Factor pushMatchingRanges, improve comments/tests

1. Factor out `pushMatchingRanges`:
   This then allows us to ...
2. Add unit tests for `pushMatchingRanges`
   In effect, these tests verify where matches are highlighted in suggestions.
3. Added Utils.zip.  This helps simplify `pushMatchingRanges` unit tests.
4. Improve comments.

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/utils.coffee b/lib/utils.coffee
index e89d0aa2..c997b74b 100644
--- a/lib/utils.coffee
+++ b/lib/utils.coffee
@@ -126,6 +126,14 @@ Utils =
         return 1
     0
 
+  # Zip two (or more) arrays:
+  #   - Utils.zip([ [a,b], [1,2] ]) returns [ [a,1], [b,2] ]
+  #   - Length of result is `arrays[0].length`.
+  #   - Adapted from: http://stackoverflow.com/questions/4856717/javascript-equivalent-of-pythons-zip-function
+  zip: (arrays) ->
+    arrays[0].map (_,i) ->
+      arrays.map( (array) -> array[i] )
+    
 # This creates a new function out of an existing function, where the new function takes fewer arguments. This
 # allows us to pass around functions instead of functions + a partial list of arguments.
 Function::curry = ->