Initial implementation of 'Create Method' quick fix

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/codemanipulation/StubUtility.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/codemanipulation/StubUtility.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/codemanipulation/StubUtility.java b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/codemanipulation/StubUtility.java
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+++ b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/internal/corext/codemanipulation/StubUtility.java
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+/*
+ * Copyright (c) 2012, the Dart project authors.
+ * 
+ * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
+ * 
+ * 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.google.dart.tools.internal.corext.codemanipulation;
+
+import static com.google.dart.tools.core.dom.PropertyDescriptorHelper.DART_INVOCATION_ARGS;
+import static com.google.dart.tools.core.dom.PropertyDescriptorHelper.DART_NAMED_EXPRESSION_EXPRESSION;
+import static com.google.dart.tools.core.dom.PropertyDescriptorHelper.getLocationInParent;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+import com.google.dart.compiler.ast.DartBinaryExpression;
+import com.google.dart.compiler.ast.DartExpression;
+import com.google.dart.compiler.ast.DartIdentifier;
+import com.google.dart.compiler.ast.DartInvocation;
+import com.google.dart.compiler.ast.DartMethodInvocation;
+import com.google.dart.compiler.ast.DartNamedExpression;
+import com.google.dart.compiler.ast.DartPropertyAccess;
+import com.google.dart.compiler.ast.DartUnqualifiedInvocation;
+import com.google.dart.compiler.parser.Token;
+import com.google.dart.compiler.resolver.MethodElement;
+import com.google.dart.compiler.resolver.VariableElement;
+import com.google.dart.compiler.type.Type;
+import com.google.dart.compiler.type.TypeKind;
+import com.google.dart.compiler.util.apache.StringUtils;
+import com.google.dart.tools.core.dom.StructuralPropertyDescriptor;
+import com.google.dart.tools.internal.corext.refactoring.code.ExtractUtils;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * @coverage dart.editor.ui.corext
+ */
+public class StubUtility {
+  private static final String[] KNOWN_METHOD_NAME_PREFIXES = {"get", "is", "to"};
+
+  public static String[] getVariableNameSuggestions(Type expectedType,
+      DartExpression assignedExpression, Set<String> excluded) {
+    Set<String> res = Sets.newLinkedHashSet();
+    // use expression
+    if (assignedExpression != null) {
+      String nameFromExpression = getBaseNameFromExpression(assignedExpression);
+      if (nameFromExpression != null) {
+        addAll(excluded, res, getVariableNameSuggestions(nameFromExpression));
+      }
+
+      String nameFromParent = getBaseNameFromLocationInParent(assignedExpression);
+      if (nameFromParent != null) {
+        addAll(excluded, res, getVariableNameSuggestions(nameFromParent));
+      }
+    }
+    // use type
+    if (expectedType != null && TypeKind.of(expectedType) != TypeKind.DYNAMIC) {
+      String typeName = ExtractUtils.getTypeSource(expectedType);
+      if ("int".equals(typeName)) {
+        addSingleCharacterName(excluded, res, 'i');
+      } else if ("double".equals(typeName)) {
+        addSingleCharacterName(excluded, res, 'd');
+      } else {
+        typeName = StringUtils.substringBefore(typeName, "<");
+        addAll(excluded, res, getVariableNameSuggestions(typeName));
+      }
+      res.remove(typeName);
+    }
+    // done
+    return res.toArray(new String[res.size()]);
+  }
+
+  /**
+   * Adds "toAdd" items which are not excluded.
+   */
+  private static void addAll(Set<String> excluded, Set<String> result, Collection<String> toAdd) {
+    for (String item : toAdd) {
+      // add name based on "item", but not "excluded"
+      for (int suffix = 1;; suffix++) {
+        // prepare name, just "item" or "item2", "item3", etc
+        String name = item;
+        if (suffix > 1) {
+          name += suffix;
+        }
+        // add once found not excluded
+        if (!excluded.contains(name)) {
+          result.add(name);
+          break;
+        }
+      }
+    }
+  }
+
+  private static void addSingleCharacterName(Set<String> excluded, Set<String> result, char c) {
+    while (c < 'z') {
+      String name = String.valueOf(c);
+      // may be done
+      if (!excluded.contains(name)) {
+        result.add(name);
+        break;
+      }
+      // next character
+      c = (char) (c + 1);
+    }
+  }
+
+  private static String getBaseNameFromExpression(DartExpression expression) {
+    String name = null;
+    if (expression instanceof DartBinaryExpression) {
+      DartBinaryExpression binaryExpression = (DartBinaryExpression) expression;
+      if (binaryExpression.getOperator() == Token.AS) {
+        expression = binaryExpression.getArg1();
+      }
+    }
+    if (expression instanceof DartIdentifier) {
+      DartIdentifier node = (DartIdentifier) expression;
+      return node.getName();
+    } else if (expression instanceof DartPropertyAccess) {
+      DartPropertyAccess node = (DartPropertyAccess) expression;
+      return node.getName().getName();
+    } else if (expression instanceof DartMethodInvocation) {
+      name = ((DartMethodInvocation) expression).getFunctionName().getName();
+    } else if (expression instanceof DartUnqualifiedInvocation) {
+      name = ((DartUnqualifiedInvocation) expression).getTarget().getName();
+    }
+    if (name != null) {
+      for (int i = 0; i < KNOWN_METHOD_NAME_PREFIXES.length; i++) {
+        String curr = KNOWN_METHOD_NAME_PREFIXES[i];
+        if (name.startsWith(curr)) {
+          if (name.equals(curr)) {
+            return null; // don't suggest 'get' as variable name
+          } else if (Character.isUpperCase(name.charAt(curr.length()))) {
+            return name.substring(curr.length());
+          }
+        }
+      }
+    }
+    return name;
+  }
+
+  private static String getBaseNameFromLocationInParent(DartExpression expression) {
+    StructuralPropertyDescriptor location = getLocationInParent(expression);
+    // value in named expression
+    if (location == DART_NAMED_EXPRESSION_EXPRESSION) {
+      return ((DartNamedExpression) expression.getParent()).getName().getName();
+    }
+    // positional argument
+    if (location == DART_INVOCATION_ARGS) {
+      DartInvocation invocation = (DartInvocation) expression.getParent();
+      MethodElement invocationElement = (MethodElement) invocation.getElement();
+      Object parameterId = expression.getInvocationParameterId();
+      if (parameterId instanceof Integer) {
+        int index = ((Integer) parameterId).intValue();
+        List<VariableElement> parameters = invocationElement.getParameters();
+        if (index < parameters.size()) {
+          return parameters.get(index).getName();
+        }
+      }
+    }
+    // unknown
+    return null;
+  }
+
+  /**
+   * @return all variants of names by removing leading words by one.
+   */
+  private static List<String> getVariableNameSuggestions(String name) {
+    List<String> result = Lists.newArrayList();
+    String[] parts = name.split("(?<!(^|[A-Z]))(?=[A-Z])|(?<!^)(?=[A-Z][a-z])");
+    for (int i = 0; i < parts.length; i++) {
+      String suggestion = parts[i].toLowerCase() + StringUtils.join(parts, "", i + 1, parts.length);
+      result.add(suggestion);
+    }
+    return result;
+  }
+
+}