCALVARIABLE arg1 [Ljava/lang/String; L0 L1 1
+    LOCALVARIABLE arg2 I L0 L1 2
+}
+""", bytecode);
+
+        Assertions.assertEquals("""
+package example;
+
+public class Example {
+   String myMethod(String[] arg1, int arg2) {
+      return arg1[arg2];
+   }
+}
+""", decompileToJava(bytes));
+    }
+
     @Test
     void testSynthetic() {
         ClassDef def = ClassDef.builder("example.Example")

diff --git a/sourcegen-model/src/main/java/io/micronaut/sourcegen/model/ExpressionDef.java b/sourcegen-model/src/main/java/io/micronaut/sourcegen/model/ExpressionDef.java
@@ -57,6 +57,20 @@ default ArrayElement arrayElement(int index) {
         return new ArrayElement(this, index);
     }
 
+    /**
+     * Check an array element.
+     *
+     * @param index The index
+     * @return The array element
+     * @since 1.5
+     */
+    default ArrayElement arrayElement(ExpressionDef index) {
+        if (!index.type().equals(TypeDef.Primitive.INT)) {
+            throw new IllegalStateException("Illegal array index type: " + index.type());
+        }
+        return new ArrayElement(this, index);
+    }
+
     /**
      * Check if the instance is of the type.
      *
@@ -1254,22 +1268,33 @@ record InstanceOf(ExpressionDef expression,
     /**
      * The get array element expression.
      *
-     * @param expression The expression
-     * @param type       The component type
-     * @param index      The index
+     * @param expression      The expression
+     * @param type            The component type
+     * @param indexExpression The index expression
      * @author Denis Stepanov
      * @since 1.5
      */
     @Experimental
     record ArrayElement(ExpressionDef expression,
                         TypeDef type,
-                        int index) implements ExpressionDef {
+                        ExpressionDef indexExpression) implements ExpressionDef {
+
+        public ArrayElement(ExpressionDef expression,
+                            TypeDef type,
+                            int index) {
+            this(expression, type, ExpressionDef.constant(index));
+        }
 
         public ArrayElement(ExpressionDef expression,
                             int index) {
             this(expression, findComponentType(expression.type()), index);
         }
 
+        public ArrayElement(ExpressionDef expression,
+                            ExpressionDef indexExpression) {
+            this(expression, findComponentType(expression.type()), indexExpression);
+        }
+
         private static TypeDef findComponentType(TypeDef arrayType) {
             if (arrayType instanceof TypeDef.Array array) {
                 return array.componentType();