Cleanup of API for qualified names of expressions

Added PyQualifiedExpression.asQualifiedName() and moved utility
functions to PyPsiUtils. Expression classes can now cache the results
of calculating their qualified names.

python/psi-api/src/com/jetbrains/python/psi/PyQualifiedExpression.java

@@ -17,6 +17,7 @@ package com.jetbrains.python.psi;
 
 import com.intellij.lang.ASTNode;
 import com.intellij.psi.PsiPolyVariantReference;
+import com.intellij.psi.util.QualifiedName;
 import com.jetbrains.python.psi.resolve.PyResolveContext;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -37,6 +38,12 @@ public interface PyQualifiedExpression extends PyExpression {
    */
   boolean isQualified();
 
+  /**
+   * Returns the qualified name for the expression if all the qualifiers are qualified expressions.
+   */
+  @Nullable
+  QualifiedName asQualifiedName();
+
   /**
    * Returns the name to the right of the qualifier.
    *

python/psi-api/src/com/jetbrains/python/psi/PyReferenceExpression.java

@@ -16,11 +16,9 @@
 package com.jetbrains.python.psi;
 
 import com.intellij.psi.PsiPolyVariantReference;
-import com.intellij.psi.util.QualifiedName;
 import com.jetbrains.python.psi.resolve.PyResolveContext;
 import com.jetbrains.python.psi.resolve.QualifiedResolveResult;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 /**
  * @author yole
@@ -40,9 +38,6 @@ public interface PyReferenceExpression extends PyQualifiedExpression, PyReferenc
   @NotNull
   QualifiedResolveResult followAssignmentsChain(PyResolveContext resolveContext);
 
-  @Nullable
-  QualifiedName asQualifiedName();
-
   @NotNull
   PsiPolyVariantReference getReference();
 }

python/psi-api/src/com/jetbrains/python/psi/impl/PyPsiUtils.java

@@ -23,6 +23,7 @@ import com.intellij.psi.*;
 import com.intellij.psi.stubs.StubElement;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.psi.util.QualifiedName;
 import com.intellij.util.ArrayUtil;
 import com.intellij.util.containers.ContainerUtil;
 import com.jetbrains.python.PyTokenTypes;
@@ -32,6 +33,7 @@ import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Array;
 import java.util.ArrayList;
+import java.util.LinkedList;
 import java.util.List;
 
 /**
@@ -375,6 +377,65 @@ public class PyPsiUtils {
     return element.getTextOffset() <= element2.getTextOffset();
   }
 
+  @Nullable
+  public static QualifiedName asQualifiedName(@Nullable PyExpression expr) {
+    return expr instanceof PyQualifiedExpression ? ((PyQualifiedExpression)expr).asQualifiedName() : null;
+  }
+
+  @Nullable
+  public static PyExpression getFirstQualifier(@NotNull PyQualifiedExpression expr) {
+    final List<PyExpression> expressions = unwindQualifiers(expr);
+    if (!expressions.isEmpty()) {
+      return expressions.get(0);
+    }
+    return null;
+  }
+
+  @NotNull
+  public static String toPath(@Nullable PyQualifiedExpression expr) {
+    if (expr != null) {
+      final QualifiedName qName = expr.asQualifiedName();
+      if (qName != null) {
+        return qName.toString();
+      }
+      final String name = expr.getName();
+      if (name != null) {
+        return name;
+      }
+    }
+    return "";
+  }
+
+  @Nullable
+  protected static QualifiedName asQualifiedName(@NotNull PyQualifiedExpression expr) {
+    return fromReferenceChain(unwindQualifiers(expr));
+  }
+
+  @NotNull
+  private static List<PyExpression> unwindQualifiers(@NotNull final PyQualifiedExpression expr) {
+    final List<PyExpression> path = new LinkedList<PyExpression>();
+    PyQualifiedExpression e = expr;
+    while (e != null) {
+      path.add(0, e);
+      final PyExpression q = e.getQualifier();
+      e = q instanceof PyQualifiedExpression ? (PyQualifiedExpression)q : null;
+    }
+    return path;
+  }
+
+  @Nullable
+  private static QualifiedName fromReferenceChain(@NotNull List<PyExpression> components) {
+    final List<String> componentNames = new ArrayList<String>(components.size());
+    for (PyExpression component : components) {
+      final String refName = (component instanceof PyQualifiedExpression) ? ((PyQualifiedExpression)component).getReferencedName() : null;
+      if (refName == null) {
+        return null;
+      }
+      componentNames.add(refName);
+    }
+    return QualifiedName.fromComponents(componentNames);
+  }
+
   private static abstract class TopLevelVisitor extends PyRecursiveElementVisitor {
     public void visitPyElement(final PyElement node) {
       super.visitPyElement(node);

python/psi-api/src/com/jetbrains/python/psi/impl/PyQualifiedNameFactory.java

@@ -1,48 +0,0 @@
-/*
- * Copyright 2000-2013 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.jetbrains.python.psi.impl;
-
-import com.intellij.psi.util.QualifiedName;
-import com.jetbrains.python.psi.PyExpression;
-import com.jetbrains.python.psi.PyQualifiedExpression;
-import com.jetbrains.python.psi.PyReferenceExpression;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.ArrayList;
-import java.util.List;
-
-/**
- * @author yole
- */
-public class PyQualifiedNameFactory {
-  @Nullable
-  public static QualifiedName fromReferenceChain(List<PyExpression> components) {
-    List<String> componentNames = new ArrayList<String>(components.size());
-    for (PyExpression component : components) {
-      final String refName = (component instanceof PyQualifiedExpression) ? ((PyQualifiedExpression)component).getReferencedName() : null;
-      if (refName == null) {
-        return null;
-      }
-      componentNames.add(refName);
-    }
-    return QualifiedName.fromComponents(componentNames);
-  }
-
-  @Nullable
-  public static QualifiedName fromExpression(PyExpression expr) {
-    return expr instanceof PyReferenceExpression ? ((PyReferenceExpression) expr).asQualifiedName() : null;
-  }
-}