feat(#65): Decompilation of simple constructs

pom.xml

@@ -137,7 +137,7 @@ SOFTWARE.
     <dependency>
       <groupId>org.eolang</groupId>
       <artifactId>jeo-maven-plugin</artifactId>
-      <version>0.2.15</version>
+      <version>0.2.16</version>
     </dependency>
     <dependency>
       <groupId>com.jcabi</groupId>

src/it/decompile-compile/target/generated-sources/xmir/org/eolang/jeo/Bar.xmir

@@ -59,7 +59,6 @@
                   </o>
                </o>
             </o>
-            <o base="tuple" name="trycatchblocks"/>
          </o>
          <o abstract="" name="j$foo">
             <o base="int" data="bytes" name="access">00 00 00 00 00 00 00 01</o>
@@ -105,7 +104,6 @@
                   </o>
                </o>
             </o>
-            <o base="tuple" name="trycatchblocks"/>
          </o>
       </o>
    </objects>

src/main/java/org/eolang/opeo/ast/Add.java

@@ -23,6 +23,9 @@
  */
 package org.eolang.opeo.ast;
 
+import java.util.ArrayList;
+import java.util.List;
+import org.objectweb.asm.Opcodes;
 import org.xembly.Directive;
 import org.xembly.Directives;
 
@@ -65,4 +68,13 @@ public Iterable<Directive> toXmir() {
             .append(this.right.toXmir())
             .up();
     }
+
+    @Override
+    public List<AstNode> opcodes() {
+        final List<AstNode> res = new ArrayList<>(0);
+        res.addAll(this.left.opcodes());
+        res.addAll(this.right.opcodes());
+        res.add(new Opcode(Opcodes.IADD));
+        return res;
+    }
 }

src/main/java/org/eolang/opeo/ast/AstNode.java

@@ -23,6 +23,7 @@
  */
 package org.eolang.opeo.ast;
 
+import java.util.List;
 import org.xembly.Directive;
 
 /**
@@ -42,4 +43,10 @@ public interface AstNode {
      * @return XMIR XML.
      */
     Iterable<Directive> toXmir();
+
+    /**
+     * Bytecode instructions.
+     * @return List of opcodes.
+     */
+    List<AstNode> opcodes();
 }

src/main/java/org/eolang/opeo/ast/Constructor.java

@@ -86,6 +86,11 @@ public Iterable<Directive> toXmir() {
         return directives.up();
     }
 
+    @Override
+    public List<AstNode> opcodes() {
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
+
     /**
      * Print arguments.
      * @return Arguments string.

src/main/java/org/eolang/opeo/ast/InstanceField.java

@@ -23,6 +23,7 @@
  */
 package org.eolang.opeo.ast;
 
+import java.util.List;
 import org.xembly.Directive;
 import org.xembly.Directives;
 
@@ -65,4 +66,9 @@ public Iterable<Directive> toXmir() {
             .append(this.source.toXmir())
             .up();
     }
+
+    @Override
+    public List<AstNode> opcodes() {
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
 }

src/main/java/org/eolang/opeo/ast/Invocation.java

@@ -111,6 +111,11 @@ public Iterable<Directive> toXmir() {
         return directives.up();
     }
 
+    @Override
+    public List<AstNode> opcodes() {
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
+
     /**
      * Print arguments.
      * @return Arguments

src/main/java/org/eolang/opeo/ast/Label.java

@@ -0,0 +1,68 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016-2023 Objectionary.com
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package org.eolang.opeo.ast;
+
+import java.util.Collections;
+import java.util.List;
+import org.xembly.Directive;
+import org.xembly.Directives;
+
+/**
+ * Label ast node.
+ * @since 0.1
+ */
+public final class Label implements AstNode {
+
+    /**
+     * Label identifier.
+     */
+    private final AstNode identifier;
+
+    /**
+     * Constructor.
+     * @param identifier Label identifier.
+     */
+    public Label(final AstNode identifier) {
+        this.identifier = identifier;
+    }
+
+    @Override
+    public String print() {
+        return String.format(": %s", this.identifier.print());
+    }
+
+    @Override
+    public Iterable<Directive> toXmir() {
+        return new Directives()
+            .add("o")
+            .attr("base", "label")
+            .append(this.identifier.toXmir())
+            .up();
+    }
+
+    @Override
+    public List<AstNode> opcodes() {
+        return Collections.singletonList(this);
+    }
+}

src/main/java/org/eolang/opeo/ast/Literal.java

@@ -23,7 +23,10 @@
  */
 package org.eolang.opeo.ast;
 
+import java.util.Collections;
+import java.util.List;
 import org.eolang.jeo.representation.directives.DirectivesData;
+import org.objectweb.asm.Opcodes;
 import org.xembly.Directive;
 
 /**
@@ -50,6 +53,19 @@ public Iterable<Directive> toXmir() {
         return new DirectivesData(this.object);
     }
 
+    @Override
+    public List<AstNode> opcodes() {
+        final List<AstNode> result;
+        if (this.object instanceof Integer) {
+            result = Collections.singletonList(Literal.opcode((Integer) this.object));
+        } else if (this.object instanceof String) {
+            result = Collections.singletonList(Literal.opcode((String) this.object));
+        } else {
+            throw new UnsupportedOperationException("Not implemented yet");
+        }
+        return result;
+    }
+
     @Override
     public String print() {
         final String result;
@@ -60,4 +76,46 @@ public String print() {
         }
         return result;
     }
+
+    /**
+     * Convert string into an opcode.
+     * @param value String value.
+     * @return Opcode.
+     */
+    private static Opcode opcode(final String value) {
+        return new Opcode(Opcodes.LDC, value);
+    }
+
+    /**
+     * Convert integer into an opcode.
+     * @param value Integer value.
+     * @return Opcode.
+     */
+    private static Opcode opcode(final int value) {
+        final Opcode res;
+        switch (value) {
+            case 0:
+                res = new Opcode(Opcodes.ICONST_0);
+                break;
+            case 1:
+                res = new Opcode(Opcodes.ICONST_1);
+                break;
+            case 2:
+                res = new Opcode(Opcodes.ICONST_2);
+                break;
+            case 3:
+                res = new Opcode(Opcodes.ICONST_3);
+                break;
+            case 4:
+                res = new Opcode(Opcodes.ICONST_4);
+                break;
+            case 5:
+                res = new Opcode(Opcodes.ICONST_5);
+                break;
+            default:
+                res = new Opcode(Opcodes.BIPUSH, value);
+                break;
+        }
+        return res;
+    }
 }

src/main/java/org/eolang/opeo/ast/Mul.java

@@ -23,6 +23,7 @@
  */
 package org.eolang.opeo.ast;
 
+import java.util.List;
 import org.xembly.Directive;
 import org.xembly.Directives;
 
@@ -65,4 +66,9 @@ public Iterable<Directive> toXmir() {
             .append(this.right.toXmir())
             .up();
     }
+
+    @Override
+    public List<AstNode> opcodes() {
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
 }

src/main/java/org/eolang/opeo/ast/Opcode.java

@@ -26,6 +26,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 import org.eolang.jeo.representation.directives.DirectivesInstruction;
 import org.eolang.parser.XMIR;
 import org.xembly.Directive;
@@ -38,6 +39,11 @@
  */
 public final class Opcode implements AstNode {
 
+    /**
+     * Opcodes counting.
+     */
+    private static final AtomicBoolean COUNTING = new AtomicBoolean(true);
+
     /**
      * Opcode.
      */
@@ -82,7 +88,7 @@ public Opcode(final int opcode, final boolean counting) {
      * @param operands Opcode operands
      */
     public Opcode(final int opcode, final List<Object> operands) {
-        this(opcode, operands, true);
+        this(opcode, operands, Opcode.COUNTING.get());
     }
 
     /**
@@ -106,4 +112,22 @@ public String print() {
     public Iterable<Directive> toXmir() {
         return new DirectivesInstruction(this.bytecode, this.counting, this.operands.toArray());
     }
+
+    @Override
+    public List<AstNode> opcodes() {
+        return List.of(this);
+    }
+
+    /**
+     * Disable opcodes counting.
+     * It is useful for tests.
+     * @todo #65:30min Remove public static method 'disableCounting()' from Opcode.
+     *  Currently it is used in tests. We should find another
+     *  way to disable opcodes counting in tests. When we find
+     *  the way to do it, we should remove this method.
+     */
+    @SuppressWarnings("PMD.ProhibitPublicStaticMethods")
+    public static void disableCounting() {
+        Opcode.COUNTING.set(false);
+    }
 }