Fix scoring to favor exact substring matches

spec/filter-spec.coffee

@@ -15,13 +15,13 @@ rootPath = (segments...) ->
 
 describe "filtering", ->
   it "returns an array of the most accurate results", ->
-    candidates = ['Gruntfile','filter', 'bile', null, '', undefined]
-    expect(filter(candidates, 'file')).toEqual ['filter', 'Gruntfile']
+    candidates = ['Gruntfile', 'filter', 'bile', null, '', undefined]
+    expect(filter(candidates, 'file')).toEqual ['Gruntfile', 'filter']
 
   describe "when the maxResults option is set", ->
     it "limits the results to the result size", ->
       candidates = ['Gruntfile', 'filter', 'bile']
-      expect(bestMatch(candidates, 'file')).toBe 'filter'
+      expect(bestMatch(candidates, 'file')).toBe 'Gruntfile'
 
   describe "when the entries contains slashes", ->
     it "weighs basename matches higher", ->

src/scorer.coffee

@@ -48,6 +48,20 @@ exports.score = (string, query) ->
   # Return a perfect score if the file name itself matches the query.
   return 1 if queryIsLastPathSegment(string, query)
 
+  # Return a near perfect score if the query is a substring match
+  baseScore = 0
+  substrIndex = string.indexOf(query)
+  substrIndexi = string.toLowerCase().indexOf(query.toLowerCase())
+
+  if substrIndex >= 0
+    baseScore = 0.80
+    baseScore = 0.95 if substrIndex == 0
+    baseScore = 0.90 if string[substrIndex - 1] == PathSeparator
+  else if substrIndexi >= 0
+    baseScore = 0.78
+    baseScore = 0.93 if substrIndexi == 0
+    baseScore = 0.88 if string[substrIndexi - 1] == PathSeparator
+
   totalCharacterScore = 0
   queryLength = query.length
   stringLength = string.length
@@ -82,7 +96,12 @@ exports.score = (string, query) ->
     totalCharacterScore += characterScore
 
   queryScore = totalCharacterScore / queryLength
-  ((queryScore * (queryLength / stringLength)) + queryScore) / 2
+  queryScore = ((queryScore * (queryLength / stringLength)) + queryScore) / 2
+
+  if baseScore != 0
+    queryScore = baseScore + (queryScore * 0.05)
+
+  queryScore
 
 queryIsLastPathSegment = (string, query) ->
   if string[string.length - query.length - 1] is PathSeparator