Added limit() to JsonReader.

json-path/src/main/java/com/jayway/jsonpath/Configuration.java

@@ -76,19 +76,28 @@ public class Configuration {
         notNull(jsonProvider, "jsonProvider can not be null");
         notNull(mappingProvider, "mappingProvider can not be null");
         notNull(options, "setOptions can not be null");
-        notNull(evaluationListeners, "evaluationListener can not be null");
+        notNull(evaluationListeners, "evaluationListeners can not be null");
         this.jsonProvider = jsonProvider;
         this.mappingProvider = mappingProvider;
         this.options = Collections.unmodifiableSet(options);
         this.evaluationListeners = Collections.unmodifiableCollection(evaluationListeners);
     }
 
+    /**
+     * Creates a new Configuration by the provided evaluation listeners to the current listeners
+     * @param evaluationListener listeners
+     * @return a new configuration
+     */
+    public Configuration addEvaluationListeners(EvaluationListener... evaluationListener){
+        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(options).evaluationListener(evaluationListener).build();
+    }
+
     /**
      * Creates a new Configuration with the provided evaluation listeners
      * @param evaluationListener listeners
      * @return a new configuration
      */
-    public Configuration evaluationListener(EvaluationListener... evaluationListener){
+    public Configuration setEvaluationListeners(EvaluationListener... evaluationListener){
         return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(options).evaluationListener(evaluationListener).build();
     }
 
@@ -96,7 +105,7 @@ public class Configuration {
      * Returns the evaluation listeners registered in this configuration
      * @return the evaluation listeners
      */
-    public Collection<EvaluationListener> evaluationListeners(){
+    public Collection<EvaluationListener> getEvaluationListeners(){
         return evaluationListeners;
     }
 

json-path/src/main/java/com/jayway/jsonpath/ReadContext.java

@@ -70,7 +70,18 @@ public interface ReadContext {
      */
     <T> T read(JsonPath path, Class<T> type);
 
+    /**
+     * Stops evaluation when maxResults limit has been reached
+     * @param maxResults
+     * @return the read context
+     */
+    ReadContext limit(int maxResults);
 
+    /**
+     * Adds listener to the evaluation of this path
+     * @param listener listeners to add
+     * @return the read context
+     */
     ReadContext withListeners(EvaluationListener... listener);
 
 }

json-path/src/main/java/com/jayway/jsonpath/internal/JsonReader.java

@@ -145,8 +145,12 @@ public class JsonReader implements ParseContext, ReadContext {
         return convert(read(path), type, configuration);
     }
 
+    public ReadContext limit(int maxResults){
+        return withListeners(new LimitingEvaluationListener(maxResults));
+    }
+
     public ReadContext withListeners(EvaluationListener... listener){
-        return new JsonReader(json, configuration.evaluationListener(listener));
+        return new JsonReader(json, configuration.setEvaluationListeners(listener));
     }
 
 
@@ -154,4 +158,23 @@ public class JsonReader implements ParseContext, ReadContext {
         return configuration.mappingProvider().map(obj, targetType, configuration);
     }
 
+
+    private final class LimitingEvaluationListener implements EvaluationListener {
+
+        final int limit;
+
+        private LimitingEvaluationListener(int limit) {
+            this.limit = limit;
+        }
+
+
+        @Override
+        public EvaluationContinuation resultFound(FoundResult found) {
+            if(found.index() == limit - 1){
+                return EvaluationContinuation.ABORT;
+            } else {
+                return EvaluationContinuation.CONTINUE;
+            }
+        }
+    }
 }

json-path/src/main/java/com/jayway/jsonpath/internal/token/EvaluationContextImpl.java

@@ -63,9 +63,9 @@ public class EvaluationContextImpl implements EvaluationContext {
         configuration.jsonProvider().setProperty(valueResult, resultIndex, model);
         configuration.jsonProvider().setProperty(pathResult, resultIndex, path);
         resultIndex++;
-        if(!configuration().evaluationListeners().isEmpty()){
+        if(!configuration().getEvaluationListeners().isEmpty()){
             int idx = resultIndex - 1;
-            for (EvaluationListener listener : configuration().evaluationListeners()) {
+            for (EvaluationListener listener : configuration().getEvaluationListeners()) {
                 EvaluationListener.EvaluationContinuation continuation = listener.resultFound(new FoundResultImpl(idx, path, model));
                 if(EvaluationListener.EvaluationContinuation.ABORT == continuation){
                     throw new EvaluationAbortException();

json-path/src/test/java/com/jayway/jsonpath/EvaluationListenerTest.java

@@ -53,6 +53,17 @@ public class EvaluationListenerTest extends BaseTest {
         assertThat(idxs).containsExactly(0, 1, 2, 3);
     }
 
+
+    @Test
+    public void evaluation_results_can_be_limited() {
+
+        List<String> res = JsonPath.parse(JSON_DOCUMENT).limit(1).read("$..title", List.class);
+        assertThat(res).containsExactly("Sayings of the Century");
+
+        res = JsonPath.parse(JSON_DOCUMENT).limit(2).read("$..title", List.class);
+        assertThat(res).containsExactly("Sayings of the Century", "Sword of Honour");
+    }
+
     @Test
     public void multiple_evaluation_listeners_can_be_added() {
 
@@ -92,9 +103,9 @@ public class EvaluationListenerTest extends BaseTest {
         };
 
         Configuration configuration1 = Configuration.builder().evaluationListener(listener).build();
-        Configuration configuration2 = configuration1.evaluationListener();
+        Configuration configuration2 = configuration1.setEvaluationListeners();
 
-        assertThat(configuration1.evaluationListeners()).hasSize(1);
-        assertThat(configuration2.evaluationListeners()).hasSize(0);
+        assertThat(configuration1.getEvaluationListeners()).hasSize(1);
+        assertThat(configuration2.getEvaluationListeners()).hasSize(0);
     }
 }