added visitor

Author: ashwanikumar04

src/main/java/in/ashwanik/pdp/visitor/BoldText.java

@@ -0,0 +1,12 @@
+package in.ashwanik.pdp.visitor;
+
+public class BoldText extends DocumentPart {
+    BoldText(String text) {
+        super(text);
+    }
+
+    @Override
+    void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+}

src/main/java/in/ashwanik/pdp/visitor/Document.java

@@ -0,0 +1,24 @@
+package in.ashwanik.pdp.visitor;
+
+import java.util.ArrayList;
+import java.util.List;
+
+class Document {
+    private List<DocumentPart> parts;
+
+    Document() {
+        parts = new ArrayList<>();
+    }
+
+    void add(DocumentPart documentPart) {
+        parts.add(documentPart);
+    }
+
+    void clear() {
+        parts.clear();
+    }
+
+    void generate(Visitor visitor) {
+        parts.forEach(x -> x.accept(visitor));
+    }
+}

src/main/java/in/ashwanik/pdp/visitor/DocumentPart.java

@@ -0,0 +1,15 @@
+package in.ashwanik.pdp.visitor;
+
+import lombok.Getter;
+
+@Getter
+abstract class DocumentPart {
+    private final String text;
+
+    DocumentPart(String text) {
+        this.text = text;
+    }
+
+    abstract void accept(Visitor visitor);
+
+}

src/main/java/in/ashwanik/pdp/visitor/HtmlVisitor.java

@@ -0,0 +1,36 @@
+package in.ashwanik.pdp.visitor;
+
+public class HtmlVisitor implements Visitor {
+
+    private StringBuilder output;
+
+    HtmlVisitor() {
+        output = new StringBuilder();
+    }
+
+    String getOutput() {
+        return output.toString();
+    }
+
+    @Override
+    public void visit(PlainText plainText) {
+        output.append(plainText.getText());
+    }
+
+    @Override
+    public void visit(BoldText boldText) {
+        output.append("<b>");
+        output.append(boldText);
+        output.append("</b>");
+    }
+
+    @Override
+    public void visit(HyperLink hyperLink) {
+        output.append("<a");
+        output.append(" href='");
+        output.append(hyperLink.getUrl());
+        output.append("'> ");
+        output.append(hyperLink.getText());
+        output.append("</a>");
+    }
+}

src/main/java/in/ashwanik/pdp/visitor/HyperLink.java

@@ -0,0 +1,19 @@
+package in.ashwanik.pdp.visitor;
+
+import lombok.Getter;
+
+@Getter
+class HyperLink extends DocumentPart {
+    private String url;
+
+    HyperLink(String text,
+              String url) {
+        super(text);
+        this.url = url;
+    }
+
+    @Override
+    void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+}

src/main/java/in/ashwanik/pdp/visitor/MarkDownVisitor.java

@@ -0,0 +1,36 @@
+package in.ashwanik.pdp.visitor;
+
+public class MarkDownVisitor implements Visitor {
+
+    private StringBuilder output;
+
+    MarkDownVisitor() {
+        output = new StringBuilder();
+    }
+
+    String getOutput() {
+        return output.toString();
+    }
+
+    @Override
+    public void visit(PlainText plainText) {
+        output.append(plainText.getText());
+    }
+
+    @Override
+    public void visit(BoldText boldText) {
+        output.append("**");
+        output.append(boldText);
+        output.append("**");
+    }
+
+    @Override
+    public void visit(HyperLink hyperLink) {
+        output.append("[");
+        output.append(hyperLink.getUrl());
+        output.append("]");
+        output.append("(");
+        output.append(hyperLink.getText());
+        output.append(")");
+    }
+}

src/main/java/in/ashwanik/pdp/visitor/PlainText.java

@@ -0,0 +1,12 @@
+package in.ashwanik.pdp.visitor;
+
+public class PlainText extends DocumentPart {
+    PlainText(String text) {
+        super(text);
+    }
+
+    @Override
+    void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+}

src/main/java/in/ashwanik/pdp/visitor/Visitor.java

@@ -0,0 +1,9 @@
+package in.ashwanik.pdp.visitor;
+
+interface Visitor {
+    void visit(PlainText plainText);
+
+    void visit(BoldText boldText);
+
+    void visit(HyperLink hyperLink);
+}

src/test/java/in/ashwanik/pdp/visitor/DocumentUnitTest.java

@@ -0,0 +1,19 @@
+package in.ashwanik.pdp.visitor;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+public class DocumentUnitTest {
+    @Test
+    public void testDocumentConverter() {
+        Document document = new Document();
+        document.add(new PlainText("hello"));
+        document.add(new BoldText("hello"));
+        document.add(new HyperLink("hello", "http://google.com"));
+
+        HtmlVisitor visitor = new HtmlVisitor();
+        document.generate(visitor);
+        assertThat(visitor.getOutput()).isNotBlank();
+    }
+}