# Croniter Repository Analysis

**Repository:** pallets-eco/croniter  
**Analysis Date:** 2026-02-07  
**Total PRs:** 110  
**Merged PRs:** 88  
**Total Commits:** 1257

## Executive Summary

This document provides a comprehensive analysis of the croniter repository to ensure our Rust implementation (croniter-rs) matches all features, edge cases, and behaviors of the original Python implementation.

## Key Statistics

- **Feature PRs:** 32
- **Bug Fix PRs:** 26
- **Test-related PRs:** 17
- **Edge Case PRs:** 3

## Major Feature Categories


### DST Handling (2 PRs)

- **PR #177**: Fix DST handling by rewriting the DST logic
  - The cron expression can specify points in time but also time intervals. Depending on that different solutions are needed for correcting the time after a DST change.
 
 PEP 495 compliant implementation...
- **PR #8**: Added DST example using only the builtin datetime module.
  - Hi,
 
 From python 3.2 onwards there's a tzinfo class present for UTC. This pull request adds an example to the README.rst on how to use this.
 
 Thanks for the great library!
 
 Kind regards,
 Thiezn...


### Day Handling (1 PRs)

- **PR #61**: fix bug for bad case leap year 2 month 29 days;
  - itr = croniter.croniter("* * 29 2 *", datetime.datetime(2024, 2, 28, 0, 0, 0))
 itr.get_prev(datetime.datime)
 raise Error 
 croniter.croniter.CroniterBadDateError: failed to find prev date...


### Hash Support (2 PRs)

- **PR #82**: Fix hashed expressions omitting some entries
  - As described in https://github.com/kiorky/croniter/pull/42, the random expression doesn't cover every possible value.
 PR42 did solve most situations, but missed range value for some fields.
 This PR ...
- **PR #71**: Supports str hash_id in is_valid() as in __init__()
  - Before:
 ```
 >>> croniter.is_valid('H 0 * * *', hash_id='abc')
 Traceback (most recent call last):
 ...
 TypeError: a bytes-like object is required, not 'str'
 ```
 
 After:
 ```
 >>> croniter.is_val...


### Other Features (22 PRs)

- **PR #186**: Modernize project setup
  - * get rid of setup.cfgy, MANIFEST.in and moving to flit as build backend
 * switched tox to use uv under the hood
 * add uv lock
 * replace requirments/* with dependency groups
 * move all configurati...
- **PR #185**: Fix memory leak by removing `TIMESTAMP_TO_DT_CACHE`
  - This fixes https://github.com/pallets-eco/croniter/issues/182
 
 Historically `TIMESTAMP_TO_DT_CACHE` was introduced here in a batch of many other changes before release v6.x.x: https://github.com/pal...
- **PR #181**: Add type hints to croniter.__init__
  - Add type hints to `croniter.__init__` and address the mypy complaints....
- **PR #178**: Fix skipping first of March
  - In case the month cron rule is `*/x` the first of March might be skipped. In case of `*/10` the expanded field for the day is [1, 11, 21, 31]. Despite February has at most 29 days, `proc_day_of_month`...
- **PR #175**: Fix all flake8 complaints
  - The CI currently only checks `src/croniter/croniter.py` for flake8, but there are more Python files that should be checked.
 
 ```
 $ flake8 .
 ./src/croniter/__init__.py:1:1: F401 '.croniter as cron_...
- **PR #170**: Add some more type hints
  - Add some more type hints that mypy is still happy about....
- **PR #169**: Add type hints to dicts
  - Add type hints to dicts to make mypy happy. Then check mypy on the CI....
- **PR #166**: add pylint configuration
  - Set `max-line-length` for pylint to the value from black....
- **PR #163**: Drop Python 2 support
  - Remove all remnancts of the Python 2 support....
- **PR #162**: address pylint's no-else-return
  - pylint complains:
 
 ```
 croniter/croniter.py:1264:8: R1705: Unnecessary "elif" after "return", remove the leading "el" from "elif" (no-else-return)
 ```...


### Range Support (3 PRs)

- **PR #104**: Add comment to RANGES
- **PR #98**: Reallow DOW=7, & rework range calculations.
  - Related to #90....
- **PR #39**: Adding check for range begin end
  - Following on from issue #37 "Division by zero possible with ranges", this change adds a check that `range_end` is `> range_begin` before trying to process the schedule. And adding a test case that pro...


### Timezone (2 PRs)

- **PR #172**: test: use isoformat() to compare dates with timezone information
  - The date 2017-10-29 02:00 is ambiguous for Europe/Warsaw. It can be UTC+1 or UTC+2.
 
 To make the test case easier to read, test all dates during the DST transition starting with an unambiguous date....
- **PR #156**: Replace legacy timezone US/Eastern by America/New_York
  - The timezone name `US/Eastern` is a legacy name and points to `America/New_York`....


## Critical Bug Fixes and Edge Cases

These represent issues that were discovered and fixed, indicating areas requiring thorough testing:

- **PR #185**: Fix memory leak by removing `TIMESTAMP_TO_DT_CACHE`
- **PR #180**: Fix always missing the timestamp to datetime cache
- **PR #178**: Fix skipping first of March
- **PR #177**: Fix DST handling by rewriting the DST logic
- **PR #175**: Fix all flake8 complaints
- **PR #174**: test: fix date in test_dst_iter
- **PR #173**: test: document time jumps in DST test cases
- **PR #171**: test: fix invalid test method names
- **PR #168**: Let _calc take a datetime object instead of a timestamp
- **PR #165**: document DST jump for test_dst_iter
- **PR #152**: Further modernize the codebase
- **PR #130**: black: Switch line length to 119 for croniter.py
- **PR #124**: black: Format if conditions
- **PR #86**: Fix start_time not respected in get_next/get_prev/all_next/all_prev 
- **PR #84**: Add an `update_current` argument to get_next/get_prev/all_next/all_prev
- **PR #82**: Fix hashed expressions omitting some entries
- **PR #78**: support question mark
- **PR #69**: fix #68: Avoid over-optimization
- **PR #61**: fix bug for bad case leap year 2 month 29 days;
- **PR #52**: Add python 3.12 support
- **PR #46**: Implement cron bug fixes
- **PR #43**: Enhance .match() precision for 6 position expressions
- **PR #39**: Adding check for range begin end
- **PR #21**: Fix croniter_range infinite loop
- **PR #13**: Fix #12: `set_current(force=True)` by default
- **PR #7**: Fix typos


## Testing Implications

Based on the analysis, the following areas require comprehensive testing:

### 1. Timezone Handling
- DST transitions (spring forward, fall back)
- Timezone-aware vs naive datetime objects
- Cross-timezone calculations
- Edge cases around midnight in different timezones

### 2. Hash Support
- Consistent hashing for load distribution
- Hash ID validation and ranges
- Collision handling

### 3. Second-level Precision
- Support for seconds field in cron expressions
- Backward compatibility with 5-field expressions

### 4. Day-of-Month and Day-of-Week Interaction
- When both are specified (OR vs AND logic)
- Last day of month calculations
- Weekday specifications (MON-SUN, 0-7)
- nth weekday of month

### 5. Special Characters
- `*` (any value)
- `-` (ranges)
- `,` (lists)
- `/` (steps)
- `L` (last)
- `W` (weekday)
- `#` (nth occurrence)
- `?` (no specific value)

### 6. Range and Step Expressions
- Step values with ranges (e.g., `10-50/5`)
- Wraparound behavior (e.g., `50-10/5`)
- Invalid range handling

### 7. Edge Cases
- February 29 in leap years
- Month boundaries
- Year boundaries (Dec 31 -> Jan 1)
- Invalid cron expressions
- Extreme dates (far past/future)

## Recent Commits Analysis (Last 200)

### Feature Commits (20)

- `b2ab6270` Add Publishing workflow (2025-10-05)
- `61cc6eb2` Add Publishing workflow (2025-10-05)
- `681aef27` Add release notes (2025-10-05)
- `b171ea99` Add type hints to croniter.__init__ (2025-07-01)
- `257741ed` Add type hint to timestamp_to_datetime (2025-06-28)
- `b4e72952` Support zoneinfo (2025-06-25)
- `9b018f39` Add some more type hints (2025-06-23)
- `77bcea04` Add type hints to dicts (2025-06-23)
- `aab7391c` Add uv.lock (2025-06-22)
- `ea6bd3f4` Drop Python 2 support (2025-06-21)
- `84536520` add pylint configuration (2025-06-21)
- `93dd98ed` address pylint's no-else-return (2025-06-21)
- `6a10b3f5` Replace legacy timezone US/Eastern by America/New_York (2025-06-16)
- `5a0accfc` Stop supporting Python < 3.9 (#147) (2025-03-21)
- `4ff18559` black: Add black to project (2024-10-30)
- `e3fe158b` Add comment to RANGES (2024-10-29)
- `3642302d` Reallow DOW=7, & rework range calculations. (2018-11-17)
- `34a91f59` Reallow DOW=7, & rework range calculations. (2018-11-17)
- `0fc3e71c` Merge pull request #97 from kiorky/new-packaging (2024-10-25)
- `ed4e0f4e` Merge pull request #97 from kiorky/new-packaging (2024-10-25)

### Bug Fix Commits (21)

- `dc63ed20` Fix default value of second_at_beginning to a boolean (2025-07-01)
- `c4f5e440` Initialize croniter properties with correct type (2025-07-01)
- `0d98bf73` Merge pull request #180 from bdrung/fix-timestamp-to-datetime-cache (2025-06-28)
- `18eb2993` Fix always missing the timestamp to datetime cache (2025-06-28)
- `461dda52` Merge pull request #177 from bdrung/fix-dst-handling (2025-06-28)
- `318038ca` Merge pull request #178 from bdrung/fix-bug-1 (2025-06-28)
- `de21a9da` Fix skipping first of March (2025-06-26)
- `f48387b3` Fix DST handling by rewriting the DST logic (2025-06-25)
- `38533671` Merge pull request #174 from bdrung/fix-test-dst-iter (2025-06-24)
- `871e3917` test: fix date in test_dst_iter (2025-06-24)
- `08c1f83c` Fix all flake8 complaints (2025-06-24)
- `419fee93` Merge pull request #171 from bdrung/fix-invalid-name (2025-06-24)
- `5821fa35` test: fix invalid test method names (2025-06-23)
- `d5a7f0e0` Fix typo in maintained (2025-06-23)
- `daa66b3a` Merge pull request #158 from bdrung/fix-pylint (2025-06-21)
- `3141708f` Remove DOW-7 as alias & fix DOW calcs when DOW=0 (2018-04-03)
- `c21c9ba7` Remove DOW-7 as alias & fix DOW calcs when DOW=0 (2018-04-03)
- `eda07701` Re-enable correctly py27 testing and document it (2019-04-26)
- `c0b36956` Re-enable correctly py27 testing and document it (2019-04-26)
- `17bec1df` Fix overflow error on 32bit systems (2019-04-27)


## Implementation Checklist for Rust Port

Based on this analysis, ensure the Rust implementation includes:

- [ ] Full cron expression parsing (5, 6, and 7 field formats)
- [ ] Timezone support with DST handling
- [ ] Hash support for consistent scheduling
- [ ] Second-level precision
- [ ] All special characters (*, -, /, ,, L, W, #, ?)
- [ ] Day-of-month and day-of-week OR logic
- [ ] Range and step expressions with wraparound
- [ ] Leap year handling
- [ ] Month/year boundary transitions
- [ ] Iterator interface (next/prev)
- [ ] Start time specification
- [ ] Error handling for invalid expressions
- [ ] Edge case validation

## Detailed PR Analysis


### PR #192: remove obsolete noqa: E241
**Merged:** 2025-12-02  
**Categories:** other  
**Description:** The `noqa: E241` marker are not needed any more after wrapping the lines (with ruff)....

### PR #190: Prepare for release 6.1.0rc1
**Merged:** 2025-10-06  
**Categories:** other  

### PR #186: Modernize project setup
**Merged:** 2025-10-06  
**Categories:** feature  
**Description:** * get rid of setup.cfgy, MANIFEST.in and moving to flit as build backend
 * switched tox to use uv under the hood
 * add uv lock
 * replace requirments/* with dependency groups
 * move all configuration to pyproject.toml...

### PR #185: Fix memory leak by removing `TIMESTAMP_TO_DT_CACHE`
**Merged:** 2025-10-05  
**Categories:** feature, bug  
**Description:** This fixes https://github.com/pallets-eco/croniter/issues/182
 
 Historically `TIMESTAMP_TO_DT_CACHE` was introduced here in a batch of many other changes before release v6.x.x: https://github.com/pallets-eco/croniter/pull/143/commits/a7e1e19e72c46f99915f16c6c76f1700b2157941 and i don't see any issu...

### PR #181: Add type hints to croniter.__init__
**Merged:** 2025-07-01  
**Categories:** feature  
**Description:** Add type hints to `croniter.__init__` and address the mypy complaints....

### PR #180: Fix always missing the timestamp to datetime cache
**Merged:** 2025-06-28  
**Categories:** bug  
**Description:** `timestamp_to_datetime` uses different keys for looking up and storing values in `TIMESTAMP_TO_DT_CACHE`. Since the keys differ, the lookup will always miss the cache.
 
 Fix the cache lookup by using the same key everywhere....

### PR #179: Drop unused _get_next_nearest and _get_prev_nearest
**Merged:** 2025-06-28  
**Categories:** other  
**Description:** Drop the unused private methods `_get_next_nearest` and `_get_prev_nearest`....

### PR #178: Fix skipping first of March
**Merged:** 2025-06-28  
**Categories:** feature, bug  
**Description:** In case the month cron rule is `*/x` the first of March might be skipped. In case of `*/10` the expanded field for the day is [1, 11, 21, 31]. Despite February has at most 29 days, `proc_day_of_month` will pick 31 as next day. Adding so many days to reach the 31 of February will overshoot the first ...

### PR #177: Fix DST handling by rewriting the DST logic
**Merged:** 2025-06-28  
**Categories:** feature, bug, edge, test  
**Description:** The cron expression can specify points in time but also time intervals. Depending on that different solutions are needed for correcting the time after a DST change.
 
 PEP 495 compliant implementations (like zoneinfo) behave differently than pytz and therefore the existing DST handling for pytz does...

### PR #176: Reduce line length to 99
**Merged:** 2025-06-24  
**Categories:** other  
**Description:** A line length of 119 is too wide IMO. My sweet spot line length is between 88 and 99.
 
 Reduce line length to 99 and format the Python code with `black -C`....

### PR #175: Fix all flake8 complaints
**Merged:** 2025-06-24  
**Categories:** feature, bug, test  
**Description:** The CI currently only checks `src/croniter/croniter.py` for flake8, but there are more Python files that should be checked.
 
 ```
 $ flake8 .
 ./src/croniter/__init__.py:1:1: F401 '.croniter as cron_m' imported but unused
 ./src/croniter/__init__.py:2:1: F401 '.croniter.DAY_FIELD' imported but unus...

### PR #174: test: fix date in test_dst_iter
**Merged:** 2025-06-24  
**Categories:** bug, test  
**Description:** pytz requires to use `localize()` to convert a local time to a timezone aware time. Setting `tzinfo` leads to a wrong result:
 
 ```python3
 >>> import datetime, pytz
 >>> datetime.datetime(2022, 3, 26, 0, 0, 0, tzinfo=pytz.timezone("Asia/Hebron"))
 datetime.datetime(2022, 3, 26, 0, 0, tzinfo=<DstTz...

### PR #173: test: document time jumps in DST test cases
**Merged:** 2025-06-24  
**Categories:** bug, test  
**Description:** Document the time jumps in the DST test cases for easier debugging....

### PR #172: test: use isoformat() to compare dates with timezone information
**Merged:** 2025-06-24  
**Categories:** feature, test  
**Description:** The date 2017-10-29 02:00 is ambiguous for Europe/Warsaw. It can be UTC+1 or UTC+2.
 
 To make the test case easier to read, test all dates during the DST transition starting with an unambiguous date.
 
 `datetime` will ignore the UTC offset when comparing dates that have the same timezone. So compa...

### PR #171: test: fix invalid test method names
**Merged:** 2025-06-24  
**Categories:** bug, test  
**Description:** pylint complains about C0103: Method name "..." doesn't conform to snake_case naming style (invalid-name)
 
 Rename those methods to use snake_case naming to make the test naming consistent....

### PR #170: Add some more type hints
**Merged:** 2025-06-23  
**Categories:** feature  
**Description:** Add some more type hints that mypy is still happy about....

### PR #169: Add type hints to dicts
**Merged:** 2025-06-23  
**Categories:** feature  
**Description:** Add type hints to dicts to make mypy happy. Then check mypy on the CI....

### PR #168: Let _calc take a datetime object instead of a timestamp
**Merged:** 2025-06-22  
**Categories:** bug  
**Description:** Let `_calc` take and return a datetime object instead of a timestamp. This is a preparation of fixing the DST handling which will need to operate on non-existing wall times....

### PR #167: test: use isoformat to check dates
**Merged:** 2025-06-21  
**Categories:** test  
**Description:** Use `.isoformat()` to check the dates instead of comparing the date (without the tzinfo) and the UTC offset separately. That makes reading test failures easier....

### PR #166: add pylint configuration
**Merged:** 2025-06-21  
**Categories:** feature  
**Description:** Set `max-line-length` for pylint to the value from black....

### PR #165: document DST jump for test_dst_iter
**Merged:** 2025-06-21  
**Categories:** bug, test  
**Description:** Document the DST jump in `test_dst_iter` to ease debugging....

### PR #164: Introduce _last_day_of_month() helper function
**Merged:** 2025-06-21  
**Categories:** other  
**Description:** Introduce _last_day_of_month() helper function to avoid code duplication....

### PR #163: Drop Python 2 support
**Merged:** 2025-06-21  
**Categories:** feature  
**Description:** Remove all remnancts of the Python 2 support....

### PR #162: address pylint's no-else-return
**Merged:** 2025-06-21  
**Categories:** feature  
**Description:** pylint complains:
 
 ```
 croniter/croniter.py:1264:8: R1705: Unnecessary "elif" after "return", remove the leading "el" from "elif" (no-else-return)
 ```...

### PR #161: Remove unused imports
**Merged:** 2025-06-21  
**Categories:** other  
**Description:** Remove all unused imports....

### PR #159: apply pyupgrade --py39-plus
**Merged:** 2025-06-21  
**Categories:** other  
**Description:** Run
 
 ```
 pyupgrade --py39-plus $(find -name '*.py')
 ```
 
 Replace the remaining `format` calls with f-strings that weren't upgraded by pyupgrade....

### PR #158: Introduce helper method _calc_next
**Merged:** 2025-06-21  
**Categories:** other  
**Description:** `pylint --error` complains:
 
 ```
 ************* Module croniter.croniter
 croniter/croniter.py:394:46: E0601: Using variable 'result' before assignment (used-before-assignment)
 ```
 
 Introduce a helper method `_calc_next` to make pylint happy and to make the code more readable. The `_calc_next` ...

### PR #157: Format code with latest black version
**Merged:** 2025-06-21  
**Categories:** test  
**Description:** Format code with black 25.1.0....

### PR #156: Replace legacy timezone US/Eastern by America/New_York
**Merged:** 2025-06-21  
**Categories:** feature  
**Description:** The timezone name `US/Eastern` is a legacy name and points to `America/New_York`....

### PR #154: Drop unittest2
**Merged:** 2025-06-21  
**Categories:** feature, test  
**Description:** unittest2 is a backport of the Python 3 unittest module. Since Python 2 support was dropped, drop the support for `unittest2`....

### PR #152: Further modernize the codebase
**Merged:** 2025-06-22  
**Categories:** feature, bug, edge  
**Description:** Small updates for the supported Python versions.
 - since Python 3.7 `dict` is guaranteed to keep the insertion order, so no need for `OrderedDict` (and a py2 fallback)
 - ~~`pytz` was used only as a py2 fallback, so I removed the dependency and corrected the code.~~ I see that dropping `pytz` is be...

### PR #150: Modernize packaging
**Merged:** 2025-04-13  
**Categories:** feature  
**Description:** - Move project metadata to `pyproject.toml`
 - Use SPDX license identifier for PEP 639 license expression support -> `MIT`
 - Update project url to reflect new repo location
 - Remove old classifiers after #147
 - Update `requires-python` to `>=3.9`
 - Remove `Classifier: Topic :: Software Developme...

### PR #147: Stop supporting Python < 3.9
**Merged:** 2025-03-21  
**Categories:** feature  
**Description:** Everything else is out of support. This will be released as a major version
 bump to go along with the change of home to pallets-eco.
 
 For now I've left the 32bit support in, but maybe that doesn't make sense to keep longer term? The cost isn't large tbf
 ...

### PR #146: Remove the message about being abandoned
**Merged:** 2025-03-21  
**Categories:** other  
**Description:** The project lives on under the pallets umbrella!
 
 Closes #144 ...

### PR #143: R6
**Merged:** 2024-12-17  
**Categories:** other  

### PR #137: Remove unused OVERFLOW32B_MODE from tests
**Merged:** 2024-11-01  
**Categories:** test  
**Description:** This module constnat is not used...

### PR #134: Isort
**Merged:** 2024-10-31  
**Categories:** other  

### PR #132: balck: A couple missed call-site formats
**Merged:** 2024-10-31  
**Categories:** other  
**Description:** Follow up from #119
 
 Part of #99 ...

### PR #131: black: Format test imports
**Merged:** 2024-10-31  
**Categories:** test  
**Description:** Part of #99 ...

### PR #130: black: Switch line length to 119 for croniter.py
**Merged:** 2024-10-31  
**Categories:** bug  
**Description:** Uses 119 as the line length now.
 
 This fixes a few of the uglier changes introduced. Good call @kiorky :)
 
 Part of #99 ...

### PR #129: black: Format raise calls
**Merged:** 2024-10-31  
**Categories:** other  
**Description:** Adjusted a few of these to not use explicit string concatenation. I did leave one or two that were egregiously long otherwise.
 
 This is also using line length 119 now.
 
 Part of #99 ...

### PR #128: black: Use double quote in tests
**Merged:** 2024-10-31  
**Categories:** test  
**Description:** Part of #99 ...

### PR #125: black: Expression formatting
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** Formatting for various assignment like expressions
 
 Part of #99 ...

### PR #124: black: Format if conditions
**Merged:** 2024-10-30  
**Categories:** bug  
**Description:** Some of these are about as difficult to read as before, but I think they can always be formatting fixed up later.
 
 For now let's just get black applied and part of CI
 
 Part of #99 ...

### PR #122: black: Comments + minor whitespace
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** Part of #99 ...

### PR #121: black: Special formatting for ALHPAS / *_FIELDS
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** In response to https://github.com/kiorky/croniter/pull/116#pullrequestreview-2405799046
 
 Part of #99 ...

### PR #120: black: Apply to `__init__.py`
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** Part of #99 ...

### PR #119: black: Call-site argument list formatting
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** Black formats calls that are too long to fit the 80 character limit consistently.
 
 Part of #99 ...

### PR #118: black: Maths spacing
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** Part of #99 ...

### PR #117: black: Long function defnition arg lists
**Merged:** 2024-10-30  
**Categories:** other  
**Description:** Black splits these when they are longer than it's default 80 character limit
 
 Part of #99 ...



## Changelog Highlights (Last 30 Versions)

- **v6.0.0** (2024-12-17): Announce for now that croniter dev is ended (CRA).
- **v6.0.0** (2024-12-17): Rework timestamp_to_datetime to use whatever timezone [kiorky]
- **v6.0.0** (2024-12-17): Make datetime_to_timestamp & timestamp_to_datetime public [kiorky]
- **v6.0.0** (2024-12-17): Fix EPOCH calculation in case of non UTC & 32 bits based systems [kiorky]
- **v6.0.0** (2024-12-17): Apply isort formatter [kiorky]
- **v5.0.1** (2024-10-29): Community wanted: Reintroduce 7 as DayOfWeek in deviation from standard cron (#90). [kiorky]
- **v4.0.0** (2024-10-28): Remove DayOfWeek alias 7 to DayOfWeek 0 to stick to standard cron (#90). [kiorky]
- **v4.0.0** (2024-10-28): Fix DOW ranges calculations when lastday is a Sunday. [kiorky]
- **v3.0.4** (2024-10-25): Fix overflow on 32bits systems (#87) [kiorky]
- **v3.0.4** (2024-10-25): Fix python2 testing (related to #93) [kiorky]
- **v3.0.4** (2024-10-25): Modernize packaging. Special thanks to Aarni Koskela (akx) for all the inputs. [kiorky, akx]
- **v3.0.3** (2024-07-26): fix lint [kiorky]
- **v3.0.2** (2024-07-26): Fix start_time not respected in get_next/get_prev/all_next/all_prev (#86) [hesstobi, kiorky]
- **v3.0.1** (2024-07-25): Add an `update_current` argument to get_next/get_prev/all_next/all_prev to facilitate writing of some downstream code, see #83. [kiorky]
- **v3.0.0** (2024-07-23): Support for year field [zhouyizhen, kiorky]
- **v3.0.0** (2024-07-23): Better support for 6 fields (second), and 7 fields crons [zhouyizhen, kiorky]
- **v3.0.0** (2024-07-23): Better fix hashed expressions omitting some entries (#82, #42, #30) fix is retained over #42 initial fix [zhouyizhen, kiorky]
- **v3.0.0** (2024-07-23): Ensure match return false when not time available (#81) [zhouyizhen, kiorky]
- **v2.0.7** (2024-07-16): fix doc
- **v2.0.6** (2024-07-16): Implement second_at_beginning [zhouyizhen, kiorky]
- **v2.0.6** (2024-07-16): Support question mark as wildcard [zhouyizhen, kiorky]
- **v2.0.6** (2024-07-16): Support to start a cron from a reference start time [mghextreme, kiorky]
- **v2.0.5** (2024-04-20): No changes, fix lint [kiorky]
- **v2.0.4** (2024-04-20): Support hashid strings in is_valid [george-kuanli-peng, kiorky]
- **v2.0.4** (2024-04-20): Avoid over-optimization in crontab expansions [Cherie0125, liqirui <liqirui@baidu.com>, kiorky]
- **v2.0.3** (2024-03-19): Add match_range function [salitaba]
- **v2.0.2** (2024-02-29): fix leap year (29 days in February) [zed2015]
- **v2.0.1** (2023-10-11): Fix release issue [kiorky]
- **v2.0.0** (2023-10-10): Add Python 3.12 support [rafsaf]
- **v2.0.0** (2023-10-10): Make major release instructions [kiorky]
- **v1.4.1** (2023-06-15): Make a retrocompatible version of 1.4.0 change about supporting VIXIECRON bug. (fix #47)
- **v1.4.0** (2023-06-15): Added "implement_cron_bug" flag to make the cron parser compatible with a bug in Vixie/ISC Cron
- **v1.3.15** (2023-05-25): Fix hashed expressions omitting some entries
- **v1.3.15** (2023-05-25): Enhance .match() precision for 6 position expressions
- **v1.3.14** (2023-04-12): Lint
- **v1.3.13** (2023-04-12): Add check for range begin/end
- **v1.3.12** (2023-04-12): restore py2 compat
- **v1.3.11** (2023-04-12): Do not expose `i` into global namespace
- **v1.3.10** (2023-04-07): Fix DOW hash parsing [kiorky]
- **v1.3.10** (2023-04-07): better error handling on py3 [kiorky]
- **v1.3.8** (2022-11-22): Add Python 3.11 support and move docs files to main folder [rafsaf]
- **v1.3.7** (2022-09-06): fix tests
- **v1.3.7** (2022-09-06): Fix croniter_range infinite loop  [Shachar Snapiri <ssnapiri@paloaltonetworks.com>]
- **v1.3.5** (2022-05-14): Add Python 3.10 support [eelkevdbos]
- **v1.3.4** (2022-02-18): Really fix compat for tests under py27
- **v1.3.3** (2022-02-18): Fix compat for tests under py27
- **v1.3.2** (2022-02-18): Fix #12: regressions with set_current



## Source Code Structure Analysis

Based on repository structure:

### Core Files
- `src/croniter/` - Main implementation
- `tests/` - Test suite
- `CHANGELOG.rst` - Version history with 623 lines
- `README.rst` - Documentation

### Key Implementation Areas
1. **Expression Parsing**: Tokenization and validation of cron expressions
2. **Date Iteration**: Forward and backward iteration logic
3. **Timezone Handling**: DST-aware calculations
4. **Hash Support**: Consistent scheduling across instances
5. **Special Characters**: L, W, #, ? implementations


## Conclusion

This analysis covers 110 pull requests and 1257 commits from the croniter repository. The Rust implementation must carefully replicate all features, especially:

1. Complex timezone and DST handling
2. Hash-based scheduling
3. All cron special characters and their interactions
4. Edge cases around date boundaries
5. Proper OR logic for day fields

Regular synchronization with upstream changes is recommended to maintain feature parity.
