From f7688429a8215eaee690bd3b2324b1d1164eae03 Mon Sep 17 00:00:00 2001
From: Tim Van Baak <tim.vanbaak@gmail.com>
Date: Wed, 4 Mar 2020 22:28:09 -0800
Subject: [PATCH] Add parser module

---
 amanuensis/parser/__init__.py |   6 ++
 amanuensis/parser/render.py   |  25 +++++++
 amanuensis/parser/text.py     | 118 ++++++++++++++++++++++++++++++++++
 3 files changed, 149 insertions(+)
 create mode 100644 amanuensis/parser/__init__.py
 create mode 100644 amanuensis/parser/render.py
 create mode 100644 amanuensis/parser/text.py

diff --git a/amanuensis/parser/__init__.py b/amanuensis/parser/__init__.py
new file mode 100644
index 0000000..a4bccb3
--- /dev/null
+++ b/amanuensis/parser/__init__.py
@@ -0,0 +1,6 @@
+"""
+Module encapsulating all markdown parsing functionality
+"""
+
+from amanuensis.parser.text import parse_raw_markdown
+from amanuensis.parser.render import PreviewHtmlRenderer
\ No newline at end of file
diff --git a/amanuensis/parser/render.py b/amanuensis/parser/render.py
new file mode 100644
index 0000000..37bc91a
--- /dev/null
+++ b/amanuensis/parser/render.py
@@ -0,0 +1,25 @@
+"""
+Internal module encapsulating the render logic for parsed articles. Rendering
+is done via a rough approximation of the visitor pattern.
+"""
+
+
+class PreviewHtmlRenderer():
+	def TextSpan(self, span):
+		return span.innertext
+	def LineBreak(self, span):
+		return '<br>'
+	def ParsedArticle(self, span):
+		return '\n'.join([child.render(self) for child in span.spans])
+	def BodyParagraph(self, span):
+		return f'<p>{"".join([child.render(self) for child in span.spans])}</p>'
+	def SignatureParagraph(self, span):
+		return ('<hr><span class="signature"><p>'
+			f'{"".join([child.render(self) for child in span.spans])}'
+			'</p></span>')
+	def BoldSpan(self, span):
+		return f'<b>{"".join([child.render(self) for child in span.spans])}</b>'
+	def ItalicSpan(self, span):
+		return f'<i>{"".join([child.render(self) for child in span.spans])}</i>'
+	def CitationSpan(self, span):
+		return f'<a href="#">{span.cite_text}</a>'
diff --git a/amanuensis/parser/text.py b/amanuensis/parser/text.py
new file mode 100644
index 0000000..45f8868
--- /dev/null
+++ b/amanuensis/parser/text.py
@@ -0,0 +1,118 @@
+"""
+Internal module encapsulating the parsing logic for Lexipython
+markdown. Parse results are represented as a hierarchy of tokens, which
+can be rendered by a renderer.
+"""
+
+import re
+
+
+class Renderable():
+	def render(self, renderer):
+		return getattr(renderer, type(self).__name__)(self)
+
+class TextSpan(Renderable):
+	"""An unstyled length of text"""
+	def __init__(self, innertext):
+		self.innertext = innertext
+	def __str__(self):
+		return f"[{self.innertext}]"
+
+class LineBreak(Renderable):
+	"""A line break within a paragraph"""
+	def __str__(self):
+		return "<break>"
+
+class SpanContainer(Renderable):
+	"""A formatting element that wraps some amount of text"""
+	def __init__(self, spans):
+		self.spans = spans
+	def __str__(self):
+		return f"[{type(self).__name__} {' '.join([str(span) for span in self.spans])}]"
+
+class ParsedArticle(SpanContainer):
+	"""Multiple paragraphs"""
+
+class BodyParagraph(SpanContainer):
+	"""A normal paragraph"""
+
+class SignatureParagraph(SpanContainer):
+	"""A paragraph preceded by a signature mark"""
+
+class BoldSpan(SpanContainer):
+	"""A span of text inside bold marks"""
+
+class ItalicSpan(SpanContainer):
+	"""A span of text inside italic marks"""
+
+class CitationSpan(Renderable):
+	"""A citation to another article"""
+	def __init__(self, cite_text, cite_target):
+		self.cite_text = cite_text
+		self.cite_target = cite_target
+	def __str__(self):
+		return f"{{{self.cite_text}:{self.cite_target}}}"
+
+
+def parse_raw_markdown(text):
+	# Parse each paragraph individually, as no formatting applies
+	# across paragraphs
+	paragraphs = re.split(r'\n\n+', text)
+	parse_results = list(map(parse_paragraph, paragraphs))
+	return ParsedArticle(parse_results)
+
+def parse_paragraph(text):
+	# Parse the paragraph as a span of text
+	text = text.strip()
+	if text and text[0] == '~':
+		return SignatureParagraph(parse_citations(text[1:]))
+	else:
+		return BodyParagraph(parse_citations(text))
+
+def parse_citations(text):
+	cite_open = text.find("[[")
+	if cite_open > -1:
+		cite_close = text.find("]]", cite_open + 2)
+		spans_before = parse_bold(text[:cite_open])
+		spans_after = parse_citations(text[cite_close+2:])
+		text_inner = text[cite_open+2:cite_close]
+		alias_split = text_inner.split("|", 1)
+		citation = CitationSpan(alias_split[0], alias_split[-1])
+		return spans_before + [citation] + spans_after
+	# No citations, just parse the regular formatting
+	return parse_bold(text)
+
+def parse_bold(text):
+	bold_open = text.find("**")
+	if bold_open > -1:
+		bold_close = text.find("**", bold_open + 2)
+		spans_before = parse_italic(text[:bold_open])
+		spans_after = parse_bold(text[bold_close+2:])
+		spans_inner = parse_italic(text[bold_open+2:bold_close])
+		bold = BoldSpan(spans_inner)
+		return spans_before + [bold] + spans_after
+	return parse_italic(text)
+
+def parse_italic(text):
+	italic_open = text.find("//")
+	if italic_open > -1:
+		italic_close = text.find("//", italic_open + 2)
+		text_before = text[:italic_open]
+		text_inner = text[italic_open+2:italic_close]
+		text_after = text[italic_close+2:]
+		spans_before = parse_breaks(text_before)
+		spans_after = parse_italic(text_after)
+		spans_inner = parse_breaks(text_inner)
+		italic = ItalicSpan(spans_inner)
+		return spans_before + [italic] + spans_after
+	return parse_breaks(text)
+
+def parse_breaks(text):
+	if not text:
+		return []
+	splits = list(map(TextSpan, text.split("\\\\\n")))
+	spans = [splits[0]]
+	for span in splits[1:]:
+		spans.append(LineBreak())
+		spans.append(span)
+	return spans