Improved array slicing.

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

@@ -62,7 +62,11 @@ public class ArrayIndexFilter extends PathTokenFilter {
                 String trimmedCondition = trim(this.trimmedCondition, 1, 0);
                 int get = Integer.parseInt(trimmedCondition);
                 for (int i = 0; i < get; i++) {
-                    jsonProvider.setProperty(result, jsonProvider.length(result), jsonProvider.getProperty(obj, i));
+                    try {
+                        jsonProvider.setProperty(result, jsonProvider.length(result), jsonProvider.getProperty(obj, i));
+                    } catch (IndexOutOfBoundsException e){
+                        break;
+                    }
                 }
                 return result;
 
@@ -78,6 +82,10 @@ public class ArrayIndexFilter extends PathTokenFilter {
                     int start = jsonProvider.length(obj) + get;
                     int stop = jsonProvider.length(obj);
 
+                    if(start < 0){
+                        start = 0;
+                    }
+
                     for (int i = start; i < stop; i ++){
                         jsonProvider.setProperty(result, jsonProvider.length(result), jsonProvider.getProperty(obj, i));
                     }

json-path/src/test/java/com/jayway/jsonpath/internal/filter/ArrayIndexFilterTest.java

@@ -0,0 +1,51 @@
+package com.jayway.jsonpath.internal.filter;
+
+import com.jayway.jsonpath.JsonPath;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+
+/**
+ * User: kalle
+ * Date: 9/9/13
+ * Time: 8:10 AM
+ */
+public class ArrayIndexFilterTest {
+
+    private static final String JSON =  "[1, 3, 5, 7, 8, 13, 20]";
+
+    @Test
+    public void tail_does_not_throw_when_index_out_of_bounds() {
+        List<Integer> result = JsonPath.parse(JSON).read("$[-10:]");
+        assertThat(result, Matchers.contains(1, 3, 5, 7, 8, 13, 20));
+    }
+
+    @Test
+    public void head_does_not_throw_when_index_out_of_bounds() {
+        List<Integer> result = JsonPath.parse(JSON).read("$[:10]");
+        assertThat(result, Matchers.contains(1, 3, 5, 7, 8, 13, 20));
+    }
+
+    @Test
+    public void head_grabs_correct() {
+        List<Integer> result = JsonPath.parse(JSON).read("$[:3]");
+        assertThat(result, Matchers.contains(1, 3, 5));
+    }
+
+
+    @Test
+    public void tail_grabs_correct() {
+        List<Integer> result = JsonPath.parse(JSON).read("$[-3:]");
+        assertThat(result, Matchers.contains(8, 13, 20));
+    }
+
+    @Test
+    public void head_tail_grabs_correct() {
+        List<Integer> result = JsonPath.parse(JSON).read("$[0:3]");
+        assertThat(result, Matchers.contains(1, 3, 5));
+    }
+
+}