From 297b17c365cb87fda11e23c0c2f540cd7fe8e143 Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Thu, 27 Dec 2012 11:45:17 +0100
Subject: [PATCH] correct backspace and completion preview interaction

---
 .../codeInsight/lookup/impl/CompletionPreview.java  | 13 ++++++-------
 .../codeInsight/lookup/impl/LookupImpl.java         |  6 +++++-
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java b/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java
index b3c038591d45..a85e03569af3 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java
+++ b/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java
@@ -39,12 +39,12 @@ public class CompletionPreview {
   private final LookupImpl myLookup;
   private Disposable myUninstaller;
 
-  private CompletionPreview(LookupImpl lookup, final String text, final String prefix) {
+  private CompletionPreview(LookupImpl lookup, final String text, final int prefixLength) {
     myLookup = lookup;
 
     final Editor editor = myLookup.getEditor();
     final int caret = editor.getCaretModel().getOffset();
-    int previewStart = caret - prefix.length();
+    int previewStart = caret - prefixLength;
     final int previewEnd = previewStart + text.length();
 
     myLookup.performGuardedChange(new Runnable() {
@@ -54,7 +54,7 @@ public class CompletionPreview {
           public void run() {
             AccessToken token = WriteAction.start();
             try {
-              editor.getDocument().insertString(caret, text.substring(prefix.length()));
+              editor.getDocument().insertString(caret, text.substring(prefixLength));
             }
             finally {
               token.finish();
@@ -131,12 +131,11 @@ public class CompletionPreview {
       }
     }
 
-    String prefix = lookup.itemPattern(item);
-    if (prefix.length() > text.length()) {
+    int prefixLength = lookup.getPrefixLength(item);
+    if (prefixLength > text.length()) {
       return;
     }
-    
-    new CompletionPreview(lookup, text, prefix);
+    new CompletionPreview(lookup, text, prefixLength);
   }
 
   public void uninstallPreview() {
diff --git a/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/LookupImpl.java b/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/LookupImpl.java
index c66c9cd2204f..5d0df23ca057 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/LookupImpl.java
+++ b/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/LookupImpl.java
@@ -623,7 +623,7 @@ public class LookupImpl extends LightweightHint implements LookupEx, Disposable
     myFinishing = true;
     AccessToken token = WriteAction.start();
     try {
-      insertLookupString(item, myOffsets.getPrefixLength(item, this));
+      insertLookupString(item, getPrefixLength(item));
     }
     finally {
       token.finish();
@@ -638,6 +638,10 @@ public class LookupImpl extends LightweightHint implements LookupEx, Disposable
     fireItemSelected(item, completionChar);
   }
 
+  public int getPrefixLength(LookupElement item) {
+    return myOffsets.getPrefixLength(item, this);
+  }
+
   private void insertLookupString(LookupElement item, final int prefix) {
     Document document = myEditor.getDocument();