Apply suggestions provided by Federico, add an instance method for alignment and add tests that exercise the interaction between indentation, grouping and alignment

Author: DavidGregory084

src/main/java/com/opencastsoftware/prettier4j/Doc.java

@@ -236,6 +236,15 @@ public Doc indent(int indent) {
         return indent(indent, this);
     }
 
+    /**
+     * Align any line breaks within this {@link Doc} to the line position at the start of the {@link Doc}.
+     *
+     * @return the aligned document.
+     */
+    public Doc align() {
+        return align(this);
+    }
+
     /**
      * Bracket the current document by the {@code left} and {@code right} Strings,
      * indented by {@code indent} spaces.
@@ -1677,7 +1686,7 @@ public static Doc indent(int indent, Doc doc) {
     }
 
     /**
-     * Align subsequent lines of the current {@link Doc} to the current position in the line.
+     * Align any line breaks within this {@link Doc} to the line position at the start of the {@link Doc}.
      *
      * @param doc the input document
      * @return the aligned document.
@@ -2147,8 +2156,7 @@ private static int layoutEntry(RenderOptions options, Deque<Entry> inQueue, Queu
         } else if (entryDoc instanceof Align) {
             // Eliminate Align
             Align alignDoc = (Align) entryDoc;
-            int newIndent = Math.max(0, position - entryIndent);
-            inQueue.addFirst(entry(newIndent, entryMargin, alignDoc.doc()));
+            inQueue.addFirst(entry(position, entryMargin, alignDoc.doc()));
         } else if (entryDoc instanceof Margin) {
             // Eliminate Margin
             Margin marginDoc = (Margin) entryDoc;
@@ -2173,7 +2181,7 @@ private static int layoutEntry(RenderOptions options, Deque<Entry> inQueue, Queu
             outQueue.add(topEntry);
         } else if (entryDoc instanceof LineOr) {
             // Reset line length
-            position = entryIndent;
+            position = 0;
             // Note reverse order
             if (entryIndent > 0) {
                 // Send out the indent spaces

src/test/java/com/opencastsoftware/prettier4j/DocTest.java

@@ -244,6 +244,28 @@ void testBracketFlattening() {
         assertThat(actual, is(equalTo(expected)));
     }
 
+    @Test
+    void testBracketFlatteningWithAlign() {
+        // Note: the arguments are aligned with the "functionCall" element because bracket doesn't support alignment.
+        // TODO: Consider adding a `hangingBracket` combinator that aligns the bracket docs with the starting line position
+        //       and the arguments with the opening bracket doc.
+        String expected = "functionCall(\n"+
+                Indents.get(12)+"a,\n"+
+                Indents.get(12)+"b,\n"+
+                Indents.get(12)+"c\n"+
+                Indents.get(12)+")";
+        String actual = text("functionCall")
+                .append(
+                        Doc.intersperse(
+                                        Doc.text(",").append(Doc.lineOrSpace()),
+                                        Stream.of("a", "b", "c").map(Doc::text))
+                                .bracket(0, Doc.lineOrEmpty(), Doc.text("("), Doc.text(")"))
+                                .align())
+                .render(10);
+
+        assertThat(actual, is(equalTo(expected)));
+    }
+
     @Test
     void testNestedBracketFlattening() {
         String expectedWidth80 = "let x = functionCall(with, args, nestedFunctionCall(with, more, args))";
@@ -276,6 +298,45 @@ void testNestedBracketFlattening() {
         assertThat(inputDoc.render(20), is(equalTo(expectedWidth20)));
     }
 
+    @Test
+    void testNestedBracketFlatteningWithAlign() {
+        String expectedWidth80 = "let x = functionCall(with, args, nestedFunctionCall(with, more, args))";
+        String expectedWidth40 =
+                "let x = functionCall(\n"+
+                        Indents.get(20)+"with,\n"+
+                        Indents.get(20)+"args,\n"+
+                        Indents.get(20)+"nestedFunctionCall(\n"+
+                            Indents.get(38)+"with,\n"+
+                            Indents.get(38)+"more,\n"+
+                            Indents.get(38)+ "args\n"+
+                            Indents.get(38)+")\n"+
+                        Indents.get(20)+")";
+
+        Doc inputDoc = text("let")
+                .appendSpace(text("x"))
+                .appendSpace(text("="))
+                .appendSpace(text("functionCall")
+                        .append(align(
+                                intersperse(
+                                        text(",").append(lineOrSpace()),
+                                        Stream.concat(
+                                                Stream.of("with", "args").map(Doc::text),
+                                                Stream.of(text("nestedFunctionCall")
+                                                        .append(align(
+                                                                intersperse(
+                                                                        text(",").append(lineOrSpace()),
+                                                                        Stream.of("with", "more", "args").map(Doc::text)
+                                                                ).bracket(0, lineOrEmpty(), text("("), text(")"))
+                                                        )))
+                                        )
+                                ).bracket(0, lineOrEmpty(), text("("), text(")"))
+                        ))
+                );
+
+        assertThat(inputDoc.render(80), is(equalTo(expectedWidth80)));
+        assertThat(inputDoc.render(40), is(equalTo(expectedWidth40)));
+    }
+
     @Test
     void testAlignWithMultipleLines() {
         String expected =