[CodeCompletion] Improve ordering of prefix matches vs popular names

In the experimental code-completion path.

rdar://problem/24843463

Author: benlangmuir

test/SourceKit/CodeComplete/complete_fuzzy.swift

@@ -105,8 +105,8 @@ struct Test4 {
 
 // CONTEXT_SORT_2: Results for filterText: myVa [
 // CONTEXT_SORT_2-NEXT: myVarTest4
-// CONTEXT_SORT_2-NEXT: myLocalVar
 // CONTEXT_SORT_2-NEXT: myVar
+// CONTEXT_SORT_2-NEXT: myLocalVar
 
 // CONTEXT_SORT_3: Results for filterText: myVa [
 // CONTEXT_SORT_3-NEXT: myVar

test/SourceKit/CodeComplete/complete_popular_api.swift

@@ -81,10 +81,10 @@ struct OuterNominal {
 // POPULAR_STMT_0:   okay()
 // POPULAR_STMT_0:   DDModuleColor
 // POPULAR_STMT_0:   CCModuleColor
-// POPULAR_STMT_0:   EEModuleColor
-// bad() ends up here because it's an unpopular global but that's still better
-// than a random "other module" result like ModuleCollaborate.
+// bad() ends up here because it's an unpopular global but that's still
+// generally better than "other module" results.
 // POPULAR_STMT_0:   bad()
+// POPULAR_STMT_0:   EEModuleColor
 // POPULAR_STMT_0:   ModuleCollaborate
 // POPULAR_STMT_0: ]
 // POPULAR_STMT_0-LABEL: Results for filterText: col [
@@ -104,3 +104,41 @@ struct OuterNominal {
     }
   }
 }
+
+struct Outer {
+  struct ABTabularMonkey {}
+  struct ABTextMockery {}
+  struct ABTradeableEquity {}
+  struct ABVocalContour {}
+  struct ABBobtail {}
+  struct ABFont {}
+}
+
+// RUN: %complete-test -hide-none -fuzz -group=none -popular="%s.popular" -unpopular="%s.unpopular" -tok=POPULAR_VS_PREFIX_1 %s -- -I %S/Inputs | FileCheck %s -check-prefix=POPULAR_VS_PREFIX_1
+func testPopularityVsPrefixMatch1() {
+  let x: Outer.#^POPULAR_VS_PREFIX_1,,AB,ABT^#
+}
+// POPULAR_VS_PREFIX_1-LABEL: Results for filterText:  [
+// POPULAR_VS_PREFIX_1-NEXT:    ABVocalContour
+// POPULAR_VS_PREFIX_1-NEXT:    ABBobtail
+// POPULAR_VS_PREFIX_1-NEXT:    ABFont
+// POPULAR_VS_PREFIX_1-NEXT:    ABTabularMonkey
+// POPULAR_VS_PREFIX_1-NEXT:    ABTextMockery
+// POPULAR_VS_PREFIX_1-NEXT:    ABTradeableEquity
+// POPULAR_VS_PREFIX_1: ]
+// POPULAR_VS_PREFIX_1-LABEL: Results for filterText: AB [
+// POPULAR_VS_PREFIX_1-NEXT:    ABVocalContour
+// POPULAR_VS_PREFIX_1-NEXT:    ABBobtail
+// POPULAR_VS_PREFIX_1-NEXT:    ABFont
+// POPULAR_VS_PREFIX_1-NEXT:    ABTextMockery
+// POPULAR_VS_PREFIX_1-NEXT:    ABTabularMonkey
+// POPULAR_VS_PREFIX_1-NEXT:    ABTradeableEquity
+// POPULAR_VS_PREFIX_1-NEXT: ]
+// POPULAR_VS_PREFIX_1-LABEL: Results for filterText: ABT [
+// POPULAR_VS_PREFIX_1-NEXT:    ABTextMockery
+// POPULAR_VS_PREFIX_1-NEXT:    ABTabularMonkey
+// POPULAR_VS_PREFIX_1-NEXT:    ABTradeableEquity
+// POPULAR_VS_PREFIX_1-NEXT:    ABVocalContour
+// POPULAR_VS_PREFIX_1-NEXT:    ABBobtail
+// POPULAR_VS_PREFIX_1-NEXT:    ABFont
+// POPULAR_VS_PREFIX_1-NEXT: ]

test/SourceKit/CodeComplete/complete_popular_api.swift.popular

@@ -3,3 +3,6 @@ xhappy
 EEModuleColor
 DDModuleColor
 CCModuleColor
+ABVocalContour
+ABBobtail
+ABFont

tools/SourceKit/lib/Support/FuzzyStringMatcher.cpp

@@ -46,7 +46,7 @@ FuzzyStringMatcher::FuzzyStringMatcher(StringRef pattern_)
                pattern.size() * pattern.size(); // max run length score
     if (upperCharCount)                         // max uppercase match score
       maxScore += (upperCharCount + 1) * (upperCharCount + 1);
-    maxScore *= 1.1; // exact match bonus
+    maxScore *= 1.1 * 2.5; // exact prefix match bonus
   }
 }
 
@@ -501,6 +501,10 @@ CandidateSpecificMatcher::scoreCandidateTrial(unsigned firstPatternPos) {
     trialScore *= 1.1;
   }
 
+  // Exact prefix matches are the best.
+  if (!runs.empty() && runs[0].location == 0 && runs[0].length == patternLength)
+    trialScore *= 2.5;
+
   // FIXME: popular/unpopular API.
 
   // We really don't like matches that don't start at a token.

tools/SourceKit/lib/SwiftLang/CodeCompletionOrganizer.h

@@ -47,7 +47,7 @@ struct Options {
   // the same as the worst possible match N/10 "contexts" ahead of it.
   unsigned semanticContextWeight = 10 * Completion::numSemanticContexts;
   unsigned fuzzyMatchWeight = 9;
-  unsigned popularityBonus = 9;
+  unsigned popularityBonus = 5;
 };
 
 struct SwiftCompletionInfo {

unittests/SourceKit/Support/FuzzyStringMatcherTest.cpp

@@ -276,8 +276,8 @@ TEST(FuzzyStringMatcher, NormalizeSingleCharacterScore) {
 TEST(FuzzyStringMatcher, NormalizeScore) {
   FuzzyStringMatcher m("AB");
   m.normalize = true;
-  EXPECT_EQ(1.0, m.scoreCandidate("AB"));
-  EXPECT_EQ(0.0, m.scoreCandidate("BB"));
+  EXPECT_DOUBLE_EQ(1.0, m.scoreCandidate("AB"));
+  EXPECT_DOUBLE_EQ(0.0, m.scoreCandidate("BB"));
   EXPECT_GT(1.0, m.scoreCandidate("ab"));
   EXPECT_LT(0.0, m.scoreCandidate("ab"));
   EXPECT_GT(1.0, m.scoreCandidate("ABB"));
@@ -291,8 +291,8 @@ TEST(FuzzyStringMatcher, NormalizeScore) {
 
   FuzzyStringMatcher n("abc");
   n.normalize = true;
-  EXPECT_EQ(1.0, n.scoreCandidate("abc"));
-  EXPECT_EQ(1.0, n.scoreCandidate("ABC"));
+  EXPECT_DOUBLE_EQ(1.0, n.scoreCandidate("abc"));
+  EXPECT_DOUBLE_EQ(1.0, n.scoreCandidate("ABC"));
 }
 
 TEST(FuzzyStringMatcher, TokenizingCharacters) {