Add support for some basic rename refactoring

It does not work perfectly yet:
1. references are not linked together after rename
2. renaming on reference works well, but renaming on declaration renames only the declaration

src/glslplugin/lang/elements/GLSLIdentifier.java

@@ -61,7 +61,7 @@ public PsiElement setName(@NotNull String name) throws IncorrectOperationExcepti
         assert oldName != null; // we've already checked this isn't null (and thrown if it is) in checkSetName
         PsiElement newName = GLSLPsiElementFactory.createLeafElement(getProject(), name);
         getNode().replaceChild(oldName.getNode(), newName.getNode());
-        return this;
+        return newName;
     }
 
     @Nullable

src/glslplugin/lang/elements/declarations/GLSLFunctionDeclarationImpl.java

@@ -20,6 +20,11 @@
 package glslplugin.lang.elements.declarations;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiCheckedRenameElement;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiNameIdentifierOwner;
+import com.intellij.util.IncorrectOperationException;
+import glslplugin.lang.elements.GLSLIdentifier;
 import glslplugin.lang.elements.types.GLSLBasicFunctionType;
 import glslplugin.lang.elements.types.GLSLFunctionType;
 import org.jetbrains.annotations.NotNull;
@@ -28,7 +33,7 @@
 /**
  * GLSLFunctionDeclarationImpl is the psi implementation of a function declaration.
  */
-public class GLSLFunctionDeclarationImpl extends GLSLSingleDeclarationImpl implements GLSLFunctionDeclaration {
+public class GLSLFunctionDeclarationImpl extends GLSLSingleDeclarationImpl implements GLSLFunctionDeclaration, PsiNameIdentifierOwner, PsiCheckedRenameElement {
     private GLSLFunctionType type;
 
     public GLSLFunctionDeclarationImpl(@NotNull ASTNode astNode) {
@@ -95,4 +100,26 @@ private GLSLFunctionType createType() {
     public String getDeclarationDescription() {
         return "function";
     }
+
+    @Nullable
+    @Override
+    public GLSLIdentifier getNameIdentifier() {
+        final GLSLDeclarator declarator = getDeclarator();
+        if(declarator == null)return null;
+        return declarator.getNameIdentifier();
+    }
+
+    @Override
+    public PsiElement setName(@NotNull String name) throws IncorrectOperationException {
+        final GLSLIdentifier nameIdentifier = getNameIdentifier();
+        if(nameIdentifier == null)throw new IncorrectOperationException("GLSLDeclarator is null");
+        return nameIdentifier.setName(name);
+    }
+
+    @Override
+    public void checkSetName(String name) throws IncorrectOperationException {
+        final GLSLIdentifier nameIdentifier = getNameIdentifier();
+        if(nameIdentifier == null)throw new IncorrectOperationException("GLSLDeclarator is null");
+        nameIdentifier.checkSetName(name);
+    }
 }

src/glslplugin/lang/elements/declarations/GLSLFunctionDefinitionImpl.java

@@ -20,6 +20,9 @@
 package glslplugin.lang.elements.declarations;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiNameIdentifierOwner;
+import com.intellij.util.IncorrectOperationException;
 import glslplugin.lang.elements.statements.GLSLCompoundStatement;
 import org.jetbrains.annotations.Nullable;
 

src/glslplugin/lang/elements/expressions/GLSLFunctionCallExpression.java

@@ -20,7 +20,10 @@
 package glslplugin.lang.elements.expressions;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.psi.PsiCheckedRenameElement;
 import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiNameIdentifierOwner;
+import com.intellij.util.IncorrectOperationException;
 import glslplugin.lang.elements.GLSLElement;
 import glslplugin.lang.elements.GLSLIdentifier;
 import glslplugin.lang.elements.GLSLReferenceElement;
@@ -271,4 +274,13 @@ public String toString() {
             return "Function call: " + getFunctionName();
         }
     }
+
+    @Override
+    public String getName() {
+        if(isConstructor()){
+            return getType().getTypename();
+        } else {
+            return getFunctionName();
+        }
+    }
 }

src/glslplugin/lang/elements/reference/GLSLReferenceBase.java

@@ -69,7 +69,7 @@ public PsiElement handleElementRename(String newElementName) throws IncorrectOpe
         if (source instanceof PsiNamedElement) {
             return ((PsiNamedElement) source).setName(newElementName);
         }
-        throw new IncorrectOperationException("Not supported!");
+        return resolve();
     }
 
     public PsiElement bindToElement(@NotNull PsiElement element) throws IncorrectOperationException {