From 5aaed906b94337bb2136d74672e16679ab457c49 Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Wed, 10 Jun 2015 14:23:58 +0100
Subject: Rank filtered hints by score.

Thus, better matches are likely to either be first (so just hitting
<Enter> activates them) or just a <Tab> or two away.

Scoring:
   - Requires that every search term be matched.
   - Assigns higher scores to matches at the start of a word, and higher
     scores still for whole-word matches.
---
 content_scripts/link_hints.coffee | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/content_scripts/link_hints.coffee b/content_scripts/link_hints.coffee
index 107a292e..ae9d3f8f 100644
--- a/content_scripts/link_hints.coffee
+++ b/content_scripts/link_hints.coffee
@@ -565,13 +565,41 @@ class FilterHints
   filterLinkHints: (hintMarkers) ->
     idx = 0
     linkSearchString = @linkTextKeystrokeQueue.join("").toLowerCase()
+    do (scoreFunction = @scoreLinkHint linkSearchString) ->
+      linkMarker.score = scoreFunction linkMarker for linkMarker in hintMarkers
+    hintMarkers = hintMarkers[..].sort (a,b) -> b.score - a.score
 
     for linkMarker in hintMarkers
-      continue unless 0 <= linkMarker.linkText.toLowerCase().indexOf linkSearchString
+      continue unless 0 < linkMarker.score
       linkMarker.hintString = @generateHintString idx++
       @renderMarker linkMarker
       linkMarker
 
+  # Assign a score to a filter match (higher is better).  We assign a higher score for matches at the start of
+  # a word, and a considerably higher score still for matches which are whole words.
+  # Note(smblott) if linkSearchString is empty, then every hint get a score of 2.
+  scoreLinkHint: (linkSearchString) ->
+    searchWords = linkSearchString.trim().split /\s+/
+    (linkMarker) ->
+      linkWords = linkMarker.linkWords ?= linkMarker.linkText.trim().toLowerCase().split /\s+/
+
+      searchWordScores =
+        for searchWord in searchWords
+          linkWordScores =
+            for linkWord in linkWords
+              if linkWord == searchWord
+                5
+              else if linkWord.startsWith searchWord
+                2
+              else if 0 <= linkWord.indexOf searchWord
+                1
+              else
+                0
+          Math.max linkWordScores...
+
+      addFunc = (a,b) -> a + b
+      if 0 in searchWordScores then 0 else searchWordScores.reduce addFunc, 0
+
 #
 # Make each hint character a span, so that we can highlight the typed characters as you type them.
 #
-- 
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