# Molinillo Changelog

## 0.6.4 (2017-10-29)

##### Enhancements

* Reduce memory usage during resolution by making the `Vertex#requirements`
  array unique.  
  [Grey Baker](https://github.com/greysteil)
  [Jan Krutisch](https://github.com/halfbyte)

##### Bug Fixes

* None.  


## 0.6.3 (2017-09-06)

##### Enhancements

* None.  

##### Bug Fixes

* Handle the case where an unwind occurs to a requirement that directly caused
  the current conflict but could also have been unwound to directly from
  previous conflicts. In this case, filtering must not remove any possibilities
  that could have avoided the previous conflicts (even if they would not avoid
  the current one).  
  [Grey Baker](https://github.com/greysteil)


## 0.6.2 (2017-08-25)

##### Enhancements

* None.  

##### Bug Fixes

* Insist each PossibilitySet contains contiguous versions. Fixes a regression
  where an older dependency version with identical sub-dependencies to the
  latest version may be preferred over the second-latest version.  
  [Grey Baker](https://github.com/greysteil)


## 0.6.1 (2017-08-01)

##### Enhancements

* None.  

##### Bug Fixes

* Allow the set of dependencies for a given possibility to change over time,
  fixing a regression in 0.6.0.  
  [Samuel Giddins](https://github.com/segiddins)


## 0.6.0 (2017-07-27)

##### Breaking

* Objects returned by `dependencies_for` and passed to `resolve` must properly implement
  both `==` and `eql?`, such that they return `true` when they exhibit the same behavior in
  `requirement_satisfied_by?`.  

##### Enhancements

* Speed up dependency resolution by considering multiple possible versions of a
  dependency at once, grouped by sub-dependencies. Groups are then filtered as
  additional requirements are introduced. If a group's sub-dependencies cause
  conflicts the entire group can be discarded, which reduces the number of
  possibilities that have to be tested to find a resolution.  
  [Grey Baker](https://github.com/greysteil)
  [Samuel Giddins](https://github.com/segiddins)
  [#69](https://github.com/CocoaPods/Molinillo/pull/69)

* Check for locked requirements when generating a new state's possibilities
  array, and reduce possibilities set accordingly. Reduces scope for erroneous
  VersionConflict errors.  
  [Grey Baker](https://github.com/greysteil)
  [#67](https://github.com/CocoaPods/Molinillo/pull/67)

* Add `VersionConflict#message_with_trees` for consumers who prefer a more verbose
  conflict message that includes full requirement trees for all conflicts.  
  [Samuel Giddins](https://github.com/segiddins)

##### Bug Fixes

* Improve unwinding by considering previous conflicts for the same dependency
  when deciding which state to unwind to. Previously, prior conflicts were
  stored in a hash indexed by their name, with only the most recent conflict
  stored for each dependency. With this fix, Molinillo can resolve anything
  that's thrown at it. 🎉  
  [Grey Baker](https://github.com/greysteil)
  [#73](https://github.com/CocoaPods/Molinillo/pull/73)

* Only raise CircularDependency errors if they prevent resolution.  
  [Ian Young](https://github.com/iangreenleaf)
  [Grey Baker](https://github.com/greysteil)
  [#78](https://github.com/CocoaPods/Molinillo/pull/78)

* Consider additional (binding) requirements that caused a conflict when
  determining which state to unwind to. Previously, in some cases Molinillo
  would erroneously throw a VersionConflict error if multiple requirements
  combined to cause a conflict.  
  [Grey Baker](https://github.com/greysteil)
  [#72](https://github.com/CocoaPods/Molinillo/pull/72) 

* Consider previous conflicts when determining the state to unwind to. If a
  previous conflict, for a different dependency, is the reason we ended up with
  the current conflict, then unwinding to a state that would not have caused
  that conflict could prevent the current one, too.  
  [Grey Baker](https://github.com/greysteil)
  [#72](https://github.com/CocoaPods/Molinillo/pull/72)


## 0.5.7 (2017-03-03)

##### Enhancements

* None.  

##### Bug Fixes

* Keep a stack of parents per requirement, so unwinding past a swap point that
  updated the parent of the requirement works.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#5425](https://github.com/bundler/bundler/issues/5425)


## 0.5.6 (2017-02-08)

##### Enhancements

* None.  

##### Bug Fixes

* Only reset the parent of a requirement after swapping when its original parent
  was the same vertex being swapped.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#5359](https://github.com/bundler/bundler/issues/5359)
  [bundler#5362](https://github.com/bundler/bundler/issues/5362)


## 0.5.5 (2017-01-07)

##### Enhancements

* None.  

##### Bug Fixes

* Only remove requirements from the to-be-resolved list if there are no
  activated vertices depending upon them after swapping.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#5294](https://github.com/bundler/bundler/issues/5294)


## 0.5.4 (2016-11-14)

##### Enhancements

* None.  

##### Bug Fixes

* Fix unwinding when both sides of a conflict have a common parent
  requirement.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#5154](https://github.com/bundler/bundler/issues/5154)


## 0.5.3 (2016-10-28)

##### Enhancements

* None.  

##### Bug Fixes

* Fixed a regression in v0.5.2 that could cause resolution to fail after
  swapping, because stale dependencies would still be in the requirements
  list.  
  [Samuel Giddins](https://github.com/segiddins)
  [#48](https://github.com/CocoaPods/Molinillo/issues/48)

* Rename `Action.name` to `Action.action_name` to avoid overriding
  `Module.name`.  
  [Samuel Giddins](https://github.com/segiddins)
  [#50](https://github.com/CocoaPods/Molinillo/issues/50)


## 0.5.2 (2016-10-24)

##### Enhancements

* None.  

##### Bug Fixes

* Fixed a bug where `Resolution#parent_of` would return the incorrect parent for
  a dependency after swapping had occurred, resulting in resolution failing.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#5059](https://github.com/bundler/bundler/issues/5059)


## 0.5.1 (2016-09-12)

##### Enhancements

* None.  

##### Bug Fixes

* Fixed a bug where `Resolution#parent_of` would return the incorrect parent for
  a dependency, resulting in resolution failing.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#4961](https://github.com/bundler/bundler/issues/4961)


## 0.5.0 (2016-06-14)

##### Enhancements

* Add an operation log to `DependencyGraph` to eliminate the need for graph
  copies during dependency resolution, resulting in a 3-100x speedup and
  reduction in allocations.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler#4376](https://github.com/bundler/bundler/issues/4376)

* Remove all metaprogramming to reduce array allocation overhead and improve
  discoverability.  
  [Samuel Giddins](https://github.com/segiddins)

##### Bug Fixes

* None.  


## 0.4.5 (2016-04-30)

##### Enhancements

* For performance, don't needlessly dup objects in
  `Resolution#push_state_for_requirements`.  
  [Joe Rafaniello](https://github.com/jrafanie)

##### Bug Fixes

* Recursively prune requirements when removing an orphan after swapping.  
  [Daniel DeLeo](https://github.com/danielsdeleo)
  [berkshelf/solve#57](https://github.com/berkshelf/solve/issues/57)


## 0.4.4 (2016-02-28)

##### Bug Fixes

* Fix mutating a frozen string in `NoSuchDependencyError#message`.  
  [Samuel Giddins](https://github.com/segiddins)


## 0.4.3 (2016-02-18)

##### Enhancements

* Add frozen string literal comments to all ruby files.  
  [Samuel Giddins](https://github.com/segiddins)

##### Bug Fixes

* Prune the dependency list when removing an orphan after swapping.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler/bundler#4276](https://github.com/bundler/bundler/issues/4276)


## 0.4.2 (2016-01-30)

##### Bug Fixes

* Detaching a vertex correctly removes it from the list of successors of its
  predecessors.  
  [Samuel Giddins](https://github.com/segiddins)

* Vertices orphaned after swapping dependencies are properly cleaned up from the
  graph of activated specs.  
  [Samuel Giddins](https://github.com/segiddins)
  [bundler/bundler#4198](https://github.com/bundler/bundler/issues/4198)


## 0.4.1 (2015-12-30)

##### Enhancements

* Ensure every API is 100% documented.  
  [Samuel Giddins](https://github.com/segiddins)
  [#22](https://github.com/CocoaPods/Molinillo/issues/22)


## 0.4.0 (2015-07-27)

##### API Breaking Changes

* The `DependencyGraph` no longer treats root vertices specially, nor does it
  maintain a direct reference to `edges`. Additionally, `Vertex` no longer
  has a reference to its parent graph.  

##### Enhancements

* Resolution has been sped up by 25x in some pathological cases, and in general
  recursive operations on a `DependencyGraph` or `Vertex` are now `O(n)`.  
  [Samuel Giddins](https://github.com/segiddins)
  [Bundler#3803](https://github.com/bundler/bundler/issues/3803)

* Re-sorting of dependencies is skipped when the unresolved dependency list has
  not changed, speeding up resolution of fully locked graphs.  
  [Samuel Giddins](https://github.com/segiddins)


## 0.3.1 (2015-07-24)

##### Enhancements

* Add `Conflict#activated_by_name` to allow even richer version conflict
  messages.  
  [Samuel Giddins](https://github.com/segiddins)

##### Bug Fixes

* Ensure `Conflict#requirement_trees` is exhaustive.  
  [Samuel Giddins](https://github.com/segiddins)
  [Bundler#3860](https://github.com/bundler/bundler/issues/3860)


## 0.3.0 (2015-06-29)

##### Enhancements

* Add the ability to optionally skip dependencies that have no possibilities.  
  [Samuel Giddins](https://github.com/segiddins)


## 0.2.3 (2015-03-28)

##### Bug Fixes

* Silence a silly MRI warning about declaring private attributes.  
  [Piotr Szotkowski](https://github.com/chastell)
  [Bundler#3516](https://github.com/bundler/bundler/issues/3516)
  [Bundler#3525](https://github.com/bundler/bundler/issues/3525)


## 0.2.2 (2015-03-27)

##### Bug Fixes

* Use an ivar in `DependencyGraph#initialize_copy` to silence an MRI warning.  
  [Samuel Giddins](https://github.com/segiddins)
  [Bundler#3516](https://github.com/bundler/bundler/issues/3516)


## 0.2.1 (2015-02-21)

* Allow resolving some pathological cases where the backjumping algorithm would
  skip over a valid possibility.  
  [Samuel Giddins](https://github.com/segiddins)


## 0.2.0 (2014-12-25)

* Institute stricter forward checking by backjumping to the source of a
  conflict, even if that source comes from the existing spec. This further
  improves performance in highly conflicting situations when sorting heuristics
  prove misleading.  
  [Samuel Giddins](https://github.com/segiddins)
  [Smit Shah](https://github.com/Who828)

* Add support for topologically sorting a dependency graph's vertices.  
  [Samuel Giddins](https://github.com/segiddins)


## 0.1.2 (2014-11-19)

##### Enhancements

* Improve performance in highly conflicting situations by backtracking more than
  one state at a time.  
  [Samuel Giddins](https://github.com/segiddins)

##### Bug Fixes

* Ensure that recursive invocations of `detach_vertex_named` don't lead to
  messaging `nil`.  
  [Samuel Giddins](https://github.com/segiddins)
  [CocoaPods#2805](https://github.com/CocoaPods/CocoaPods/issues/2805)

## 0.1.1 (2014-11-06)

* Ensure that an unwanted exception is not raised when an error occurs before
  the initial state has been pushed upon the stack.  
  [Samuel Giddins](https://github.com/segiddins)

## 0.1.0 (2014-10-26)

* Initial release.  
  [Samuel Giddins](https://github.com/segiddins)