num_enum_derive-0.5.11/.cargo_vcs_info.json0000644000000001550000000000100143020ustar { "git": { "sha1": "b32c406accb05338cb7c59c3023f804a18271c18" }, "path_in_vcs": "num_enum_derive" }num_enum_derive-0.5.11/Cargo.toml0000644000000025640000000000100123060ustar # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies. # # If you are reading this file be aware that the original Cargo.toml # will likely look very different (and much more reasonable). # See Cargo.toml.orig for the original contents. [package] edition = "2018" name = "num_enum_derive" version = "0.5.11" authors = [ "Daniel Wagner-Hall ", "Daniel Henry-Mantilla ", "Vincent Esche ", ] description = "Internal implementation details for ::num_enum (Procedural macros to make inter-operation between primitives and enums easier)" readme = "README.md" keywords = [] categories = [] license = "BSD-3-Clause OR MIT OR Apache-2.0" repository = "https://github.com/illicitonion/num_enum" [package.metadata.docs.rs] features = ["external_doc"] [lib] proc-macro = true [dependencies.proc-macro-crate] version = "1" optional = true [dependencies.proc-macro2] version = "1" [dependencies.quote] version = "1" [dependencies.syn] version = "1.0.15" features = ["parsing"] [features] complex-expressions = ["syn/full"] default = ["std"] external_doc = [] std = ["proc-macro-crate"] num_enum_derive-0.5.11/Cargo.toml.orig000064400000000000000000000021211046102023000157540ustar 00000000000000[package] name = "num_enum_derive" version = "0.5.11" # Keep in sync with num_enum. authors = [ "Daniel Wagner-Hall ", "Daniel Henry-Mantilla ", "Vincent Esche ", ] description = "Internal implementation details for ::num_enum (Procedural macros to make inter-operation between primitives and enums easier)" edition = "2018" repository = "https://github.com/illicitonion/num_enum" keywords = [] categories = [] license = "BSD-3-Clause OR MIT OR Apache-2.0" [lib] proc-macro = true [features] # Don't depend on proc-macro-crate in no_std environments because it causes an awkward depndency # on serde with std. # # See https://github.com/illicitonion/num_enum/issues/18 std = ["proc-macro-crate"] complex-expressions = ["syn/full"] external_doc = [] default = ["std"] # disable to use in a `no_std` environment [package.metadata.docs.rs] features = ["external_doc"] [dependencies] proc-macro2 = "1" proc-macro-crate = { version = "1", optional = true } quote = "1" syn = { version = "1.0.15", features = ["parsing"] } num_enum_derive-0.5.11/LICENSE-APACHE000064400000000000000000000227731046102023000150300ustar 00000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of num_enum nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. num_enum_derive-0.5.11/README.md000064400000000000000000000160461046102023000143570ustar 00000000000000num_enum ======== Procedural macros to make inter-operation between primitives and enums easier. This crate is no_std compatible. [![crates.io](https://img.shields.io/crates/v/num_enum.svg)](https://crates.io/crates/num_enum) [![Documentation](https://docs.rs/num_enum/badge.svg)](https://docs.rs/num_enum) [![Build Status](https://travis-ci.org/illicitonion/num_enum.svg?branch=master)](https://travis-ci.org/illicitonion/num_enum) Turning an enum into a primitive -------------------------------- ```rust use num_enum::IntoPrimitive; #[derive(IntoPrimitive)] #[repr(u8)] enum Number { Zero, One, } fn main() { let zero: u8 = Number::Zero.into(); assert_eq!(zero, 0u8); } ``` `num_enum`'s `IntoPrimitive` is more type-safe than using `as`, because `as` will silently truncate - `num_enum` only derives `From` for exactly the discriminant type of the enum. Attempting to turn a primitive into an enum with try_from ---------------------------------------------- ```rust use num_enum::TryFromPrimitive; use std::convert::TryFrom; #[derive(Debug, Eq, PartialEq, TryFromPrimitive)] #[repr(u8)] enum Number { Zero, One, } fn main() { let zero = Number::try_from(0u8); assert_eq!(zero, Ok(Number::Zero)); let three = Number::try_from(3u8); assert_eq!( three.unwrap_err().to_string(), "No discriminant in enum `Number` matches the value `3`", ); } ``` Variant alternatives --------------- Sometimes a single enum variant might be representable by multiple numeric values. The `#[num_enum(alternatives = [..])]` attribute allows you to define additional value alternatives for individual variants. (The behavior of `IntoPrimitive` is unaffected by this attribute, it will always return the canonical value.) ```rust use num_enum::TryFromPrimitive; use std::convert::TryFrom; #[derive(Debug, Eq, PartialEq, TryFromPrimitive)] #[repr(u8)] enum Number { Zero = 0, #[num_enum(alternatives = [2])] OneOrTwo = 1, } fn main() { let zero = Number::try_from(0u8); assert_eq!(zero, Ok(Number::Zero)); let one = Number::try_from(1u8); assert_eq!(one, Ok(Number::OneOrTwo)); let two = Number::try_from(2u8); assert_eq!(two, Ok(Number::OneOrTwo)); let three = Number::try_from(3u8); assert_eq!( three.unwrap_err().to_string(), "No discriminant in enum `Number` matches the value `3`", ); } ``` Range expressions are also supported for alternatives, but this requires enabling the `complex-expressions` feature: ```rust use num_enum::TryFromPrimitive; use std::convert::TryFrom; #[derive(Debug, Eq, PartialEq, TryFromPrimitive)] #[repr(u8)] enum Number { Zero = 0, #[num_enum(alternatives = [2..16])] Some = 1, #[num_enum(alternatives = [17, 18..=255])] Many = 16, } fn main() { let zero = Number::try_from(0u8); assert_eq!(zero, Ok(Number::Zero)); let some = Number::try_from(15u8); assert_eq!(some, Ok(Number::Some)); let many = Number::try_from(255u8); assert_eq!(many, Ok(Number::Many)); } ``` Default variant --------------- Sometimes it is desirable to have an `Other` variant in an enum that acts as a kind of a wildcard matching all the value not yet covered by other variants. The `#[num_enum(default)]` attribute allows you to mark variant as the default. (The behavior of `IntoPrimitive` is unaffected by this attribute, it will always return the canonical value.) ```rust use num_enum::TryFromPrimitive; use std::convert::TryFrom; #[derive(Debug, Eq, PartialEq, TryFromPrimitive)] #[repr(u8)] enum Number { Zero = 0, #[num_enum(default)] NonZero = 1, } fn main() { let zero = Number::try_from(0u8); assert_eq!(zero, Ok(Number::Zero)); let one = Number::try_from(1u8); assert_eq!(one, Ok(Number::NonZero)); let two = Number::try_from(2u8); assert_eq!(two, Ok(Number::NonZero)); } ``` Safely turning a primitive into an exhaustive enum with from_primitive ------------------------------------------------------------- If your enum has all possible primitive values covered, you can derive `FromPrimitive` for it (which auto-implement stdlib's `From`): You can cover all possible values by: * Having variants for every possible value * Having a variant marked `#[num_enum(default)]` * Having a variant marked `#[num_enum(catch_all)]` * Having `#[num_enum(alternatives = [...])`s covering values not covered by a variant. ```rust use num_enum::FromPrimitive; #[derive(Debug, Eq, PartialEq, FromPrimitive)] #[repr(u8)] enum Number { Zero, #[num_enum(default)] NonZero, } fn main() { assert_eq!( Number::Zero, Number::from(0_u8), ); assert_eq!( Number::NonZero, Number::from(1_u8), ); } ``` Catch-all variant ----------------- Sometimes it is desirable to have an `Other` variant which holds the otherwise un-matched value as a field. The `#[num_enum(catch_all)]` attribute allows you to mark at most one variant for this purpose. The variant it's applied to must be a tuple variant with exactly one field matching the `repr` type. ```rust use num_enum::FromPrimitive; use std::convert::TryFrom; #[derive(Debug, Eq, PartialEq, FromPrimitive)] #[repr(u8)] enum Number { Zero = 0, #[num_enum(catch_all)] NonZero(u8), } fn main() { let zero = Number::from(0u8); assert_eq!(zero, Number::Zero); let one = Number::from(1u8); assert_eq!(one, Number::NonZero(1_u8)); let two = Number::from(2u8); assert_eq!(two, Number::NonZero(2_u8)); } ``` As this is naturally exhaustive, this is only supported for `FromPrimitive`, not also `TryFromPrimitive`. Unsafely turning a primitive into an enum with from_unchecked ------------------------------------------------------------- If you're really certain a conversion will succeed (and have not made use of `#[num_enum(default)]` or `#[num_enum(alternatives = [..])]` for any of its variants), and want to avoid a small amount of overhead, you can use unsafe code to do this conversion. Unless you have data showing that the match statement generated in the `try_from` above is a bottleneck for you, you should avoid doing this, as the unsafe code has potential to cause serious memory issues in your program. ```rust use num_enum::UnsafeFromPrimitive; #[derive(Debug, Eq, PartialEq, UnsafeFromPrimitive)] #[repr(u8)] enum Number { Zero, One, } fn main() { assert_eq!( unsafe { Number::from_unchecked(0_u8) }, Number::Zero, ); assert_eq!( unsafe { Number::from_unchecked(1_u8) }, Number::One, ); } unsafe fn undefined_behavior() { let _ = Number::from_unchecked(2); // 2 is not a valid discriminant! } ``` Optional features ----------------- Some enum values may be composed of complex expressions, for example: ```rust enum Number { Zero = (0, 1).0, One = (0, 1).1, } ``` To cut down on compile time, these are not supported by default, but if you enable the `complex-expressions` feature of your dependency on `num_enum`, these should start working. License ------- num_enum may be used under your choice of the BSD 3-clause, Apache 2, or MIT license. num_enum_derive-0.5.11/src/lib.rs000064400000000000000000001155331046102023000150040ustar 00000000000000// Not supported by MSRV #![allow(clippy::uninlined_format_args)] extern crate proc_macro; use proc_macro::TokenStream; use proc_macro2::Span; use quote::{format_ident, quote}; use std::collections::BTreeSet; use syn::{ parse::{Parse, ParseStream}, parse_macro_input, parse_quote, spanned::Spanned, Attribute, Data, DeriveInput, Error, Expr, ExprLit, ExprUnary, Fields, Ident, Lit, LitInt, LitStr, Meta, Result, UnOp, }; macro_rules! die { ($spanned:expr=> $msg:expr ) => { return Err(Error::new_spanned($spanned, $msg)) }; ( $msg:expr ) => { return Err(Error::new(Span::call_site(), $msg)) }; } fn literal(i: i128) -> Expr { Expr::Lit(ExprLit { lit: Lit::Int(LitInt::new(&i.to_string(), Span::call_site())), attrs: vec![], }) } enum DiscriminantValue { Literal(i128), Expr(Expr), } fn parse_discriminant(val_exp: &Expr) -> Result { let mut sign = 1; let mut unsigned_expr = val_exp; if let Expr::Unary(ExprUnary { op: UnOp::Neg(..), expr, .. }) = val_exp { unsigned_expr = expr; sign = -1; } if let Expr::Lit(ExprLit { lit: Lit::Int(ref lit_int), .. }) = unsigned_expr { Ok(DiscriminantValue::Literal( sign * lit_int.base10_parse::()?, )) } else { Ok(DiscriminantValue::Expr(val_exp.clone())) } } #[cfg(feature = "complex-expressions")] fn parse_alternative_values(val_expr: &Expr) -> Result> { fn range_expr_value_to_number( parent_range_expr: &Expr, range_bound_value: &Option>, ) -> Result { // Avoid needing to calculate what the lower and upper bound would be - these are type dependent, // and also may not be obvious in context (e.g. an omitted bound could reasonably mean "from the last discriminant" or "from the lower bound of the type"). if let Some(range_bound_value) = range_bound_value { let range_bound_value = parse_discriminant(range_bound_value.as_ref())?; // If non-literals are used, we can't expand to the mapped values, so can't write a nice match statement or do exhaustiveness checking. // Require literals instead. if let DiscriminantValue::Literal(value) = range_bound_value { return Ok(value); } } die!(parent_range_expr => "When ranges are used for alternate values, both bounds most be explicitly specified numeric literals") } if let Expr::Range(syn::ExprRange { from, to, limits, .. }) = val_expr { let lower = range_expr_value_to_number(val_expr, from)?; let upper = range_expr_value_to_number(val_expr, to)?; // While this is technically allowed in Rust, and results in an empty range, it's almost certainly a mistake in this context. if lower > upper { die!(val_expr => "When using ranges for alternate values, upper bound must not be less than lower bound"); } let mut values = Vec::with_capacity((upper - lower) as usize); let mut next = lower; loop { match limits { syn::RangeLimits::HalfOpen(..) => { if next == upper { break; } } syn::RangeLimits::Closed(..) => { if next > upper { break; } } } values.push(DiscriminantValue::Literal(next)); next += 1; } return Ok(values); } parse_discriminant(val_expr).map(|v| vec![v]) } #[cfg(not(feature = "complex-expressions"))] fn parse_alternative_values(val_expr: &Expr) -> Result> { parse_discriminant(val_expr).map(|v| vec![v]) } mod kw { syn::custom_keyword!(default); syn::custom_keyword!(catch_all); syn::custom_keyword!(alternatives); } struct NumEnumVariantAttributes { items: syn::punctuated::Punctuated, } impl Parse for NumEnumVariantAttributes { fn parse(input: ParseStream<'_>) -> Result { Ok(Self { items: input.parse_terminated(NumEnumVariantAttributeItem::parse)?, }) } } enum NumEnumVariantAttributeItem { Default(VariantDefaultAttribute), CatchAll(VariantCatchAllAttribute), Alternatives(VariantAlternativesAttribute), } impl Parse for NumEnumVariantAttributeItem { fn parse(input: ParseStream<'_>) -> Result { let lookahead = input.lookahead1(); if lookahead.peek(kw::default) { input.parse().map(Self::Default) } else if lookahead.peek(kw::catch_all) { input.parse().map(Self::CatchAll) } else if lookahead.peek(kw::alternatives) { input.parse().map(Self::Alternatives) } else { Err(lookahead.error()) } } } struct VariantDefaultAttribute { keyword: kw::default, } impl Parse for VariantDefaultAttribute { fn parse(input: ParseStream) -> Result { Ok(Self { keyword: input.parse()?, }) } } impl Spanned for VariantDefaultAttribute { fn span(&self) -> Span { self.keyword.span() } } struct VariantCatchAllAttribute { keyword: kw::catch_all, } impl Parse for VariantCatchAllAttribute { fn parse(input: ParseStream) -> Result { Ok(Self { keyword: input.parse()?, }) } } impl Spanned for VariantCatchAllAttribute { fn span(&self) -> Span { self.keyword.span() } } struct VariantAlternativesAttribute { keyword: kw::alternatives, _eq_token: syn::Token![=], _bracket_token: syn::token::Bracket, expressions: syn::punctuated::Punctuated, } impl Parse for VariantAlternativesAttribute { fn parse(input: ParseStream) -> Result { let content; let keyword = input.parse()?; let _eq_token = input.parse()?; let _bracket_token = syn::bracketed!(content in input); let expressions = content.parse_terminated(Expr::parse)?; Ok(Self { keyword, _eq_token, _bracket_token, expressions, }) } } impl Spanned for VariantAlternativesAttribute { fn span(&self) -> Span { self.keyword.span() } } #[derive(::core::default::Default)] struct AttributeSpans { default: Vec, catch_all: Vec, alternatives: Vec, } struct VariantInfo { ident: Ident, attr_spans: AttributeSpans, is_default: bool, is_catch_all: bool, canonical_value: Expr, alternative_values: Vec, } impl VariantInfo { fn all_values(&self) -> impl Iterator { ::core::iter::once(&self.canonical_value).chain(self.alternative_values.iter()) } fn is_complex(&self) -> bool { !self.alternative_values.is_empty() } } struct EnumInfo { name: Ident, repr: Ident, variants: Vec, } impl EnumInfo { /// Returns whether the number of variants (ignoring defaults, catch-alls, etc) is the same as /// the capacity of the repr. fn is_naturally_exhaustive(&self) -> Result { let repr_str = self.repr.to_string(); if !repr_str.is_empty() { let suffix = repr_str .strip_prefix('i') .or_else(|| repr_str.strip_prefix('u')); if let Some(suffix) = suffix { if let Ok(bits) = suffix.parse::() { let variants = 1usize.checked_shl(bits); return Ok(variants.map_or(false, |v| { v == self .variants .iter() .map(|v| v.alternative_values.len() + 1) .sum() })); } } } die!(self.repr.clone() => "Failed to parse repr into bit size"); } fn has_default_variant(&self) -> bool { self.default().is_some() } fn has_complex_variant(&self) -> bool { self.variants.iter().any(|info| info.is_complex()) } fn default(&self) -> Option<&Ident> { self.variants .iter() .find(|info| info.is_default) .map(|info| &info.ident) } fn catch_all(&self) -> Option<&Ident> { self.variants .iter() .find(|info| info.is_catch_all) .map(|info| &info.ident) } fn first_default_attr_span(&self) -> Option<&Span> { self.variants .iter() .find_map(|info| info.attr_spans.default.first()) } fn first_alternatives_attr_span(&self) -> Option<&Span> { self.variants .iter() .find_map(|info| info.attr_spans.alternatives.first()) } fn variant_idents(&self) -> Vec { self.variants .iter() .map(|variant| variant.ident.clone()) .collect() } fn expression_idents(&self) -> Vec> { self.variants .iter() .filter(|variant| !variant.is_catch_all) .map(|info| { let indices = 0..(info.alternative_values.len() + 1); indices .map(|index| format_ident!("{}__num_enum_{}__", info.ident, index)) .collect() }) .collect() } fn variant_expressions(&self) -> Vec> { self.variants .iter() .map(|variant| variant.all_values().cloned().collect()) .collect() } } impl Parse for EnumInfo { fn parse(input: ParseStream) -> Result { Ok({ let input: DeriveInput = input.parse()?; let name = input.ident; let data = match input.data { Data::Enum(data) => data, Data::Union(data) => die!(data.union_token => "Expected enum but found union"), Data::Struct(data) => die!(data.struct_token => "Expected enum but found struct"), }; let repr: Ident = { let mut attrs = input.attrs.into_iter(); loop { if let Some(attr) = attrs.next() { if let Ok(Meta::List(meta_list)) = attr.parse_meta() { if let Some(ident) = meta_list.path.get_ident() { if ident == "repr" { let mut nested = meta_list.nested.iter(); if nested.len() != 1 { die!(attr => "Expected exactly one `repr` argument" ); } let repr = nested.next().unwrap(); let repr: Ident = parse_quote! { #repr }; if repr == "C" { die!(repr => "repr(C) doesn't have a well defined size" ); } else { break repr; } } } } } else { die!("Missing `#[repr({Integer})]` attribute"); } } }; let mut variants: Vec = vec![]; let mut has_default_variant: bool = false; let mut has_catch_all_variant: bool = false; // Vec to keep track of the used discriminants and alt values. let mut discriminant_int_val_set = BTreeSet::new(); let mut next_discriminant = literal(0); for variant in data.variants.into_iter() { let ident = variant.ident.clone(); let discriminant = match &variant.discriminant { Some(d) => d.1.clone(), None => next_discriminant.clone(), }; let mut attr_spans: AttributeSpans = Default::default(); let mut raw_alternative_values: Vec = vec![]; // Keep the attribute around for better error reporting. let mut alt_attr_ref: Vec<&Attribute> = vec![]; // `#[num_enum(default)]` is required by `#[derive(FromPrimitive)]` // and forbidden by `#[derive(UnsafeFromPrimitive)]`, so we need to // keep track of whether we encountered such an attribute: let mut is_default: bool = false; let mut is_catch_all: bool = false; for attribute in &variant.attrs { if attribute.path.is_ident("default") { if has_default_variant { die!(attribute => "Multiple variants marked `#[default]` or `#[num_enum(default)]` found" ); } else if has_catch_all_variant { die!(attribute => "Attribute `default` is mutually exclusive with `catch_all`" ); } attr_spans.default.push(attribute.span()); is_default = true; has_default_variant = true; } if attribute.path.is_ident("num_enum") { match attribute.parse_args_with(NumEnumVariantAttributes::parse) { Ok(variant_attributes) => { for variant_attribute in variant_attributes.items { match variant_attribute { NumEnumVariantAttributeItem::Default(default) => { if has_default_variant { die!(default.keyword => "Multiple variants marked `#[default]` or `#[num_enum(default)]` found" ); } else if has_catch_all_variant { die!(default.keyword => "Attribute `default` is mutually exclusive with `catch_all`" ); } attr_spans.default.push(default.span()); is_default = true; has_default_variant = true; } NumEnumVariantAttributeItem::CatchAll(catch_all) => { if has_catch_all_variant { die!(catch_all.keyword => "Multiple variants marked with `#[num_enum(catch_all)]`" ); } else if has_default_variant { die!(catch_all.keyword => "Attribute `catch_all` is mutually exclusive with `default`" ); } match variant .fields .iter() .collect::>() .as_slice() { [syn::Field { ty: syn::Type::Path(syn::TypePath { path, .. }), .. }] if path.is_ident(&repr) => { attr_spans.catch_all.push(catch_all.span()); is_catch_all = true; has_catch_all_variant = true; } _ => { die!(catch_all.keyword => "Variant with `catch_all` must be a tuple with exactly 1 field matching the repr type" ); } } } NumEnumVariantAttributeItem::Alternatives(alternatives) => { attr_spans.alternatives.push(alternatives.span()); raw_alternative_values.extend(alternatives.expressions); alt_attr_ref.push(attribute); } } } } Err(err) => { if cfg!(not(feature = "complex-expressions")) { let attribute_str = format!("{}", attribute.tokens); if attribute_str.contains("alternatives") && attribute_str.contains("..") { // Give a nice error message suggesting how to fix the problem. die!(attribute => "Ranges are only supported as num_enum alternate values if the `complex-expressions` feature of the crate `num_enum` is enabled".to_string()) } } die!(attribute => format!("Invalid attribute: {}", err) ); } } } } if !is_catch_all { match &variant.fields { Fields::Named(_) | Fields::Unnamed(_) => { die!(variant => format!("`{}` only supports unit variants (with no associated data), but `{}::{}` was not a unit variant.", get_crate_name(), name, ident)); } Fields::Unit => {} } } let discriminant_value = parse_discriminant(&discriminant)?; // Check for collision. // We can't do const evaluation, or even compare arbitrary Exprs, // so unfortunately we can't check for duplicates. // That's not the end of the world, just we'll end up with compile errors for // matches with duplicate branches in generated code instead of nice friendly error messages. if let DiscriminantValue::Literal(canonical_value_int) = discriminant_value { if discriminant_int_val_set.contains(&canonical_value_int) { die!(ident => format!("The discriminant '{}' collides with a value attributed to a previous variant", canonical_value_int)) } } // Deal with the alternative values. let mut flattened_alternative_values = Vec::new(); let mut flattened_raw_alternative_values = Vec::new(); for raw_alternative_value in raw_alternative_values { let expanded_values = parse_alternative_values(&raw_alternative_value)?; for expanded_value in expanded_values { flattened_alternative_values.push(expanded_value); flattened_raw_alternative_values.push(raw_alternative_value.clone()) } } if !flattened_alternative_values.is_empty() { let alternate_int_values = flattened_alternative_values .into_iter() .map(|v| { match v { DiscriminantValue::Literal(value) => Ok(value), DiscriminantValue::Expr(expr) => { if let Expr::Range(_) = expr { if cfg!(not(feature = "complex-expressions")) { // Give a nice error message suggesting how to fix the problem. die!(expr => "Ranges are only supported as num_enum alternate values if the `complex-expressions` feature of the crate `num_enum` is enabled".to_string()) } } // We can't do uniqueness checking on non-literals, so we don't allow them as alternate values. // We could probably allow them, but there doesn't seem to be much of a use-case, // and it's easier to give good error messages about duplicate values this way, // rather than rustc errors on conflicting match branches. die!(expr => "Only literals are allowed as num_enum alternate values".to_string()) }, } }) .collect::>>()?; let mut sorted_alternate_int_values = alternate_int_values.clone(); sorted_alternate_int_values.sort_unstable(); let sorted_alternate_int_values = sorted_alternate_int_values; // Check if the current discriminant is not in the alternative values. if let DiscriminantValue::Literal(canonical_value_int) = discriminant_value { if let Some(index) = alternate_int_values .iter() .position(|&x| x == canonical_value_int) { die!(&flattened_raw_alternative_values[index] => format!("'{}' in the alternative values is already attributed as the discriminant of this variant", canonical_value_int)); } } // Search for duplicates, the vec is sorted. Warn about them. if (1..sorted_alternate_int_values.len()).any(|i| { sorted_alternate_int_values[i] == sorted_alternate_int_values[i - 1] }) { let attr = *alt_attr_ref.last().unwrap(); die!(attr => "There is duplication in the alternative values"); } // Search if those discriminant_int_val_set where already attributed. // (discriminant_int_val_set is BTreeSet, and iter().next_back() is the is the maximum in the set.) if let Some(last_upper_val) = discriminant_int_val_set.iter().next_back() { if sorted_alternate_int_values.first().unwrap() <= last_upper_val { for (index, val) in alternate_int_values.iter().enumerate() { if discriminant_int_val_set.contains(val) { die!(&flattened_raw_alternative_values[index] => format!("'{}' in the alternative values is already attributed to a previous variant", val)); } } } } // Reconstruct the alternative_values vec of Expr but sorted. flattened_raw_alternative_values = sorted_alternate_int_values .iter() .map(|val| literal(val.to_owned())) .collect(); // Add the alternative values to the the set to keep track. discriminant_int_val_set.extend(sorted_alternate_int_values); } // Add the current discriminant to the the set to keep track. if let DiscriminantValue::Literal(canonical_value_int) = discriminant_value { discriminant_int_val_set.insert(canonical_value_int); } variants.push(VariantInfo { ident, attr_spans, is_default, is_catch_all, canonical_value: discriminant, alternative_values: flattened_raw_alternative_values, }); // Get the next value for the discriminant. next_discriminant = match discriminant_value { DiscriminantValue::Literal(int_value) => literal(int_value.wrapping_add(1)), DiscriminantValue::Expr(expr) => { parse_quote! { #repr::wrapping_add(#expr, 1) } } } } EnumInfo { name, repr, variants, } }) } } /// Implements `Into` for a `#[repr(Primitive)] enum`. /// /// (It actually implements `From for Primitive`) /// /// ## Allows turning an enum into a primitive. /// /// ```rust /// use num_enum::IntoPrimitive; /// /// #[derive(IntoPrimitive)] /// #[repr(u8)] /// enum Number { /// Zero, /// One, /// } /// /// let zero: u8 = Number::Zero.into(); /// assert_eq!(zero, 0u8); /// ``` #[proc_macro_derive(IntoPrimitive, attributes(num_enum, catch_all))] pub fn derive_into_primitive(input: TokenStream) -> TokenStream { let enum_info = parse_macro_input!(input as EnumInfo); let catch_all = enum_info.catch_all(); let name = &enum_info.name; let repr = &enum_info.repr; let body = if let Some(catch_all_ident) = catch_all { quote! { match enum_value { #name::#catch_all_ident(raw) => raw, rest => unsafe { *(&rest as *const #name as *const Self) } } } } else { quote! { enum_value as Self } }; TokenStream::from(quote! { impl From<#name> for #repr { #[inline] fn from (enum_value: #name) -> Self { #body } } }) } /// Implements `From` for a `#[repr(Primitive)] enum`. /// /// Turning a primitive into an enum with `from`. /// ---------------------------------------------- /// /// ```rust /// use num_enum::FromPrimitive; /// /// #[derive(Debug, Eq, PartialEq, FromPrimitive)] /// #[repr(u8)] /// enum Number { /// Zero, /// #[num_enum(default)] /// NonZero, /// } /// /// let zero = Number::from(0u8); /// assert_eq!(zero, Number::Zero); /// /// let one = Number::from(1u8); /// assert_eq!(one, Number::NonZero); /// /// let two = Number::from(2u8); /// assert_eq!(two, Number::NonZero); /// ``` #[proc_macro_derive(FromPrimitive, attributes(num_enum, default, catch_all))] pub fn derive_from_primitive(input: TokenStream) -> TokenStream { let enum_info: EnumInfo = parse_macro_input!(input); let krate = Ident::new(&get_crate_name(), Span::call_site()); let is_naturally_exhaustive = enum_info.is_naturally_exhaustive(); let catch_all_body = match is_naturally_exhaustive { Ok(is_naturally_exhaustive) => { if is_naturally_exhaustive { quote! { unreachable!("exhaustive enum") } } else if let Some(default_ident) = enum_info.default() { quote! { Self::#default_ident } } else if let Some(catch_all_ident) = enum_info.catch_all() { quote! { Self::#catch_all_ident(number) } } else { let span = Span::call_site(); let message = "#[derive(num_enum::FromPrimitive)] requires enum to be exhaustive, or a variant marked with `#[default]`, `#[num_enum(default)]`, or `#[num_enum(catch_all)`"; return syn::Error::new(span, message).to_compile_error().into(); } } Err(err) => { return err.to_compile_error().into(); } }; let EnumInfo { ref name, ref repr, .. } = enum_info; let variant_idents: Vec = enum_info.variant_idents(); let expression_idents: Vec> = enum_info.expression_idents(); let variant_expressions: Vec> = enum_info.variant_expressions(); debug_assert_eq!(variant_idents.len(), variant_expressions.len()); TokenStream::from(quote! { impl ::#krate::FromPrimitive for #name { type Primitive = #repr; fn from_primitive(number: Self::Primitive) -> Self { // Use intermediate const(s) so that enums defined like // `Two = ONE + 1u8` work properly. #![allow(non_upper_case_globals)] #( #( const #expression_idents: #repr = #variant_expressions; )* )* #[deny(unreachable_patterns)] match number { #( #( #expression_idents )|* => Self::#variant_idents, )* #[allow(unreachable_patterns)] _ => #catch_all_body, } } } impl ::core::convert::From<#repr> for #name { #[inline] fn from ( number: #repr, ) -> Self { ::#krate::FromPrimitive::from_primitive(number) } } // The Rust stdlib will implement `#name: From<#repr>` for us for free! impl ::#krate::TryFromPrimitive for #name { type Primitive = #repr; const NAME: &'static str = stringify!(#name); #[inline] fn try_from_primitive ( number: Self::Primitive, ) -> ::core::result::Result< Self, ::#krate::TryFromPrimitiveError, > { Ok(::#krate::FromPrimitive::from_primitive(number)) } } }) } /// Implements `TryFrom` for a `#[repr(Primitive)] enum`. /// /// Attempting to turn a primitive into an enum with `try_from`. /// ---------------------------------------------- /// /// ```rust /// use num_enum::TryFromPrimitive; /// use std::convert::TryFrom; /// /// #[derive(Debug, Eq, PartialEq, TryFromPrimitive)] /// #[repr(u8)] /// enum Number { /// Zero, /// One, /// } /// /// let zero = Number::try_from(0u8); /// assert_eq!(zero, Ok(Number::Zero)); /// /// let three = Number::try_from(3u8); /// assert_eq!( /// three.unwrap_err().to_string(), /// "No discriminant in enum `Number` matches the value `3`", /// ); /// ``` #[proc_macro_derive(TryFromPrimitive, attributes(num_enum))] pub fn derive_try_from_primitive(input: TokenStream) -> TokenStream { let enum_info: EnumInfo = parse_macro_input!(input); let krate = Ident::new(&get_crate_name(), Span::call_site()); let EnumInfo { ref name, ref repr, .. } = enum_info; let variant_idents: Vec = enum_info.variant_idents(); let expression_idents: Vec> = enum_info.expression_idents(); let variant_expressions: Vec> = enum_info.variant_expressions(); debug_assert_eq!(variant_idents.len(), variant_expressions.len()); let default_arm = match enum_info.default() { Some(ident) => { quote! { _ => ::core::result::Result::Ok( #name::#ident ) } } None => { quote! { _ => ::core::result::Result::Err( ::#krate::TryFromPrimitiveError { number } ) } } }; TokenStream::from(quote! { impl ::#krate::TryFromPrimitive for #name { type Primitive = #repr; const NAME: &'static str = stringify!(#name); fn try_from_primitive ( number: Self::Primitive, ) -> ::core::result::Result< Self, ::#krate::TryFromPrimitiveError > { // Use intermediate const(s) so that enums defined like // `Two = ONE + 1u8` work properly. #![allow(non_upper_case_globals)] #( #( const #expression_idents: #repr = #variant_expressions; )* )* #[deny(unreachable_patterns)] match number { #( #( #expression_idents )|* => ::core::result::Result::Ok(Self::#variant_idents), )* #[allow(unreachable_patterns)] #default_arm, } } } impl ::core::convert::TryFrom<#repr> for #name { type Error = ::#krate::TryFromPrimitiveError; #[inline] fn try_from ( number: #repr, ) -> ::core::result::Result> { ::#krate::TryFromPrimitive::try_from_primitive(number) } } }) } #[cfg(feature = "proc-macro-crate")] fn get_crate_name() -> String { let found_crate = proc_macro_crate::crate_name("num_enum").unwrap_or_else(|err| { eprintln!("Warning: {}\n => defaulting to `num_enum`", err,); proc_macro_crate::FoundCrate::Itself }); match found_crate { proc_macro_crate::FoundCrate::Itself => String::from("num_enum"), proc_macro_crate::FoundCrate::Name(name) => name, } } // Don't depend on proc-macro-crate in no_std environments because it causes an awkward dependency // on serde with std. // // no_std dependees on num_enum cannot rename the num_enum crate when they depend on it. Sorry. // // See https://github.com/illicitonion/num_enum/issues/18 #[cfg(not(feature = "proc-macro-crate"))] fn get_crate_name() -> String { String::from("num_enum") } /// Generates a `unsafe fn from_unchecked (number: Primitive) -> Self` /// associated function. /// /// Allows unsafely turning a primitive into an enum with from_unchecked. /// ------------------------------------------------------------- /// /// If you're really certain a conversion will succeed, and want to avoid a small amount of overhead, you can use unsafe /// code to do this conversion. Unless you have data showing that the match statement generated in the `try_from` above is a /// bottleneck for you, you should avoid doing this, as the unsafe code has potential to cause serious memory issues in /// your program. /// /// ```rust /// use num_enum::UnsafeFromPrimitive; /// /// #[derive(Debug, Eq, PartialEq, UnsafeFromPrimitive)] /// #[repr(u8)] /// enum Number { /// Zero, /// One, /// } /// /// fn main() { /// assert_eq!( /// Number::Zero, /// unsafe { Number::from_unchecked(0_u8) }, /// ); /// assert_eq!( /// Number::One, /// unsafe { Number::from_unchecked(1_u8) }, /// ); /// } /// /// unsafe fn undefined_behavior() { /// let _ = Number::from_unchecked(2); // 2 is not a valid discriminant! /// } /// ``` #[proc_macro_derive(UnsafeFromPrimitive, attributes(num_enum))] pub fn derive_unsafe_from_primitive(stream: TokenStream) -> TokenStream { let enum_info = parse_macro_input!(stream as EnumInfo); if enum_info.has_default_variant() { let span = enum_info .first_default_attr_span() .cloned() .expect("Expected span"); let message = "#[derive(UnsafeFromPrimitive)] does not support `#[num_enum(default)]`"; return syn::Error::new(span, message).to_compile_error().into(); } if enum_info.has_complex_variant() { let span = enum_info .first_alternatives_attr_span() .cloned() .expect("Expected span"); let message = "#[derive(UnsafeFromPrimitive)] does not support `#[num_enum(alternatives = [..])]`"; return syn::Error::new(span, message).to_compile_error().into(); } let EnumInfo { ref name, ref repr, .. } = enum_info; let doc_string = LitStr::new( &format!( r#" Transmutes `number: {repr}` into a [`{name}`]. # Safety - `number` must represent a valid discriminant of [`{name}`] "#, repr = repr, name = name, ), Span::call_site(), ); TokenStream::from(quote! { impl #name { #[doc = #doc_string] #[inline] pub unsafe fn from_unchecked(number: #repr) -> Self { ::core::mem::transmute(number) } } }) } /// Implements `core::default::Default` for a `#[repr(Primitive)] enum`. /// /// Whichever variant has the `#[default]` or `#[num_enum(default)]` attribute will be returned. /// ---------------------------------------------- /// /// ```rust /// #[derive(Debug, Eq, PartialEq, num_enum::Default)] /// #[repr(u8)] /// enum Number { /// Zero, /// #[default] /// One, /// } /// /// assert_eq!(Number::One, Number::default()); /// assert_eq!(Number::One, ::default()); /// ``` #[proc_macro_derive(Default, attributes(num_enum, default))] pub fn derive_default(stream: TokenStream) -> TokenStream { let enum_info = parse_macro_input!(stream as EnumInfo); let default_ident = match enum_info.default() { Some(ident) => ident, None => { let span = Span::call_site(); let message = "#[derive(num_enum::Default)] requires enum to be exhaustive, or a variant marked with `#[default]` or `#[num_enum(default)]`"; return syn::Error::new(span, message).to_compile_error().into(); } }; let EnumInfo { ref name, .. } = enum_info; TokenStream::from(quote! { impl ::core::default::Default for #name { #[inline] fn default() -> Self { Self::#default_ident } } }) }