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{"files":{"Cargo.toml":"5c36e95cf82b83461ddd6ccdfb64aad8bedeb2222a87437d8c68eb7201dbe3d2","LICENSE-APACHE":"62c7a1e35f56406896d7aa7ca52d0cc0d272ac022b5d2796e7d6905db8a3636a","LICENSE-BSD":"0be96d891d00e0ae0df75d7f3289b12871c000a1f5ac744f3b570768d4bb277c","LICENSE-MIT":"23f18e03dc49df91622fe2a76176497404e46ced8a715d9d2b67a7446571cca3","README.md":"338e12501163f84e7c9652269672af9b4449798fe29adee921bca33f4f52a99b","src/lib.rs":"ee897da050bac895fadd6a044923d92922697214ea53e8ab07f310933e843db3"},"package":"96667db765a921f7b295ffee8b60472b686a51d4f21c2ee4ffdb94c7013b65a6"}

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# 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 = "2021"
rust-version = "1.56.0"
name = "num_enum_derive"
version = "0.6.1"
authors = [
"Daniel Wagner-Hall <dawagner@gmail.com>",
"Daniel Henry-Mantilla <daniel.henry.mantilla@gmail.com>",
"Vincent Esche <regexident@gmail.com>",
]
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"
resolver = "1"
[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 = "2"
features = ["parsing"]
[features]
complex-expressions = ["syn/full"]
default = ["std"]
external_doc = []
std = ["proc-macro-crate"]

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Copyright (c) 2018, Daniel Wagner-Hall
All rights reserved.
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
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* Neither the name of num_enum nor the names of its
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Permission is hereby granted, free of charge, to any
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num_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 (or the stdlib `#[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::FromPrimitive;
use std::convert::TryFrom;
#[derive(Debug, Eq, PartialEq, FromPrimitive)]
#[repr(u8)]
enum Number {
Zero = 0,
#[num_enum(default)]
NonZero = 1,
}
fn main() {
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);
}
```
Only `FromPrimitive` pays attention to `default` attributes, `TryFromPrimitive` ignores them.
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 unchecked_transmute_from
-----------------------------------------------------------------------
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.
Note that this derive ignores any `default`, `catch_all`, and `alternatives` attributes on the enum.
If you need support for conversions from these values, you should use `TryFromPrimitive` or `FromPrimitive`.
- This means, for instance, that the following is UB:
```rust,no_run
use num_enum::UnsafeFromPrimitive;
#[derive(UnsafeFromPrimitive)]
#[repr(u8)]
enum Number {
Zero = 0,
// Same for `#[num_enum(catch_all)]`, and `#[num_enum(alternatives = [2, ...])]`
#[num_enum(default)]
One = 1,
}
let _undefined_behavior = unsafe { Number::unchecked_transmute_from(2) };
```
```rust
use num_enum::UnsafeFromPrimitive;
#[derive(Debug, Eq, PartialEq, UnsafeFromPrimitive)]
#[repr(u8)]
enum Number {
Zero,
One,
}
fn main() {
assert_eq!(
unsafe { Number::unchecked_transmute_from(0_u8) },
Number::Zero,
);
assert_eq!(
unsafe { Number::unchecked_transmute_from(1_u8) },
Number::One,
);
}
unsafe fn undefined_behavior() {
let _ = Number::unchecked_transmute_from(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.

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// 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, ToTokens};
use std::collections::BTreeSet;
use syn::{
parse::{Parse, ParseStream},
parse_macro_input, parse_quote, Attribute, Data, DeriveInput, Error, Expr, ExprLit, ExprUnary,
Fields, Ident, Lit, LitInt, 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<DiscriminantValue> {
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::<i128>()?,
))
} else {
Ok(DiscriminantValue::Expr(val_exp.clone()))
}
}
#[cfg(feature = "complex-expressions")]
fn parse_alternative_values(val_expr: &Expr) -> Result<Vec<DiscriminantValue>> {
fn range_expr_value_to_number(
parent_range_expr: &Expr,
range_bound_value: &Option<Box<Expr>>,
) -> Result<i128> {
// 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 {
start, end, limits, ..
}) = val_expr
{
let lower = range_expr_value_to_number(val_expr, start)?;
let upper = range_expr_value_to_number(val_expr, end)?;
// 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<Vec<DiscriminantValue>> {
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<NumEnumVariantAttributeItem, syn::Token![,]>,
}
impl Parse for NumEnumVariantAttributes {
fn parse(input: ParseStream<'_>) -> Result<Self> {
Ok(Self {
items: input.parse_terminated(NumEnumVariantAttributeItem::parse, syn::Token![,])?,
})
}
}
enum NumEnumVariantAttributeItem {
Default(VariantDefaultAttribute),
CatchAll(VariantCatchAllAttribute),
Alternatives(VariantAlternativesAttribute),
}
impl Parse for NumEnumVariantAttributeItem {
fn parse(input: ParseStream<'_>) -> Result<Self> {
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<Self> {
Ok(Self {
keyword: input.parse()?,
})
}
}
struct VariantCatchAllAttribute {
keyword: kw::catch_all,
}
impl Parse for VariantCatchAllAttribute {
fn parse(input: ParseStream) -> Result<Self> {
Ok(Self {
keyword: input.parse()?,
})
}
}
struct VariantAlternativesAttribute {
_keyword: kw::alternatives,
_eq_token: syn::Token![=],
_bracket_token: syn::token::Bracket,
expressions: syn::punctuated::Punctuated<Expr, syn::Token![,]>,
}
impl Parse for VariantAlternativesAttribute {
fn parse(input: ParseStream) -> Result<Self> {
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, syn::Token![,])?;
Ok(Self {
_keyword: keyword,
_eq_token,
_bracket_token,
expressions,
})
}
}
struct VariantInfo {
ident: Ident,
is_default: bool,
is_catch_all: bool,
canonical_value: Expr,
alternative_values: Vec<Expr>,
}
impl VariantInfo {
fn all_values(&self) -> impl Iterator<Item = &Expr> {
::core::iter::once(&self.canonical_value).chain(self.alternative_values.iter())
}
}
struct EnumInfo {
name: Ident,
repr: Ident,
variants: Vec<VariantInfo>,
}
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<bool> {
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 suffix == "size" {
return Ok(false);
} else if let Ok(bits) = suffix.parse::<u32>() {
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 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 variant_idents(&self) -> Vec<Ident> {
self.variants
.iter()
.map(|variant| variant.ident.clone())
.collect()
}
fn expression_idents(&self) -> Vec<Vec<Ident>> {
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<Vec<Expr>> {
self.variants
.iter()
.map(|variant| variant.all_values().cloned().collect())
.collect()
}
}
impl Parse for EnumInfo {
fn parse(input: ParseStream) -> Result<Self> {
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 Meta::List(meta_list) = &attr.meta {
if let Some(ident) = meta_list.path.get_ident() {
if ident == "repr" {
let mut nested = meta_list.tokens.clone().into_iter();
let repr = match (nested.next(), nested.next()) {
(Some(repr), None) => repr,
_ => die!(attr =>
"Expected exactly one `repr` argument"
),
};
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<VariantInfo> = 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 raw_alternative_values: Vec<Expr> = 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`"
);
}
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`"
);
}
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::<Vec<_>>()
.as_slice()
{
[syn::Field {
ty: syn::Type::Path(syn::TypePath { path, .. }),
..
}] if path.is_ident(&repr) => {
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) => {
raw_alternative_values.extend(alternatives.expressions);
alt_attr_ref.push(attribute);
}
}
}
}
Err(err) => {
if cfg!(not(feature = "complex-expressions")) {
let tokens = attribute.meta.to_token_stream();
let attribute_str = format!("{}", 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::<Result<Vec<i128>>>()?;
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,
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<Primitive>` for a `#[repr(Primitive)] enum`.
///
/// (It actually implements `From<Enum> 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<Primitive>` 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<Ident> = enum_info.variant_idents();
let expression_idents: Vec<Vec<Ident>> = enum_info.expression_idents();
let variant_expressions: Vec<Vec<Expr>> = 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)
}
}
#[doc(hidden)]
impl ::#krate::CannotDeriveBothFromPrimitiveAndTryFromPrimitive for #name {}
})
}
/// Implements `TryFrom<Primitive>` 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<Ident> = enum_info.variant_idents();
let expression_idents: Vec<Vec<Ident>> = enum_info.expression_idents();
let variant_expressions: Vec<Vec<Expr>> = enum_info.variant_expressions();
debug_assert_eq!(variant_idents.len(), variant_expressions.len());
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<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 )|*
=> ::core::result::Result::Ok(Self::#variant_idents),
)*
#[allow(unreachable_patterns)]
_ => ::core::result::Result::Err(
::#krate::TryFromPrimitiveError { number }
),
}
}
}
impl ::core::convert::TryFrom<#repr> for #name {
type Error = ::#krate::TryFromPrimitiveError<Self>;
#[inline]
fn try_from (
number: #repr,
) -> ::core::result::Result<Self, ::#krate::TryFromPrimitiveError<Self>>
{
::#krate::TryFromPrimitive::try_from_primitive(number)
}
}
#[doc(hidden)]
impl ::#krate::CannotDeriveBothFromPrimitiveAndTryFromPrimitive for #name {}
})
}
#[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 unchecked_transmute_from(number: Primitive) -> Self`
/// associated function.
///
/// Allows unsafely turning a primitive into an enum with unchecked_transmute_from
/// ------------------------------------------------------------------------------
///
/// 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.
///
/// Note that this derive ignores any `default`, `catch_all`, and `alternatives` attributes on the enum.
/// If you need support for conversions from these values, you should use `TryFromPrimitive` or `FromPrimitive`.
///
/// ```rust
/// use num_enum::UnsafeFromPrimitive;
///
/// #[derive(Debug, Eq, PartialEq, UnsafeFromPrimitive)]
/// #[repr(u8)]
/// enum Number {
/// Zero,
/// One,
/// }
///
/// fn main() {
/// assert_eq!(
/// Number::Zero,
/// unsafe { Number::unchecked_transmute_from(0_u8) },
/// );
/// assert_eq!(
/// Number::One,
/// unsafe { Number::unchecked_transmute_from(1_u8) },
/// );
/// }
///
/// unsafe fn undefined_behavior() {
/// let _ = Number::unchecked_transmute_from(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);
let krate = Ident::new(&get_crate_name(), Span::call_site());
let EnumInfo {
ref name, ref repr, ..
} = enum_info;
TokenStream::from(quote! {
impl ::#krate::UnsafeFromPrimitive for #name {
type Primitive = #repr;
unsafe fn unchecked_transmute_from(number: Self::Primitive) -> 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, <Number as ::core::default::Default>::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
}
}
})
}