Issue #191 fixes both $..allTheThings.max() and $.max($..allTheThings)

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

@@ -1,11 +1,15 @@
 package com.jayway.jsonpath.internal.function;
 
+import com.jayway.jsonpath.internal.EvaluationContext;
 import com.jayway.jsonpath.internal.Path;
 import com.jayway.jsonpath.internal.function.latebinding.ILateBindingValue;
-import com.jayway.jsonpath.internal.function.latebinding.PathLateBindingValue;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
 
 /**
- * Created by [email protected] on 12/10/15.
+ * Defines a parameter as passed to a function with late binding support for lazy evaluation.
  */
 public class Parameter {
     private ParamType type;
@@ -65,4 +69,63 @@ public String getJson() {
     public void setJson(String json) {
         this.json = json;
     }
+
+    /**
+     * Translate the collection of parameters into a collection of values of type T.
+     *
+     * @param type
+     *      The type to translate the collection into.
+     *
+     * @param ctx
+     *      Context.
+     *
+     * @param parameters
+     *      Collection of parameters.
+     *
+     * @param <T>
+     *      Type T returned as a List of T.
+     *
+     * @return
+     *      List of T either empty or containing contents.
+     */
+    public static <T> List<T> toList(final Class<T> type, final EvaluationContext ctx, final List<Parameter> parameters) {
+        List<T> values = new ArrayList();
+        if (null != parameters) {
+            for (Parameter param : parameters) {
+                consume(type, ctx, values, param.getValue());
+            }
+        }
+        return values;
+    }
+
+    /**
+     * Either consume the object as an array and add each element to the collection, or alternatively add each element
+     *
+     * @param expectedType
+     *      the expected class type to consume, if null or not of this type the element is not added to the array.
+     *
+     * @param ctx
+     *      the JSON context to determine if this is an array or value.
+     *
+     * @param collection
+     *      The collection to append into.
+     *
+     * @param value
+     *      The value to evaluate.
+     */
+    public static void consume(Class expectedType, EvaluationContext ctx, Collection collection, Object value) {
+        if (ctx.configuration().jsonProvider().isArray(value)) {
+            for (Object o : ctx.configuration().jsonProvider().toIterable(value)) {
+                if (o != null && expectedType.isAssignableFrom(o.getClass())) {
+                    collection.add(o);
+                } else if (o != null && expectedType == String.class) {
+                    collection.add(o.toString());
+                }
+            }
+        } else {
+            if (value != null && expectedType.isAssignableFrom(value.getClass())) {
+                collection.add(value);
+            }
+        }
+    }
 }

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

@@ -21,7 +21,6 @@
  * Leverages the function's name in order to determine which function to execute which is maintained internally
  * here via a static map
  *
- * Created by mattg on 6/27/15.
  */
 public class PathFunctionFactory {
 

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

@@ -48,12 +48,9 @@ public Object invoke(String currentPath, PathRef parent, Object model, Evaluatio
             }
         }
         if (parameters != null) {
-            for (Parameter param : parameters) {
-                Object value = param.getValue();
-                if (null != value && value instanceof Number) {
-                    count++;
-                    next((Number)value);
-                }
+            for (Number value : Parameter.toList(Number.class, ctx, parameters)) {
+                count++;
+                next(value);
             }
         }
         if (count != 0) {

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

@@ -11,7 +11,6 @@
  * 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
@@ -26,11 +25,8 @@ public Object invoke(String currentPath, PathRef parent, Object model, Evaluatio
             }
         }
         if (parameters != null) {
-            for (Parameter param : parameters) {
-		Object value = param.getValue();
-                if (value != null) {
-                    result.append(value.toString());
-                }
+            for (String value : Parameter.toList(String.class, ctx, parameters)) {
+                result.append(value);
             }
         }
         return result.toString();

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

@@ -19,9 +19,13 @@
 import com.jayway.jsonpath.internal.EvaluationContext;
 import com.jayway.jsonpath.internal.Path;
 import com.jayway.jsonpath.internal.PathRef;
+import com.jayway.jsonpath.internal.function.ParamType;
+import com.jayway.jsonpath.internal.function.Parameter;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.Arrays;
+
 public class CompiledPath implements Path {
 
     private static final Logger logger = LoggerFactory.getLogger(CompiledPath.class);
@@ -32,7 +36,7 @@ public class CompiledPath implements Path {
 
 
     public CompiledPath(RootPathToken root, boolean isRootPath) {
-        this.root = root;
+        this.root = invertScannerFunctionRelationship(root);
         this.isRootPath = isRootPath;
     }
 
@@ -41,6 +45,48 @@ public boolean isRootPath() {
         return isRootPath;
     }
 
+
+
+    /**
+     * In the event the writer of the path referenced a function at the tail end of a scanner, augment the query such
+     * that the root node is the function and the parameter to the function is the scanner.   This way we maintain
+     * relative sanity in the path expression, functions either evaluate scalar values or arrays, they're
+     * not re-entrant nor should they maintain state, they do however take parameters.
+     *
+     * @param path
+     *      this is our old root path which will become a parameter (assuming there's a scanner terminated by a function
+     *
+     * @return
+     *      A function with the scanner as input, or if this situation doesn't exist just the input path
+     */
+    private RootPathToken invertScannerFunctionRelationship(final RootPathToken path) {
+        if (path.isFunctionPath() && path.next() instanceof ScanPathToken) {
+            PathToken token = path;
+            PathToken prior = null;
+            while (null != (token = token.next()) && !(token instanceof FunctionPathToken)) {
+                prior = token;
+            }
+            // Invert the relationship $..path.function() to $.function($..path)
+            if (token instanceof FunctionPathToken) {
+                prior.setNext(null);
+                path.setTail(prior);
+
+                // Now generate a new parameter from our path
+                Parameter parameter = new Parameter();
+                parameter.setPath(new CompiledPath(path, true));
+                parameter.setType(ParamType.PATH);
+                ((FunctionPathToken)token).setParameters(Arrays.asList(parameter));
+                RootPathToken functionRoot = new RootPathToken('$');
+                functionRoot.setTail(token);
+                functionRoot.setNext(token);
+
+                // Define the function as the root
+                return functionRoot;
+            }
+        }
+        return path;
+    }
+
     @Override
     public EvaluationContext evaluate(Object document, Object rootDocument, Configuration configuration, boolean forUpdate) {
         if (logger.isDebugEnabled()) {

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

@@ -20,7 +20,7 @@ public class FunctionPathToken extends PathToken {
 
     private final String functionName;
     private final String pathFragment;
-    private final List<Parameter> functionParams;
+    private List<Parameter> functionParams;
 
     public FunctionPathToken(String pathFragment, List<Parameter> parameters) {
         this.pathFragment = pathFragment + ((parameters != null && parameters.size() > 0) ? "(...)" : "()");
@@ -81,4 +81,7 @@ public String getPathFragment() {
     }
 
 
+    public void setParameters(List<Parameter> parameters) {
+        this.functionParams = parameters;
+    }
 }

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

@@ -215,4 +215,7 @@ public void invoke(PathFunction pathFunction, String currentPath, PathRef parent
 
     protected abstract String getPathFragment();
 
+    public void setNext(final PathToken next) {
+        this.next = next;
+    }
 }

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

@@ -76,4 +76,8 @@ public boolean isTokenDefinite() {
     public boolean isFunctionPath() {
         return (tail instanceof FunctionPathToken);
     }
+
+    public void setTail(PathToken token) {
+        this.tail = token;
+    }
 }

json-path/src/test/java/com/jayway/jsonpath/internal/function/Issue191.java

@@ -0,0 +1,67 @@
+package com.jayway.jsonpath.internal.function;
+
+import com.jayway.jsonpath.Configuration;
+import com.jayway.jsonpath.Configurations;
+import com.jayway.jsonpath.JsonPath;
+import org.junit.Test;
+
+import java.io.InputStream;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * TDD for Issue 191
+ *
+ * Shows aggregation across fields rather than within a single entity.
+ *
+ */
+public class Issue191 {
+
+    private Configuration conf = Configurations.GSON_CONFIGURATION;
+
+    @Test
+    public void testResultSetNumericComputation() {
+        InputStream stream = ClassLoader.getSystemResourceAsStream("issue_191.json");
+        Long value = JsonPath.parse(stream).read("$.sum($..timestamp)", Long.class);
+        assertEquals("Expected the max function to consume the aggregation parameters and calculate the max over the result set",
+                Long.valueOf(35679716813L), value);
+    }
+
+    @Test
+    public void testResultSetNumericComputationTail() {
+        InputStream stream = ClassLoader.getSystemResourceAsStream("issue_191.json");
+        Long value = JsonPath.parse(stream).read("$..timestamp.sum()", Long.class);
+        assertEquals("Expected the max function to consume the aggregation parameters and calculate the max over the result set",
+                Long.valueOf(35679716813L), value);
+    }
+
+    @Test
+    public void testResultSetNumericComputationRecursiveReplacement() {
+        InputStream stream = ClassLoader.getSystemResourceAsStream("issue_191.json");
+        Long value = JsonPath.parse(stream).read("$.max($..timestamp.avg(), $..timestamp.stddev())", Long.class);
+        assertEquals("Expected the max function to consume the aggregation parameters and calculate the max over the result set",
+                Long.valueOf(1427188672L), value);
+    }
+
+    @Test
+    public void testMultipleResultSetSums() {
+        InputStream stream = ClassLoader.getSystemResourceAsStream("issue_191.json");
+        Long value = JsonPath.parse(stream).read("$.sum($..timestamp, $..cpus)", Long.class);
+        assertEquals("Expected the max function to consume the aggregation parameters and calculate the max over the result set",
+                Long.valueOf(35679716835L), value);
+    }
+
+    @Test
+    public void testConcatResultSet() {
+        InputStream stream = ClassLoader.getSystemResourceAsStream("issue_191.json");
+        String concatResult = JsonPath.parse(stream).read("$.concat($..state)", String.class);
+        assertEquals("Expected a string length to be a concat of all of the states", concatResult.length(), 806);
+    }
+
+    @Test
+    public void testConcatWithNumericValueAsString() {
+        InputStream stream = ClassLoader.getSystemResourceAsStream("issue_191.json");
+        String concatResult = JsonPath.parse(stream).read("$.concat($..cpus)", String.class);
+        assertEquals("Expected a string length to be a concat of all of the cpus", concatResult.length(), 489);
+    }
+}