Avoid false positives on builtin fns errors.

Author: josephwilk

app/server/sonicpi/lib/sonicpi/preparser.rb

@@ -23,8 +23,11 @@ class PreParseError < StandardError ; end
     def self.preparse(rb)
       SonicPi::SpiderAPI.ring_fns.each do |fn|
         fn = fn[:name].to_s
-        rb.gsub!(/\((\s*)#{fn}(\s)/, '\1' + ' ' + fn + '(\2')
-        raise PreParseError, "You may not use the built-in fn names as variable names.\n You attempted to use: #{fn}" if rb.match(/\W#{fn}\s*=[\s\w]/)
+        rb.gsub!(/\((\s*)#{fn}(\s)/, '\1' + fn + '(\2')
+
+        if rb.match(/(?!\B)\W?#{fn}\s*=[\s\w]/)
+          raise PreParseError, "You may not use the built-in fn names as variable names.\n You attempted to use: #{fn}"
+        end
       end
       rb
     end

app/server/sonicpi/test/test_preparser.rb

@@ -15,22 +15,6 @@
 require_relative "../../core"
 require_relative "../lib/sonicpi/preparser"
 
-module SonicPi
-  module PreParser
-
-    class PreParseError < StandardError ; end
-
-    def self.preparse(rb)
-      SonicPi::SpiderAPI.ring_fns.each do |fn|
-        fn = fn[:name].to_s
-        rb.gsub!(/\((\s*)#{fn}(\s)/, '\1' + fn + '(\2')
-        raise PreParseError, "You may not use the built-in fn names as variable names.\n You attempted to use: #{fn}" if rb.match(/\W?#{fn}\s*=[\s\w]/)
-      end
-      rb
-    end
-  end
-end
-
 module SonicPi
   class PreParserTester < Test::Unit::TestCase
     def test_no_change
@@ -50,5 +34,19 @@ def test_raises_on_assignment_to_ring_fn
         PreParser.preparse(a)
       end
     end
+
+    def test_partial_matches_on_builtin_fns
+      a = "testscale = 10"
+      assert_nothing_thrown PreParser::PreParseError do
+        PreParser.preparse(a)
+      end
+    end
+
+    def test_using_a_builtin_raises_an_exception
+      a = "scale = 10"
+      assert_raise PreParser::PreParseError do
+        PreParser.preparse(a)
+      end
+    end
   end
 end