1 files changed, 223 insertions, 0 deletions
diff --git a/blog/blog/gemtext.py b/blog/blog/gemtext.py
new file mode 100644
index 00000000..66298e3f
--- /dev/null
+++ b/blog/blog/gemtext.py
@@ -0,0 +1,223 @@
+import dataclasses
+import re
+import typing
+
+
+def parse(s):
+    """
+    >>> parse('''# Header 1
+    ... 
+    ... ## Header 2
+    ... 
+    ... ### Header 3
+    ... 
+    ... * List 1
+    ... * List 2
+    ... 
+    ... > First line quote.
+    ... > Second line of quote.
+    ... 
+    ... ```
+    ... Fenced
+    ... Lines
+    ... ```
+    ... 
+    ... Paragraph.
+    ... 
+    ... Another paragraph.
+    ... ''')
+    [Header(level=1, text='Header 1'),
+     Line(text=''),
+     Header(level=2, text='Header 2'),
+     Line(text=''),
+     Header(level=3, text='Header 3'),
+     Line(text=''),
+     List(items=[ListItem(text='List 1'),
+                 ListItem(text='List 2')]),
+     Line(text=''),
+     BlockQuote(lines=[BlockQuoteLine(text='First line quote.'),
+                       BlockQuoteLine(text='Second line of quote.')]),
+     Line(text=''),
+     Pre(content='Fenced\\nLines\\n'),
+     Line(text=''),
+     Line(text='Paragraph.'),
+     Line(text=''),
+     Line(text='Another paragraph.')]
+    """
+
+    lines = s.splitlines()
+
+    i = 0
+    gem = []
+
+    while i < len(lines):
+        line = parse_line(lines[i])
+
+        if isinstance(line, Link):
+            gem.append(line)
+            i = i + 1
+            continue
+
+        if isinstance(line, Header):
+            gem.append(line)
+            i = i + 1
+            continue
+
+        if isinstance(line, ListItem):
+            items = []
+            while i < len(lines) and isinstance(parse_line(lines[i]), ListItem):
+                items.append(parse_line(lines[i]))
+                i = i + 1
+            gem.append(List(items))
+            continue
+
+        if isinstance(line, BlockQuoteLine):
+            quotes = []
+            while i < len(lines) and isinstance(parse_line(lines[i]), BlockQuoteLine):
+                quotes.append(parse_line(lines[i]))
+                i = i + 1
+            gem.append(BlockQuote(quotes))
+            continue
+
+        if isinstance(line, PreFence):
+            content = ""
+            i = i + 1
+            while i < len(lines) and not isinstance(parse_line(lines[i]), PreFence):
+                content += lines[i]
+                content += "\n"
+                i = i + 1
+            gem.append(Pre(content))
+            i = i + 1
+            continue
+
+        gem.append(line)
+        i = i + 1
+
+    return gem
+
+
+def parse_line(l):
+    if Link.is_link(l):
+        return Link(l)
+    if Header.is_header(l):
+        return Header(l)
+    if ListItem.is_list_item(l):
+        return ListItem(l)
+    if BlockQuoteLine.is_block_quote_line(l):
+        return BlockQuoteLine(l)
+    if PreFence.is_pre_fence(l):
+        return PreFence()
+    return Line(l)
+
+
+@dataclasses.dataclass
+class Link:
+    """
+    >>> Link("=> http://example.com")
+    Link(url='http://example.com', text=None)
+
+    >>> Link("=> http://example.com Example text")
+    Link(url='http://example.com', text='Example text')
+    """
+
+    url: str
+    text: typing.Optional[str]
+
+    def __init__(self, line: str):
+        assert Link.is_link(line)
+        parts = line.split(None, 2)
+        self.url = parts[1]
+        self.text = parts[2] if len(parts) > 2 else None
+
+    @staticmethod
+    def is_link(line: str):
+        return line.startswith("=>")
+
+@dataclasses.dataclass
+class Header:
+    """
+    >>> Header("# Level one")
+    Header(level=1, text='Level one')
+
+    >>> Header("## Level two")
+    Header(level=2, text='Level two')
+
+    >>> Header("### Level three")
+    Header(level=3, text='Level three')
+    """
+
+    level: int
+    text: str
+
+    def __init__(self, line: str):
+        assert Header.is_header(line)
+        hashes, self.text = line.split(None, 1)
+        self.level = len(hashes)
+
+    @staticmethod
+    def is_header(line: str):
+        return re.match("#{1,3} .*", line)
+
+@dataclasses.dataclass
+class ListItem:
+    """
+    >>> ListItem("* foo")
+    ListItem(text='foo')
+    """
+
+    text: str
+
+    def __init__(self, line: str):
+        assert ListItem.is_list_item(line)
+        self.text = line[2:]
+
+    @staticmethod
+    def is_list_item(line: str):
+        return line.startswith("* ")
+
+
+@dataclasses.dataclass
+class BlockQuoteLine:
+    """
+    >>> BlockQuoteLine("> foo")
+    BlockQuoteLine(text='foo')
+
+    >>> BlockQuoteLine(">foo")
+    BlockQuoteLine(text='foo')
+    """
+
+    text: str
+
+    def __init__(self, line: str):
+        assert BlockQuoteLine.is_block_quote_line(line)
+        self.text = line[2:] if line.startswith("> ") else line[1:]
+
+    @staticmethod
+    def is_block_quote_line(line: str):
+        return line.startswith(">")
+
+
+class PreFence:
+    @staticmethod
+    def is_pre_fence(line: str):
+        return line == "```"
+
+
+@dataclasses.dataclass
+class Line:
+    text: str
+
+
+@dataclasses.dataclass
+class List:
+    items: typing.List[ListItem]
+
+
+@dataclasses.dataclass
+class BlockQuote:
+    lines: typing.List[BlockQuoteLine]
+
+
+@dataclasses.dataclass
+class Pre:
+    content: str