add caching option

Author: sidhant92

build.gradle

@@ -40,6 +40,7 @@ dependencies {
     implementation 'org.apache.maven:maven-artifact:3.5.2'
     implementation 'org.antlr:antlr4-runtime:4.11.1'
     implementation 'io.vavr:vavr:0.10.4'
+    implementation 'com.github.ben-manes.caffeine:caffeine:2.9.3'
 
     compileOnly 'org.projectlombok:lombok:1.18.26'
     annotationProcessor 'org.projectlombok:lombok:1.18.26'

src/main/java/com/github/sidhant92/boolparser/parser/BoolExpressionParser.java

@@ -9,4 +9,6 @@
  */
 public interface BoolExpressionParser {
     Try<Token> parseExpression(final String expression);
+
+    Try<Token> parseExpression(final String expression, final boolean useCache, final int maxCacheSize);
 }

src/main/java/com/github/sidhant92/boolparser/parser/antlr/BoolParser.java

@@ -3,25 +3,52 @@
 import org.antlr.v4.runtime.CharStreams;
 import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.tree.ParseTreeWalker;
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import com.github.sidhant92.boolparser.domain.Token;
 import com.github.sidhant92.boolparser.parser.BoolExpressionParser;
 import io.vavr.control.Try;
 
 public class BoolParser implements BoolExpressionParser {
+    private boolean useCache;
+
+    private Cache<String, Token> cache;
+
+    private final ParseTreeWalker parseTreeWalker = new ParseTreeWalker();
+
+    private final BooleanFilterListener listener = new BooleanFilterListener();
+
+    private static final int MAX_CACHE_SIZE = 500;
+
     @Override
     public Try<Token> parseExpression(final String expression) {
+        return parseExpression(expression, false, MAX_CACHE_SIZE);
+    }
+
+    @Override
+    public Try<Token> parseExpression(final String expression, final boolean useCache, final int maxCacheSize) {
+        this.useCache = useCache;
+        if (useCache) {
+            this.cache = Caffeine.newBuilder().maximumSize(maxCacheSize).build();
+        }
         return Try.of(() -> getNode(expression));
     }
 
     private Token getNode(final String expression) {
+        if (useCache) {
+            return cache.get(expression, this::parse);
+        }
+        return parse(expression);
+    }
+
+    private Token parse(final String expression) {
         BooleanExpressionLexer filterLexer = new BooleanExpressionLexer(CharStreams.fromString(expression));
         CommonTokenStream commonTokenStream = new CommonTokenStream(filterLexer);
         BooleanExpressionParser filterParser = new BooleanExpressionParser(commonTokenStream);
         BooleanExpressionParser.ParseContext filterContext = filterParser.parse();
 
-        ParseTreeWalker parseTreeWalker = new ParseTreeWalker();
-        final BooleanFilterListener listener = new BooleanFilterListener();
         parseTreeWalker.walk(listener, filterContext);
+
         return listener.getNode();
     }
 }

src/test/java/com/github/sidhant92/boolparser/parser/antlr/BooleanFilterBoolParserTest.java

@@ -104,7 +104,7 @@ public void testSingleDecimalToken() {
 
     @Test
     public void testSingleIntRangeToken() {
-        final Try<Token> nodeOptional = boolExpressionBoolParser.parseExpression("age: 18 TO 44");
+        final Try<Token> nodeOptional = boolExpressionBoolParser.parseExpression("age 18 TO 44");
         assertTrue(nodeOptional.isSuccess());
         assertEquals(nodeOptional.get().getTokenType().name(), TokenType.NUMERIC_RANGE.name());
         verifyNumericRangeToken((NumericRangeToken) nodeOptional.get(), "age", 18, 44);
@@ -120,7 +120,7 @@ public void testGreaterThan() {
 
     @Test
     public void testSingleDecimalRangeToken() {
-        final Try<Token> nodeOptional = boolExpressionBoolParser.parseExpression("age: 18.4 TO 44.2");
+        final Try<Token> nodeOptional = boolExpressionBoolParser.parseExpression("age 18.4 TO 44.2");
         assertTrue(nodeOptional.isSuccess());
         assertEquals(nodeOptional.get().getTokenType().name(), TokenType.NUMERIC_RANGE.name());
         verifyNumericRangeToken((NumericRangeToken) nodeOptional.get(), "age", 18.4, 44.2);