From 00f1ff9f8a1f853ca1a009a9382b00ae644bfdb8 Mon Sep 17 00:00:00 2001
From: Matt Singleton <matt@xcolour.net>
Date: Mon, 1 Feb 2021 09:31:55 -0600
Subject: checkpoint

---
 fsm.py | 174 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 174 insertions(+)
 create mode 100644 fsm.py

(limited to 'fsm.py')

diff --git a/fsm.py b/fsm.py
new file mode 100644
index 0000000..40f9c2d
--- /dev/null
+++ b/fsm.py
@@ -0,0 +1,174 @@
+import sys
+
+class StackFSM(object):
+    """
+    Implement a finite state machine that uses a stack to
+    manage state.
+    """
+
+    def __init__(self):
+        self._state_stack = []
+
+    def _current_state(self):
+        if len(self._state_stack) > 0:
+            return self._state_stack[-1]
+        return None
+
+    def update(self):
+        fn = self._current_state()
+        if fn is not None:
+            fn()
+
+    def push_state(self, state):
+        self._state_stack.append(state)
+
+    def pop_state(self):
+        return self._state_stack.pop()
+
+class Parser(object):
+
+    def __init__(self, document, output=None):
+        self._document = document
+        if output is None:
+            output = sys.stdout
+        self._output = output
+        self._offset = 0
+        self._blanks = 0
+        self._fsm = StackFSM()
+
+    def parse(self):
+        self._fsm.push_state(self.text_state)
+        while self._fsm._current_state() is not None:
+            self._fsm.update()
+
+    def text_state(self):
+        if len(self._document) <= self._offset:
+            self._fsm.pop_state()
+            return
+        line = self._document[self._offset]
+        if line.strip() == '':
+            self._blanks += 1
+        else:
+            self._blanks = 0
+        if line.strip() == '```':
+            self._fsm.pop_state()
+            self._fsm.push_state(self.pre_state)
+            self._output.write('<pre>\n')
+            self._offset += 1
+        elif line.startswith('* '):
+            self._fsm.pop_state()
+            self._fsm.push_state(self.list_state)
+            self._output.write('<ul>\n')
+        elif line.startswith('=>'):
+            self._fsm.pop_state()
+            self._fsm.push_state(self.link_state)
+            self._output.write('<ul>\n')
+        else:
+            if line.startswith('# '):
+                self._output.write('<h1>{}</h1>\n'.format(line[2:]))
+            elif line.startswith('## '):
+                self._output.write('<h2>{}</h2>\n'.format(line[3:]))
+            elif line.startswith('### '):
+                self._output.write('<h3>{}</h3>\n'.format(line[4:]))
+            elif line.startswith('> '):
+                self._output.write('<blockquote>{}</blockquote>\n'.format(line[2:]))
+            elif line.strip() == '':
+                if self._blanks > 1:
+                    self._output.write('<br/>\n')
+            else:
+                self._output.write('<p>{}</p>\n'.format(line))
+            self._offset += 1
+
+    def pre_state(self):
+        if len(self._document) < self._offset:
+            self.pop_state()
+            return
+        line = self._document[self._offset]
+        if line.strip() == '```':
+            self._fsm.pop_state()
+            self._fsm.push_state(self.text_state)
+            self._output.write('</pre>\n')
+            self._offset += 1
+        elif line.startswith('* '):
+            self._fsm.pop_state()
+            self._fsm.push_state(self.list_state)
+            self._output.write('<ul>\n')
+        elif line.startswith('=>'):
+            self._fsm.pop_state()
+            self._fsm.push_state(self.link_state)
+            self._output.write('<ul>\n')
+        else:
+            self._output.write(line + '\n')
+            self._offset += 1
+
+    def list_state(self):
+        if len(self._document) < self._offset:
+            self.pop_state()
+            return
+        line = self._document[self._offset]
+        if line.startswith('* '):
+            self._output.write('<li>{}</li>\n'.format(line[2:]))
+            self._offset += 1
+        else:
+            self._fsm.pop_state()
+            self._fsm.push_state(self.text_state)
+            self._output.write('</ul>\n')
+
+    def link_state(self):
+        if len(self._document) < self._offset:
+            self.pop_state()
+            return
+        line = self._document[self._offset]
+        if line.startswith('=>'):
+            parts = line[2:].split(None, 2)
+            if len(parts) == 1:
+                self._output.write('<li><a href="{}">{}</a></li>\n'.format(parts[0], parts[0]))
+            else:
+                self._output.write('<li><a href="{}">{}</a></li>\n'.format(parts[0], parts[1]))
+            self._offset += 1
+        else:
+            self._fsm.pop_state()
+            self._fsm.push_state(self.text_state)
+            self._output.write('</ul>\n')
+
+document = """
+# h1
+hello
+hello
+
+## h2
+```
+code
+code
+```
+### h3
+hello
+
+
+hello
+
+### lists
+* hello
+* two
+* three
+
+text
+
+* one
+* two
+* three
+
+### links
+=>https://example.com hello
+=> https://example.com two
+=>  https://example.com three
+
+text
+
+=>https://example.com
+=> https://example.com
+=>  https://example.com
+"""
+
+p = Parser(document.split('\n'))
+p.parse()
-- 
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