Crate fieldx_aux

Expand description

§fieldx_aux

Helper crate for fieldx and any third-party crates that extend its functionality.

fieldx is heavily based on the darling crate, which greatly simplifies proc-macro development, but also imposes some constraints on attribute argument syntax. This crate overcomes these limitations and provides support for attribute kinds required to implement fieldx.

Here is a brief breakdown of what is provided:

Support for nested arguments, i.e. those that look like arg1("value", trigger, subarg(...)).
Support for syntax elements not covered by the darling crate, such as some_type(crate::types::Foo) and error(crate::error::Error, crate::error::Error::SomeProblem("with details"))¹.
A set of types implementing standard fieldx arguments like helpers or literal values.

§Usage

Imagine we are implementing a field-level attribute foo using the darling::FromField trait, and we want it to accept the following arguments:

trigger: enables or disables certain functionality
action: specifies a method with special meaning
comment: accepts arbitrary text
vis: indicates whether field-related code should be public, and if so, which kind of pub modifier to use

A field declaration may take the following form with the attribute:

    #[foo(
        trigger,
        action("method_name", private),
        comment("Whatever we consider useful."),
        vis(pub(crate))
    )]
    bar: usize,

For this, you’ll need the following declaration somewhere in your proc-macro implementation:

#derive(FromField)
#[darling(attributes(foo))]
struct FooField {
    // ... skipping some darling default fields ...

    trigger: Option<FXBool>,
    action: Option<FXHelper>,
    comment: Option<FXString>,
    vis: Option<FXSynValue<syn::Visibility>>,
}

That’s all; this crate will take care of implementing the arguments for you!

Here, the first argument of error()—Error—is an enum, and SomeProblem is one of its variants. ↩

Re-exports§

pub use crate::accessor_helper::FXAccessorHelper;
pub use crate::accessor_helper::FXAccessorMode;
pub use crate::attributes::FXAttribute;
pub use crate::base_helper::FXBaseHelper;
pub use crate::builder_helper::FXBuilderHelper;
pub use crate::default_arg::FXDefault;
pub use crate::doc_arg::FXDocArg;
pub use crate::fallible::FXFallible;
pub use crate::nesting_attr::FXNestingAttr;
pub use crate::nesting_attr::FromNestAttr;
pub use crate::serde_helper::FXSerdeHelper;
pub use crate::setter_helper::FXSetterHelper;
pub use crate::syn_value::FXPunctuated;
pub use crate::syn_value::FXSynTupleArg;
pub use crate::syn_value::FXSynValueArg;
pub use crate::value::FXValueArg;
pub use crate::with_origin::FXOrig;
pub use crate::property::*;
pub use crate::traits::*;

Modules§

accessor_helper: Implementation of accessor helper (get argument of fxstruct/fieldx attributes).
attributes: attributes* family of arguments.
base_helper: The most basic helper declaration
builder_helper: Parameters of builder pattern and builder object.
default_arg: Default value.
doc_arg
fallible: Argument that signals possibility of errors.
nesting_attr: Argument nesting support module.
property
serde_helper
setter_helper
syn_value: Support for types that are not supported by darling but implement syn::parse::Parse
traits
value: Literal value arguments
with_origin: Trait for objects that know their origins.

Macros§

ident_or_alias
set_literals: Generate implementation of set_literals method for FromNestAttr trait.
validate_exclusives: Generate validate_exclusives that would return a darling::Result if two arguments of an attribute are conflicting with each other.
validate_no_macro_args: Generate function to produce errors on sub-arguments that won’t be used in certain context.

Enums§

FXSyncMode: Concurrency mode

Type Aliases§

FXAccessor: Accessor helper
FXAttributes
FXBool: Boolean literal
FXBuilder: Builder helper
FXDoc: doc argument
FXHelper: Standard helper
FXSerde: serde argument
FXSetter: Setter helper
FXString: String literal
FXSynTuple: Standard tuple for types implementing syn::parse::Parse
FXSynValue: Standard type implementing syn::parse::Parse
FXValue: Standard literal value

Attribute Macros§

fxhelper: This macro is used to generate helper structs. It adds the following fields to support related helper functionality:

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