added support of multiple object properties in non-leaf path node

Semantics of this case is the same as semantics of ArrayPathToken with multiple array indices specified.

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

@@ -272,6 +272,29 @@ public final class Utils {
         }
     }
 
+    /**
+     * Check if one and only one condition is true; otherwise
+     * throw an exception with the specified message.
+     * @param message error describing message
+     * @param expressions the boolean expressions to check
+     * @throws IllegalArgumentException if zero or more than one expressions are true
+     */
+    public static void onlyOneIsTrue(final String message, final boolean ... expressions) {
+        if (! onlyOneIsTrueNonThrow(expressions)) {
+            throw new IllegalArgumentException(message);
+        }
+    }
+
+    public static boolean onlyOneIsTrueNonThrow(final boolean ... expressions) {
+        int count = 0;
+        for (final boolean expression : expressions) {
+            if (expression && ++count > 1) {
+                return false;
+            }
+        }
+        return 1 == count;
+    }
+
     /**
      * <p>Validate that the specified argument character sequence is
      * neither {@code null} nor a length of zero (no characters);

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

@@ -44,7 +44,9 @@ public abstract class PathToken {
             Object propertyVal = readObjectProperty(property, model, ctx);
             if(propertyVal == JsonProvider.UNDEFINED){
                 // Conditions below heavily depend on current token type (and its logic) and are not "universal",
-                // so this code is quite dangerous. Better safe than sorry.
+                // so this code is quite dangerous (I'd rather rewrite it & move to PropertyPathToken and implemented
+                // WildcardPathToken as a dynamic multi prop case of PropertyPathToken).
+                // Better safe than sorry.
                 assert this instanceof PropertyPathToken : "only PropertyPathToken is supported";
 
                 if(isLeaf()) {
@@ -60,9 +62,12 @@ public abstract class PathToken {
 
                     }
                 } else {
-                    if(!isUpstreamDefinite() &&
+                    if (! (isUpstreamDefinite() && isTokenDefinite()) &&
                        !ctx.options().contains(Option.REQUIRE_PROPERTIES) ||
                        ctx.options().contains(Option.SUPPRESS_EXCEPTIONS)){
+                        // If there is some indefiniteness in the path and properties are not required - we'll ignore
+                        // absent property. And also in case of exception suppression - so that other path evaluation
+                        // branches could be examined.
                         return;
                     } else {
                         throw new PathNotFoundException("Missing property in path " + evalPath);
@@ -78,9 +83,7 @@ public abstract class PathToken {
         } else {
             String evalPath = currentPath + "[" + Utils.join(", ", "'", properties) + "]";
 
-            if (!isLeaf()) {
+            assert isLeaf() : "non-leaf multi props handled elsewhere";
-                throw new InvalidPathException("Multi properties can only be used as path leafs: " + evalPath);
-            }
 
             Object merged = ctx.jsonProvider().createMap();
             for (String property : properties) {

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

@@ -14,12 +14,16 @@
  */
 package com.jayway.jsonpath.internal.token;
 
+import com.jayway.jsonpath.InvalidPathException;
 import com.jayway.jsonpath.PathNotFoundException;
 import com.jayway.jsonpath.internal.PathRef;
 import com.jayway.jsonpath.internal.Utils;
 
+import java.util.ArrayList;
 import java.util.List;
 
+import static com.jayway.jsonpath.internal.Utils.onlyOneIsTrueNonThrow;
+
 /**
  *
  */
@@ -28,6 +32,9 @@ public class PropertyPathToken extends PathToken {
     private final List<String> properties;
 
     public PropertyPathToken(List<String> properties) {
+        if (properties.isEmpty()) {
+            throw new InvalidPathException("Empty properties");
+        }
         this.properties = properties;
     }
 
@@ -35,8 +42,24 @@ public class PropertyPathToken extends PathToken {
         return properties;
     }
 
+    public boolean singlePropertyCase() {
+        return properties.size() == 1;
+    }
+
+    public boolean multiPropertyMergeCase() {
+        return isLeaf() && properties.size() > 1;
+    }
+
+    public boolean multiPropertyIterationCase() {
+        // Semantics of this case is the same as semantics of ArrayPathToken with INDEX_SEQUENCE operation.
+        return ! isLeaf() && properties.size() > 1;
+    }
+
     @Override
     public void evaluate(String currentPath, PathRef parent, Object model, EvaluationContextImpl ctx) {
+        // Can't assert it in ctor because isLeaf() could be changed later on.
+        assert onlyOneIsTrueNonThrow(singlePropertyCase(), multiPropertyMergeCase(), multiPropertyIterationCase());
+
         if (!ctx.jsonProvider().isMap(model)) {
             if (! isUpstreamDefinite()) {
                 return;
@@ -45,12 +68,24 @@ public class PropertyPathToken extends PathToken {
             }
         }
 
+        if (singlePropertyCase() || multiPropertyMergeCase()) {
             handleObjectProperty(currentPath, model, ctx, properties);
+            return;
+        }
+
+        assert multiPropertyIterationCase();
+        final List<String> currentlyHandledProperty = new ArrayList<String>(1);
+        currentlyHandledProperty.add(null);
+        for (final String property : properties) {
+            currentlyHandledProperty.set(0, property);
+            handleObjectProperty(currentPath, model, ctx, currentlyHandledProperty);
+        }
     }
 
     @Override
     boolean isTokenDefinite() {
-        return true;
+        // in case of leaf multiprops will be merged, so it's kinda definite
+        return singlePropertyCase() || multiPropertyMergeCase();
     }
 
     @Override

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

@@ -6,6 +6,8 @@ import java.util.HashMap;
 import java.util.Map;
 
 import static com.jayway.jsonpath.JsonPath.using;
+import static com.jayway.jsonpath.TestUtils.assertEvaluationThrows;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 public class MultiPropTest {
@@ -60,5 +62,60 @@ public class MultiPropTest {
         using(conf).parse(model).read("$['a', 'x']", Map.class);
     }
 
+    @Test
+    public void multi_props_can_be_non_leafs() {
+        Object result = JsonPath.parse("{\"a\": {\"v\": 5}, \"b\": {\"v\": 4}, \"c\": {\"v\": 1}}").read(
+                "$['a', 'c'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+    }
+
+    @Test
+    public void nonexistent_non_leaf_multi_props_ignored() {
+        Object result = JsonPath.parse("{\"a\": {\"v\": 5}, \"b\": {\"v\": 4}, \"c\": {\"v\": 1}}").read(
+                "$['d', 'a', 'c', 'm'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+    }
+
+    @Test
+    public void multi_props_with_post_filter() {
+        Object result = JsonPath.parse("{\"a\": {\"v\": 5}, \"b\": {\"v\": 4}, \"c\": {\"v\": 1, \"flag\": true}}").read(
+                "$['a', 'c'][?(@.flag)].v");
+        assertThat(result).asList().containsOnly(1);
+    }
+
+    @Test
+    public void deep_scan_does_not_affect_non_leaf_multi_props() {
+        // deep scan + multiprop is quite redundant scenario, but it's not forbidden, so we'd better check
+        final String json = "{\"v\": [[{}, 1, {\"a\": {\"v\": 5}, \"b\": {\"v\": 4}, \"c\": {\"v\": 1, \"flag\": true}}]]}";
+        Object result = JsonPath.parse(json).read("$..['a', 'c'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+
+        result = JsonPath.parse(json).read("$..['a', 'c'][?(@.flag)].v");
+        assertThat(result).asList().containsOnly(1);
+    }
 
+    @Test
+    public void multi_props_can_be_in_the_middle() {
+        final String json = "{\"x\": [null, {\"a\": {\"v\": 5}, \"b\": {\"v\": 4}, \"c\": {\"v\": 1}}]}";
+        Object result = JsonPath.parse(json).read("$.x[1]['a', 'c'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+        result = JsonPath.parse(json).read("$.x[*]['a', 'c'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+        result = JsonPath.parse(json).read("$[*][*]['a', 'c'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+
+        result = JsonPath.parse(json).read("$.x[1]['d', 'a', 'c', 'm'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+        result = JsonPath.parse(json).read("$.x[*]['d', 'a', 'c', 'm'].v");
+        assertThat(result).asList().containsOnly(5, 1);
+    }
+
+    @Test
+    public void non_leaf_multi_props_can_be_required() {
+        final Configuration conf = Configuration.defaultConfiguration().addOptions(Option.REQUIRE_PROPERTIES);
+        final String json = "{\"a\": {\"v\": 5}, \"b\": {\"v\": 4}, \"c\": {\"v\": 1}}";
+
+        assertThat(using(conf).parse(json).read("$['a', 'c'].v")).asList().containsOnly(5, 1);
+        assertEvaluationThrows(json, "$['d', 'a', 'c', 'm'].v", PathNotFoundException.class, conf);
+    }
 }

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

@@ -19,7 +19,7 @@ public class PathTokenTest extends BaseTest {
 
         assertThat(makePathReturningTail(makePPT("foo"), makePPT("bar")).isUpstreamDefinite()).isTrue();
 
-        // assertThat(makePathReturningTail(makePPT("foo", "foo2"), makePPT("bar")).isUpstreamDefinite()).isFalse();
+        assertThat(makePathReturningTail(makePPT("foo", "foo2"), makePPT("bar")).isUpstreamDefinite()).isFalse();
 
         assertThat(makePathReturningTail(new WildcardPathToken(), makePPT("bar")).isUpstreamDefinite()).isFalse();