227 lines
9.1 KiB
Python
227 lines
9.1 KiB
Python
# The MIT License (MIT)
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#
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# Copyright (c) 2016 Adam Schubert
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import re
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from typing import ClassVar
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from .Exception import FormatError, MissingFieldError
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from .Options import Options
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class ExpressionParser:
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_expression = ""
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_options: Options
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_cron_days: ClassVar[dict[int, str]] = {
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0: "SUN",
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1: "MON",
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2: "TUE",
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3: "WED",
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4: "THU",
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5: "FRI",
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6: "SAT",
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}
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_cron_months: ClassVar[dict[int, str]] = {
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1: "JAN",
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2: "FEB",
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3: "MAR",
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4: "APR",
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5: "MAY",
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6: "JUN",
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7: "JUL",
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8: "AUG",
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9: "SEP",
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10: "OCT",
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11: "NOV",
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12: "DEC",
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}
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def __init__(self, expression: str, options: Options) -> None:
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"""Initializes a new instance of the ExpressionParser class
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Args:
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expression: The cron expression string
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options: Parsing options
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"""
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self._expression = expression
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self._options = options
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def parse(self) -> list[str]:
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"""Parses the cron expression string
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Returns:
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A 7 part string array, one part for each component of the cron expression (seconds, minutes, etc.)
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Raises:
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MissingFieldException: if _expression is empty or None
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FormatException: if _expression has wrong format
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"""
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# Initialize all elements of parsed array to empty strings
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parsed = ["", "", "", "", "", "", ""]
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if not self._expression:
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msg = "ExpressionDescriptor.expression"
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raise MissingFieldError(msg)
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expression_parts_temp = self._expression.split()
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expression_parts_temp_length = len(expression_parts_temp)
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if expression_parts_temp_length < 5:
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msg = f"Error: Expression only has {expression_parts_temp_length} parts. At least 5 part are required."
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raise FormatError(msg)
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if expression_parts_temp_length == 5:
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# 5 part cron so shift array past seconds element
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for i, expression_part_temp in enumerate(expression_parts_temp):
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parsed[i + 1] = expression_part_temp
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elif expression_parts_temp_length == 6:
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# We will detect if this 6 part expression has a year specified and if so we will shift the parts and treat the
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# first part as a minute part rather than a second part.
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# Ways we detect:
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# 1. Last part is a literal year (i.e. 2020)
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# 2. 3rd or 5th part is specified as "?" (DOM or DOW)
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year_regex = re.compile(r"\d{4}$")
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is_year_with_no_seconds_part = bool(year_regex.search(expression_parts_temp[5])) or "?" in [expression_parts_temp[4], expression_parts_temp[2]]
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for i, expression_part_temp in enumerate(expression_parts_temp):
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if is_year_with_no_seconds_part:
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# Shift parts over by one
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parsed[i + 1] = expression_part_temp
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else:
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parsed[i] = expression_part_temp
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elif expression_parts_temp_length == 7:
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parsed = expression_parts_temp
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else:
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msg = f"Error: Expression has too many parts ({expression_parts_temp_length}). Expression must not have more than 7 parts."
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raise FormatError(msg)
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self.normalize_expression(parsed)
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return parsed
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def normalize_expression(self, expression_parts: list[str]) -> None:
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"""Converts cron expression components into consistent, predictable formats.
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Args:
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expression_parts: A 7 part string array, one part for each component of the cron expression
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Returns:
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None
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"""
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# convert ? to * only for DOM and DOW
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expression_parts[3] = expression_parts[3].replace("?", "*")
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expression_parts[5] = expression_parts[5].replace("?", "*")
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# convert 0/, 1/ to */
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if expression_parts[0].startswith("0/"):
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expression_parts[0] = expression_parts[0].replace("0/", "*/") # seconds
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if expression_parts[1].startswith("0/"):
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expression_parts[1] = expression_parts[1].replace("0/", "*/") # minutes
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if expression_parts[2].startswith("0/"):
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expression_parts[2] = expression_parts[2].replace("0/", "*/") # hours
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if expression_parts[3].startswith("1/"):
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expression_parts[3] = expression_parts[3].replace("1/", "*/") # DOM
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if expression_parts[4].startswith("1/"):
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expression_parts[4] = expression_parts[4].replace("1/", "*/") # Month
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if expression_parts[5].startswith("1/"):
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expression_parts[5] = expression_parts[5].replace("1/", "*/") # DOW
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if expression_parts[6].startswith("1/"):
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expression_parts[6] = expression_parts[6].replace("1/", "*/") # Years
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# Adjust DOW based on dayOfWeekStartIndexZero option
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def digit_replace(match: re.Match[str]) -> str:
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match_value = match.group()
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dow_digits = re.sub(r"\D", "", match_value)
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dow_digits_adjusted = dow_digits
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if self._options.day_of_week_start_index_zero:
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if dow_digits == "7":
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dow_digits_adjusted = "0"
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else:
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dow_digits_adjusted = str(int(dow_digits) - 1)
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return match_value.replace(dow_digits, dow_digits_adjusted)
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expression_parts[5] = re.sub(r"(^\d)|([^#/\s]\d)", digit_replace, expression_parts[5])
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# Convert DOM '?' to '*'
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if expression_parts[3] == "?":
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expression_parts[3] = "*"
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# convert SUN-SAT format to 0-6 format
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for day_number in self._cron_days:
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expression_parts[5] = expression_parts[5].upper().replace(self._cron_days[day_number], str(day_number))
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# convert JAN-DEC format to 1-12 format
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for month_number in self._cron_months:
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expression_parts[4] = expression_parts[4].upper().replace(
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self._cron_months[month_number], str(month_number))
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# convert 0 second to (empty)
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if expression_parts[0] == "0":
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expression_parts[0] = ""
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# If time interval is specified for seconds or minutes and next time part is single item, make it a "self-range" so
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# the expression can be interpreted as an interval 'between' range.
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# For example:
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# 0-20/3 9 * * * => 0-20/3 9-9 * * * (9 => 9-9)
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# */5 3 * * * => */5 3-3 * * * (3 => 3-3)
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star_and_slash = ["*", "/"]
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has_part_zero_star_and_slash = any(ext in expression_parts[0] for ext in star_and_slash)
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has_part_one_star_and_slash = any(ext in expression_parts[1] for ext in star_and_slash)
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has_part_two_special_chars = any(ext in expression_parts[2] for ext in ["*", "-", ",", "/"])
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if not has_part_two_special_chars and (has_part_zero_star_and_slash or has_part_one_star_and_slash):
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expression_parts[2] += f"-{expression_parts[2]}"
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# Loop through all parts and apply global normalization
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length = len(expression_parts)
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for i in range(length):
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# convert all '*/1' to '*'
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if expression_parts[i] == "*/1":
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expression_parts[i] = "*"
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"""
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Convert Month,DOW,Year step values with a starting value (i.e. not '*') to between expressions.
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This allows us to reuse the between expression handling for step values.
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For Example:
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- month part '3/2' will be converted to '3-12/2' (every 2 months between March and December)
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- DOW part '3/2' will be converted to '3-6/2' (every 2 days between Tuesday and Saturday)
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"""
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if "/" in expression_parts[i] and not any(exp in expression_parts[i] for exp in ["*", "-", ","]):
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choices = {
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4: "12",
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5: "6",
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6: "9999",
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}
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step_range_through = choices.get(i)
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if step_range_through is not None:
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parts = expression_parts[i].split("/")
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expression_parts[i] = f"{parts[0]}-{step_range_through}/{parts[1]}"
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