private void rankingExpressionParserParse(int repetitions, String values, int expectedMapSize) {
        Map<String,Double> map = new HashMap<>();
        for (int i=0; i<repetitions; i++) {
            rankingExpressionParserParse(values, map);
            if ( map.size()!=expectedMapSize)
                throw new RuntimeException("Expected size: " + expectedMapSize + ", actual size: " + map.size());
            map.clear();
        }
    }
A benchmark of map parsing.
Expected time on Jon's mac: 200 microseconds per 1k size map.

@author bratseth
vespajlib/src/test/java/com/yahoo/text/MapParserMicroBenchmark.java