Handle more styles of comments (#4)

Author: jimschubert

src/main/java/com/github/jimschubert/rewrite/docker/internal/DockerfileParser.java

@@ -435,7 +435,16 @@ Docker.Instruction parse() {
 
         private Docker.@NotNull Comment parseComment() {
             StringWithPadding stringWithPadding = StringWithPadding.of(instruction.toString());
-            Docker.Literal commentLiteral = createLiteral(stringWithPadding.content()).withPrefix(stringWithPadding.prefix());
+            Docker.Literal commentLiteral = createLiteral(stringWithPadding.content());
+            if (commentLiteral == null) {
+                // if the comment is empty, we need to create a literal with an empty string
+                commentLiteral = Docker.Literal.build(
+                        Quoting.UNQUOTED,
+                        Space.EMPTY,
+                        "",
+                        Space.EMPTY);
+            }
+            commentLiteral = commentLiteral.withPrefix(stringWithPadding.prefix());
             return new Docker.Comment(
                     Tree.randomId(),
                     state.prefix(),
@@ -831,7 +840,7 @@ private static String handleInstructionType(String line, InstructionParser parse
         } else if (instructionType != null) {
             parser.instructionType = instructionType;
             // remove the first word from line
-            line = (spaceIndex == -1) ? line : line.substring(spaceIndex);
+            line = (spaceIndex == -1) ? line.substring(0, firstWord.length()-1) : line.substring(spaceIndex);
         } else if (state.prefix() != null && !state.prefix().isEmpty()) {
             // if there was any prefix stored previously, add it to the multiline instruction
             // this is a special case for multi-line instructions like comments
@@ -882,6 +891,10 @@ private static Class<? extends Docker.Instruction> instructionFromText(String s)
             case COMMENT:
                 return Docker.Comment.class;
             default:
+                // special case for non-standard comments
+                if (s.startsWith("#")) {
+                    return Docker.Comment.class;
+                }
                 return null;
         }
     }

src/test/java/com/github/jimschubert/rewrite/docker/internal/DockerfileParserTest.java

@@ -36,6 +36,58 @@ void testCommentSingleWithTrailingSpace() {
         assertComment(comment, " ", "This is a comment", "\t\t");
     }
 
+    @Test
+    void testHeaderStyleComments() {
+        DockerfileParser parser = new DockerfileParser();
+        Docker.Document doc = parser.parse(new ByteArrayInputStream(
+                """
+                #
+                # NOTE: THIS DOCKERFILE IS GENERATED VIA "apply-templates.sh"
+                #
+                # PLEASE DO NOT EDIT IT DIRECTLY.
+                #
+                
+                FROM alpine:3.21
+                """.getBytes(StandardCharsets.UTF_8)));
+
+        Docker.Stage stage = assertSingleStageWithChildCount(doc, 6);
+        assertComment((Docker.Comment) stage.getChildren().get(0), "", "", "");
+        assertComment((Docker.Comment) stage.getChildren().get(1), " ", "NOTE: THIS DOCKERFILE IS GENERATED VIA \"apply-templates.sh\"", "");
+        assertComment((Docker.Comment) stage.getChildren().get(2), "", "", "");
+        assertComment((Docker.Comment) stage.getChildren().get(3), " ", "PLEASE DO NOT EDIT IT DIRECTLY.", "");
+        assertComment((Docker.Comment) stage.getChildren().get(4), "", "", "");
+
+        Docker.From from = (Docker.From) stage.getChildren().get(5);
+        assertEquals(Space.EMPTY, from.getPrefix());
+        assertLiteral(from.getImage(), Quoting.UNQUOTED, " ", "alpine", "");
+        assertEquals("3.21", from.getTag());
+        assertEquals("", from.getImage().getTrailing().getWhitespace());
+        assertEquals(" ", from.getImage().getPrefix().getWhitespace());
+    }
+
+    @Test
+    void testFlowerboxStyleComments() {
+        DockerfileParser parser = new DockerfileParser();
+        Docker.Document doc = parser.parse(new ByteArrayInputStream(
+                """
+                ################################################
+                # ####
+                # This is a comment
+                #####
+                ################################################
+                """.getBytes(StandardCharsets.UTF_8)));
+
+        Docker.Stage stage = assertSingleStageWithChildCount(doc, 5);
+        // note that this is one character less than the first line, because the first # is the "instruction"
+        assertComment((Docker.Comment) stage.getChildren().get(0), "", "###############################################", "");
+        assertComment((Docker.Comment) stage.getChildren().get(1), " ", "####", "");
+        assertComment((Docker.Comment) stage.getChildren().get(2), " ", "This is a comment", "");
+        // note the lack of the prefix space
+        assertComment((Docker.Comment) stage.getChildren().get(3), "", "####", "");
+        // note that this is one character less than the last line, because the first # is the "instruction"
+        assertComment((Docker.Comment) stage.getChildren().get(4), "", "###############################################", "");
+    }
+
     @Test
     void testRetainCarriageReturn() {
         DockerfileParser parser = new DockerfileParser();