Add a cycle detector for generic Graphs and mir::Bodys
#64622
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rust-highfive
added
the
S-waiting-on-review
|
This probably doesn't need to be reviewed by @eddyb (I r?-ed out of habit). |
|
Maybe r? @Centril |
Centril
reviewed
Sep 19, 2019
ecstatic-morse
force-pushed
the
cycle-detector
branch
from
b6a63b9 to
c3aeef7
Compare
|
r? @oli-obk Some more docs would indeed be great. |
ecstatic-morse
force-pushed
the
cycle-detector
branch
from
c3aeef7 to
3cfe61a
Compare
ecstatic-morse
force-pushed
the
cycle-detector
branch
from
3cfe61a to
c9e4816
Compare
|
I added some more docs comparing this depth-first search to the one in Introduction to Algorithms. Hopefully it's easier to follow now. |
|
@bors r+ Thanks, that helps |
|
📌 Commit c9e4816 has been approved by |
bors
added
S-waiting-on-bors
Centril
added a commit
to Centril/rust
that referenced
this pull request
Sep 24, 2019
…i-obk Add a cycle detector for generic `Graph`s and `mir::Body`s Cycle detection is one way to differentiate the upcoming `const_loop` feature flag (rust-lang#52000) from the `const_if_match` one (rust-lang#49146). It would be possible to use the existing implementation of strongly-connected components for this but less efficient. The ["tri-color" terminology](http://www.cs.cornell.edu/courses/cs2112/2012sp/lectures/lec24/lec24-12sp.html) is common in introductory data structures and algorithms courses: black nodes are settled, grey nodes are visited, and white nodes have no state. This particular implementation is iterative and uses a well-known technique where "node settled" events are kept on the stack alongside nodes to visit. When a settled event is popped, we know that all successors of that node have been visited and themselves settled. If we encounter a successor node that has been visited (is on the stack) but not yet settled, we have found a cycle. r? @eddyb
Centril
added a commit
to Centril/rust
that referenced
this pull request
Sep 24, 2019
…i-obk Add a cycle detector for generic `Graph`s and `mir::Body`s Cycle detection is one way to differentiate the upcoming `const_loop` feature flag (rust-lang#52000) from the `const_if_match` one (rust-lang#49146). It would be possible to use the existing implementation of strongly-connected components for this but less efficient. The ["tri-color" terminology](http://www.cs.cornell.edu/courses/cs2112/2012sp/lectures/lec24/lec24-12sp.html) is common in introductory data structures and algorithms courses: black nodes are settled, grey nodes are visited, and white nodes have no state. This particular implementation is iterative and uses a well-known technique where "node settled" events are kept on the stack alongside nodes to visit. When a settled event is popped, we know that all successors of that node have been visited and themselves settled. If we encounter a successor node that has been visited (is on the stack) but not yet settled, we have found a cycle. r? @eddyb
bors
added a commit
that referenced
this pull request
Sep 24, 2019
Rollup of 16 pull requests Successful merges: - #63356 (Issue#63183: Add fs::read_dir() and ReadDir warning about iterator order + example) - #63934 (Fix coherence checking for impl trait in type aliases) - #64016 (Streamline `Compiler`) - #64296 (Document the unstable iter_order_by library feature) - #64443 (rustdoc: general cleanup) - #64622 (Add a cycle detector for generic `Graph`s and `mir::Body`s) - #64689 (Refactor macro by example) - #64698 (Recover on `const X = 42;` and infer type + Error Stash API) - #64702 (Remove unused dependencies) - #64717 (update mem::discriminant test to use assert_eq and assert_ne over comparison operators) - #64720 ( remove rtp.rs, and move rtpSpawn and RTP_ID_ERROR to libc) - #64721 (Fixed issue from #64447) - #64725 (fix one typo) - #64737 (fix several issues in String docs) - #64742 (relnotes: make compatibility section more sterile and fix rustc version) - #64748 (Fix #64744. Account for the Zero sub-pattern case.) Failed merges: r? @ghost
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
7 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Cycle detection is one way to differentiate the upcoming
const_loopfeature flag (#52000) from theconst_if_matchone (#49146). It would be possible to use the existing implementation of strongly-connected components for this but less efficient.The "tri-color" terminology is common in introductory data structures and algorithms courses: black nodes are settled, grey nodes are visited, and white nodes have no state. This particular implementation is iterative and uses a well-known technique where "node settled" events are kept on the stack alongside nodes to visit. When a settled event is popped, we know that all successors of that node have been visited and themselves settled. If we encounter a successor node that has been visited (is on the stack) but not yet settled, we have found a cycle.
r? @eddyb