deranged-macros 0.3.0

Ranged integers
Documentation 
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//! Representation of all fixed-size primitive integers.

use proc_macro::{Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};

use crate::helpers::{compile_error, with_span};
use crate::Integer;

/// The minimum and maximum values for a primitive integer.
#[derive(Debug)]
enum MinMax {
    #[allow(clippy::missing_docs_in_private_items)]
    U8(u8, u8),
    #[allow(clippy::missing_docs_in_private_items)]
    U16(u16, u16),
    #[allow(clippy::missing_docs_in_private_items)]
    U32(u32, u32),
    #[allow(clippy::missing_docs_in_private_items)]
    U64(u64, u64),
    #[allow(clippy::missing_docs_in_private_items)]
    U128(u128, u128),
    #[allow(clippy::missing_docs_in_private_items)]
    I8(i8, i8),
    #[allow(clippy::missing_docs_in_private_items)]
    I16(i16, i16),
    #[allow(clippy::missing_docs_in_private_items)]
    I32(i32, i32),
    #[allow(clippy::missing_docs_in_private_items)]
    I64(i64, i64),
    #[allow(clippy::missing_docs_in_private_items)]
    I128(i128, i128),
}

/// The spans for the minimum and maximum values in [`MinMax`].
#[derive(Debug)]
struct MinMaxSpan(Span, Span);

/// A min-max spanned pair of primitive integers.
#[derive(Debug)]
pub(crate) struct Type<const OPTIONAL: bool>(MinMax, MinMaxSpan);

impl<const OPTIONAL: bool> Type<OPTIONAL> {
    /// Obtain the primitive integer type from a minimum-maximum pair.
    pub(crate) fn from_min_max(min: &Integer, max: &Integer) -> Result<Self, TokenStream> {
        let spans = MinMaxSpan(min.span, max.span);

        if let (Some(min_value), Some(max_value)) = (min.to_unsigned(), max.to_unsigned()) {
            Ok(Self(MinMax::U8(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_unsigned(), max.to_unsigned()) {
            Ok(Self(MinMax::U16(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_unsigned(), max.to_unsigned()) {
            Ok(Self(MinMax::U32(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_unsigned(), max.to_unsigned()) {
            Ok(Self(MinMax::U64(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_unsigned(), max.to_unsigned()) {
            Ok(Self(MinMax::U128(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_signed(), max.to_signed()) {
            Ok(Self(MinMax::I8(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_signed(), max.to_signed()) {
            Ok(Self(MinMax::I16(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_signed(), max.to_signed()) {
            Ok(Self(MinMax::I32(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_signed(), max.to_signed()) {
            Ok(Self(MinMax::I64(min_value, max_value), spans))
        } else if let (Some(min_value), Some(max_value)) = (min.to_signed(), max.to_signed()) {
            Ok(Self(MinMax::I128(min_value, max_value), spans))
        } else {
            Err(compile_error(
                "minimum and maximum values cannot be represented by any one primitive integer",
                None,
            ))
        }
    }

    /// Convert a type into a `TokenStream`.
    pub(crate) fn into_tokens(self) -> TokenStream {
        #[allow(clippy::missing_docs_in_private_items)]
        macro_rules! maybe_optional {
            ($name:literal) => {
                if OPTIONAL {
                    concat!("Option", $name)
                } else {
                    $name
                }
            };
        }

        let Self(min_max, span) = self;
        let MinMaxSpan(min_span, max_span) = span;

        let (type_name, min_token, max_token) = match min_max {
            MinMax::U8(min, max) => (
                maybe_optional!("RangedU8"),
                Literal::u8_unsuffixed(min),
                Literal::u8_unsuffixed(max),
            ),
            MinMax::U16(min, max) => (
                maybe_optional!("RangedU16"),
                Literal::u16_unsuffixed(min),
                Literal::u16_unsuffixed(max),
            ),
            MinMax::U32(min, max) => (
                maybe_optional!("RangedU32"),
                Literal::u32_unsuffixed(min),
                Literal::u32_unsuffixed(max),
            ),
            MinMax::U64(min, max) => (
                maybe_optional!("RangedU64"),
                Literal::u64_unsuffixed(min),
                Literal::u64_unsuffixed(max),
            ),
            MinMax::U128(min, max) => (
                maybe_optional!("RangedU128"),
                Literal::u128_unsuffixed(min),
                Literal::u128_unsuffixed(max),
            ),
            MinMax::I8(min, max) => (
                maybe_optional!("RangedI8"),
                Literal::i8_unsuffixed(min),
                Literal::i8_unsuffixed(max),
            ),
            MinMax::I16(min, max) => (
                maybe_optional!("RangedI16"),
                Literal::i16_unsuffixed(min),
                Literal::i16_unsuffixed(max),
            ),
            MinMax::I32(min, max) => (
                maybe_optional!("RangedI32"),
                Literal::i32_unsuffixed(min),
                Literal::i32_unsuffixed(max),
            ),
            MinMax::I64(min, max) => (
                maybe_optional!("RangedI64"),
                Literal::i64_unsuffixed(min),
                Literal::i64_unsuffixed(max),
            ),
            MinMax::I128(min, max) => (
                maybe_optional!("RangedI128"),
                Literal::i128_unsuffixed(min),
                Literal::i128_unsuffixed(max),
            ),
        };

        TokenStream::from_iter([
            TokenTree::Punct(Punct::new(':', Spacing::Joint)),
            TokenTree::Punct(Punct::new(':', Spacing::Alone)),
            TokenTree::Ident(Ident::new("deranged", Span::mixed_site())),
            TokenTree::Punct(Punct::new(':', Spacing::Joint)),
            TokenTree::Punct(Punct::new(':', Spacing::Alone)),
            TokenTree::Ident(Ident::new(type_name, Span::call_site())),
            TokenTree::Punct(Punct::new(':', Spacing::Joint)),
            TokenTree::Punct(Punct::new(':', Spacing::Alone)),
            TokenTree::Punct(Punct::new('<', Spacing::Alone)),
            with_span(TokenTree::Literal(min_token), min_span),
            TokenTree::Punct(Punct::new(',', Spacing::Alone)),
            with_span(TokenTree::Literal(max_token), max_span),
            TokenTree::Punct(Punct::new('>', Spacing::Alone)),
        ])
    }
}