This is an implementation of a map and set for integer keys. It's an ordered container (by byte order, which is sorted order for integers and byte strings when done in the right direction) with O(1) worst-case lookup, removal and insertion. There's no rebalancing or rehashing so it's actually O(1) without amortizing any costs.
The fanout can be adjusted in multiples of 2 from 2-ary through 256-ary, but it's hardcoded at 16-ary because there isn't a way to expose that in the type system yet. To keep things simple, it also only allows `uint` keys, but later I'll expand it to all the built-in integer types and byte arrays.
There's quite a bit of room for performance improvement, along with the boost that will come with dropping the headers on `Owned` `~` and getting rid of the overhead from the stack switches to the allocator. It currently does suffix compression for a single node and then splits into two n-ary trie nodes, which could be replaced with an array for at least 4-8 suffixes before splitting it. There's also the option of doing path compression, which may be a good or a bad idea and depends a lot on the data stored.
I want to share the test suite with the other maps so that's why I haven't duplicated all of the existing integer key tests in this file. I'll send in another pull request to deal with that.
Current benchmark numbers against the other map types:
TreeMap:
Sequential integers:
insert: 0.798295
search: 0.188931
remove: 0.435923
Random integers:
insert: 1.557661
search: 0.758325
remove: 1.720527
LinearMap:
Sequential integers:
insert: 0.272338
search: 0.141179
remove: 0.190273
Random integers:
insert: 0.293588
search: 0.162677
remove: 0.206142
TrieMap:
Sequential integers:
insert: 0.0901
search: 0.012223
remove: 0.084139
Random integers:
insert: 0.392719
search: 0.261632
remove: 0.470401
@graydon is using an earlier version of this for the garbage collection implementation, so that's why I added this to libcore. I left out the `next` and `prev` methods *for now* because I just wanted the essentials first.
My merges for #5143 missed a couple other copies. This patch corrects this, and gets stage0 to compile libsyntax with `#[deny(vecs_implicitly_copyable)]`. stage1 still fails though.
Before:
````
test.rs:3:21: 3:30 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^~~~~~~~~
````
After:
````
test.rs:3:27: 3:28 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^
````
Good morning,
It's taken a long time, but I finally am almost done freeing libsyntax of `vecs_implicitly_copyable` in this pull request, but I'm running into some issues. I've confirmed that all but the last commit (which only disables `vecs_implicitly_copyable` pass the `check` tests. The last commit errors with this message, which makes no sense to me:
```
/Users/erickt/rust/rust/src/libcore/num/f32.rs:35:37: 35:43 error: expected `,` but found `=`
/Users/erickt/rust/rust/src/libcore/num/f32.rs:35 pub pure fn $name($( $arg : $arg_ty ),*) -> $rv {
^~~~~~
```
and this stack trace:
```
#1 0x00000001000b059b in sys::begin_unwind_::_a923ca4ae164c::_06 ()
#2 0x00000001000b0542 in sys::begin_unwind::anon::anon::expr_fn_13876 ()
#3 0x00000001000048a1 in sys::begin_unwind::_8ec273289fc0adc0::_06 ()
#4 0x00000001005df999 in diagnostic::__extensions__::meth_7941::span_fatal::_efdf2d14612d79ec::_06 ()
#5 0x0000000100682d48 in parse::parser::__extensions__::meth_16938::fatal::_8aa3239426747a3::_06 ()
#6 0x00000001006850b8 in parse::common::__extensions__::meth_17005::expect::_d3604ec6c7698d5f::_06 ()
#7 0x00000001006b59f1 in parse::common::__extensions__::parse_seq_to_before_end_17860::_48c79835f9eb1011::_06 ()
#8 0x00000001006a50f7 in parse::parser::__extensions__::meth_17606::parse_fn_decl::_14f3785fe78967d::_06 ()
#9 0x00000001006b6f59 in parse::parser::__extensions__::meth_17987::parse_item_fn::_8a6be529cf7b2ca5::_06 ()
#10 0x00000001006ac839 in parse::parser::__extensions__::meth_17761::parse_item_or_view_item::_bfead947d6dd7d25::_06 ()
#11 0x00000001006c8b8f in parse::parser::__extensions__::meth_18364::parse_item::_96b54e33f65abe76::_06 ()
#12 0x000000010076179f in ext::tt::macro_rules::add_new_extension::generic_extension::anon::anon::expr_fn_23365 ()
#13 0x000000010072e793 in ext::expand::expand_item_mac::_a4f486c4465cfb1b::_06 ()
#14 0x00000001007b5ad3 in __morestack ()
```
There also a bunch of new warnings that I haven't cleaned up yet: https://gist.github.com/erickt/5048251.
@nikomatsakis thought there might be some scary bug in the parser caused by moving a vector in the parser instead of copying it, which is why I'm filing this pull request before it's ready. Thanks for any help!
This allows `TreeMap`/`TreeSet` to fully express their requirements and reduces the comparisons from ~1.5 per level to 1 which really helps for string keys.
I also added `ReverseIter` to the prelude exports because I forgot when I originally added it.
The fix is straight-forward, but there are several changes
while fixing the issue.
1) disallow `mut` keyword when making a new struct
In code base, there are following code,
```rust
struct Foo { mut a: int };
let a = Foo { mut a: 1 };
```
This is because of structural record, which is
deprecated corrently (see issue #3089) In structural
record, `mut` keyword should be allowd to control
mutability. But without structural record, we don't
need to allow `mut` keyword while constructing struct.
2) disallow structural records in parser level
This is related to 1). With structural records, there
is an ambiguity between empty block and empty struct
To solve the problem, I change parser to stop parsing
structural records. I think this is not a problem,
because structural records are not compiled already.
Misc. issues
There is an ambiguity between empty struct vs. empty match stmt.
with following code,
```rust
match x{} {}
```
Two interpretation is possible, which is listed blow
```rust
match (x{}) {} // matching with newly-constructed empty struct
(match x{}) {} // matching with empty enum(or struct) x
// and then empty block
```
It seems that there is no such code in rust code base, but
there is one test which uses empty match statement:
https://github.com/mozilla/rust/blob/incoming/src/test/run-pass/issue-3037.rs
All other cases could be distinguished with look-ahead,
but this can't be. One possible solution is wrapping with
parentheses when matching with an uninhabited type.
```rust
enum what { }
fn match_with_empty(x: what) -> ~str {
match (x) { //use parentheses to remove the ambiguity
}
}
```
- Removed space between struct name and parentheses
- Fixed indentation of the rest of the file (missing end)
- Don't print parentheses for structs with no fields
- Added test
I have seen a few people confused on how to explicitly instantiate generic functions, since the syntax differs from C++'s and C#'s, which is probably where most people asking questions about generic functions are coming from. The only use of the `::<T>` syntax in the reference right now is in the section on paths, which is possibly not where someone trying to find out about generic functions is going to start looking. The tutorial doesn't mention it at all, but I think it's all right to make the reference a tiny bit more redundant and avoid stuffing the tutorial with syntax details.
----
The "Generic functions" subsection mentions that generic functions are instantiated based on context, so let's also mention right away (with a link to the #paths section) that an explicit form is available.
This also adds an example that explicitly instantiates a generic function to the function call expression section.
Before:
````
test.rs:3:21: 3:30 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^~~~~~~~~
````
After:
````
test.rs:3:27: 3:28 error: expected constant integer for repeat count but found variable
test.rs:3 let a = ~[0, ..n]; //~ ERROR expected constant integer for repeat count but found variable
^
````
This adds a few words about unit-like struct types (`struct Foo;`) in the sections for `struct` items, structure expressions and structure types (and fixes an adjacent typo or two). The added text is at the same time triply redundant because of how the sections are split and rather brief because I don't think there's that much to say about field-less structs without digressing into `impl`s and generic functions and whatnot, but it's probably better than nothing for a start.
The added arm for the grammar of struct expressions is really awkward. It's just
| expr_path
which is clearly not unambiguously a struct expression, but it didn't feel right not to add anything to the grammar chunk (and I can't tell whether the arm for enum-like structs is somehow unambiguous with regular enum expressions, either). Is this okay?
This changes various type_names to TypeNames and fixes the example for `tcp::accept` that was still using the old `match` syntax and `{|args| ...}` closures.
The `accept` example was fairly outdated. I was just going to stay away from all the IO things until the scheduler revamp lands, but `accept` is probably one of the obvious starting points for networking stuff for a learner, and I don't want to get in the way of anyone's enthusiasm.
Doesn't touch non-comment lines, so I hope I will get away without learning about unit tests. It doesn't seem like the test system is set up to extract tests from doc comments right now.
- Removed space between struct name and parentheses
- Fixed indentation of the rest of the file (missing end)
- Don't print parentheses for structs with no fields
- Added test
