feat(yakshaintellij): add ability to fold sections

editor/intellij/src/main/java/org/intellij/sdk/language/YakshaFolderBuilder.java

@@ -0,0 +1,65 @@
+package org.intellij.sdk.language;
+
+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.project.DumbAware;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.SyntaxTraverser;
+import org.intellij.sdk.language.psi.YakshaClassBlock;
+import org.intellij.sdk.language.psi.YakshaDefBlock;
+import org.intellij.sdk.language.psi.YakshaDslOuterBlock;
+import org.intellij.sdk.language.psi.YakshaEnumBlock;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class YakshaFolderBuilder extends FoldingBuilderEx implements DumbAware {
+    @Override
+    public FoldingDescriptor @NotNull [] buildFoldRegions(@NotNull PsiElement root, @NotNull Document document, boolean quick) {
+        return SyntaxTraverser.psiTraverser(root)
+                .filter(i -> (i instanceof YakshaClassBlock || i instanceof YakshaDefBlock || i instanceof YakshaEnumBlock || i instanceof YakshaDslOuterBlock))
+                .map(i -> new YakshaFoldingDesc(i, getRange(i)))
+                .toList().toArray(new FoldingDescriptor[0]);
+    }
+
+    @Override
+    public @Nullable String getPlaceholderText(@NotNull ASTNode node) {
+        return "...";
+    }
+
+    @Override
+    public boolean isCollapsedByDefault(@NotNull ASTNode node) {
+        return false;
+    }
+
+    private static TextRange getRange(PsiElement elm) {
+        TextRange range = elm.getTextRange();
+        final String text = elm.getText();
+        if (elm instanceof YakshaDefBlock || elm instanceof YakshaClassBlock || elm instanceof YakshaEnumBlock || elm instanceof YakshaDslOuterBlock) {
+            if (text.endsWith("\r\n\r\n")) {
+                return new TextRange(range.getStartOffset(), range.getEndOffset() - 4);
+            } else if (text.endsWith("\r\n")) {
+                return new TextRange(range.getStartOffset(), range.getEndOffset() - 2);
+            } else if (text.endsWith("\n\n")) {
+                return new TextRange(range.getStartOffset(), range.getEndOffset() - 2);
+            } else if (text.endsWith("\n")) {
+                return new TextRange(range.getStartOffset(), range.getEndOffset() - 1);
+            }
+        }
+        return range;
+    }
+
+    public static class YakshaFoldingDesc extends FoldingDescriptor {
+
+        public YakshaFoldingDesc(PsiElement element, TextRange range) {
+            super(element.getNode(), range);
+        }
+
+        @Override
+        public @Nullable String getPlaceholderText() {
+            return "...";
+        }
+    }
+}

editor/intellij/src/main/resources/META-INF/plugin.xml

@@ -41,6 +41,9 @@
         <lang.psiStructureViewFactory
                 language="Yaksha"
                 implementationClass="org.intellij.sdk.language.YakshaStructureViewFactory"/>
+        <lang.foldingBuilder
+                language="Yaksha"
+                implementationClass="org.intellij.sdk.language.YakshaFolderBuilder"/>
         <annotator
                 language="Yaksha"
                 implementationClass="org.intellij.sdk.language.YakshaAnnotator"/>