Add writer indentation policy controls.

Set the default indentation to 0.

src/main/java/com/moandjiezana/toml/MapValueWriter.java

@@ -56,7 +56,7 @@ class MapValueWriter implements ValueWriter {
 
       ValueWriter valueWriter = WRITERS.findWriterFor(fromValue);
       if (valueWriter.isTable() || valueWriter == TABLE_ARRAY_VALUE_WRITER) {
-        valueWriter.write(fromValue, context.extend(quoteKey(key)));
+        valueWriter.write(fromValue, context.pushTable(quoteKey(key)));
       }
     }
   }

src/main/java/com/moandjiezana/toml/TableArrayValueWriter.java

@@ -16,7 +16,7 @@ class TableArrayValueWriter extends ArrayValueWriter {
   public void write(Object value, WriterContext context) {
     Collection values = normalize(value);
 
-    WriterContext subContext = context.extend().setIsArrayOfTable(true);
+    WriterContext subContext = context.pushTableFromArray();
 
     for (Object elem : values) {
       WRITERS.write(elem, subContext);

src/main/java/com/moandjiezana/toml/TomlWriter.java

@@ -24,6 +24,9 @@ import static com.moandjiezana.toml.ValueWriters.WRITERS;
  * </code></pre>
  */
 public class TomlWriter {
+
+  private WriterIndentationPolicy indentationPolicy = new WriterIndentationPolicy();
+
   /**
    * Creates a TomlWriter instance.
    */
@@ -36,7 +39,7 @@ public class TomlWriter {
    * @return a string containing the TOML representation of the given Object
    */
   public String write(Object from) {
-    return WRITERS.write(from);
+    return WRITERS.write(from, this);
   }
 
   /**
@@ -73,4 +76,21 @@ public class TomlWriter {
     writer.write(write(from));
     writer.close();
   }
+
+  public WriterIndentationPolicy getIndentationPolicy() {
+    return indentationPolicy;
+  }
+
+  /**
+   * Set the {@link WriterIndentationPolicy} for this writer.
+   *
+   * If unset, the default policy (no indentation) is used.
+   *
+   * @param indentationPolicy the new policy
+   * @return this TomlWriter instance
+   */
+  public TomlWriter setIndentationPolicy(WriterIndentationPolicy indentationPolicy) {
+    this.indentationPolicy = indentationPolicy;
+    return this;
+  }
 }

src/main/java/com/moandjiezana/toml/ValueWriters.java

@@ -23,8 +23,8 @@ class ValueWriters {
     return OBJECT_VALUE_WRITER;
   }
 
-  String write(Object value) {
+  String write(Object value, TomlWriter tomlWriter) {
-    WriterContext context = new WriterContext();
+    WriterContext context = new WriterContext(tomlWriter);
     write(value, context);
 
     return context.output.toString();

src/main/java/com/moandjiezana/toml/WriterContext.java

@@ -1,26 +1,43 @@
 package com.moandjiezana.toml;
 
+import java.util.Arrays;
+
 class WriterContext {
   private String key = "";
+  private String currentTableIndent = "";
+  private String currentFieldIndent = "";
   private boolean isArrayOfTable = false;
+  private final TomlWriter tomlWriter;
   StringBuilder output = new StringBuilder();
 
-  WriterContext(String key, StringBuilder output) {
+  WriterContext(String key, String tableIndent, StringBuilder output, TomlWriter tomlWriter) {
     this.key = key;
+    this.currentTableIndent = tableIndent;
+    this.currentFieldIndent = tableIndent + fillStringWithSpaces(tomlWriter.getIndentationPolicy().getKeyValueIndent());
     this.output = output;
+    this.tomlWriter = tomlWriter;
   }
 
-  WriterContext() {
+  WriterContext(TomlWriter tomlWriter) {
+    this.tomlWriter = tomlWriter;
+  }
+
+  WriterContext pushTable(String newKey) {
+    String newIndent = "";
+    if (!key.isEmpty()) {
+      newIndent = growIndent(tomlWriter.getIndentationPolicy());
     }
 
-  WriterContext extend(String newKey) {
     String fullKey = key + (key.isEmpty() ? newKey : "." + newKey);
 
-    return new WriterContext(fullKey, output);
+    return new WriterContext(fullKey, newIndent, output, tomlWriter);
   }
 
-  WriterContext extend() {
+  WriterContext pushTableFromArray() {
-    return new WriterContext(key, output);
+    WriterContext subContext = new WriterContext(key, currentTableIndent, output, tomlWriter);
+    subContext.setIsArrayOfTable(true);
+
+    return subContext;
   }
 
   void writeKey() {
@@ -32,6 +49,8 @@ class WriterContext {
       output.append('\n');
     }
 
+    output.append(currentTableIndent);
+
     if (isArrayOfTable) {
       output.append("[[").append(key).append("]]\n");
     } else {
@@ -40,11 +59,24 @@ class WriterContext {
   }
 
   void indent() {
-    output.append(key.isEmpty() ? "" : "  ");
+    if (!key.isEmpty()) {
+      output.append(currentFieldIndent);
+    }
   }
 
   WriterContext setIsArrayOfTable(boolean isArrayOfTable) {
     this.isArrayOfTable = isArrayOfTable;
     return this;
   }
+
+  private String growIndent(WriterIndentationPolicy indentationPolicy) {
+    return currentTableIndent + fillStringWithSpaces(indentationPolicy.getTableIndent());
+  }
+
+  private String fillStringWithSpaces(int count) {
+    char[] chars = new char[count];
+    Arrays.fill(chars, ' ');
+
+    return new String(chars);
+  }
 }

src/main/java/com/moandjiezana/toml/WriterIndentationPolicy.java

@@ -0,0 +1,41 @@
+package com.moandjiezana.toml;
+
+/**
+ * Controls how a {@link TomlWriter} indents tables and key/value pairs.
+ *
+ * The default policy is to not indent.
+ */
+public class WriterIndentationPolicy {
+  private int tableIndent = 0;
+  private int keyValueIndent = 0;
+
+  public int getTableIndent() {
+    return tableIndent;
+  }
+
+  /**
+   * Sets the number of spaces a nested table name is indented.
+   *
+   * @param tableIndent number of spaces to indent
+   * @return this WriterIndentationPolicy instance
+   */
+  public WriterIndentationPolicy setTableIndent(int tableIndent) {
+    this.tableIndent = tableIndent;
+    return this;
+  }
+
+  public int getKeyValueIndent() {
+    return keyValueIndent;
+  }
+
+  /**
+   * Sets the number of spaces key/value pairs within a table are indented.
+   *
+   * @param keyValueIndent number of spaces to indent
+   * @return this WriterIndentationPolicy instance
+   */
+  public WriterIndentationPolicy setKeyValueIndent(int keyValueIndent) {
+    this.keyValueIndent = keyValueIndent;
+    return this;
+  }
+}

src/test/java/com/moandjiezana/toml/ValueWriterTest.java

@@ -60,8 +60,6 @@ public class ValueWriterTest {
     return dateString;
   }
 
-  @Test
-  public void should_write_nested_map() {
   class SubChild {
     int anInt;
   }
@@ -75,6 +73,7 @@ public class ValueWriterTest {
     boolean aBoolean;
   }
 
+  private Parent buildNestedMap() {
     Parent parent = new Parent();
     parent.aMap = new LinkedHashMap<String, Object>();
     parent.aMap.put("foo", 1);
@@ -86,7 +85,63 @@ public class ValueWriterTest {
     parent.child.subChild.anInt = 4;
     parent.aBoolean = true;
 
-    String output = new TomlWriter().write(parent);
+    return parent;
+  }
+
+  @Test
+  public void should_write_nested_map() {
+    String output = new TomlWriter().write(buildNestedMap());
+    String expected = "aBoolean = true\n\n" +
+        "[aMap]\n" +
+        "foo = 1\n" +
+        "bar = \"value1\"\n" +
+        "\"baz.x\" = true\n\n" +
+        "[child]\n" +
+        "anInt = 2\n\n" +
+        "[child.subChild]\n" +
+        "anInt = 4\n";
+    assertEquals(expected, output);
+  }
+
+  @Test
+  public void should_follow_indentation_policy_of_indented_values() {
+    String output = new TomlWriter().
+        setIndentationPolicy(new WriterIndentationPolicy().setKeyValueIndent(2)).
+        write(buildNestedMap());
+    String expected = "aBoolean = true\n\n" +
+        "[aMap]\n" +
+        "  foo = 1\n" +
+        "  bar = \"value1\"\n" +
+        "  \"baz.x\" = true\n\n" +
+        "[child]\n" +
+        "  anInt = 2\n\n" +
+        "[child.subChild]\n" +
+        "  anInt = 4\n";
+    assertEquals(expected, output);
+  }
+
+  @Test
+  public void should_follow_indentation_policy_of_indented_tables() {
+    String output = new TomlWriter().
+        setIndentationPolicy(new WriterIndentationPolicy().setTableIndent(2)).
+        write(buildNestedMap());
+    String expected = "aBoolean = true\n\n" +
+        "[aMap]\n" +
+        "foo = 1\n" +
+        "bar = \"value1\"\n" +
+        "\"baz.x\" = true\n\n" +
+        "[child]\n" +
+        "anInt = 2\n\n" +
+        "  [child.subChild]\n" +
+        "  anInt = 4\n";
+    assertEquals(expected, output);
+  }
+
+  @Test
+  public void should_follow_indentation_policy_of_indented_tables_and_values() {
+    String output = new TomlWriter().
+        setIndentationPolicy(new WriterIndentationPolicy().setTableIndent(2).setKeyValueIndent(2)).
+        write(buildNestedMap());
     String expected = "aBoolean = true\n\n" +
         "[aMap]\n" +
         "  foo = 1\n" +