Add simple XML parsing

10 files changed, 258 insertions, 0 deletions

diff --git a/pom.xml b/pom.xml
index 5e9fcb8..605626f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -28,5 +28,11 @@
       <version>1.16.6</version>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>18.0</version>
+      <scope>runtime</scope>
+    </dependency>
   </dependencies>
 </project>
\ No newline at end of file
diff --git a/src/main/java/org/zwobble/mammoth/xml/ElementName.java b/src/main/java/org/zwobble/mammoth/xml/ElementName.java
new file mode 100644
index 0000000..1d70c36
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/ElementName.java
@@ -0,0 +1,8 @@
+package org.zwobble.mammoth.xml;
+
+import lombok.Value;
+
+@Value
+public class ElementName {
+    private String localName;
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/SimpleSax.java b/src/main/java/org/zwobble/mammoth/xml/SimpleSax.java
new file mode 100644
index 0000000..8165552
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/SimpleSax.java
@@ -0,0 +1,54 @@
+package org.zwobble.mammoth.xml;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.stream.IntStream;
+
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.parsers.SAXParserFactory;
+
+import org.xml.sax.Attributes;
+import org.xml.sax.InputSource;
+import org.xml.sax.SAXException;
+import org.xml.sax.helpers.DefaultHandler;
+
+import static java.util.stream.Collectors.toMap;
+
+import lombok.val;
+
+public class SimpleSax {
+    public static void parseString(String value, SimpleSaxHandler handler) {
+        val parserFactory = SAXParserFactory.newInstance();
+        parserFactory.setNamespaceAware(true);
+        try {
+            val saxParser = parserFactory.newSAXParser();
+            val xmlReader = saxParser.getXMLReader();
+            xmlReader.setContentHandler(new DefaultHandler() {
+                @Override
+                public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
+                    final ElementName name = new ElementName(localName);
+                    val attributesMap = IntStream.range(0, attributes.getLength())
+                        .boxed()
+                        .collect(toMap(
+                            index -> new ElementName(attributes.getLocalName(index)),
+                            attributes::getValue
+                        ));
+                    handler.startElement(name, attributesMap);
+                }
+                
+                @Override
+                public void endElement(String uri, String localName, String qName) throws SAXException {
+                    handler.endElement();
+                }
+                
+                @Override
+                public void characters(char[] ch, int start, int length) throws SAXException {
+                    handler.characters(new String(ch, start, length));
+                }
+            });
+            xmlReader.parse(new InputSource(new StringReader(value)));
+        } catch (ParserConfigurationException | SAXException | IOException exception) {
+            throw new RuntimeException(exception);
+        }
+    }
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/SimpleSaxHandler.java b/src/main/java/org/zwobble/mammoth/xml/SimpleSaxHandler.java
new file mode 100644
index 0000000..f56a940
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/SimpleSaxHandler.java
@@ -0,0 +1,9 @@
+package org.zwobble.mammoth.xml;
+
+import java.util.Map;
+
+public interface SimpleSaxHandler {
+    void startElement(ElementName name, Map<ElementName, String> attributes);
+    void endElement();
+    void characters(String string);
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/XmlElement.java b/src/main/java/org/zwobble/mammoth/xml/XmlElement.java
new file mode 100644
index 0000000..a49f5f8
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/XmlElement.java
@@ -0,0 +1,30 @@
+package org.zwobble.mammoth.xml;
+
+import java.util.List;
+import java.util.Map;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+
+import lombok.EqualsAndHashCode;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+
+@RequiredArgsConstructor
+@EqualsAndHashCode
+@ToString
+public class XmlElement implements XmlNode {
+    public XmlElement(String name) {
+        this(name, ImmutableMap.of());
+    }
+    
+    public XmlElement(String name, Map<String, String> attributes) {
+        this(name, attributes, ImmutableList.of());
+    }
+    
+    @Getter
+    private final String name;
+    private final Map<String, String> attributes;
+    private final List<XmlNode> children;
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/XmlElementBuilder.java b/src/main/java/org/zwobble/mammoth/xml/XmlElementBuilder.java
new file mode 100644
index 0000000..16b4865
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/XmlElementBuilder.java
@@ -0,0 +1,25 @@
+package org.zwobble.mammoth.xml;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+class XmlElementBuilder {
+    private final String name;
+    private final Map<String, String> attributes;
+    private final List<XmlNode> children;
+
+    XmlElementBuilder(String name, Map<String, String> attributes) {
+        this.name = name;
+        this.attributes = attributes;
+        this.children = new ArrayList<>();
+    }
+    
+    XmlElement build() {
+        return new XmlElement(name, attributes, children);
+    }
+
+    void addChild(XmlNode node) {
+        children.add(node);
+    }
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/XmlNode.java b/src/main/java/org/zwobble/mammoth/xml/XmlNode.java
new file mode 100644
index 0000000..c91e100
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/XmlNode.java
@@ -0,0 +1,5 @@
+package org.zwobble.mammoth.xml;
+
+public interface XmlNode {
+
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/XmlParser.java b/src/main/java/org/zwobble/mammoth/xml/XmlParser.java
new file mode 100644
index 0000000..360c174
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/XmlParser.java
@@ -0,0 +1,54 @@
+package org.zwobble.mammoth.xml;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Map;
+
+import static java.util.stream.Collectors.toMap;
+
+import lombok.val;
+
+public class XmlParser {
+    public static XmlElement parseString(String value) {
+        val nodeGenerator = new NodeGenerator();
+        SimpleSax.parseString(value, nodeGenerator);
+        return nodeGenerator.getRoot();
+    }
+    
+    private static class NodeGenerator implements SimpleSaxHandler {
+        private final Deque<XmlElementBuilder> elementStack;
+        
+        public NodeGenerator() {
+            elementStack = new ArrayDeque<>();
+        }
+        
+        public XmlElement getRoot() {
+            return elementStack.getFirst().build();
+        }
+
+        @Override
+        public void startElement(ElementName name, Map<ElementName, String> attributes) {
+            val simpleAttributes = attributes
+                .entrySet()
+                .stream()
+                .collect(toMap(
+                    entry -> entry.getKey().getLocalName(),
+                    entry -> entry.getValue()));
+            val element = new XmlElementBuilder(name.getLocalName(), simpleAttributes);
+            elementStack.add(element);
+        }
+
+        @Override
+        public void endElement() {
+            if (elementStack.size() > 1) {
+                val element = elementStack.removeLast();
+                elementStack.getLast().addChild(element.build());   
+            }            
+        }
+
+        @Override
+        public void characters(String string) {
+            elementStack.getLast().addChild(new XmlTextNode(string));
+        }
+    }
+}
diff --git a/src/main/java/org/zwobble/mammoth/xml/XmlTextNode.java b/src/main/java/org/zwobble/mammoth/xml/XmlTextNode.java
new file mode 100644
index 0000000..0d63273
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/xml/XmlTextNode.java
@@ -0,0 +1,8 @@
+package org.zwobble.mammoth.xml;
+
+import lombok.Value;
+
+@Value
+public class XmlTextNode implements XmlNode {
+    private String value;
+}
diff --git a/src/test/java/org/zwobble/mammoth/tests/xml/XmlParserTests.java b/src/test/java/org/zwobble/mammoth/tests/xml/XmlParserTests.java
new file mode 100644
index 0000000..1ce5d7d
--- /dev/null
+++ b/src/test/java/org/zwobble/mammoth/tests/xml/XmlParserTests.java
@@ -0,0 +1,59 @@
+package org.zwobble.mammoth.tests.xml;
+
+import org.junit.Test;
+import org.zwobble.mammoth.xml.XmlElement;
+import org.zwobble.mammoth.xml.XmlParser;
+import org.zwobble.mammoth.xml.XmlTextNode;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+public class XmlParserTests {
+    @Test
+    public void canParseSelfClosingElement() {
+        assertThat(
+            XmlParser.parseString("<body/>"),
+            is(new XmlElement("body")));
+        assertThat(
+            XmlParser.parseString("<values/>"),
+            is(new XmlElement("values")));
+    }
+    
+    @Test
+    public void canParseEmptyElementWithSeparateClosingTag() {
+        assertThat(
+            XmlParser.parseString("<body></body>"),
+            is(new XmlElement("body")));
+    }
+    
+    @Test
+    public void canParseAttributesOfTag() {
+        assertThat(
+            XmlParser.parseString("<body name='bob'></body>"),
+            is(new XmlElement("body", ImmutableMap.of("name", "bob"))));
+    }
+    
+    @Test
+    public void canParseElementWithDescendantElements() {
+        assertThat(
+            XmlParser.parseString("<body><a><b/></a><a/></body>"),
+            is(new XmlElement("body", ImmutableMap.of(), ImmutableList.of(
+                new XmlElement("a", ImmutableMap.of(), ImmutableList.of(
+                    new XmlElement("b")
+                )),
+                new XmlElement("a")
+            ))));
+    }
+    
+    @Test
+    public void canParseTextNodes() {
+        assertThat(
+            XmlParser.parseString("<body>Hello!</body>"),
+            is(new XmlElement("body", ImmutableMap.of(), ImmutableList.of(
+                new XmlTextNode("Hello!")
+            ))));
+    }
+}