production code refactored

TDD-pure-function/src/main/java/de/edu/hsfulda/ciip/tdd/BownlingCalculator.java

@@ -4,18 +4,34 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class BownlingCalculator {
+	private static final int PINS_IN_FRAME = 10;
+	private static final String SPARE = "(\\d)/ (\\d)";
+	private static final String INCOMPLETE_FRAME = "\\d";
+
+	@FunctionalInterface
+	private interface FrameCalculator {
+		int evaluate(Matcher frameStructure);
+	}
+
+	private static final int SPARE_FRAME_FOLLOWING_THROW = 2;
+	private static final int SPARE_FRAME_FIRST_THROW = 1;
 
 	public int evaluate(String listOfThrows) {
 		int sum = 0;
-		Matcher singleDigit = Pattern.compile("\\d").matcher(listOfThrows);
-		while (singleDigit.find()) {
-			sum += Integer.parseInt(singleDigit.group());
-		}
-		singleDigit = Pattern.compile("(\\d)/ (\\d)").matcher(listOfThrows);
+		sum += evaluateFrames(listOfThrows, INCOMPLETE_FRAME, m -> Integer.parseInt(m.group()));
+		sum += evaluateFrames(listOfThrows, SPARE, m -> PINS_IN_FRAME//
+				- Integer.parseInt(m.group(SPARE_FRAME_FIRST_THROW))
+				+ Integer.parseInt(m.group(SPARE_FRAME_FOLLOWING_THROW)));
+		return sum;
+	}
+
+	private int evaluateFrames(String listOfThrows, String frameStructurePattern, FrameCalculator frameCalculator) {
+		Matcher singleDigit = Pattern.compile(frameStructurePattern).matcher(listOfThrows);
+		int frameValue = 0;
 		while (singleDigit.find()) {
-			sum += 10 - Integer.parseInt(singleDigit.group(1)) + Integer.parseInt(singleDigit.group(2));
+			frameValue += frameCalculator.evaluate(singleDigit);
 		}
-		return sum;
+		return frameValue;
 	}
 
 }