Implement the join function and add two testcases

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

@@ -9,6 +9,7 @@ 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.Join;
 import com.jayway.jsonpath.internal.function.text.Length;
 
 import java.util.Collections;
@@ -40,6 +41,7 @@ public class PathFunctionFactory {
 
         // Text Functions
         map.put("concat", Concatenate.class);
+        map.put("join", Join.class);
 
         // JSON Entity Functions
         map.put(Length.TOKEN_NAME, Length.class);

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

@@ -0,0 +1,47 @@
+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;
+
+public class Join implements PathFunction {
+    @Override
+    public Object invoke(String currentPath, PathRef parent, Object model, EvaluationContext ctx, List<Parameter> parameters) {
+        StringBuilder result = new StringBuilder();
+
+        List<String> strings = null;
+        String separator = " ";
+        if (null != parameters){
+            strings = Parameter.toList(String.class, ctx, parameters);
+            if (strings.size() == 0)
+                separator = " ";
+            else
+                separator = strings.remove(strings.size() - 1);
+        }
+
+        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());
+                    result.append(separator);
+                }
+            }
+        }
+
+        if (null != strings){
+            for (String string : strings){
+                result.append(string);
+                result.append(separator);
+            }
+        }
+
+        if (result.length() > 0)
+            return result.delete(result.length() - separator.length(), result.length()).toString();
+        else
+            return result;
+    }
+}

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

@@ -42,6 +42,8 @@ public class PathCompiler {
     private static final char SINGLE_QUOTE = '\'';
     private static final char DOUBLE_QUOTE = '"';
 
+    private static final char ESACAPE = '\\';
+
     private final LinkedList<Predicate> filterStack;
     private final CharacterIndex path;
 
@@ -364,6 +366,15 @@ public class PathCompiler {
                         }
                     }
                     break;
+                case ESACAPE:
+                    char next = path.currentChar();
+                    if (groupQuote == 1 && (next == ',' || next == '\"')){
+                        parameter.append(next);
+                        path.incrementPosition(1);
+                        priorChar = 0;
+                        continue;
+                    }
+                    break;
             }
 
             if (type != null && !(c == COMMA && 0 == groupBrace && 0 == groupBracket && 1 == groupParen)) {

json-path/src/test/java/com/jayway/jsonpath/internal/function/Issue623.java

@@ -0,0 +1,49 @@
+package com.jayway.jsonpath.internal.function;
+
+import com.jayway.jsonpath.Configuration;
+import com.jayway.jsonpath.Configurations;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@RunWith(Parameterized.class)
+public class Issue623 extends BaseFunctionTest{
+    private static final Logger logger = LoggerFactory.getLogger(NumericPathFunctionTest.class);
+    private Configuration conf;
+
+    @Parameterized.Parameters
+    public static Iterable<Configuration> configurations() {
+        return Configurations.configurations();
+    }
+
+    public Issue623(Configuration conf) {
+        logger.debug("Testing with configuration {}", conf.getClass().getName());
+        this.conf = conf;
+    }
+
+    @Test
+    public void joinFunctionSimpleTest() {
+        verifyTextFunction(conf, "$.text.join()", "a b c d e f");
+        verifyTextFunction(conf, "$.text.join(\"\\, \")", "a, b, c, d, e, f");
+        verifyTextFunction(conf, "$.text.join(\"1\", \"2\", \"3\", \"-\")", "a-b-c-d-e-f-1-2-3");
+    }
+
+    @Test
+    public void testJoinNestedTest() {
+        String json = "{\"document\" : { " +
+                "\"text\" : [ " +
+                "{ \"value\": \"a\", \"int\": \"1\" }, " +
+                "{ \"value\": \"b\", \"int\": \"2\" }, " +
+                "{ \"value\": \"c\", \"int\": \"3\" }, " +
+                "{ \"value\": \"d\", \"int\": \"4\" }, " +
+                "{ \"value\": \"e\", \"int\": \"5\" }, " +
+                "{ \"value\": \"f\", \"int\": \"6\" } ]}}";
+
+        verifyFunction(conf, "join(" +
+                "$.join($.document.text[*]['value'], \"\t\"), " +
+                "$.join($.document.text[*]['int'], \"\t\"), " +
+                "\"\n\")", json, "a\tb\tc\td\te\tf\n1\t2\t3\t4\t5\t6");
+    }
+}