Milestone4 haitong

README-M4.md

@@ -0,0 +1,18 @@
+# Milestone 4 – Stream support for **JSONObject**
+
+## What is Added
+
+| Item | Description |
+|------|-------------|
+| `JSONObject.JSONNode` | Immutable leaf wrapper containing an absolute `path` and its `value`. |
+| `Stream<JSONNode> JSONObject.toStream()` | Depth-first, **lazy** flattening of any `JSONObject/JSONArray` into a `Stream`. Only leaf nodes are emitted (low memory footprint). |
+
+Path conventions
+* Object keys: `/parent/child`
+* Array items:  `/array[0]/child`
+
+---
+
+## Run the test class
+```bash
+mvn -Dtest=org.json.junit.milestone4.tests.JSONObjectStreamTest test

src/main/java/org/json/JSONObject.java

@@ -17,6 +17,8 @@
 import java.util.*;
 import java.util.Map.Entry;
 import java.util.regex.Pattern;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
 
 /**
  * A JSONObject is an unordered collection of name/value pairs. Its external
@@ -3030,4 +3032,64 @@ private static String removeLeadingZerosOfNumber(String value){
         if (negativeFirstChar) {return "-0";}
         return "0";
     }
+
+    //    ---------------------------- Milestone 4 ------------------------------
+
+    /**
+     * Represents a node in the JSON object tree, with path and value.
+     */
+    public static class JSONNode {
+        private final String path;
+        private final Object value;
+
+        public JSONNode(String path, Object value) {
+            this.path = path;
+            this.value = value;
+        }
+
+        public String getPath() {
+            return path;
+        }
+
+        public Object getValue() {
+            return value;
+        }
+
+        @Override
+        public String toString() {
+            return "JSONNode{path='" + path + "', value=" + value + '}';
+        }
+    }
+
+    /**
+     * Convert this JSONObject into a stream of JSONNode, allowing chained operations.
+     * @return Stream of JSONNode objects (each has a full path and a value)
+     */
+    public Stream<JSONNode> toStream() {
+        return toStream("", this);
+    }
+
+    /**
+     * Recursive helper method to flatten JSONObject/JSONArray into JSONNode stream.
+     */
+    private Stream<JSONNode> toStream(String path, Object value) {
+        if (value instanceof JSONObject) {
+            JSONObject obj = (JSONObject) value;
+            return obj.keySet().stream()
+                    .flatMap(key -> {
+                        String newPath = path.isEmpty() ? "/" + key : path + "/" + key;
+                        return toStream(newPath, obj.get(key));
+                    });
+        } else if (value instanceof JSONArray) {
+            JSONArray array = (JSONArray) value;
+            return IntStream.range(0, array.length())
+                    .boxed()
+                    .flatMap(i -> {
+                        String newPath = path + "[" + i + "]";
+                        return toStream(newPath, array.get(i));
+                    });
+        } else {
+            return Stream.of(new JSONNode(path, value));
+        }
+    }
 }

src/test/java/org/json/junit/milestone4/tests/JSONObjectStreamTest.java

@@ -0,0 +1,74 @@
+package org.json.junit.milestone4.tests;
+
+import org.json.JSONObject;
+import org.json.JSONObject.JSONNode;
+import org.json.XML;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.Optional;
+import java.util.Scanner;
+import java.util.stream.Collectors;
+
+import static org.junit.Assert.*;
+
+/**
+ * Unit tests for the JSONObject.toStream() extension (Milestone 4) – JUnit 4 / Java 8.
+ */
+public class JSONObjectStreamTest {
+
+    private static JSONObject catalog;
+
+    @BeforeClass
+    public static void loadXml() throws Exception {
+        try (InputStream in = JSONObjectStreamTest.class.getResourceAsStream("/books.xml")) {
+            assertNotNull("books.xml must be on the class-path (src/test/resources)", in);
+
+            String xml;
+            try (Scanner scanner = new Scanner(in, StandardCharsets.UTF_8.name())) {
+                scanner.useDelimiter("\\A");
+                xml = scanner.hasNext() ? scanner.next() : "";
+            }
+
+            catalog = XML.toJSONObject(xml);
+        }
+    }
+
+    @Test
+    public void extractTitles() {
+        List<String> titles = catalog.toStream()
+                .filter(n -> n.getPath().endsWith("/title"))
+                .map(n -> n.getValue().toString())
+                .collect(Collectors.toList());
+
+        assertEquals(12, titles.size());
+        assertTrue(titles.contains("XML Developer's Guide"));
+        assertTrue(titles.contains("Visual Studio 7: A Comprehensive Guide"));
+    }
+
+    @Test
+    public void findExactPath() {
+        String wantedPath = "/catalog/book[0]/author";
+        Optional<JSONNode> node = catalog.toStream()
+                .filter(n -> n.getPath().equals(wantedPath))
+                .findFirst();
+
+        assertTrue(node.isPresent());
+        assertEquals("Gambardella, Matthew", node.get().getValue());
+    }
+
+    @Test
+    public void filterCheapBooks() {
+        List<JSONNode> cheapPrices = catalog.toStream()
+                .filter(n -> n.getPath().endsWith("/price"))
+                .filter(n -> Double.parseDouble(n.getValue().toString()) < 10.0)
+                .collect(Collectors.toList());
+
+        assertEquals(8, cheapPrices.size());
+        assertTrue(cheapPrices.stream()
+                .allMatch(n -> Double.parseDouble(n.getValue().toString()) < 10.0));
+    }
+}

src/test/resources/books.xml

@@ -0,0 +1,120 @@
+<?xml version="1.0"?>
+<catalog>
+    <book id="bk101">
+        <author>Gambardella, Matthew</author>
+        <title>XML Developer's Guide</title>
+        <genre>Computer</genre>
+        <price>44.95</price>
+        <publish_date>2000-10-01</publish_date>
+        <description>An in-depth look at creating applications
+            with XML.</description>
+    </book>
+    <book id="bk102">
+        <author>Ralls, Kim</author>
+        <title>Midnight Rain</title>
+        <genre>Fantasy</genre>
+        <price>5.95</price>
+        <publish_date>2000-12-16</publish_date>
+        <description>A former architect battles corporate zombies,
+            an evil sorceress, and her own childhood to become queen
+            of the world.</description>
+    </book>
+    <book id="bk103">
+        <author>Corets, Eva</author>
+        <title>Maeve Ascendant</title>
+        <genre>Fantasy</genre>
+        <price>5.95</price>
+        <publish_date>2000-11-17</publish_date>
+        <description>After the collapse of a nanotechnology
+            society in England, the young survivors lay the
+            foundation for a new society.</description>
+    </book>
+    <book id="bk104">
+        <author>Corets, Eva</author>
+        <title>Oberon's Legacy</title>
+        <genre>Fantasy</genre>
+        <price>5.95</price>
+        <publish_date>2001-03-10</publish_date>
+        <description>In post-apocalypse England, the mysterious
+            agent known only as Oberon helps to create a new life
+            for the inhabitants of London. Sequel to Maeve
+            Ascendant.</description>
+    </book>
+    <book id="bk105">
+        <author>Corets, Eva</author>
+        <title>The Sundered Grail</title>
+        <genre>Fantasy</genre>
+        <price>5.95</price>
+        <publish_date>2001-09-10</publish_date>
+        <description>The two daughters of Maeve, half-sisters,
+            battle one another for control of England. Sequel to
+            Oberon's Legacy.</description>
+    </book>
+    <book id="bk106">
+        <author>Randall, Cynthia</author>
+        <title>Lover Birds</title>
+        <genre>Romance</genre>
+        <price>4.95</price>
+        <publish_date>2000-09-02</publish_date>
+        <description>When Carla meets Paul at an ornithology
+            conference, tempers fly as feathers get ruffled.</description>
+    </book>
+    <book id="bk107">
+        <author>Thurman, Paula</author>
+        <title>Splish Splash</title>
+        <genre>Romance</genre>
+        <price>4.95</price>
+        <publish_date>2000-11-02</publish_date>
+        <description>A deep sea diver finds true love twenty
+            thousand leagues beneath the sea.</description>
+    </book>
+    <book id="bk108">
+        <author>Knorr, Stefan</author>
+        <title>Creepy Crawlies</title>
+        <genre>Horror</genre>
+        <price>4.95</price>
+        <publish_date>2000-12-06</publish_date>
+        <description>An anthology of horror stories about roaches,
+            centipedes, scorpions  and other insects.</description>
+    </book>
+    <book id="bk109">
+        <author>Kress, Peter</author>
+        <title>Paradox Lost</title>
+        <genre>Science Fiction</genre>
+        <price>6.95</price>
+        <publish_date>2000-11-02</publish_date>
+        <description>After an inadvertant trip through a Heisenberg
+            Uncertainty Device, James Salway discovers the problems
+            of being quantum.</description>
+    </book>
+    <book id="bk110">
+        <author>O'Brien, Tim</author>
+        <title>Microsoft .NET: The Programming Bible</title>
+        <genre>Computer</genre>
+        <price>36.95</price>
+        <publish_date>2000-12-09</publish_date>
+        <description>Microsoft's .NET initiative is explored in
+            detail in this deep programmer's reference.</description>
+    </book>
+    <book id="bk111">
+        <author>O'Brien, Tim</author>
+        <title>MSXML3: A Comprehensive Guide</title>
+        <genre>Computer</genre>
+        <price>36.95</price>
+        <publish_date>2000-12-01</publish_date>
+        <description>The Microsoft MSXML3 parser is covered in
+            detail, with attention to XML DOM interfaces, XSLT processing,
+            SAX and more.</description>
+    </book>
+    <book id="bk112">
+        <author>Galos, Mike</author>
+        <title>Visual Studio 7: A Comprehensive Guide</title>
+        <genre>Computer</genre>
+        <price>49.95</price>
+        <publish_date>2001-04-16</publish_date>
+        <description>Microsoft Visual Studio 7 is explored in depth,
+            looking at how Visual Basic, Visual C++, C#, and ASP+ are
+            integrated into a comprehensive development
+            environment.</description>
+    </book>
+</catalog>