Test for string, added concat function

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

@@ -6,6 +6,8 @@ import com.jayway.jsonpath.internal.function.numeric.Max;
 import com.jayway.jsonpath.internal.function.numeric.Min;
 import com.jayway.jsonpath.internal.function.numeric.StandardDeviation;
 import com.jayway.jsonpath.internal.function.numeric.Sum;
+import com.jayway.jsonpath.internal.function.text.Concatenate;
+import com.jayway.jsonpath.internal.function.text.Length;
 
 import java.util.Collections;
 import java.util.HashMap;
@@ -35,10 +37,14 @@ public class PathFunctionFactory {
         map.put("min", Min.class);
         map.put("max", Max.class);
 
+        // Text Functions
+        map.put("concat", Concatenate.class);
+
         // JSON Entity Functions
         map.put("length", Length.class);
         map.put("size", Length.class);
 
+
         FUNCTIONS = Collections.unmodifiableMap(map);
     }
 

json-path/src/main/java/com/jayway/jsonpath/internal/function/text/Concatenate.java

@@ -0,0 +1,37 @@
+package com.jayway.jsonpath.internal.function.text;
+
+import com.jayway.jsonpath.internal.EvaluationContext;
+import com.jayway.jsonpath.internal.PathRef;
+import com.jayway.jsonpath.internal.function.Parameter;
+import com.jayway.jsonpath.internal.function.PathFunction;
+
+import java.util.List;
+
+/**
+ * String function concat - simple takes a list of arguments and/or an array and concatenates them together to form a
+ * single string
+ *
+ * Created by mgreenwood on 12/11/15.
+ */
+public class Concatenate implements PathFunction {
+    @Override
+    public Object invoke(String currentPath, PathRef parent, Object model, EvaluationContext ctx, List<Parameter> parameters) {
+        StringBuffer result = new StringBuffer();
+        if(ctx.configuration().jsonProvider().isArray(model)){
+            Iterable<?> objects = ctx.configuration().jsonProvider().toIterable(model);
+            for (Object obj : objects) {
+                if (obj instanceof String) {
+                    result.append(obj.toString());
+                }
+            }
+        }
+        if (parameters != null) {
+            for (Parameter param : parameters) {
+                if (param.getCachedValue() != null) {
+                    result.append(param.getCachedValue().toString());
+                }
+            }
+        }
+        return result.toString();
+    }
+}

json-path/src/main/java/com/jayway/jsonpath/internal/function/text/Length.java

@@ -1,7 +1,9 @@
-package com.jayway.jsonpath.internal.function;
+package com.jayway.jsonpath.internal.function.text;
 
 import com.jayway.jsonpath.internal.EvaluationContext;
 import com.jayway.jsonpath.internal.PathRef;
+import com.jayway.jsonpath.internal.function.Parameter;
+import com.jayway.jsonpath.internal.function.PathFunction;
 
 import java.util.List;
 

json-path/src/test/java/com/jayway/jsonpath/internal/function/BaseFunctionTest.java

@@ -39,6 +39,10 @@ public class BaseFunctionTest {
         verifyFunction(conf, pathExpr, NUMBER_SERIES, expectedValue);
     }
 
+    protected void verifyTextFunction(Configuration conf, String pathExpr, Object expectedValue) {
+        verifyFunction(conf, pathExpr, TEXT_SERIES, expectedValue);
+    }
+
     protected String getResourceAsText(String resourceName) throws IOException {
         return new Scanner(BaseFunctionTest.class.getResourceAsStream(resourceName), "UTF-8").useDelimiter("\\A").next();
     }

json-path/src/test/java/com/jayway/jsonpath/internal/function/NestedFunctionTest.java

@@ -54,4 +54,14 @@ public class NestedFunctionTest extends BaseFunctionTest {
     public void testJsonInnerArgumentArray() {
         verifyMathFunction(conf, "$.sum(5, 3, $.numbers.max(), 2)", 20.0);
     }
+
+    @Test
+    public void testStringConcat() {
+        verifyTextFunction(conf, "$.text.concat()", "abcdef");
+    }
+
+    @Test
+    public void testStringConcatWithJSONParameter() {
+        verifyTextFunction(conf, "$.text.concat(\"-\", \"ghijk\")", "abcdef-ghijk");
+    }
 }