rhai

This version replaces all internal usage of HashMap with BTreeMap, which should result in some speed improvement because a BTreeMap is leaner when the number of items held is small. Most, if not all, collections in Rhai hold very few data items, so this is a typical scenario of many tiny-sized collections.

The Rhai object map type, Map, used to be an alias to HashMap and is now aliased to BTreeMap instead. This is also because, in the vast majority of usage cases, the number of properties held by an object map is small.

HashMap and BTreeMap have almost identical public API's so this change is unlikely to break existing code.

SmartString is used to store identifiers (which tend to be short, fewer than 23 characters, and ASCII-based) because they can usually be stored inline. Map keys now also use SmartString.

In addition, there is now support for line continuation in strings (put \ at the end of line) as well as multi-line literal strings (wrapped by back-ticks: `...`).

Finally, all function signature/metadata methods are now grouped under the umbrella metadata feature. This avoids spending precious resources maintaining metadata for functions for the vast majority of use cases where such information is not required.

Bug fixes

• The feature flags no_index + no_object now compile without errors.

Breaking changes

• The traits RegisterFn and RegisterResultFn are removed. Engine::register_fn and Engine::register_result_fn are now implemented directly on Engine.
• FnPtr::call_dynamic now takes &NativeCallContext instead of consuming it.
• All Module::set_fn_XXX methods are removed, in favor of Module::set_native_fn.
• Array::reduce and Array::reduce_rev now take a Dynamic as initial value instead of a function pointer.
• protected, super are now reserved keywords.
• The Module::set_fn_XXX API now take &str as the function name instead of Into<String>.
• The reflections API such as Engine::gen_fn_signatures, Module::update_fn_metadata etc. are put under the metadata feature gate.
• The shebang #! is now a reserved symbol.
• Shebangs at the very beginning of script files are skipped when loading them.
• SmartString is used for identifiers by default. Currently, a PR branch is pulled for no-std builds. The official crate will be used once SmartString is fixed to support no-std.
• Map is now an alias to BTreeMap<SmartString, Dynamic> instead of HashMap because most object maps hold few properties.
• EvalAltResult::FnWrongDefinition is renamed WrongFnDefinition for consistency.

New features

• Line continuation (via \) and multi-line literal strings (wrapped with `) support are added.
• Rhai scripts can now start with a shebang #! which is ignored.

Enhancements

• Replaced all HashMap usage with BTreeMap for better performance because collections in Rhai are tiny.
• Engine::register_result_fn no longer requires the successful return type to be Dynamic. It can now be any clonable type.
• #[rhai_fn(return_raw)] can now return Result<T, Box<EvalAltResult> > where T is any clonable type instead of Result<Dynamic, Box<EvalAltResult> >.
• Dynamic::clone_cast is added to simplify casting from a &Dynamic.

This version runs faster due to optimizations done on AST node structures. It also fixes a number of panic bugs related to passing shared values as function call arguments.

Bug fixes

• Panic when passing a shared string into a registered function as &str argument is fixed.
• Panic when calling switch statements on custom types is fixed.
• Potential overflow panics in range(from, to, step) is fixed.
• &mut String parameters in registered functions no longer panic when passed a string.
• Some expressions involving shared variables now work properly, for example x in shared_value, return shared_value, obj.field = shared_value etc. Previously, the resultant value is still shared which is counter-intuitive.
• Errors in native Rust functions now contain the correct function call positions.
• Fixed error types in EvalAltResult::ErrorMismatchDataType which were swapped.

Breaking changes

• Dynamic::as_str is removed because it does not properly handle shared values.
• Zero step in the range function now raises an error instead of creating an infinite stream.
• Error variable captured by catch is now an object map containing error fields.
• EvalAltResult::clear_position is renamed EvalAltResult::take_position and returns the position taken.
• private functions in an AST can now be called with call_fn etc.
• NativeCallContext::call_fn_dynamic_raw no longer has the pub_only parameter.
• Module::update_fn_metadata input parameter is changed.
• Function keywords (e.g. type_of, eval, Fn) can no longer be overloaded. It is more trouble than worth. To disable these keywords, use Engine::disable_symbol.
• is_def_var and is_def_fn are now reserved keywords.
• Engine::id field is removed because it is never used.
• num-traits is now a required dependency.
• The in operator is now implemented on top of the contains function and is no longer restricted to a few specific types.
• EvalAltResult::ErrorInExpr is removed because the in operator now calls contains.
• The methods AST::walk, Expr::walk, Stmt::walk and ASTNode::walk and the callbacks they take now return bool to optionally terminate the recursive walk.

Enhancements

• Layout of AST nodes is optimized to reduce redirections, so speed is improved.
• Function calls are more optimized and should now run faster.
• range function now supports negative step and decreasing streams (i.e. to < from).
• More information is provided to the error variable captured by the catch statement in an object map.
• Previously, private functions in an AST cannot be called with call_fn etc. This is inconvenient when trying to call a function inside a script which also serves as a loadable module exporting part (but not all) of the functions. Now, all functions (private or not) can be called in an AST. The private keyword is relegated to preventing a function from being exported.
• Dynamic::as_unit just for completeness sake.
• bytes method added for strings to get length quickly (if the string is ASCII-only).
• FileModuleResolver can now enable/disable caching.
• Recursively walking an AST can now be terminated in the middle.

This version introduces functions with Dynamic parameters acting as wildcards.

Bug fixes

• Bug in Position::is_beginning_of_line is fixed.

Breaking changes

• For plugin functions, constants passed to methods (i.e. &mut parameter) now raise an error unless the functions are marked with #[rhai_fn(pure)].
• Visibility (i.e. pub or not) for generated plugin modules now follow the visibility of the underlying module.
• Comparison operators between the sames types or different numeric types now throw errors when they're not defined instead of returning the default. Only comparing between different types will return the default.
• Default stack-overflow and top-level expression nesting limits for release builds are lowered to 64 from 128.
• Engine::call_fn_dynamic takes an additional parameter to optionally evaluate the given AST before calling the function.

New features

• Functions are now allowed to have Dynamic arguments.
• #[rhai_fn(pure)] attribute to mark a plugin function with &mut parameter as pure so constants can be passed to it. Without it, passing a constant value into the &mut parameter will now raise an error.

Enhancements

• Built-in operators between FLOAT/Decimal and INT are now implemented for more speed under those cases.
• Error position in eval statements is now wrapped in an EvalAltResult::ErrorInFunctionCall.
• Position now implements Add and AddAssign.
• Scope now implements IntoIterator.
• Strings now have the -/-= operators and the remove method to delete a sub-string/character.
• Strings now have the split_rev method and variations of split with maximum number of segments.
• Arrays now have the split method.
• Comparisons between FLOAT/Decimal and INT are now built in.
• Comparisons between string and char are now built in.
• Engine::call_fn_dynamic can now optionally evaluate the given AST before calling the function.

This version is an incremental release with a number of enhancements and bug fixes.

Notice that there are a number of breaking changes, especially with regards to replacing the ~ exponential operator with **, and the addition of the decimal feature that turns on Decimal support.

Bug fixes

• Empty statements (i.e. statements with only one ;) now parse correctly and no longer hang.
• continue, break and return statements no longer panic inside a try .. catch block.
• round function for f64 is now implemented correctly.

Breaking changes

• In order to be consistent with other scripting languages:
  • the power/exponentiation operator is changed from ~ to **; ~ is now a reserved symbol
  • the power/exponentiation operator now binds to the right
  • trigonometry functions now take radians and return radians instead of degrees
• Dynamic::into_shared is no longer available under no_closure. It used to panic.
• Token::is_operator is renamed to Token::is_symbol.
• AST::clone_functions_only_filtered, AST::merge_filtered, AST::combine_filtered and AST::retain_functions now take Fn instead of FnMut as the filter predicate.

New features

• Scientific notation is supported for floating-point number literals.
• A new feature, decimal, enables the Decimal data type. When both no_float and decimal features are enabled, floating-point literals parse to Decimal.

Enhancements

• Functions resolution cache is used in more cases, making repeated function calls faster.
• Added atan(x, y) and hypot(x, y) to BasicMathPackage.
• Added standard arithmetic operators between FLOAT/Decimal and INT.

This version streamlines compiling for WASM.

Rust compiler minimum version is raised to 1.49.

Bug fixes

• Parameters passed to plugin module functions were sometimes erroneously consumed. This is now fixed.
• Fixes compilation errors in metadata feature build.
• Stacking ! operators now work properly.
• Off-by-one error in insert method for arrays is fixed.
• Invalid property access now throws the appropriate error instead of panics.

Breaking changes

• Rust compiler requirement raised to 1.49.
• NativeCallContext::new taker an additional parameter containing the name of the function called.
• Engine::set_doc_comments is renamed Engine::enable_doc_comments.

New features

• Two new features, wasm-bindgen and stdweb, to specify the JS interop layer for WASM builds. wasm-bindgen used to be required.

Enhancements

• ahash is used to hash function call parameters. This should yield speed improvements.
• Dynamic and ImmutableString now implement serde::Serialize and serde::Deserialize.
• NativeCallContext has a new field containing the name of the function called, useful when the same Rust function is registered under multiple names in Rhai.
• New functions PI() and E() to return mathematical constants, and to_radians and to_degrees to convert between radians and degrees.

Bug fixes

• no_std feature now compiles correctly (bug introduced in 0.19.9).
• Bug in FileModuleResolver::clear_cache_for_path path mapping fixed.
• Some optimizer fringe cases are fixed - related to constants propagation when the evil eval is present.

Breaking changes

• The error variant EvalAltResult::ErrorInFunctionCall has a new parameter holding the source of the function.
• ParseErrorType::WrongFnDefinition is renamed FnWrongDefinition.
• Redefining an existing function within the same script now throws a new ParseErrorType::FnDuplicatedDefinition. This is to prevent accidental overwriting an earlier function definition.
• AST::set_source is now split into AST::set_source and AST::clear_source.

New features

• Engine::compile_into_self_contained compiles a script into an AST and eagerly resolves all import statements with string literal paths. The resolved modules are directly embedded into the AST. When the AST is later evaluated, import statements directly yield the pre-resolved modules without going through the resolution process once again.
• AST::walk, Stmt::walk and Expr::walk internal API's to recursively walk an AST.

Enhancements

• Source information is provided when there is an error within a call to a function defined in another module.
• Source information is provided to the NativeCallContext for native Rust functions.
• EvalAltResult::clear_position to clear the position information of an error - useful when only the message is needed and the position doesn't need to be printed out.
• A new optional function resolve_ast is added to the ModuleResolver trait for advanced usage.

This version fixes a bug introduced in 0.19.8 which breaks property access within closures.

It also removes the confusing differences between packages and modules by unifying the terminology and API under the global umbrella of modules.

Bug fixes

• Fix bug when accessing properties in closures.
• Fix bug when accessing a deep index with a function call.
• Fix bug that sometimes allow assigning to an invalid l-value.
• Fix off-by-one error with Engine::set_max_call_levels.

Breaking changes

• Engine::load_package is renamed Engine::register_global_module and now must explicitly pass a shared [Module].
• Engine::register_module is renamed Engine::register_static_module and now must explicitly pass a shared [Module].
• Package::get is renamed Package::as_shared_module.
• Engine::set_module_resolver now takes a straight module resolver instead of an Option. To disable module resolving, use the new DummyModuleResolver.

Enhancements

• Scope is now Clone + Hash.
• Engine::register_static_module now supports sub-module paths (e.g. foo::bar::baz).
• Engine::register_custom_operator now accepts reserved symbols.
• Engine::register_custom_operator now returns an error if given a precedence of zero.
• The examples repl and rhai_runner are moved into bin and renamed rhai-repl and rhai-run respectively.

This version makes it easier to generate documentation for a Rhai code base.

Each function defined in an AST can optionally attach doc-comments (which, as in Rust, are comments prefixed by either /// or /**). Doc-comments allow third-party tools to automatically generate documentation for functions defined in a Rhai script.

A new API, Engine::gen_fn_metadata_to_json and Engine::gen_fn_metadata_with_ast_to_json, paired with the new metadata feature, exports the full list of functions metadata (including those in an AST) as a JSON document.

There are also a sizable number of bug fixes.

Bug fixes

• Unary prefix operators -, + and ! now bind correctly when applied to an expression. Previously, -x.len is parsed as (-x).len which is obviously counter-intuitive.
• Indexing of namespace-qualified variables now work properly, such as path::to::var[x].
• Constants are no longer propagated by the optimizer if shadowed by a non-constant variable.
• A constant passed as the this parameter to Rhai functions now throws an error if assigned to.
• Generic type parameter of Engine::register_iterator is IntoIterator instead of Iterator.
• Fixes parsing of block comments ending with **/ or inner blocks starting with //*.

Breaking changes

• Engine::on_progress now takes u64 instead of &u64.
• The closure for Engine::on_debug now takes two additional parameters: source: Option<&str> and pos: Position.
• AST::iter_functions now returns ScriptFnMetadata.
• The parser function passed to Engine::register_custom_syntax_raw now takes an additional parameter containing the look-ahead symbol.

New features

• AST::iter_functions now returns ScriptFnMetadata which includes, among others, doc-comments for functions prefixed by /// or /**.
• Doc-comments can be enabled/disabled with the new Engine::set_doc_comments method.
• A new feature metadata is added that pulls in serde_json and enables Engine::gen_fn_metadata_to_json and Engine::gen_fn_metadata_with_ast_to_json which exports the full list of functions metadata (including those inside an AST) in JSON format.
• Engine::on_debug provides two additional parameters: source: Option<&str> and pos: Position, containing the current source (if any) and position of the debug statement.
• NativeCallContext and EvalContext both expose source() which returns the current source, if any.

Enhancements

• A functions lookup cache is added to make function call resolution faster.
• Capturing a constant variable in a closure is now supported, with no cloning.
• A look-ahead symbol is provided to custom syntax parsers, which can be used to parse variable-length symbol streams.

Bug fixes

• Fixes compilation errors with certain feature flag combinations.

Enhancements

• Property getters/setters and indexers defined in a plugin module are by default #[rhai_fn(global)].
• to_debug is a new standard function for converting a value into debug format.
• Arrays and object maps now print values using to_debug (if available).

This version adds the switch statement.

It also allows exposing selected module functions (usually methods) to the global namespace. This is very convenient when encapsulating the API of a custom Rust type into a module while having methods and iterators registered on the custom type work normally.

A new gen_fn_signatures API enables enumerating the registered functions of an Engine for documentation purposes. It also prepares the way for a future reflection API.

Bug fixes

• Custom syntax that introduces a shadowing variable now works properly.

Breaking changes

• Module::set_fn, Module::set_raw_fn and Module::set_fn_XXX_mut all take an additional parameter of FnNamespace.
• Module::set_fn takes a further parameter with a list of parameter names/types plus the function return type, if any.
• Module::get_sub_module_mut is removed.
• begin, end, unless are now reserved keywords.
• EvalPackage is removed in favor of Engine::disable_symbol.

New features

• New switch statement.
• New do ... while and do ... until statements.
• New Engine::gen_fn_signatures, Module::gen_fn_signatures and PackagesCollection::gen_fn_signatures to generate a list of signatures for functions registered.
• New Engine::register_static_module to register a module as a sub-module in the global namespace.
• New set_exported_global_fn! macro to register a plugin function and expose it to the global namespace.
• Module::set_fn_XXX_mut can expose a module function to the global namespace. This is convenient when registering an API for a custom type.
• Module::set_getter_fn, Module::set_setter_fn, Module::set_indexer_get_fn, Module::set_indexer_set_fn all expose the function to the global namespace by default. This is convenient when registering an API for a custom type.
• New Module::update_fn_metadata to update a module function's parameter names and types.
• New #[rhai_fn(global)] and #[rhai_fn(internal)] attributes to determine whether a function defined in a plugin module should be exposed to the global namespace. This is convenient when defining an API for a custom type.
• New get_fn_metadata_list to get the metadata of all script-defined functions in scope.

Enhancements

• New constants under Dynamic including UNIT, TRUE, FALSE, ZERO, ONE etc.
• Floating-point numbers ending with a decimal point without a trailing 0 are supported.

This version fixes a bug that prevents compilation with the internals feature. It also speeds up importing modules.

Bug fixes

• Fixes compilation error when using the internals feature. Bug introduced in 0.19.4.
• Importing script files recursively no longer panics.

Breaking changes

• Modules imported at global level can now be accessed in functions.
• ModuleResolver::resolve now returns Shared<Module> for better resources sharing when loading modules.
• ParseErrorType::DuplicatedExport is removed as multiple export's are now allowed.

Enhancements

• Modules imported via import statements at global level can now be used in functions. There is no longer any need to re-import the modules at the beginning of each function block.
• Modules imported via import statements are encapsulated into the AST when loading a module from a script file.
• export keyword can now be tagged onto let and const statements as a short-hand, e.g.: export let x = 42;
• Variables can now be export-ed multiple times under different names.
• index_of, == and != are defined for arrays.
• == and != are defined for object maps.

This version basically cleans up the code structure in preparation for a potential 1.0 release in the future. Most scripts should see a material speed increase.

This version also adds a low-level API for more flexibility when defining custom syntax.

Bug fixes

• Fixes Send + Sync for EvalAltResult under the sync feature. Bug introduced with 0.19.3.

Breaking changes

• Custom syntax can no longer start with a keyword (even a reserved one), even if it has been disabled. That is to avoid breaking scripts later when the keyword is no longer disabled.

Changes to Error Handling

• EvalAltResult::ErrorAssignmentToUnknownLHS is moved to ParseError::AssignmentToInvalidLHS. ParseError::AssignmentToCopy is removed.
• EvalAltResult::ErrorDataTooLarge is simplified.
• Engine::on_progress closure signature now returns Option<Dynamic> with the termination value passed on to EvalAltResult::ErrorTerminated.
• ParseErrorType::BadInput now wraps a LexError instead of a text string.

New features

• f32_float feature to set FLOAT to f32.
• Low-level API for custom syntax allowing more flexibility in designing the syntax.
• Module::fill_with to poly-fill a module with another.
• Scripts terminated via Engine::on_progress can now pass on a value as a termination token.

Enhancements

• Essential AST structures like Expr and Stmt are packed into smaller sizes (16 bytes and 32 bytes on 64-bit), stored inline for more cache friendliness, and de-Boxed as much as possible.
• Scope is optimized for cache friendliness.

This version streamlines some of the advanced API's, and adds the try ... catch statement to catch exceptions.

Breaking changes

• EvalAltResult::ErrorReadingScriptFile is removed in favor of the new EvalAltResult::ErrorSystem.
• EvalAltResult::ErrorLoopBreak is renamed to EvalAltResult::LoopBreak.
• Engine::register_raw_fn and FnPtr::call_dynamic function signatures have changed.
• Callback signatures to Engine::on_var and Engine::register_custom_syntax have changed.
• EvalAltResult::ErrorRuntime now wraps a Dynamic instead of a string.
• Default call stack depth for debug builds is reduced to 8 (from 12) because it keeps overflowing the stack in GitHub CI!
• Keyword thread is reserved.

New features

• The plugins system is enhanced to support functions taking a NativeCallContext as the first parameter.
• throw statement can now throw any value instead of just text strings.
• New try ... catch statement to catch exceptions.

Enhancements

• Calling eval or Fn in method-call style, which is an error, is now caught during parsing.
• func!() call style is valid even under no_closure feature.

Bug fix on call module functions.

This version adds a variable resolver with the ability to short-circuit variable access, plus a whole bunch of array methods.

Breaking changes

• AST::iter_functions now returns an iterator instead of taking a closure.
• Module::get_script_function_by_signature renamed to Module::get_script_fn and returns &<Shared<ScriptFnDef> >.
• Module::num_fn, Module::num_var and Module::num_iter are removed and merged into Module::count.
• The merge_namespaces parameter to Module::eval_ast_as_new is removed and now defaults to true.
• GlobalFileModuleResolver is removed because its performance gain over the FileModuleResolver is no longer very significant.
• The following EvalAltResult variants are removed and merged into EvalAltResult::ErrorMismatchDataType: ErrorCharMismatch, ErrorNumericIndexExpr, ErrorStringIndexExpr, ErrorImportExpr, ErrorLogicGuard, ErrorBooleanArgMismatch
• Scope::iter_raw returns an iterator with an additional field indicating whether the variable is constant or not.
• rhai::ser and rhai::de namespaces are merged into rhai::serde.
• New reserved symbols: ++, --, .., ....
• Callback signature for custom syntax implementation function is changed to allow for more flexibility.
• Default call stack depth for debug builds is reduced to 12 (from 16).
• Precedence for ~ is raised, while in is moved below logic comparison operators.

New features

• New Engine::on_var to register a variable resolver.
• const statements can now take any expression (or none at all) instead of only constant values.
• OptimizationLevel::Simple now eagerly evaluates built-in binary operators of primary types (if not overloaded).
• is_def_var() to detect if variable is defined, and is_def_fn() to detect if script function is defined.
• Dynamic::from(&str) now constructs a Dynamic with a copy of the string as value.
• AST::combine and AST::combine_filtered allows combining two AST's without creating a new one.
• map, filter, reduce, reduce_rev, some, all, extract, splice, chop and sort functions for arrays.
• New Module::set_iterable and Module::set_iterator to define type iterators more easily. Engine::register_iterator is changed to use the simpler version.

Enhancements

• Many one-liners and few-liners are now marked #[inline] or [inline(always)], just in case it helps when LTO is not turned on.

The major new feature for this version is Plugins support, powered by procedural macros. Plugins make it extremely easy to develop and register Rust functions with an Engine.

Bug fixes

• if statement with an empty true block would not evaluate the false block. This is now fixed.
• Fixes a bug in Module::set_fn_4_mut.
• Module API's now properly handle &str and String parameters.
• Indexers are available under no_object.
• Registered operator-assignment functions (e.g. +=) now work correctly.

Breaking changes

• Engine::register_set_result and Engine::register_indexer_set_result now take a function that returns Result<(), Box<EvalAltResult> >.
• Engine::register_indexer_XXX and Module::set_indexer_XXX panic when the type is Array, Map or String.
• EvalAltResult has a new variant ErrorInModule which holds errors when loading an external module.
• Module::eval_ast_as_new now takes an extra boolean parameter, indicating whether to encapsulate the entire module into a separate namespace.
• Functions in FileModuleResolver loaded modules now can cross-call each other in addition to functions in the global namespace. For the old behavior, use MergingFileModuleResolver instead.
• New EvalAltResult::ErrorInModule variant capturing errors when loading a module from a script file.

New features

• Plugins support via procedural macros.
• Scripted functions are allowed in packages.
• parse_int and parse_float functions for parsing numbers; split function for splitting strings.
• AST::iter_functions and Module::iter_script_fn_info to iterate functions.
• Functions iteration functions for AST and Module now take FnMut instead of Fn.
• New FileModuleResolver that encapsulates the entire AST of the module script, allowing function cross-calling. The old version is renamed MergingFileModuleResolver.
• + and - operators for timestamps to increment/decrement by seconds.

Bug fixes

• Engine::compile_expression, Engine::eval_expression etc. no longer parse anonymous functions and closures.
• Imported modules now work inside closures.
• Closures that capture now work under no_object.

New features

• Adds Module::combine_flatten to combine two modules while flattening to the root level.

Bug fixes

• Fixes bug that prevents calling functions in closures.
• Fixes bug that erroneously consumes the first argument to a namespace-qualified function call.

Breaking changes

• Module::contains_fn and Module::get_script_fn no longer take the public_only parameter.

New features

• Adds Engine::register_get_result, Engine::register_set_result, Engine::register_indexer_get_result, Engine::register_indexer_set_result API.
• Adds Module::combine to combine two modules.
• Engine::parse_json now also accepts a JSON object starting with #{.

This version adds:

• Anonymous functions (in Rust closure syntax). Simplifies creation of single-use ad-hoc functions.
• Currying of function pointers.
• Closures - auto-currying of anonymous functions to capture shared variables from the external scope. Use the no_closure feature to disable sharing values and capturing.
• Binding the this pointer in a function pointer call.
• Capturing call scope via func!(...) syntax.

New features

• call can now be called function-call style for function pointers - this is to handle builds with no_object.
• Reserve language keywords, such as print, eval, call, this etc.
• x.call(f, ...) allows binding x to this for the function referenced by the function pointer f.
• Anonymous functions are supported in the syntax of a Rust closure, e.g. |x, y, z| x + y - z.
• Custom syntax now works even without the internals feature.
• Currying of function pointers is supported via the new curry keyword.
• Automatic currying of anonymous functions to capture shared variables from the external scope.
• Capturing of the calling scope for function call via the func!(...) syntax.
• Module::set_indexer_get_set_fn is added as a short-hand of both Module::set_indexer_get_fn and Module::set_indexer_set_fn.
• New unicode-xid-ident feature to allow Unicode Standard Annex #31 for identifiers.
• Scope::iter_raw returns an iterator with a reference to the underlying Dynamic value (which may be shared).

Breaking changes

• Language keywords are now reserved (even when disabled) and they can no longer be used as variable names.
• Function signature for defining custom syntax is simplified.
• Engine::register_raw_fn_XXX API shortcuts are removed.
• PackagesCollection::get_fn, PackagesCollection::contains_fn, Module::get_fn and Module::contains_fn now take an additional public_only parameter indicating whether only public functions are accepted.
• The iterator returned by Scope::iter now contains a clone of the Dynamic value (unshared).
• Engine::register_global_module takes any type that is Into<PackageLibrary>.
• Error in Engine::register_custom_syntax is no longer Box-ed.

Housekeeping

• Most compilation warnings are eliminated via feature gates.

This version adds:

• serde support for working with Dynamic values (particularly object maps).
• Low-level API to register functions.
• Surgically disable keywords and/or operators in the language.
• Define custom operators.
• Extend the language via custom syntax.

Bug fixes

• Fixed method calls in the middle of a dot chain.

Breaking changes

• EvalAltResult::ErrorMismatchOutputType has an extra argument containing the name of the requested type.
• Engine::call_fn_dynamic take an extra argument, allowing a Dynamic value to be bound to the this pointer.
• Precedence of the % (modulo) operator is lowered to below bit shifts. This is to handle the case of x < < 3 % 10.

New features

• New serde feature to allow serializing/deserializing to/from Dynamic values using serde. This is particularly useful when converting a Rust struct to a Dynamic object map and back.
• Engine::disable_symbol to surgically disable keywords and/or operators.
• Engine::register_custom_operator to define a custom operator.
• Engine::register_custom_syntax to define a custom syntax.
• New low-level API Engine::register_raw_fn.
• New low-level API Module::set_raw_fn mirroring Engine::register_raw_fn.
• AST::clone_functions_only, AST::clone_functions_only_filtered and AST::clone_statements_only to clone only part of an AST.
• The boolean ^ (XOR) operator is added.
• FnPtr is exposed as the function pointer type.
• rhai::module_resolvers::ModuleResolversCollection added to try a list of module resolvers.
• It is now possible to mutate the first argument of a namespace-qualified function call when the argument is a simple variable (but not a module constant).
• Many configuration/setting API's now returns &mut Self so that the calls can be chained.
• String parameters in functions are supported (but inefficiently).

Bug fix release to fix errors when compiling with features.

The major new feature in this version is OOP - well, poor man's OOP, that is.

The README is officially transferred to The Rhai Book.

An online Playground is available.

Breaking changes

• The trait function ModuleResolver::resolve no longer takes a Scope as argument.
• Functions defined in script now differentiates between using method-call style and normal function-call style. The method-call style will bind the object to the this parameter instead of consuming the first parameter.
• Imported modules are no longer stored in the Scope. Scope::push_module is removed. Therefore, cannot rely on module imports to persist across invocations using a Scope.
• AST::retain_functions is used for another purpose. The old AST::retain_functions is renamed to AST::clear_statements.

New features

• Support for function pointers via Fn(name) and Fn.call(...) syntax - a poor man's first-class function.
• Support for calling script-defined functions in method-call style with this binding to the object.
• Special support in object maps for OOP.
• Expanded the AST API for fine-tuned manipulation of functions.

Enhancements

• The Rhai Book is online. Most content in the original README was transferred to the Book.
• New feature internals to expose internal data structures (e.g. the AST nodes).

This is a minor release which enables updating indexers (via registered indexer setters) and supports functions with &str parameters (maps transparently to ImmutableString). WASM is also a tested target.

Bug fix

• let s="abc"; s[1].change_to('X'); now correctly sets the character 'X' into 's' yielding "aXc".

Breaking changes

• Callback closure passed to Engine::on_progress now takes &u64 instead of u64 to be consistent with other callback signatures.
• Engine::register_indexer is renamed to Engine::register_indexer_get.
• Module::set_indexer_fn is renamed to Module::set_indexer_get_fn.
• The tuple ParseError now exposes the internal fields and the ParseError::error_type and ParseError::position methods are removed. The first tuple field is the ParseErrorType and the second tuple field is the Position.
• Engine::call_fn_dynamic now takes any type that implements IntoIterator<Item = Dynamic>.

New features

• Indexers are now split into getters and setters (which now support updates). The API is split into Engine::register_indexer_get and Engine::register_indexer_set with Engine::register_indexer_get_set being a short-hand. Similarly, Module::set_indexer_get_fn and Module::set_indexer_set_fn are added.
• Engine:register_fn and Engine:register_result_fn accepts functions that take parameters of type &str (immutable string slice), which maps directly to ImmutableString. This is to avoid needing wrappers for functions taking string parameters.
• Set maximum limit on data sizes: Engine::set_max_string_size, Engine::set_max_array_size and Engine::set_max_map_size.
• Supports trailing commas on array literals, object map literals, function definitions and function calls.
• Enhances support for compiling to WASM.

This version uses immutable strings (ImmutableString type) and built-in operator functions (e.g. +, >, +=) to improve speed, plus some bug fixes.

Regression fix

• Do not optimize script with eval_expression - it is assumed to be one-off and short.

Bug fixes

• Indexing with an index or dot expression now works property (it compiled wrongly before). For example, let s = "hello"; s[s.len-1] = 'x'; now works property instead of causing a runtime error.
• if expressions are not supposed to be allowed when compiling for expressions only. This is fixed.

Breaking changes

• Engine::compile_XXX functions now return ParseError instead of Box<ParseError>.
• The RegisterDynamicFn trait is merged into the RegisterResultFn trait which now always returns RhaiResult.
• Default maximum limit on levels of nested function calls is fine-tuned and set to a different value.
• Some operator functions are now built in (see Speed enhancements below), so they are available even under Engine::new_raw.
• Strings are now immutable. The type rhai::ImmutableString is used instead of std::string::String. This is to avoid excessive cloning of strings. All native-Rust functions taking string parameters should switch to rhai::ImmutableString (which is either Rc<String> or Arc<String> depending on whether the sync feature is used).
• Native Rust functions registered with the Engine also mutates the first argument when called in normal function-call style (previously the first argument will be passed by value if not called in method-call style). Of course, if the first argument is a calculated value (e.g. result of an expression), then mutating it has no effect, but at least it is not cloned.
• Some built-in methods (e.g. len for string, floor for FLOAT) now have property versions in addition to methods to simplify coding.

New features

• Set limit on maximum level of nesting expressions and statements to avoid panics during parsing.
• New EvalPackage to disable eval.
• Module::set_getter_fn, Module::set_setter_fn and Module:set_indexer_fn to register getter/setter/indexer functions.
• Engine::call_fn_dynamic for more control in calling script functions.

Speed enhancements

• Common operators (e.g. +, >, ==) now call into highly efficient built-in implementations for standard types (i.e. INT, FLOAT, bool, char, () and ImmutableString) if not overridden by a registered function. This yields a 5-10% speed benefit depending on script operator usage. Scripts running tight loops will see significant speed-up.
• Common assignment operators (e.g. +=, %=) now call into highly efficient built-in implementations for standard types (i.e. INT, FLOAT, bool, char, () and ImmutableString) if not overridden by a registered function.
• Implementations of common operators for standard types are removed from the ArithmeticPackage and LogicPackage (and therefore the CorePackage) because they are now always available, even under Engine::new_raw.
• Operator-assignment statements (e.g. +=) are now handled directly and much faster.
• Strings are now immutable and use the rhai::ImmutableString type, eliminating large amounts of cloning.
• For Native Rust functions taking a first &mut parameter, the first argument is passed by reference instead of by value, even if not called in method-call style. This allows many functions declared with &mut parameter to avoid excessive cloning. For example, if a is a large array, getting its length in this manner: len(a) used to result in a full clone of a before taking the length and throwing the copy away. Now, a is simply passed by reference, avoiding the cloning altogether.
• A custom hasher simply passes through u64 keys without hashing to avoid function call hash keys (which are by themselves u64) being hashed twice.

The major features for this release is modules, script resource limits, and speed improvements (mainly due to avoiding allocations).

New features

• Modules and module resolvers allow loading external scripts under a module namespace. A module can contain constant variables, Rust functions and Rhai functions.
• export variables and private functions.
• Indexers for Rust types.
• Track script evaluation progress and terminate script run.
• Set limit on maximum number of operations allowed per script run.
• Set limit on maximum number of modules loaded per script run.
• A new API, Engine::compile_scripts_with_scope, can compile a list of script segments without needing to first concatenate them together into one large string.
• Stepped range function with a custom step.

Speed improvements

StaticVec

A script contains many lists - statements in a block, arguments to a function call etc. In a typical script, most of these lists tend to be short - e.g. the vast majority of function calls contain fewer than 4 arguments, while most statement blocks have fewer than 4-5 statements, with one or two being the most common. Before, dynamic Vec's are used to hold these short lists for very brief periods of time, causing allocations churn.

In this version, large amounts of allocations are avoided by converting to a StaticVec - a list type based on a static array for a small number of items (currently four) - wherever possible plus other tricks. Most real-life scripts should see material speed increases.

Pre-computed variable lookups

Almost all variable lookups, as well as lookups in loaded modules, are now pre-computed. A variable's name is almost never used to search for the variable in the current scope.

Getters and setter function names are also pre-computed and cached, so no string allocations are performed during a property get/set call.

Pre-computed function call hashes

Lookup of all function calls, including Rust and Rhai ones, are now through pre-computed hashes. The function name is no longer used to search for a function, making function call dispatches much faster.

Large Boxes for expressions and statements

The expression (Expr) and statement (Stmt) types are modified so that all of the variants contain only one single Box to a large allocated structure containing all the fields. This makes the Expr and Stmt types very small (only one single pointer) and improves evaluation speed due to cache efficiency.

Error handling

Previously, when an error occurs inside a function call, the error position reported is the function call site. This makes it difficult to diagnose the actual location of the error within the function.

A new error variant EvalAltResult::ErrorInFunctionCall is added in this version. It wraps the internal error returned by the called function, including the error position within the function.