u_num_it/
lib.rs

1extern crate proc_macro;
2
3use std::{collections::HashMap, str::FromStr};
4
5use proc_macro2::{Literal, Span, TokenStream, TokenTree};
6
7use quote::{quote, ToTokens};
8use syn::{
9    parse::Parse, parse_macro_input, spanned::Spanned, Expr, ExprArray, ExprMatch, Ident, Pat, PatRange,
10    RangeLimits, Token,
11};
12
13#[derive(Hash, PartialEq, Eq, Debug, Clone, Copy)]
14enum UType {
15    N,
16    P,
17    U,
18    False,
19    None,
20    Literal(isize),
21}
22
23impl std::fmt::Display for UType {
24    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
25        match self {
26            UType::N => write!(f, "N"),
27            UType::P => write!(f, "P"),
28            UType::U => write!(f, "U"),
29            UType::False => write!(f, "False"),
30            UType::None => write!(f, ""),
31            UType::Literal(_) => write!(f, ""),
32        }
33    }
34}
35
36struct UNumIt {
37    range: Vec<isize>,
38    arms: HashMap<UType, Box<Expr>>,
39    expr: Box<Expr>,
40}
41
42fn range_boundary(val: &Option<Box<Expr>>) -> syn::Result<Option<isize>> {
43    if let Some(val) = val.clone() {
44        let string = val.to_token_stream().to_string().replace(' ', "");
45        let value = string
46            .parse::<isize>()
47            .map_err(|e| syn::Error::new(val.span(), format!("{e}: `{string}`").as_str()))?;
48
49        Ok(Some(value))
50    } else {
51        Ok(None)
52    }
53}
54
55impl Parse for UNumIt {
56    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
57        // Try to parse as array first, then fallback to range
58        let range: Vec<isize> = if input.peek(syn::token::Bracket) {
59            // Parse array syntax: [1, 2, 8, 22]
60            let array: ExprArray = input.parse()?;
61            array.elems.iter().map(|expr| {
62                let string = expr.to_token_stream().to_string().replace(' ', "");
63                string.parse::<isize>()
64                    .map_err(|e| syn::Error::new(expr.span(), format!("invalid number in array: {e}")))
65            }).collect::<syn::Result<Vec<isize>>>()?
66        } else {
67            // Parse range syntax: 1..10 or 1..=10
68            let range: PatRange = input.parse()?;
69            let start = range_boundary(&range.start)?.unwrap_or(0);
70            let end = range_boundary(&range.end)?.unwrap_or(isize::MAX);
71            match &range.limits {
72                RangeLimits::HalfOpen(_) => (start..end).collect(),
73                RangeLimits::Closed(_) => (start..=end).collect(),
74            }
75        };
76
77        input.parse::<Token![,]>()?;
78        let matcher: ExprMatch = input.parse()?;
79
80        let mut arms = HashMap::new();
81
82        for arm in matcher.arms.iter() {
83            let u_type = match &arm.pat {
84                Pat::Ident(t) => match t.ident.to_token_stream().to_string().as_str() {
85                    "N" => UType::N,
86                    "P" => UType::P,
87                    "U" => UType::U,
88                    "False" => UType::False,
89                    _ => {
90                        return Err(syn::Error::new(
91                            t.span(),
92                            "exepected idents N | P | U, False or _",
93                        ))
94                    }
95                },
96                Pat::Lit(lit_expr) => {
97                    // Parse literal numbers in match arms
98                    let lit_str = lit_expr.to_token_stream().to_string();
99                    let value = lit_str.parse::<isize>().map_err(|e| {
100                        syn::Error::new(lit_expr.span(), format!("invalid literal: {e}"))
101                    })?;
102                    UType::Literal(value)
103                }
104                Pat::Wild(_) => UType::None,
105                _ => return Err(syn::Error::new(arm.pat.span(), "exepected ident")),
106            };
107            let arm_expr = arm.body.clone();
108            if arms.insert(u_type, arm_expr.clone()).is_some() {
109                return Err(syn::Error::new(arm_expr.span(), "duplicate type"));
110            }
111        }
112
113        if arms.get(&UType::P).and(arms.get(&UType::U)).is_some() {
114            return Err(syn::Error::new(
115                matcher.span(),
116                "ambiguous type, don't use P and U in the same macro call",
117            ));
118        }
119
120        // Check for conflict between literal 0 and False (they represent the same value in typenum)
121        if arms.get(&UType::Literal(0)).and(arms.get(&UType::False)).is_some() {
122            return Err(syn::Error::new(
123                matcher.span(),
124                "ambiguous type, don't use literal 0 and False in the same macro call (they represent the same value)",
125            ));
126        }
127
128        let expr = matcher.expr;
129
130        Ok(UNumIt { range, arms, expr })
131    }
132}
133
134fn make_match_arm(i: &isize, body: &Expr, u_type: UType) -> TokenStream {
135    let match_expr = TokenTree::Literal(Literal::from_str(i.to_string().as_str()).unwrap());
136    
137    // Determine the typenum type for all cases
138    let i_str = if *i != 0 {
139        i.abs().to_string()
140    } else {
141        Default::default()
142    };
143    
144    // Determine the type variant based on UType
145    let u_type_for_typenum = match u_type {
146        UType::Literal(val) if val == 0 => UType::False,
147        UType::Literal(val) if val < 0 => UType::N,
148        UType::Literal(val) if val > 0 => UType::P,
149        _ => u_type,
150    };
151    
152    let typenum_type = TokenTree::Ident(Ident::new(
153        format!("{}{}", u_type_for_typenum, i_str).as_str(),
154        Span::mixed_site(),
155    ));
156    let type_variant = quote!(typenum::consts::#typenum_type);
157    
158    // All match arms get NumType and use body as-is (no pattern replacement)
159    let body_tokens = body.to_token_stream();
160    
161    quote! {
162        #match_expr => {
163            type NumType = #type_variant;
164            #body_tokens
165        },
166    }
167}
168
169/// matches `typenum::consts` in a given range or array
170///
171/// use with an open or closed range, or an array of arbitrary numbers
172///
173/// use `P` | `N` | `U` | `False` | `_` or literals `1` | `-1` as match arms
174///
175/// a `NumType` type alias is available in each match arm,
176/// resolving to the specific typenum type for that value.
177/// Use `NumType` to reference the resolved type in the match arm body.
178///
179/// ## Example (range)
180///
181/// ```
182/// let x = 3;
183///
184/// u_num_it::u_num_it!(1..10, match x {
185///     U => {
186///         // NumType is typenum::consts::U3 when x=3
187///         let val = NumType::new();
188///         println!("{:?}", val);
189///         // UInt { msb: UInt { msb: UTerm, lsb: B1 }, lsb: B1 }
190///         
191///         use typenum::ToInt;
192///         let num: usize = NumType::to_int();
193///         assert_eq!(num, 3);
194///     }
195/// })
196/// ```
197///
198/// ## Example (array)
199///
200/// ```
201/// let x = 8;
202///
203/// u_num_it::u_num_it!([1, 2, 8, 22], match x {
204///     P => {
205///         // NumType is typenum::consts::P8 when x=8
206///         use typenum::ToInt;
207///         let num: i32 = NumType::to_int();
208///         assert_eq!(num, 8);
209///     }
210/// })
211/// ```
212#[proc_macro]
213pub fn u_num_it(tokens: proc_macro::TokenStream) -> proc_macro::TokenStream {
214    let UNumIt { range, arms, expr } = parse_macro_input!(tokens as UNumIt);
215
216    let pos_u = arms.get(&UType::U).is_some();
217
218    let expanded_arms = range.iter().filter_map(|i| {
219        // First check if there's a specific literal match for this number
220        if let Some(body) = arms.get(&UType::Literal(*i)) {
221            return Some(make_match_arm(i, body, UType::Literal(*i)));
222        }
223        
224        // Otherwise, use the general type patterns
225        match i {
226            0 => arms
227                .get(&UType::False)
228                .map(|body| make_match_arm(i, body, UType::False)),
229            i if *i < 0 => arms
230                .get(&UType::N)
231                .map(|body| make_match_arm(i, body, UType::N)),
232            i if *i > 0 => {
233                if pos_u {
234                    arms.get(&UType::U)
235                        .map(|body| make_match_arm(i, body, UType::U))
236                } else {
237                    arms.get(&UType::P)
238                        .map(|body| make_match_arm(i, body, UType::P))
239                }
240            }
241            _ => unreachable!(),
242        }
243    });
244
245    let fallback = arms
246        .get(&UType::None)
247        .map(|body| {
248            quote! {
249                _ => {
250                    #body
251                }
252            }
253        })
254        .unwrap_or_else(|| {
255            let first = range.first().unwrap_or(&0);
256            let last = range.last().unwrap_or(&0);
257            quote! {
258                i => unreachable!("{i} is not in range {}-{:?}", #first, #last)
259            }
260        });
261
262    let expanded = quote! {
263        match #expr {
264            #(#expanded_arms)*
265            #fallback
266        }
267    };
268
269    proc_macro::TokenStream::from(expanded)
270}
u_num_it/lib.rs

u_num_it/
lib.rs
