Implement HashMap.find_with_or_insert_with() #14196
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This was removed when the Robin Hood hash map came along, but it is a useful thing to have. The comment is taken directly from what was there before (e.g. in 0.9) but with appropriate language changes (like `StrBuf` instead of `~str`).
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See https://github.com/teepee/teepee/blob/master/src/httpcommon/headers/mod.rs#L307..L314 and https://github.com/teepee/teepee/blob/master/src/httpcommon/headers/mod.rs#L347..L354 for the case where I want it. (Removed from PR description text when it became out of date:
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It seems that this is a legitimate usecase of a mangle. |
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This looks good to me, but I really like the name I still think that there's some space for a better Just my little design ramblings. Feel free to merge as is. |
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| /// | ||
| /// for (k, v) in map.iter() { | ||
| /// println!("{} -> {:?}", *k, *v); |
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We've been generally avoiding :?, does {} not suffice here?
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This is just the example that existed in 0.9 with the fixes that were necessary to get it to compile. Seeing as there appears to be acceptance of reintroducing this method, I’ll improve the example now.
This also entails swapping the order of the find and insert callbacks so that their order matches the order of the terms in the method name.
chris-morgan
changed the title
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I’ve fixed up the examples to skip using r? |
| /// | ||
| /// for (k, v) in map.iter() { | ||
| /// println!("{} -> {}", *k, *v); | ||
| /// } |
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This would be a little clearer if you asserted equality instead of printing, because I can't see what it prints without actually running the code locally. Instead you could use something like
assert_eq!(map.len(), 3);
assert_eq!(map.get("a key"), vec!["value", "new value"]);
asesrt_eq!(map.get("b key"), vec!["value", "new value"]);
assert_eq!(map.get("z key"), vec!["new value", "value"]);This lets us test it automatically and also makes it more obvious what the expected result is.
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OK, not quite so much my fault; caused by #14240. |
This used to be called `mangle` and was removed when the Robin Hood hash map came along, but it is a useful thing to have in certain situations (I just hit it with my Teepee header representation), so I want it back. The method is renamed to `find_with_or_insert_with`, also with the parameters swapped to make sense—find and then insert, not insert and then find. /cc @cgaebel
This used to be called
mangleand was removed when the Robin Hood hash map came along, but it is a useful thing to have in certain situations (I just hit it with my Teepee header representation), so I want it back.The method is renamed to
find_with_or_insert_with, also with the parameters swapped to make sense—find and then insert, not insert and then find./cc @cgaebel