From 3cb6d6b1de0f43baf8a87b322d677ed6399ef53c Mon Sep 17 00:00:00 2001
From: Kalle Stenflo <kalle.stenflo@gmail.com>
Date: Mon, 6 Oct 2014 14:01:52 +0200
Subject: [PATCH] Added EvaluationListener support.

---
 .../com/jayway/jsonassert/JsonAssertTest.java |   3 -
 .../com/jayway/jsonpath/Configuration.java    |  52 +++++++--
 .../jayway/jsonpath/EvaluationListener.java   |  49 +++++++++
 .../java/com/jayway/jsonpath/ReadContext.java |   1 +
 .../jsonpath/internal/CompiledPath.java       |   4 +-
 .../internal/EvaluationAbortException.java    |   4 +
 .../jayway/jsonpath/internal/JsonReader.java  |  13 +++
 .../internal/token/EvaluationContextImpl.java |  40 ++++++-
 .../java/com/jayway/jsonpath/BaseTest.java    |   1 -
 .../jsonpath/EvaluationListenerTest.java      | 100 ++++++++++++++++++
 10 files changed, 255 insertions(+), 12 deletions(-)
 create mode 100644 json-path/src/main/java/com/jayway/jsonpath/EvaluationListener.java
 create mode 100644 json-path/src/main/java/com/jayway/jsonpath/internal/EvaluationAbortException.java
 create mode 100644 json-path/src/test/java/com/jayway/jsonpath/EvaluationListenerTest.java

diff --git a/json-path-assert/src/test/java/com/jayway/jsonassert/JsonAssertTest.java b/json-path-assert/src/test/java/com/jayway/jsonassert/JsonAssertTest.java
index 05fb6dd8..2e7f902f 100644
--- a/json-path-assert/src/test/java/com/jayway/jsonassert/JsonAssertTest.java
+++ b/json-path-assert/src/test/java/com/jayway/jsonassert/JsonAssertTest.java
@@ -1,9 +1,6 @@
 package com.jayway.jsonassert;
 
 import com.jayway.jsonpath.InvalidPathException;
-import com.jayway.jsonpath.JsonPath;
-import com.jayway.jsonpath.internal.Path;
-import com.jayway.jsonpath.internal.PathCompiler;
 import org.junit.Test;
 
 import java.io.InputStream;
diff --git a/json-path/src/main/java/com/jayway/jsonpath/Configuration.java b/json-path/src/main/java/com/jayway/jsonpath/Configuration.java
index 1e19081e..bdffa116 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/Configuration.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/Configuration.java
@@ -18,7 +18,12 @@ import com.jayway.jsonpath.internal.spi.json.JsonSmartJsonProvider;
 import com.jayway.jsonpath.internal.spi.mapper.DefaultMappingProvider;
 import com.jayway.jsonpath.spi.json.JsonProvider;
 import com.jayway.jsonpath.spi.mapper.MappingProvider;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.Set;
@@ -31,6 +36,8 @@ import static java.util.Arrays.asList;
  */
 public class Configuration {
 
+    private static final Logger logger = LoggerFactory.getLogger(Configuration.class);
+
     private static Defaults DEFAULTS = new Defaults() {
 
         private final MappingProvider mappingProvider = new DefaultMappingProvider();
@@ -50,6 +57,8 @@ public class Configuration {
         }
     };
 
+
+
     /**
      * Set Default configuration
      * @param defaults default configuration settings
@@ -61,14 +70,34 @@ public class Configuration {
     private final JsonProvider jsonProvider;
     private final MappingProvider mappingProvider;
     private final Set<Option> options;
+    private final Collection<EvaluationListener> evaluationListeners;
 
-    private Configuration(JsonProvider jsonProvider, MappingProvider mappingProvider, EnumSet<Option> options) {
+    private Configuration(JsonProvider jsonProvider, MappingProvider mappingProvider, EnumSet<Option> options, Collection<EvaluationListener> evaluationListeners) {
         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");
         this.jsonProvider = jsonProvider;
         this.mappingProvider = mappingProvider;
         this.options = Collections.unmodifiableSet(options);
+        this.evaluationListeners = Collections.unmodifiableCollection(evaluationListeners);
+    }
+
+    /**
+     * Creates a new Configuration with the provided evaluation listeners
+     * @param evaluationListener listeners
+     * @return a new configuration
+     */
+    public Configuration evaluationListener(EvaluationListener... evaluationListener){
+        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(options).evaluationListener(evaluationListener).build();
+    }
+
+    /**
+     * Returns the evaluation listeners registered in this configuration
+     * @return the evaluation listeners
+     */
+    public Collection<EvaluationListener> evaluationListeners(){
+        return evaluationListeners;
     }
 
     /**
@@ -77,7 +106,7 @@ public class Configuration {
      * @return a new configuration
      */
     public Configuration jsonProvider(JsonProvider newJsonProvider) {
-        return Configuration.builder().jsonProvider(newJsonProvider).mappingProvider(mappingProvider).options(options).build();
+        return Configuration.builder().jsonProvider(newJsonProvider).mappingProvider(mappingProvider).options(options).evaluationListener(evaluationListeners).build();
     }
 
     /**
@@ -94,7 +123,7 @@ public class Configuration {
      * @return a new configuration
      */
     public Configuration mappingProvider(MappingProvider newMappingProvider) {
-        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(newMappingProvider).options(options).build();
+        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(newMappingProvider).options(options).evaluationListener(evaluationListeners).build();
     }
 
     /**
@@ -114,7 +143,7 @@ public class Configuration {
         EnumSet<Option> opts = EnumSet.noneOf(Option.class);
         opts.addAll(this.options);
         opts.addAll(asList(options));
-        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(opts).build();
+        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(opts).evaluationListener(evaluationListeners).build();
     }
 
     /**
@@ -123,7 +152,7 @@ public class Configuration {
      * @return
      */
     public Configuration setOptions(Option... options) {
-        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(options).build();
+        return Configuration.builder().jsonProvider(jsonProvider).mappingProvider(mappingProvider).options(options).evaluationListener(evaluationListeners).build();
     }
 
     /**
@@ -167,6 +196,7 @@ public class Configuration {
         private JsonProvider jsonProvider;
         private MappingProvider mappingProvider;
         private EnumSet<Option> options = EnumSet.noneOf(Option.class);
+        private Collection<EvaluationListener> evaluationListener = new ArrayList<EvaluationListener>();
 
         public ConfigurationBuilder jsonProvider(JsonProvider provider) {
             this.jsonProvider = provider;
@@ -190,6 +220,16 @@ public class Configuration {
             return this;
         }
 
+        public ConfigurationBuilder evaluationListener(EvaluationListener... listener){
+            this.evaluationListener = Arrays.asList(listener);
+            return this;
+        }
+
+        public ConfigurationBuilder evaluationListener(Collection<EvaluationListener> listeners){
+            this.evaluationListener = listeners == null ? Collections.<EvaluationListener>emptyList() : listeners;
+            return this;
+        }
+
         public Configuration build() {
             if (jsonProvider == null) {
                 jsonProvider = DEFAULTS.jsonProvider();
@@ -197,7 +237,7 @@ public class Configuration {
             if(mappingProvider == null){
                 mappingProvider = DEFAULTS.mappingProvider();
             }
-            return new Configuration(jsonProvider, mappingProvider, options);
+            return new Configuration(jsonProvider, mappingProvider, options, evaluationListener);
         }
     }
 
diff --git a/json-path/src/main/java/com/jayway/jsonpath/EvaluationListener.java b/json-path/src/main/java/com/jayway/jsonpath/EvaluationListener.java
new file mode 100644
index 00000000..94515931
--- /dev/null
+++ b/json-path/src/main/java/com/jayway/jsonpath/EvaluationListener.java
@@ -0,0 +1,49 @@
+package com.jayway.jsonpath;
+
+/**
+ * A listener that can be registered on a {@link com.jayway.jsonpath.Configuration} that is notified when a
+ * result is added to the result of this path evaluation.
+ */
+public interface EvaluationListener {
+
+    /**
+     * Callback invoked when result is found
+     * @param found the found result
+     * @return continuation instruction
+     */
+    EvaluationContinuation resultFound(FoundResult found);
+
+    public static enum EvaluationContinuation {
+        /**
+         * Evaluation continues
+         */
+        CONTINUE,
+        /**
+         * Current result is included but no further evaluation will be performed.
+         */
+        ABORT
+    }
+
+    /**
+     *
+     */
+    public interface FoundResult {
+        /**
+         * the index of this result. First result i 0
+         * @return index
+         */
+        int index();
+
+        /**
+         * The path of this result
+         * @return path
+         */
+        String path();
+
+        /**
+         * The result object
+         * @return the result object
+         */
+        Object result();
+    }
+}
diff --git a/json-path/src/main/java/com/jayway/jsonpath/ReadContext.java b/json-path/src/main/java/com/jayway/jsonpath/ReadContext.java
index b77be18c..529190c6 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/ReadContext.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/ReadContext.java
@@ -71,5 +71,6 @@ public interface ReadContext {
     <T> T read(JsonPath path, Class<T> type);
 
 
+    ReadContext withListeners(EvaluationListener... listener);
 
 }
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/CompiledPath.java b/json-path/src/main/java/com/jayway/jsonpath/internal/CompiledPath.java
index 5c52ff16..bd1431c2 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/CompiledPath.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/CompiledPath.java
@@ -46,7 +46,9 @@ public class CompiledPath implements Path {
         }
 
         EvaluationContextImpl ctx = new EvaluationContextImpl(this, rootDocument, configuration);
-        root.evaluate("", document, ctx);
+        try {
+            root.evaluate("", document, ctx);
+        } catch (EvaluationAbortException abort){};
 
         return ctx;
     }
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/EvaluationAbortException.java b/json-path/src/main/java/com/jayway/jsonpath/internal/EvaluationAbortException.java
new file mode 100644
index 00000000..19a93dfb
--- /dev/null
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/EvaluationAbortException.java
@@ -0,0 +1,4 @@
+package com.jayway.jsonpath.internal;
+
+public class EvaluationAbortException extends RuntimeException {
+}
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/JsonReader.java b/json-path/src/main/java/com/jayway/jsonpath/internal/JsonReader.java
index e0d9ab3b..01e88966 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/JsonReader.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/JsonReader.java
@@ -15,6 +15,7 @@
 package com.jayway.jsonpath.internal;
 
 import com.jayway.jsonpath.Configuration;
+import com.jayway.jsonpath.EvaluationListener;
 import com.jayway.jsonpath.JsonPath;
 import com.jayway.jsonpath.ParseContext;
 import com.jayway.jsonpath.Predicate;
@@ -44,6 +45,13 @@ public class JsonReader implements ParseContext, ReadContext {
         this.configuration = configuration;
     }
 
+    private JsonReader(Object json, Configuration configuration) {
+        notNull(json, "json can not be null");
+        notNull(configuration, "configuration can not be null");
+        this.configuration = configuration;
+        this.json = json;
+    }
+
     //------------------------------------------------
     //
     // ParseContext impl
@@ -137,6 +145,11 @@ public class JsonReader implements ParseContext, ReadContext {
         return convert(read(path), type, configuration);
     }
 
+    public ReadContext withListeners(EvaluationListener... listener){
+        return new JsonReader(json, configuration.evaluationListener(listener));
+    }
+
+
     private <T> T convert(Object obj, Class<T> targetType, Configuration configuration){
         return configuration.mappingProvider().map(obj, targetType, configuration);
     }
diff --git a/json-path/src/main/java/com/jayway/jsonpath/internal/token/EvaluationContextImpl.java b/json-path/src/main/java/com/jayway/jsonpath/internal/token/EvaluationContextImpl.java
index 806c17d6..f7fdf64f 100644
--- a/json-path/src/main/java/com/jayway/jsonpath/internal/token/EvaluationContextImpl.java
+++ b/json-path/src/main/java/com/jayway/jsonpath/internal/token/EvaluationContextImpl.java
@@ -15,8 +15,10 @@
 package com.jayway.jsonpath.internal.token;
 
 import com.jayway.jsonpath.Configuration;
+import com.jayway.jsonpath.EvaluationListener;
 import com.jayway.jsonpath.Option;
 import com.jayway.jsonpath.PathNotFoundException;
+import com.jayway.jsonpath.internal.EvaluationAbortException;
 import com.jayway.jsonpath.internal.EvaluationContext;
 import com.jayway.jsonpath.internal.Path;
 import com.jayway.jsonpath.spi.json.JsonProvider;
@@ -24,7 +26,6 @@ import com.jayway.jsonpath.spi.json.JsonProvider;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
-import java.util.Objects;
 import java.util.Set;
 
 import static com.jayway.jsonpath.internal.Utils.notNull;
@@ -62,6 +63,15 @@ public class EvaluationContextImpl implements EvaluationContext {
         configuration.jsonProvider().setProperty(valueResult, resultIndex, model);
         configuration.jsonProvider().setProperty(pathResult, resultIndex, path);
         resultIndex++;
+        if(!configuration().evaluationListeners().isEmpty()){
+            int idx = resultIndex - 1;
+            for (EvaluationListener listener : configuration().evaluationListeners()) {
+                EvaluationListener.EvaluationContinuation continuation = listener.resultFound(new FoundResultImpl(idx, path, model));
+                if(EvaluationListener.EvaluationContinuation.ABORT == continuation){
+                    throw new EvaluationAbortException();
+                }
+            }
+        }
     }
 
     public JsonProvider jsonProvider() {
@@ -116,4 +126,32 @@ public class EvaluationContextImpl implements EvaluationContext {
         return res;
     }
 
+    private class FoundResultImpl implements EvaluationListener.FoundResult {
+
+        private final int index;
+        private final String path;
+        private final Object result;
+
+        private FoundResultImpl(int index, String path, Object result) {
+            this.index = index;
+            this.path = path;
+            this.result = result;
+        }
+
+        @Override
+        public int index() {
+            return index;
+        }
+
+        @Override
+        public String path() {
+            return path;
+        }
+
+        @Override
+        public Object result() {
+            return result;
+        }
+    }
+
 }
diff --git a/json-path/src/test/java/com/jayway/jsonpath/BaseTest.java b/json-path/src/test/java/com/jayway/jsonpath/BaseTest.java
index 650595ec..0c8a4a32 100644
--- a/json-path/src/test/java/com/jayway/jsonpath/BaseTest.java
+++ b/json-path/src/test/java/com/jayway/jsonpath/BaseTest.java
@@ -5,7 +5,6 @@ import com.jayway.jsonpath.internal.spi.json.GsonJsonProvider;
 import com.jayway.jsonpath.internal.spi.json.JacksonJsonProvider;
 import com.jayway.jsonpath.internal.spi.mapper.GsonMappingProvider;
 import com.jayway.jsonpath.internal.spi.mapper.JacksonMappingProvider;
-import com.jayway.jsonpath.internal.token.EvaluationContextImpl;
 import com.jayway.jsonpath.internal.token.PredicateContextImpl;
 
 import java.util.HashMap;
diff --git a/json-path/src/test/java/com/jayway/jsonpath/EvaluationListenerTest.java b/json-path/src/test/java/com/jayway/jsonpath/EvaluationListenerTest.java
new file mode 100644
index 00000000..0d7b22a4
--- /dev/null
+++ b/json-path/src/test/java/com/jayway/jsonpath/EvaluationListenerTest.java
@@ -0,0 +1,100 @@
+package com.jayway.jsonpath;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class EvaluationListenerTest extends BaseTest {
+
+
+    @Test
+    public void an_evaluation_listener_can_abort_after_one_result_using_fluent_api() {
+        EvaluationListener firstResultListener = new EvaluationListener() {
+            @Override
+            public EvaluationContinuation resultFound(FoundResult found) {
+                return EvaluationContinuation.ABORT;
+            }
+        };
+        List<String> title = JsonPath.parse(JSON_DOCUMENT).withListeners(firstResultListener).read("$..title", List.class);
+        assertThat(title).containsExactly("Sayings of the Century");
+    }
+
+    @Test
+    public void an_evaluation_listener_can_abort_after_one_result_using_configuration() {
+        EvaluationListener firstResultListener = new EvaluationListener() {
+            @Override
+            public EvaluationContinuation resultFound(FoundResult found) {
+                return EvaluationContinuation.ABORT;
+            }
+        };
+        Configuration configuration = Configuration.builder().evaluationListener(firstResultListener).build();
+
+        List<String> title = JsonPath.using(configuration).parse(JSON_DOCUMENT).read("$..title", List.class);
+        assertThat(title).containsExactly("Sayings of the Century");
+    }
+
+    @Test
+    public void an_evaluation_lister_can_continue() {
+
+        final List<Integer> idxs = new ArrayList<Integer>();
+
+        EvaluationListener firstResultListener = new EvaluationListener() {
+            @Override
+            public EvaluationContinuation resultFound(FoundResult found) {
+                idxs.add(found.index());
+                return EvaluationContinuation.CONTINUE;
+            }
+        };
+        List<String> title = JsonPath.parse(JSON_DOCUMENT).withListeners(firstResultListener).read("$..title", List.class);
+        assertThat(title).containsExactly("Sayings of the Century", "Sword of Honour", "Moby Dick", "The Lord of the Rings");
+        assertThat(idxs).containsExactly(0, 1, 2, 3);
+    }
+
+    @Test
+    public void multiple_evaluation_listeners_can_be_added() {
+
+        final List<Integer> idxs1 = new ArrayList<Integer>();
+        final List<Integer> idxs2 = new ArrayList<Integer>();
+
+        EvaluationListener listener1 = new EvaluationListener() {
+            @Override
+            public EvaluationContinuation resultFound(FoundResult found) {
+                idxs1.add(found.index());
+                return EvaluationContinuation.CONTINUE;
+            }
+        };
+
+        EvaluationListener listener2 = new EvaluationListener() {
+            @Override
+            public EvaluationContinuation resultFound(FoundResult found) {
+                idxs2.add(found.index());
+                return EvaluationContinuation.CONTINUE;
+            }
+        };
+
+        List<String> title = JsonPath.parse(JSON_DOCUMENT).withListeners(listener1, listener2).read("$..title", List.class);
+        assertThat(title).containsExactly("Sayings of the Century", "Sword of Honour", "Moby Dick", "The Lord of the Rings");
+        assertThat(idxs1).containsExactly(0, 1, 2, 3);
+        assertThat(idxs2).containsExactly(0, 1, 2, 3);
+    }
+
+    @Test
+    public void evaluation_listeners_can_be_cleared() {
+
+        EvaluationListener listener = new EvaluationListener() {
+            @Override
+            public EvaluationContinuation resultFound(FoundResult found) {
+                return EvaluationContinuation.CONTINUE;
+            }
+        };
+
+        Configuration configuration1 = Configuration.builder().evaluationListener(listener).build();
+        Configuration configuration2 = configuration1.evaluationListener();
+
+        assertThat(configuration1.evaluationListeners()).hasSize(1);
+        assertThat(configuration2.evaluationListeners()).hasSize(0);
+    }
+}