diff -r 000000000000 -r 55b4c97d44c5 ldraw.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ldraw.py	Sun Dec 10 15:37:26 2017 +0200
@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+import linetypes
+import re
+from geometry import *
+
+class BadLdrawLine(Exception):
+    pass
+
+def parse_ldraw_code(line):
+    line = line.strip()
+    if not line:
+        return linetypes.EmptyLine()
+    if line == '0':
+        return linetypes.Comment('')
+    if line.startswith('0 '):
+        return linetypes.Comment(line[2:].strip())
+    if line.startswith('1 '):
+        return parse_ldraw_subfile_reference(line)
+    if line.startswith('2 '):
+        return parse_ldraw_line(line)
+    ...
+
+def parse_ldraw_subfile_reference(line):
+    pattern = r'^1\s+(\d+)' + r'\s+([^ ]+)' * (3 + 9 + 1) + r'\s*$'
+    match = re.search(pattern, line)
+    if not match:
+        raise BadLdrawLine('unable to parse')
+    groups = list(match.groups())
+    indices = {
+        'color': 0,
+        'anchor': slice(1, 4),
+        'matrix': slice(4, 13),
+        'subfile_path': 13
+    }
+    try:
+        color = int(groups[indices['color']])
+        vertex_values = [float(x) for x in groups[indices['anchor']]]
+        matrix_values = [float(x) for x in groups[indices['matrix']]]
+    except ValueError:
+        raise BadLdrawLine('bad numeric values')
+    return linetypes.SubfileReference(
+        color = color,
+        anchor = Vertex(*vertex_values),
+        matrix = TransformationMatrix(matrix_values),
+        subfile_path = groups[indices['subfile_path']]
+    )
+
+def generic_parse_polygon(line, *, type_code, vertex_count):
+    pattern = r'^' \
+        + str(type_code) \
+        + '\s+(\d+)' \
+        + r'\s+([^ ]+)' * (vertex_count * 3) \
+        + r'\s*$'
+    match = re.search(pattern, line)
+    if not match:
+        raise BadLdrawLine(str.format('cannot parse type-{} line', type_code))
+    vertices = []
+    for vertex_index in range(vertex_count):
+        slice_begin = 1 + vertex_index * 3
+        slice_end = 1 + (vertex_index + 1) * 3
+        coordinates = match.groups()[slice_begin:slice_end]
+        assert(len(coordinates) == 3)
+        try:
+            coordinates = [float(x) for x in coordinates]
+        except ValueError:
+            raise BadLdrawLine('bad numeric values')
+        vertices.append(Vertex(*coordinates))
+    return {
+        'color': int(match.group(1)),
+        'vertices': vertices,
+    }
+
+def parse_ldraw_line(line):
+    parse_result = generic_parse_polygon(line, type_code = 2, vertex_count = 2)
+    line_segment = LineSegment(*parse_result['vertices'])
+    return linetypes.LineSegment(
+        color = parse_result['color'],
+        geometry = line_segment)
+
+def read_ldraw(file, *, libraries):
+    result = list()
+    for line in file:
+        result.append(parse_ldraw_code(line))
+    return result
+
+if __name__ == '__main__':
+    from sys import argv
+    libraries = [{'path': '/home/teemu/ldraw', 'role': 'official'}]
+    with open(argv[1], 'r') as file:
+        model = read_ldraw(file, libraries = libraries)
+        from pprint import pprint
+        pprint(model)