feat(parser): implement RawMessage

The NewRawMessage function returns a RawMessage struct, which has broken
the given commit message down into separate lines, and also grouped the
lines into paragraphs.

This should make it easier to implement proper conventional commit
parser, linter, and formatter.

raw_message.go

@@ -0,0 +1,50 @@
+package conventionalcommit
+
+// RawMessage represents a commit message in a more structured form than a
+// simple string or byte slice. This makes it easier to process a message for
+// the purposes of extracting detailed information, linting, and formatting.
+type RawMessage struct {
+	// Lines is a list of all individual lines of text in the commit message,
+	// which also includes the original line number, making it easy to pass a
+	// single Line around while still knowing where in the original commit
+	// message it belongs.
+	Lines Lines
+
+	// Paragraphs is a list of textual paragraphs in the commit message. A
+	// paragraph is defined as any continuous sequence of lines which are not
+	// empty or consist of only whitespace.
+	Paragraphs []*Paragraph
+}
+
+// NewRawMessage returns a RawMessage, with the given commit message broken down
+// into individual lines of text, with sequential non-empty lines grouped into
+// paragraphs.
+func NewRawMessage(message []byte) *RawMessage {
+	r := &RawMessage{
+		Lines:      Lines{},
+		Paragraphs: []*Paragraph{},
+	}
+
+	if len(message) == 0 {
+		return r
+	}
+
+	r.Lines = NewLines(message)
+	r.Paragraphs = NewParagraphs(r.Lines)
+
+	return r
+}
+
+// Bytes renders the RawMessage back into a byte slice which is identical to the
+// original input byte slice given to NewRawMessage. This includes retaining the
+// original line break types for each line.
+func (s *RawMessage) Bytes() []byte {
+	return s.Lines.Bytes()
+}
+
+// String renders the RawMessage back into a string which is identical to the
+// original input byte slice given to NewRawMessage. This includes retaining the
+// original line break types for each line.
+func (s *RawMessage) String() string {
+	return s.Lines.String()
+}