128 lines
6.5 KiB
Markdown
128 lines
6.5 KiB
Markdown
Rhai Release Notes
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==================
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Version 0.14.2
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==============
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Regression fix
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--------------
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* Do not optimize script with `eval_expression` - it is assumed to be one-off and short.
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Bug fixes
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---------
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* Indexing with an index or dot expression now works property (it compiled wrongly before).
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For example, `let s = "hello"; s[s.len-1] = 'x';` now works property instead of an error.
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Breaking changes
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----------------
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* `Engine::compile_XXX` functions now return `ParseError` instead of `Box<ParseError>`.
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* The `RegisterDynamicFn` trait is merged into the `RegisterResutlFn` trait which now always returns
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`Result<Dynamic, Box<EvalAltResult>>`.
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* Default maximum limit on levels of nested function calls is fine-tuned and set to a different value.
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* Some operator functions are now built in (see _Speed enhancements_ below), so they are available even
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under `Engine::new_raw`.
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* Strings are now immutable. The type `rhai::ImmutableString` is used instead of `std::string::String`.
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This is to avoid excessive cloning of strings. All native-Rust functions taking string parameters
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should switch to `rhai::ImmutableString` (which is either `Rc<String>` or `Arc<String>` depending on
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whether the `sync` feature is used).
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* Native Rust functions registered with the `Engine` also mutates the first argument when called in
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normal function-call style (previously the first argument will be passed by _value_ if not called
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in method-call style). Of course, if the first argument is a calculated value (e.g. result of an
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expression), then mutating it has no effect, but at least it is not cloned.
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* Some built-in methods (e.g. `len` for string, `floor` for `FLOAT`) now have _property_ versions in
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addition to methods to simplify coding.
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New features
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------------
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* Set limit on maximum level of nesting expressions and statements to avoid panics during parsing.
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* New `EvalPackage` to disable `eval`.
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* `Module::set_getter_fn`, `Module::set_setter_fn` and `Module:set_indexer_fn` to register getter/setter/indexer functions.
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Speed enhancements
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------------------
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* Common operators (e.g. `+`, `>`, `==`) now call into highly efficient built-in implementations for standard types
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(i.e. `INT`, `FLOAT`, `bool`, `char`, `()` and `ImmutableString`) if not overridden by a registered function.
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This yields a 5-10% speed benefit depending on script operator usage. Scripts running tight loops will see
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significant speed-up.
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* Common assignment operators (e.g. `+=`, `%=`) now call into highly efficient built-in implementations for
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standard types (i.e. `INT`, `FLOAT`, `bool`, `char`, `()` and `ImmutableString`) if not overridden by a registered function.
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* Implementations of common operators for standard types are removed from the `ArithmeticPackage` and `LogicPackage`
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(and therefore the `CorePackage`) because they are now always available, even under `Engine::new_raw`.
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* Operator-assignment statements (e.g. `+=`) are now handled directly and much faster.
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* Strings are now _immutable_ and use the `rhai::ImmutableString` type, eliminating large amounts of cloning.
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* For Native Rust functions taking a first `&mut` parameter, the first argument is passed by reference instead of
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by value, even if not called in method-call style. This allows many functions declared with `&mut` parameter to avoid
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excessive cloning. For example, if `a` is a large array, getting its length in this manner: `len(a)` used to result
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in a full clone of `a` before taking the length and throwing the copy away. Now, `a` is simply passed by reference,
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avoiding the cloning altogether.
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Version 0.14.1
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==============
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The major features for this release is modules, script resource limits, and speed improvements
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(mainly due to avoiding allocations).
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New features
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------------
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* Modules and _module resolvers_ allow loading external scripts under a module namespace.
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A module can contain constant variables, Rust functions and Rhai functions.
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* `export` variables and `private` functions.
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* _Indexers_ for Rust types.
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* Track script evaluation progress and terminate script run.
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* Set limit on maximum number of operations allowed per script run.
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* Set limit on maximum number of modules loaded per script run.
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* A new API, `Engine::compile_scripts_with_scope`, can compile a list of script segments without needing to
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first concatenate them together into one large string.
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* Stepped `range` function with a custom step.
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Speed improvements
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------------------
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### `StaticVec`
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A script contains many lists - statements in a block, arguments to a function call etc.
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In a typical script, most of these lists tend to be short - e.g. the vast majority of function calls contain
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fewer than 4 arguments, while most statement blocks have fewer than 4-5 statements, with one or two being
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the most common. Before, dynamic `Vec`'s are used to hold these short lists for very brief periods of time,
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causing allocations churn.
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In this version, large amounts of allocations are avoided by converting to a `StaticVec` -
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a list type based on a static array for a small number of items (currently four) -
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wherever possible plus other tricks. Most real-life scripts should see material speed increases.
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### Pre-computed variable lookups
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Almost all variable lookups, as well as lookups in loaded modules, are now pre-computed.
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A variable's name is almost never used to search for the variable in the current scope.
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_Getters_ and _setter_ function names are also pre-computed and cached, so no string allocations are
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performed during a property get/set call.
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### Pre-computed function call hashes
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Lookup of all function calls, including Rust and Rhai ones, are now through pre-computed hashes.
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The function name is no longer used to search for a function, making function call dispatches
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much faster.
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### Large Boxes for expressions and statements
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The expression (`Expr`) and statement (`Stmt`) types are modified so that all of the variants contain only
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one single `Box` to a large allocated structure containing _all_ the fields. This makes the `Expr` and
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`Stmt` types very small (only one single pointer) and improves evaluation speed due to cache efficiency.
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Error handling
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--------------
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Previously, when an error occurs inside a function call, the error position reported is the function
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call site. This makes it difficult to diagnose the actual location of the error within the function.
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A new error variant `EvalAltResult::ErrorInFunctionCall` is added in this version.
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It wraps the internal error returned by the called function, including the error position within the function.
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