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Diffstat (limited to 'io_convert_image_to_mesh_img/pvl/parse.py')
| -rw-r--r-- | io_convert_image_to_mesh_img/pvl/parse.py | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/io_convert_image_to_mesh_img/pvl/parse.py b/io_convert_image_to_mesh_img/pvl/parse.py new file mode 100644 index 00000000..3a87d2f3 --- /dev/null +++ b/io_convert_image_to_mesh_img/pvl/parse.py @@ -0,0 +1,147 @@ +# This file is a part of the HiRISE DTM Importer for Blender +# +# Copyright (C) 2017 Arizona Board of Regents on behalf of the Planetary Image +# Research Laboratory, Lunar and Planetary Laboratory at the University of +# Arizona. +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the Free +# Software Foundation, either version 3 of the License, or (at your option) +# any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +# for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see <http://www.gnu.org/licenses/>. + +"""PVL Label Parsing""" + +import collections +import re + +from . import patterns +from .label import Label + +Quantity = collections.namedtuple('Quantity', ['value', 'units']) + + +class PVLParseError(Exception): + """Error parsing PVL file""" + def __init__(self, message): + super(PVLParseError, self).__init__(message) + + +class LabelParser: + """A PVL Parser""" + @staticmethod + def load(path): + """ + Load a dict-like representation of a PVL label header + + Parameters + ---------- + path : str + Path to a file containing a PVL header + + Returns + ---------- + label : pvl.Label + + """ + raw = LabelParser._read(path) + return Label(**LabelParser._parse(raw)) + + @staticmethod + def _read(path): + """ + Get the PVL header from a file as a string + + Parameters + ---------- + path : str + Path to a file containing a PVL header + + Returns + ---------- + raw : str + + Notes + --------- + * This function assumes that the file begins with a PVL header + and it will read lines from the file until it encounters + a PVL end statement. + + To-Do + --------- + * This could be more robust. What happens if there is no label + in the file? + + """ + with open(path, 'rb') as f: + raw = '' + while True: + try: + line = f.readline().decode() + raw += line + if re.match(patterns.END, line): + break + except UnicodeDecodeError: + raise PVLParseError("Error parsing PVL label from " + "file: {}".format(path)) + return raw + + @staticmethod + def _remove_comments(raw): + return re.sub(patterns.COMMENT, '', raw) + + @staticmethod + def _parse(raw): + raw = LabelParser._remove_comments(raw) + label_iter = re.finditer(patterns.STATEMENT, raw) + return LabelParser._parse_iter(label_iter) + + @staticmethod + def _parse_iter(label_iter): + """Recursively parse a PVL label iterator""" + obj = {} + while True: + try: + # Try to fetch the next match from the iter + match = next(label_iter) + val = match.group('val') + key = match.group('key') + # Handle nested object groups + if key == 'OBJECT': + obj.update({ + val: LabelParser._parse_iter(label_iter) + }) + elif key == 'END_OBJECT': + return obj + # Add key/value pair to dict + else: + # Should this value be a numeric type? + try: + val = LabelParser._convert_to_numeric(val) + except ValueError: + pass + # Should this value have units? + if match.group('units'): + val = Quantity(val, match.group('units')) + # Add it to the dict + obj.update({key: val}) + except StopIteration: + break + return obj + + @staticmethod + def _convert_to_numeric(s): + """Convert a string to its appropriate numeric type""" + if re.match(patterns.INTEGER, s): + return int(s) + elif re.match(patterns.FLOATING, s): + return float(s) + else: + raise ValueError |