Add result objects

6 files changed, 116 insertions, 33 deletions

diff --git a/src/main/java/org/zwobble/mammoth/Mammoth.java b/src/main/java/org/zwobble/mammoth/Mammoth.java
index 05080cf..7282082 100644
--- a/src/main/java/org/zwobble/mammoth/Mammoth.java
+++ b/src/main/java/org/zwobble/mammoth/Mammoth.java
@@ -13,15 +13,16 @@ import java.util.zip.ZipFile;
 import static com.google.common.collect.Iterables.transform;
 
 public class Mammoth {
-    public static String convertToHtml(File file) {
+    public static Result<String> convertToHtml(File file) {
         try (ZipFile zipFile = new ZipFile(file)) {
             ZipEntry entry = zipFile.getEntry("word/document.xml");
             XmlElement documentXml = OfficeXml.parseXml(zipFile.getInputStream(entry));
 
             Styles styles = Styles.EMPTY;
             Numbering numbering = Numbering.EMPTY;
-            Document document = new DocumentXmlReader(new BodyXmlReader(styles, numbering)).readElement(documentXml);
-            return convertToHtml(document);
+            DocumentXmlReader reader = new DocumentXmlReader(new BodyXmlReader(styles, numbering));
+            return reader.readElement(documentXml)
+                .map(Mammoth::convertToHtml);
         } catch (IOException e) {
             throw new UnsupportedOperationException("Should return a result of failure");   
         }
diff --git a/src/main/java/org/zwobble/mammoth/Result.java b/src/main/java/org/zwobble/mammoth/Result.java
new file mode 100644
index 0000000..0665364
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/Result.java
@@ -0,0 +1,34 @@
+package org.zwobble.mammoth;
+
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+import java.util.function.Function;
+
+public class Result<T> {
+    public static <T> Result<List<T>> concat(Iterable<Result<T>> results) {
+        ImmutableList.Builder<T> elements = ImmutableList.builder();
+        for (Result<T> result : results) {
+            elements.add(result.value);
+        }
+        return new Result<>(elements.build());
+    }
+
+    public static <T> Result<T> success(T value) {
+        return new Result<>(value);
+    }
+
+    private final T value;
+
+    public Result(T value) {
+        this.value = value;
+    }
+
+    public T getValue() {
+        return value;
+    }
+
+    public <R> Result<R> map(Function<T, R> function) {
+        return new Result<>(function.apply(value));
+    }
+}
diff --git a/src/main/java/org/zwobble/mammoth/docx/BodyXmlReader.java b/src/main/java/org/zwobble/mammoth/docx/BodyXmlReader.java
index 334f925..26958dd 100644
--- a/src/main/java/org/zwobble/mammoth/docx/BodyXmlReader.java
+++ b/src/main/java/org/zwobble/mammoth/docx/BodyXmlReader.java
@@ -1,17 +1,17 @@
 package org.zwobble.mammoth.docx;
 
-import com.google.common.collect.ImmutableList;
 import org.zwobble.mammoth.documents.*;
 import org.zwobble.mammoth.util.MammothOptionals;
 import org.zwobble.mammoth.xml.XmlElement;
 import org.zwobble.mammoth.xml.XmlElementLike;
 import org.zwobble.mammoth.xml.XmlNode;
 
-import java.util.List;
 import java.util.Optional;
 
-import static com.google.common.collect.Iterables.*;
-import static org.zwobble.mammoth.util.MammothLists.list;
+import static com.google.common.collect.Iterables.filter;
+import static com.google.common.collect.Iterables.transform;
+import static org.zwobble.mammoth.docx.ReadResult.EMPTY_SUCCESS;
+import static org.zwobble.mammoth.docx.ReadResult.success;
 
 public class BodyXmlReader {
     private final Styles styles;
@@ -22,38 +22,37 @@ public class BodyXmlReader {
         this.numbering = numbering;
     }
 
-    public List<DocumentElement> readElement(XmlElement element) {
+    public ReadResult readElement(XmlElement element) {
         switch (element.getName()) {
             case "w:t":
-                return list(new Text(element.innerText()));
+                return success(new Text(element.innerText()));
             case "w:r":
-                return list(new Run(readElements(element.children())));
+                return readElements(element.children()).map(Run::new);
             case "w:p":
-                return list(readParagraph(element));
+                return readParagraph(element);
 
             case "w:pPr":
-                return list();
+                return EMPTY_SUCCESS;
 
             default:
                 // TODO: emit warning
-                return list();
+                return EMPTY_SUCCESS;
         }
     }
 
-    public List<DocumentElement> readElements(Iterable<XmlNode> nodes) {
-        return ImmutableList.copyOf(
-            concat(
-                transform(
-                    filter(nodes, XmlElement.class),
-                    this::readElement)));
+    public ReadResult readElements(Iterable<XmlNode> nodes) {
+        return ReadResult.concat(
+            transform(
+                filter(nodes, XmlElement.class),
+                this::readElement));
     }
 
-    private Paragraph readParagraph(XmlElement element) {
+    private ReadResult readParagraph(XmlElement element) {
         XmlElementLike properties = element.findChildOrEmpty("w:pPr");
-        return new Paragraph(
-            readParagraphStyle(properties),
-            readNumbering(properties),
-            readElements(element.children()));
+        Optional<Style> paragraphStyle = readParagraphStyle(properties);
+        Optional<NumberingLevel> numbering = readNumbering(properties);
+        return readElements(element.children())
+            .map(children -> new Paragraph(paragraphStyle, numbering, children));
     }
 
     private Optional<Style> readParagraphStyle(XmlElementLike properties) {
diff --git a/src/main/java/org/zwobble/mammoth/docx/DocumentXmlReader.java b/src/main/java/org/zwobble/mammoth/docx/DocumentXmlReader.java
index 0b51774..98570f2 100644
--- a/src/main/java/org/zwobble/mammoth/docx/DocumentXmlReader.java
+++ b/src/main/java/org/zwobble/mammoth/docx/DocumentXmlReader.java
@@ -1,5 +1,6 @@
 package org.zwobble.mammoth.docx;
 
+import org.zwobble.mammoth.Result;
 import org.zwobble.mammoth.documents.Document;
 import org.zwobble.mammoth.xml.XmlElement;
 
@@ -10,8 +11,10 @@ public class DocumentXmlReader {
         this.bodyReader = bodyReader;
     }
 
-    public Document readElement(XmlElement element) {
+    public Result<Document> readElement(XmlElement element) {
         XmlElement body = element.findChild("w:body");
-        return new Document(bodyReader.readElements(body.children()));
+        return bodyReader.readElements(body.children())
+            .toResult()
+            .map(Document::new);
     }
 }
diff --git a/src/main/java/org/zwobble/mammoth/docx/NotesXmlReader.java b/src/main/java/org/zwobble/mammoth/docx/NotesXmlReader.java
index 06d17ca..7cd0419 100644
--- a/src/main/java/org/zwobble/mammoth/docx/NotesXmlReader.java
+++ b/src/main/java/org/zwobble/mammoth/docx/NotesXmlReader.java
@@ -1,6 +1,6 @@
 package org.zwobble.mammoth.docx;
 
-import com.google.common.collect.ImmutableList;
+import org.zwobble.mammoth.Result;
 import org.zwobble.mammoth.documents.Note;
 import org.zwobble.mammoth.xml.XmlElement;
 
@@ -18,9 +18,9 @@ public class NotesXmlReader {
         this.noteType = noteType;
     }
 
-    public List<Note> readElement(XmlElement element) {
+    public Result<List<Note>> readElement(XmlElement element) {
         Iterable<XmlElement> elements = filter(element.findChildren("w:" + noteType), this::isNoteElement);
-        return ImmutableList.copyOf(transform(elements, this::readNoteElement));
+        return Result.concat(transform(elements, this::readNoteElement));
     }
 
     private boolean isNoteElement(XmlElement element) {
@@ -33,9 +33,11 @@ public class NotesXmlReader {
         return type.equals("continuationSeparator") || type.equals("separator");
     }
 
-    private Note readNoteElement(XmlElement element) {
-        return new Note(
-            element.getAttribute("w:id"),
-            bodyReader.readElements(element.children()));
+    private Result<Note> readNoteElement(XmlElement element) {
+        return bodyReader.readElements(element.children())
+            .toResult()
+            .map(children -> new Note(
+                element.getAttribute("w:id"),
+                children));
     }
 }
diff --git a/src/main/java/org/zwobble/mammoth/docx/ReadResult.java b/src/main/java/org/zwobble/mammoth/docx/ReadResult.java
new file mode 100644
index 0000000..f3eb7ce
--- /dev/null
+++ b/src/main/java/org/zwobble/mammoth/docx/ReadResult.java
@@ -0,0 +1,44 @@
+package org.zwobble.mammoth.docx;
+
+import com.google.common.collect.ImmutableList;
+import org.zwobble.mammoth.Result;
+import org.zwobble.mammoth.documents.DocumentElement;
+
+import java.util.List;
+import java.util.function.Function;
+
+import static org.zwobble.mammoth.util.MammothLists.list;
+
+public class ReadResult {
+    public static final ReadResult EMPTY_SUCCESS = success(list());
+
+    public static ReadResult concat(Iterable<ReadResult> results) {
+        ImmutableList.Builder<DocumentElement> elements = ImmutableList.builder();
+        for (ReadResult result : results) {
+            elements.addAll(result.elements);
+        }
+        return new ReadResult(elements.build());
+    }
+
+    public static ReadResult success(DocumentElement element) {
+        return success(list(element));
+    }
+
+    public static ReadResult success(List<DocumentElement> elements) {
+        return new ReadResult(elements);
+    }
+
+    private final List<DocumentElement> elements;
+
+    public ReadResult(List<DocumentElement> elements) {
+        this.elements = elements;
+    }
+
+    public ReadResult map(Function<List<DocumentElement>, DocumentElement> function) {
+        return new ReadResult(list(function.apply(elements)));
+    }
+
+    public Result<List<DocumentElement>> toResult() {
+        return new Result<>(elements);
+    }
+}