Include required parameter names when completing a method call.

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartServerProposal.java

Index: editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartServerProposal.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartServerProposal.java b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartServerProposal.java
index 8770763537247031410f1486a8b0976428a28e47..09a8b9cb499eaa3214c321e8373ae95f802bcb69 100644
--- a/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartServerProposal.java
+++ b/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartServerProposal.java
@@ -95,6 +95,7 @@ import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.URL;
+import java.util.List;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
@@ -154,14 +155,41 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
 
   private Image image;
 
-  /** Offset needed when the proposal is applied */
+  /**
+   * The offset into {@link replacementString} where the cursor should be placed if the proposal is
+   * accepted. Computed by computeReplacement().
+   */
   private int selectionOffset = 0;
 
   /**
+   * The length of text that should be selected if the proposal is accepted. Computed by
+   * computeReplacement().
+   */
+  private int selectionLength = 0;
+
+  /**
    * The {@link IInformationControlCreator} for documentation.
    */
   private IInformationControlCreator informationControlCreator;
 
+  /**
+   * The replacement string, or null if it has not yet been computed. Computed by
+   * computeReplacement().
+   */
+  private String replacementString = null;
+
+  /**
+   * If the completion is a method call with at least one argument, offsets within replacementString
+   * of the arguments. Otherwise null. Computed by computeReplacement().
+   */
+  private int[] argumentOffsets = null;
+
+  /**
+   * If the completion is a method call with at least one argument, the lengths of the arguments.
+   * Otherwise null. Computed by computeReplacement().

[danrubel, 2015/01/06 23:49:36]

I recommend dropping the "Computed by ..." from all the above comments. It is
not needed to understand the field and will not be noticed by the refactoring
tools. If it is important to document this, then perhaps use @see

More specifically... there is no 'computeReplacement()' method.

[Paul Berry, 2015/01/07 15:39:14]

Whoops, that was supposed to be computeCompletion().  IMHO, if a field isn't
valid for the full lifetime of the object, the documentation for the field
should say so.  I've fixed the comment and used a @see link.

+   */
+  private int[] argumentLengths = null;
+
   public DartServerProposal(DartServerProposalCollector collector, CompletionSuggestion suggestion) {
     this.collector = collector;
     this.suggestion = suggestion;
@@ -197,7 +225,6 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
        */
       if (replacementLength == 0 && trigger == '.') {
         doc.replace(offset, 0, Character.toString(trigger));
-        selectionOffset = 1;
         return;
       }
       /*
@@ -211,31 +238,18 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
        * Insert the suggestion
        */
       doc.replace(replacementOffset, replacementLength, completion);
-      selectionOffset = completion.length();
       /*
        * If the suggestion has parameters, initiate entering parameters
        */
-      int newOffset = replacementOffset + completion.length();
-      String param = getParamString();
-      if (param != null) {
-        doc.replace(newOffset, 0, "()");
-        ++newOffset;
-        ++selectionOffset;
-        if (param.length() == 2) { // param is "()"
-          ++selectionOffset;
-          return;
-        }
-        LinkedPositionGroup group = new LinkedPositionGroup();
-        group.addPosition(new LinkedPosition(doc, newOffset, 0, LinkedPositionGroup.NO_STOP));
-
+      if (argumentLengths != null) {
+        // Set up linked position groups for the arguments.
         LinkedModeModel model = new LinkedModeModel();
-        model.addGroup(group);
+        buildLinkedModeModel(model, doc, replacementOffset);
         model.forceInstall();
 
         LinkedModeUI ui = new EditorLinkedModeUI(model, viewer);
-        ui.setSimpleMode(true);
         ui.setExitPolicy(new ExitPolicy(')', doc, viewer));
-        ui.setExitPosition(viewer, newOffset + 1, 0, Integer.MAX_VALUE);
+        ui.setExitPosition(viewer, replacementOffset + completion.length(), 0, Integer.MAX_VALUE);
         ui.setCyclingMode(LinkedModeUI.CYCLE_NEVER);
         ui.enter();
         return;
@@ -244,8 +258,12 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
        * Insert the trigger character typed if it is not enter or null
        */
       if (trigger != '\0' && trigger != '\n') {
-        doc.replace(newOffset, 0, Character.toString(trigger));
+        doc.replace(
+            replacementOffset + selectionOffset,
+            selectionLength,
+            Character.toString(trigger));
         ++selectionOffset;
+        selectionLength = 0;
         return;
       }
     } catch (BadLocationException e) {
@@ -373,7 +391,8 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
 
   @Override
   public Point getSelection(IDocument document) {
-    return new Point(collector.getReplacementOffset() + selectionOffset, 0);
+    computeCompletion();
+    return new Point(collector.getReplacementOffset() + selectionOffset, selectionLength);
   }
 
   @Override
@@ -430,6 +449,64 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
         || CharOperation.camelCaseMatch(pattern, 0, pattern.length, name, 0, name.length, false);
   }
 
+  protected void buildLinkedModeModel(LinkedModeModel model, IDocument document, int baseOffset)
+      throws BadLocationException {
+    // TODO(paulberry): consider extending to support optional arguments, as
+    // FilledArgumentNamesMethodProposal does.
+    for (int i = 0; i != argumentOffsets.length; i++) {
+      LinkedPositionGroup group = new LinkedPositionGroup();
+      LinkedPosition pos = new LinkedPosition(
+          document,
+          baseOffset + argumentOffsets[i],
+          argumentLengths[i],
+          LinkedPositionGroup.NO_STOP);
+      group.addPosition(pos);
+      model.addGroup(group);
+    }
+  }
+
+  /**
+   * Compute {@link replacementString} and {@link selectionOffset} if they haven't been computed

[danrubel, 2015/01/06 23:49:36]

If you are listing specifically what it computes, do you want to list them all?
selectionLength, argumentOffsets, argumentLengths?

[Paul Berry, 2015/01/07 15:39:14]

Oops, yes, I do.  Fixed.

+   * already.
+   */
+  private void computeCompletion() {
+    if (replacementString != null) {
+      // Already computed.
+      return;
+    }
+    List<String> parameterNames = suggestion.getParameterNames();
+    if (parameterNames == null) {
+      // Just complete a single identifier.
+      replacementString = suggestion.getCompletion();
+      selectionOffset = replacementString.length();
+      selectionLength = 0;
+    } else {
+      // Complete with the identifier, parens, and arguments.
+      StringBuffer buffer = new StringBuffer(suggestion.getCompletion());
+      buffer.append('(');
+      int requiredParameterCount = suggestion.getRequiredParameterCount();
+      if (requiredParameterCount > 0) {
+        argumentOffsets = new int[requiredParameterCount];
+        argumentLengths = new int[requiredParameterCount];
+        for (int i = 0; i < requiredParameterCount; i++) {
+          if (i != 0) {
+            buffer.append(", ");
+          }
+          argumentOffsets[i] = buffer.length();
+          buffer.append(parameterNames.get(i));
+          argumentLengths[i] = buffer.length() - argumentOffsets[i];
+        }
+        selectionOffset = argumentOffsets[0];
+        selectionLength = argumentLengths[0];
+      } else {
+        selectionOffset = buffer.length();
+        selectionLength = 0;
+      }
+      buffer.append(')');
+      replacementString = buffer.toString();
+    }
+  }
+
   private Image computeImage() {
     ImageDescriptorRegistry fRegistry = DartToolsPlugin.getImageDescriptorRegistry();
     ImageDescriptor descriptor = null;
@@ -514,7 +591,8 @@ public class DartServerProposal implements ICompletionProposal, ICompletionPropo
   }
 
   private String getCompletion() {
-    return suggestion.getCompletion();
+    computeCompletion();
+    return replacementString;
   }
 
   /**