typenum-consts 0.1.1

Procedural macros that take a literal integer (or the result of an evaluation of simple mathematical expressions or an environment variable whose value is a literal integer) and convert it to a `typenum::Unsigned` / `typenum::Integer` type-level positive/negative/unsigned integer.
Documentation 
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use crate::ast::{LitInteger, MathExprs};
use crate::{exprs_impl::eval_exprs, uconst_impl};
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
use syn::{Error, LitInt, Result};

pub(crate) fn tnconst_impl_lit_integer(lit_integer: LitInteger) -> Result<TokenStream2> {
    match lit_integer {
        LitInteger::Unsigned { lit_integer } => uconst_impl::uconst_impl(lit_integer),
        LitInteger::Positive { lit_integer } => pconst_impl(lit_integer),
        LitInteger::Negative { lit_integer } => nconst_impl(lit_integer),
    }
}

pub(crate) fn tnconst_impl_math_exprs(math_exprs: MathExprs) -> Result<TokenStream2> {
    tnconst_impl_lit_integer(eval_exprs(math_exprs)?)
}

pub(crate) fn pconst_impl_lit_integer(lit_integer: LitInteger) -> Result<TokenStream2> {
    match lit_integer {
        LitInteger::Unsigned { lit_integer } => pconst_impl(lit_integer),
        LitInteger::Positive { lit_integer } => pconst_impl(lit_integer),
        LitInteger::Negative { lit_integer } => Err(
            Error::new(lit_integer.span(), "using `pconst![...]` but the inputs to the macro results in an negative literal integer")
        ),
    }
}

pub(crate) fn pconst_impl_math_exprs(math_exprs: MathExprs) -> Result<TokenStream2> {
    pconst_impl_lit_integer(eval_exprs(math_exprs)?)
}

pub(crate) fn nconst_impl_math_exprs(math_exprs: MathExprs) -> Result<TokenStream2> {
    nconst_impl_lit_integer(eval_exprs(math_exprs)?)
}

pub(crate) fn nconst_impl_lit_integer(lit_integer: LitInteger) -> Result<TokenStream2> {
    match lit_integer {
        LitInteger::Unsigned { lit_integer } => Err(
            Error::new(lit_integer.span(), "using `nconst![...]` but the inputs to the macro results in an unsigned literal integer")
        ),
        LitInteger::Positive { lit_integer } => Err(
            Error::new(lit_integer.span(), "using `nconst![...]` but the inputs to the macro results in an positive literal integer")
        ),
        LitInteger::Negative { lit_integer } => nconst_impl(lit_integer),
    }
}

pub(crate) fn uconst_impl_lit_integer(lit_integer: LitInteger) -> Result<TokenStream2> {
    match lit_integer {
        LitInteger::Unsigned { lit_integer } => uconst_impl::uconst_impl(lit_integer),
        LitInteger::Positive { lit_integer } => Err(
            Error::new(lit_integer.span(), "using `uconst![...]` but the inputs to the macro results in an positive literal integer")
        ),
        LitInteger::Negative { lit_integer } => Err(
            Error::new(lit_integer.span(), "using `uconst![...]` but the inputs to the macro results in an negative literal integer")
        ),
    }
}

pub(crate) fn uconst_impl_math_exprs(math_exprs: MathExprs) -> Result<TokenStream2> {
    uconst_impl_lit_integer(eval_exprs(math_exprs)?)
}

/// Fundamental Helper for `pconst![...]`
pub(crate) fn pconst_impl(lit_integer: LitInt) -> Result<TokenStream2> {
    let unsigned_ts = uconst_impl::uconst_impl(lit_integer)?;
    Ok(quote!(
        ::typenum::PInt<#unsigned_ts>
    ))
}

pub(crate) fn nconst_impl(lit_integer: LitInt) -> Result<TokenStream2> {
    let mut lit_integer_ = lit_integer.base10_parse::<isize>()?;
    if lit_integer_ < 0 {
        lit_integer_ *= -1;
    }
    let lit_integer = LitInt::new(format!("{}", lit_integer_).as_str(), lit_integer.span());
    let unsigned_ts = uconst_impl::uconst_impl(lit_integer)?;
    Ok(quote!(
        ::typenum::NInt<#unsigned_ts>
    ))
}