IDEA-68698 Elements with exactly same prefix (and same proximity) should be placed at the top of the list

java/java-tests/testData/codeInsight/completion/normalSorting/PreferMoreMatching.java

@@ -0,0 +1,9 @@
+class FooOCSomething {}
+class FooObjectCollector {}
+
+class Foo {
+    {
+        FooOC<caret>
+    }
+
+}

java/java-tests/testSrc/com/intellij/codeInsight/completion/NormalCompletionOrderingTest.java

@@ -209,6 +209,10 @@ public class NormalCompletionOrderingTest extends CompletionSortingTestCase {
     checkPreferredItems(0, "else", "element");
   }
 
+  public void testPreferMoreMatching() {
+    checkPreferredItems(0, "FooOCSomething", "FooObjectCollector");
+  }
+
   public void testPreferSamePackageOverImported() {
     myFixture.addClass("package bar; public class Bar1 {}");
     myFixture.addClass("package bar; public class Bar2 {}");

platform/lang-impl/src/com/intellij/codeInsight/completion/PrefixMatchingWeigher.java

@@ -15,12 +15,11 @@
  */
 package com.intellij.codeInsight.completion;
 
+import com.intellij.codeInsight.CodeInsightSettings;
 import com.intellij.codeInsight.lookup.LookupElement;
-import com.intellij.openapi.util.text.StringUtil;
+import com.intellij.psi.codeStyle.NameUtil;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.Set;
-
 /**
  * @author peter
 */
@@ -29,27 +28,16 @@ public class PrefixMatchingWeigher extends CompletionWeigher {
   public Comparable weigh(@NotNull final LookupElement item, @NotNull final CompletionLocation location) {
     final String prefix = location.getCompletionParameters().getLookup().itemPattern(item);
 
-    if (prefix.isEmpty()) {
-      return 0;
+    final int setting = CodeInsightSettings.getInstance().COMPLETION_CASE_SENSITIVE;
+    final NameUtil.MatchingCaseSensitivity sensitivity =
+      setting == CodeInsightSettings.NONE ? NameUtil.MatchingCaseSensitivity.NONE :
+      setting == CodeInsightSettings.FIRST_LETTER ? NameUtil.MatchingCaseSensitivity.FIRST_LETTER : NameUtil.MatchingCaseSensitivity.ALL;
+    final NameUtil.MinusculeMatcher matcher = new NameUtil.MinusculeMatcher(prefix, sensitivity);
+
+    int max = Integer.MIN_VALUE;
+    for (String lookupString : item.getAllLookupStrings()) {
+      max = Math.max(max, matcher.matchingDegree(lookupString));
     }
-
-    final Set<String> strings = item.getAllLookupStrings();
-    final String prefixHumps = StringUtil.capitalsOnly(prefix);
-
-    if (StringUtil.isNotEmpty(prefixHumps)) {
-      for (String lookupString : strings) {
-        if (StringUtil.capitalsOnly(lookupString).startsWith(prefixHumps)) return 100;
-      }
-    }
-
-    for (String lookupString : strings) {
-      if (lookupString.startsWith(prefix)) return 5;
-    }
-    for (String lookupString : strings) {
-      if (StringUtil.startsWithIgnoreCase(lookupString, prefix)) return 1;
-    }
-
-
-    return 0;
+    return max;
   }
 }