feat(objectionary#889): speed up DirectivesSeq

src/main/java/org/eolang/jeo/representation/directives/DirectivesSeq.java

@@ -82,21 +82,16 @@ private DirectivesSeq(final String name, final Iterable<Directive>... elements)
 
     @Override
     public Iterator<Directive> iterator() {
+        final List<Directives> all = this.stream()
+            .map(Directives::new)
+            .collect(Collectors.toList());
         return new DirectivesJeoObject(
-            String.format("seq.of%d", this.size()),
+            String.format("seq.of%d", all.size()),
             this.name,
-            this.stream().map(Directives::new).collect(Collectors.toList())
+            all
         ).iterator();
     }
 
-    /**
-     * Size of the sequence.
-     * @return Size.
-     */
-    private long size() {
-        return this.stream().count();
-    }
-
     /**
      * Stream of directives.
      * @return Stream of directives.

src/main/java/org/eolang/jeo/representation/xmir/XmlNode.java

@@ -23,7 +23,6 @@
  */
 package org.eolang.jeo.representation.xmir;
 
-import com.jcabi.xml.XML;
 import com.jcabi.xml.XMLDocument;
 import java.util.ArrayList;
 import java.util.List;

src/test/java/org/eolang/jeo/representation/XmirRepresentationTest.java

@@ -185,12 +185,11 @@ void convertsToXmirAndBack() {
             );
         }
         final long end = System.currentTimeMillis();
-        final long l = end - start;
         Logger.info(
             this,
             "We made %d attempts to convert bytecode to xmir and back in %[ms]s",
             attempts,
-            l
+            end - start
         );
 
     }

src/test/java/org/eolang/jeo/representation/directives/DirectivesSeqTest.java

@@ -24,8 +24,13 @@
 package org.eolang.jeo.representation.directives;
 
 import com.jcabi.matchers.XhtmlMatchers;
+import java.util.stream.Stream;
 import org.hamcrest.MatcherAssert;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.xembly.Directives;
 import org.xembly.ImpossibleModificationException;
 import org.xembly.Xembler;
 
@@ -52,4 +57,48 @@ void convertsToNumberedSeq() throws ImpossibleModificationException {
             )
         );
     }
+
+    @ParameterizedTest
+    @MethodSource("sequences")
+    void correctlyComputesSize(
+        final DirectivesSeq actual, final int expected
+    ) throws ImpossibleModificationException {
+        MatcherAssert.assertThat(
+            "The size of the sequence is not as expected",
+            new Xembler(actual).xml(),
+            XhtmlMatchers.hasXPath(
+                String.format(
+                    "/o[contains(@base,'seq.of%d') and @name='@']",
+                    expected
+                )
+            )
+        );
+    }
+
+    /**
+     * Sequences to test.
+     * @return Stream of arguments.
+     */
+    private static Stream<Arguments> sequences() {
+        return Stream.of(
+            Arguments.of(
+                new DirectivesSeq(
+                    new DirectivesValue("1"), new DirectivesValue("2")
+                ),
+                2
+            ),
+            Arguments.of(new DirectivesSeq(), 0),
+            Arguments.of(new DirectivesSeq(new Directives(), new Directives()), 0),
+            Arguments.of(
+                new DirectivesSeq(
+                    new DirectivesValue("1"), new Directives(),
+                    new Directives(), new DirectivesValue("4")
+                ),
+                2
+            ),
+            Arguments.of(
+                new DirectivesSeq(), 0
+            )
+        );
+    }
 }