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Should the reverse iterators on strings and vectors be removed? #9391

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Kimundi opened this issue Sep 21, 2013 · 2 comments
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Should the reverse iterators on strings and vectors be removed? #9391

Kimundi opened this issue Sep 21, 2013 · 2 comments
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C-cleanup Category: PRs that clean code up or issues documenting cleanup.

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@Kimundi
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Kimundi commented Sep 21, 2013

Most common iterators also implement DoubleEndedIterator, which means we can turn an Iterator into an reverse Iterator. The replacement would look like this:

"foo".rev_iter()             -> "foo".iter().invert()
"foo".byte_rev_iter()        -> "foo".byte_iter().invert()
"foo".char_offset_rev_iter() -> "foo".char_offset_iter().invert()
"foo".split_rev_iter()       -> "foo".split_iter().invert()
@Kimundi Kimundi mentioned this issue Sep 21, 2013
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@bluss
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bluss commented Sep 22, 2013

Fyi, splitn_iter is not a double-ended iterator today, because "split on 'x' 5 times from the front" is not easily reversible. If you change the definition to "split on 'x' 5 times from either end we take elements from", it would be, but that's an inconsistent step away from other double ended iterators.

(On the others, I'm sympathetic. 18 iterator methods is a lot.)

@Kimundi
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Kimundi commented Sep 22, 2013

Ah, didn't realize that. We'd have to keep splitn separate then.

@Kimundi Kimundi mentioned this issue Sep 23, 2013
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This was referenced Nov 18, 2013
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bors added a commit that referenced this issue Nov 26, 2013
@bors
auto merge of #10622 : Kimundi/rust/str_de_iter, r=alexcrichton
21990cd 
This PR removes almost all `_iter` suffixes in various APIs of the codebase that return Iterators, as discussed in #9440.

As a summarize for the intend behind this PR:

- Iterators are the recommended way to provide a potentially lazy list of values, no need to name them painfully verbose. If anything, functions that return a specific container type should have more verbose names.
- We have a static type system, so no need to encode the return value of a constructor function into its name.

Following is a possibly incomplete list of all renamings I performed in the codebase. For a few of them I'm a bit unsure whether the new name still properly expresses their functionality, so feedback would be welcome:

~~~
&str : word_iter()             -> words()
       line_iter()             -> lines()
       any_line_iter()         -> lines_any()
       iter()                  -> chars()
       char_offset_iter()      -> char_indices()
       byte_iter()             -> bytes()
       split_iter()            -> split()
       splitn_iter()           -> splitn()
       split_str_iter()        -> split_str()
       split_terminator_iter() -> split_terminator()
       matches_index_iter()    -> match_indices()
       nfd_iter()              -> nfd_chars()
       nfkd_iter()             -> nfkd_chars()
      
&[T] : split_iter()        -> split()
       splitn_iter()       -> splitn()
       window_iter()       -> windows()
       chunk_iter()        -> chunks()
       permutations_iter() -> permutations()
      
extra:bitv::Bitv :  rev_liter()    -> rev_iter()
                    common_iter()  -> commons()
                    outlier_iter() -> outliers()

extra::treemap::{...} : lower_bound_iter() -> lower_bound()
                        upper_bound_iter() -> upper_bound()
                       
std::trie::{...} : bound_iter()       -> bound()
                   lower_bound_iter() -> lower_bound()
                   upper_bound_iter() -> upper_bound()

rustpkg::package_id::{...} : prefixes_iter() -> prefixes()

std::hashmap::{...} : difference_iter()           -> difference()
                      symmetric_difference_iter() -> symmetric_difference()
                      intersection_iter()         -> intersection()
                      union_iter()                -> union()
                     
std::path::{posix, windows} : component_iter()     -> components()
                              str_component_iter() -> str_components()

... not showing all identical renamings for reverse versions
~~~

---

I'm also planning a few more changes, like removing all unnecessary `_rev` constructors (#9391), or reducing the `split` variants on `&str` to a more versatile and concise system.
@gereeter gereeter mentioned this issue Apr 20, 2014
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@bors bors closed this as completed in 9f484e6 May 1, 2014
Jarcho pushed a commit to Jarcho/rust that referenced this issue Aug 31, 2022
@lukaslueg
Fix missing parens in suboptimal_flops sugg
26a6891 
Fixes rust-lang#9391
Jarcho pushed a commit to Jarcho/rust that referenced this issue Aug 31, 2022
@bors
Auto merge of rust-lang#9394 - lukaslueg:issue9391, r=Jarcho
4df6032 
Fix missing parens in `suboptimal_flops` suggestion

Fixes rust-lang#9391. The problem is simple enough, I didn't check if the same problem occurs elsewhere, though.

changelog: fix missing parenthesis in `suboptimal_flops` suggestion
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Removed rev_iter in favor of DoubleEndedIterator gereeter/rust
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@Kimundi @bluss