Resolve "Foldable aspects"

Closes #4 (closed)

src/main/java/org/jastadd/tooling/aspect/AspectFoldingBuilder.java

+package org.jastadd.tooling.aspect;
+
+
+import com.intellij.lang.ASTNode;
+import com.intellij.lang.folding.FoldingBuilderEx;
+import com.intellij.lang.folding.FoldingDescriptor;
+import com.intellij.openapi.editor.Document;
+import com.intellij.openapi.editor.FoldingGroup;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.util.PsiTreeUtil;
+import org.jastadd.tooling.aspect.psi.JastAddAspectAspectDeclaration;
+import org.jastadd.tooling.aspect.psi.JastAddAspectBlock;
+import org.jastadd.tooling.aspect.psi.JastAddAspectClassDeclaration;
+import org.jastadd.tooling.aspect.psi.JastAddAspectConstructorDeclaration;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+public class AspectFoldingBuilder extends FoldingBuilderEx {
+
+  @Override
+  public FoldingDescriptor @NotNull [] buildFoldRegions(@NotNull PsiElement root, @NotNull Document document, boolean quick) {
+    List<FoldingDescriptor> descriptors = new ArrayList<>();
+    Collection<JastAddAspectAspectDeclaration> aspectDeclarations = PsiTreeUtil.findChildrenOfType(root, JastAddAspectAspectDeclaration.class);
+    for (final JastAddAspectAspectDeclaration aspectDeclaration : aspectDeclarations) {
+      descriptors.add(new FoldingDescriptor(aspectDeclaration.getNode(),
+        new TextRange(aspectDeclaration.getAspectBody().getTextRange().getStartOffset() + 1,
+          aspectDeclaration.getAspectBody().getTextRange().getEndOffset() - 1)));
+    }
+    Collection<JastAddAspectClassDeclaration> classDeclarations = PsiTreeUtil.findChildrenOfType(root, JastAddAspectClassDeclaration.class);
+    for (final JastAddAspectClassDeclaration classDeclaration : classDeclarations) {
+      descriptors.add(new FoldingDescriptor(classDeclaration.getNode(),
+        new TextRange(classDeclaration.getClassBody().getTextRange().getStartOffset() + 1,
+          classDeclaration.getClassBody().getTextRange().getEndOffset() - 1)));
+    }
+    Collection<JastAddAspectBlock> aspectBlocks = PsiTreeUtil.findChildrenOfType(root, JastAddAspectBlock.class);
+    for (final JastAddAspectBlock block : aspectBlocks) {
+      descriptors.add(new FoldingDescriptor(block.getNode(),
+        new TextRange(block.getTextRange().getStartOffset() + 1,
+          block.getTextRange().getEndOffset() - 1)));
+    }
+    return descriptors.toArray(new FoldingDescriptor[0]);
+  }
+
+  @Nullable
+  @Override
+  public String getPlaceholderText(@NotNull ASTNode node) {
+    return " ... ";
+  }
+
+  @Override
+  public boolean isCollapsedByDefault(@NotNull ASTNode node) {
+    return false;
+  }
+
+}