"Navigating the PSI" and "PSI References" sections

psi_demo.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="PLUGIN_MODULE" version="4">
+  <component name="DevKit.ModuleBuildProperties" url="file://$MODULE_DIR$/resources/META-INF/plugin.xml" />
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/resources" type="java-resource" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

resources/META-INF/plugin.xml

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+<idea-plugin>
+  <id>com.jetbrains.psidemo</id>
+  <name>PSI demo</name>
+  <version>1.0</version>
+  <vendor email="support@yourcompany.com" url="http://www.yourcompany.com">YourCompany</vendor>
+
+  <!-- please see http://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/build_number_ranges.html for description -->
+  <idea-version since-build="173.0"/>
+
+  <!-- please see http://www.jetbrains.org/intellij/sdk/docs/basics/getting_started/plugin_compatibility.html
+       on how to target different products -->
+  <!-- uncomment to enable plugin in all products
+  <depends>com.intellij.modules.lang</depends>
+  -->
+
+  <extensions defaultExtensionNs="com.intellij">
+    <!-- Add your extensions here -->
+  </extensions>
+
+  <actions>
+    <action class="com.intellij.tutorials.psi.PsiNavigationDemoAction" id="PsiNavigationDemo" text="PSI Navigation Demo...">
+      <add-to-group group-id="ToolsMenu" anchor="last"/>
+    </action>
+  </actions>
+
+</idea-plugin>

src/com/intellij/tutorials/psi/PsiNavigationDemoAction.java

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+package com.intellij.tutorials.psi;
+
+import com.intellij.openapi.actionSystem.AnAction;
+import com.intellij.openapi.actionSystem.AnActionEvent;
+import com.intellij.openapi.actionSystem.CommonDataKeys;
+import com.intellij.openapi.editor.Editor;
+import com.intellij.openapi.ui.Messages;
+import com.intellij.psi.*;
+import com.intellij.psi.util.PsiTreeUtil;
+
+public class PsiNavigationDemoAction extends AnAction {
+    @Override
+    public void actionPerformed(AnActionEvent anActionEvent) {
+        Editor editor = anActionEvent.getData(CommonDataKeys.EDITOR);
+        PsiFile psiFile = anActionEvent.getData(CommonDataKeys.PSI_FILE);
+        if (editor == null || psiFile == null) return;
+        int offset = editor.getCaretModel().getOffset();
+
+        final StringBuilder infoBuilder = new StringBuilder();
+        PsiElement element = psiFile.findElementAt(offset);
+        infoBuilder.append("Element at caret: ").append(element).append("\n");
+        if (element != null) {
+            PsiMethod containingMethod = PsiTreeUtil.getParentOfType(element, PsiMethod.class);
+            infoBuilder
+                    .append("Containing method: ")
+                    .append(containingMethod != null ? containingMethod.getName() : "none")
+                    .append("\n");
+            if (containingMethod != null) {
+                PsiClass containingClass = containingMethod.getContainingClass();
+                infoBuilder
+                        .append("Containing class: ")
+                        .append(containingClass != null ? containingClass.getName() : "none")
+                        .append("\n");
+
+                infoBuilder.append("Local variables:\n");
+                containingMethod.accept(new JavaRecursiveElementVisitor() {
+                    @Override
+                    public void visitLocalVariable(PsiLocalVariable variable) {
+                        super.visitLocalVariable(variable);
+                        infoBuilder.append(variable.getName()).append("\n");
+                    }
+                });
+            }
+        }
+        Messages.showMessageDialog(anActionEvent.getProject(), infoBuilder.toString(), "PSI Info", null);
+    }
+
+    @Override
+    public void update(AnActionEvent e) {
+        Editor editor = e.getData(CommonDataKeys.EDITOR);
+        PsiFile psiFile = e.getData(CommonDataKeys.PSI_FILE);
+        e.getPresentation().setEnabled(editor != null && psiFile != null);
+    }
+}