CLEANUP: Dry up codegen, remove needless RubyArray usage, ensure cons…

…ecutive numbering of generated classes

Fixes elastic#9312

logstash-core/src/main/java/org/logstash/config/ir/compiler/ClassFields.java

@@ -14,18 +14,6 @@ final class ClassFields {
 
     private final Collection<Closure> afterInit = new ArrayList<>();
 
-    /**
-     * Add a field of given type that is initialized by the given {@link SyntaxElement} that will
-     * be executed in the class body.
-     * Renders as e.g. {@code private final Ruby field5 = RubyUtil.RUBY}.
-     * @param type Type of the field
-     * @param initializer Syntax to initialize it in-line.
-     * @return The field's syntax element that can be used in method bodies
-     */
-    public ValueSyntaxElement add(final Class<?> type, final SyntaxElement initializer) {
-        return addField(FieldDefinition.withInitializer(definitions.size(), type, initializer));
-    }
-
     /**
      * Adds a field holding the given {@link Object}.
      * @param obj Object to add field for

logstash-core/src/main/java/org/logstash/config/ir/compiler/ComputeStepSyntaxElement.java

@@ -13,7 +13,6 @@
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.concurrent.atomic.AtomicInteger;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.StreamSupport;
@@ -25,7 +24,7 @@
 /**
  * One step of a compiled pipeline that compiles to a {@link Dataset}.
  */
-public final class ComputeStepSyntaxElement<T extends Dataset> implements SyntaxElement {
+public final class ComputeStepSyntaxElement<T extends Dataset> {
 
     private static final Path SOURCE_DIR = debugDir();
 
@@ -37,36 +36,26 @@ public final class ComputeStepSyntaxElement<T extends Dataset> implements Syntax
     private static final Map<ComputeStepSyntaxElement<?>, Class<? extends Dataset>> CLASS_CACHE
         = new HashMap<>();
 
-    /**
-     * Sequence number to ensure unique naming for runtime compiled classes.
-     */
-    private static final AtomicInteger SEQUENCE = new AtomicInteger(0);
-
     /**
      * Pattern to remove redundant {@code ;} from formatted code since {@link Formatter} does not
      * remove those.
      */
     private static final Pattern REDUNDANT_SEMICOLON = Pattern.compile("\n[ ]*;\n");
 
-    private final String name;
-
     private final Iterable<MethodSyntaxElement> methods;
 
     private final ClassFields fields;
 
     private final Class<T> type;
 
-    ComputeStepSyntaxElement(final Iterable<MethodSyntaxElement> methods,
-        final ClassFields fields, final Class<T> interfce) {
-        this(
-            String.format("CompiledDataset%d", SEQUENCE.incrementAndGet()), methods, fields,
-            interfce
-        );
+    public static <T extends Dataset> ComputeStepSyntaxElement<T> create(
+        final Iterable<MethodSyntaxElement> methods, final ClassFields fields,
+        final Class<T> interfce) {
+        return new ComputeStepSyntaxElement<>(methods, fields, interfce);
     }
 
-    private ComputeStepSyntaxElement(final String name, final Iterable<MethodSyntaxElement> methods,
+    private ComputeStepSyntaxElement(final Iterable<MethodSyntaxElement> methods,
         final ClassFields fields, final Class<T> interfce) {
-        this.name = name;
         this.methods = methods;
         this.fields = fields;
         type = interfce;
@@ -82,7 +71,8 @@ public T instantiate() {
                 if (CLASS_CACHE.containsKey(this)) {
                     clazz = CLASS_CACHE.get(this);
                 } else {
-                    final String code = generateCode();
+                    final String name = String.format("CompiledDataset%d", CLASS_CACHE.size());
+                    final String code = generateCode(name);
                     final Path sourceFile = SOURCE_DIR.resolve(String.format("%s.java", name));
                     Files.write(sourceFile, code.getBytes(StandardCharsets.UTF_8));
                     COMPILER.cookFile(sourceFile.toFile());
@@ -102,15 +92,25 @@ public T instantiate() {
     }
 
     @Override
-    public String generateCode() {
+    public int hashCode() {
+        return normalizedSource().hashCode();
+    }
+
+    @Override
+    public boolean equals(final Object other) {
+        return other instanceof ComputeStepSyntaxElement &&
+            normalizedSource().equals(((ComputeStepSyntaxElement<?>) other).normalizedSource());
+    }
+
+    private String generateCode(final String name) {
         try {
             return REDUNDANT_SEMICOLON.matcher(new Formatter().formatSource(
                 String.format(
                     "package org.logstash.generated;\npublic final class %s implements %s { %s }",
                     name,
                     type.getName(),
                     SyntaxFactory.join(
-                        fields.inlineAssigned().generateCode(), fieldsAndCtor(),
+                        fields.inlineAssigned().generateCode(), fieldsAndCtor(name),
                         combine(
                             StreamSupport.stream(methods.spliterator(), false)
                                 .toArray(SyntaxElement[]::new)
@@ -123,22 +123,6 @@ public String generateCode() {
         }
     }
 
-    @Override
-    public int hashCode() {
-        return normalizedSource().hashCode();
-    }
-
-    @Override
-    public boolean equals(final Object other) {
-        return other instanceof ComputeStepSyntaxElement &&
-            normalizedSource().equals(((ComputeStepSyntaxElement<?>) other).normalizedSource());
-    }
-
-    @Override
-    public String toString() {
-        return generateCode();
-    }
-
     private static Path debugDir() {
         final Path sourceDir;
         try {
@@ -181,16 +165,15 @@ private Object[] ctorArguments() {
      * @return Source of this class, with its name set to {@code CONSTANT}.
      */
     private String normalizedSource() {
-        return new ComputeStepSyntaxElement<>("CONSTANT", methods, fields, type)
-            .generateCode();
+        return this.generateCode("CONSTANT");
     }
 
     /**
      * Generates the Java code for defining one field and constructor argument for each given value.
      * constructor for
      * @return Java Source String
      */
-    private String fieldsAndCtor() {
+    private String fieldsAndCtor(final String name) {
         final Closure constructor = new Closure();
         final FieldDeclarationGroup ctorFields = fields.ctorAssigned();
         final Collection<VariableDefinition> ctor = new ArrayList<>();