First attempt at Python port, expand tests.

packages/python/parser.py

@@ -0,0 +1,35 @@
+from typing import TypedDict
+
+class LineData(TypedDict):
+  line: str
+  indent: str
+  level: int
+  offsetHead: int
+  offsetTail: int
+
+def createLineData(line: str = '', indent: str = ' ') -> LineData:
+  return { "line": line, "indent": indent, "level": 0, "offsetHead": 0, "offsetTail": 0 }
+
+def parseLine(lineData: LineData) -> LineData:
+  # if ((typeof lineData !== 'object' || !lineData) || typeof lineData.level !== 'number') throw new Error(`'lineData' must be an object with string line and numeric level properties`)
+  # if (typeof lineData.indent !== 'string' || lineData.indent.length === 0 || lineData.indent.length > 1) throw new Error(`'lineData.indent' must be a single-character string`)
+  # if (typeof lineData.line !== 'string') throw new Error(`'lineData.line' must be a string`)
+
+  level = 0
+
+  # Repeat previous level for blank lines.
+  if len(lineData['line']) == 0:
+    lineData['level'] = lineData['level']
+    lineData['offsetHead'] = 0
+    lineData['offsetTail'] = 0
+  else:
+    while level < len(lineData['line']) and lineData['line'][level] == lineData['indent'] and level <= lineData['level'] + 1:
+      level += 1
+    lineData['level'] = level
+    lineData['offsetHead'] = level
+    lineData['offsetTail'] = level
+
+    while lineData['offsetTail'] < len(lineData['line']) and lineData['line'][lineData['offsetTail']] != ' ':
+      lineData['offsetTail'] += 1
+
+  return lineData