use proc_macro::TokenStream;use quote::{format_ident, quote};use syn::{    parse::Parse, parse::ParseStream, parse_macro_input, punctuated::Punctuated, LitInt, Token,}; struct DynamicSpacingInput {    values: Punctuated<DynamicSpacingValue, Token![,]>,} // The input for the derive macro is a list of values.//// When a single value is provided, the standard spacing formula is// used to derive the of spacing values.//// When a tuple of three values is provided, the values are used as// the spacing values directly.enum DynamicSpacingValue {    Single(LitInt),    Tuple(LitInt, LitInt, LitInt),} impl Parse for DynamicSpacingInput {    fn parse(input: ParseStream) -> syn::Result<Self> {        Ok(DynamicSpacingInput {            values: input.parse_terminated(DynamicSpacingValue::parse)?,        })    }} impl Parse for DynamicSpacingValue {    fn parse(input: ParseStream) -> syn::Result<Self> {        if input.peek(syn::token::Paren) {            let content;            syn::parenthesized!(content in input);            let a: LitInt = content.parse()?;            content.parse::<Token![,]>()?;            let b: LitInt = content.parse()?;            content.parse::<Token![,]>()?;            let c: LitInt = content.parse()?;            Ok(DynamicSpacingValue::Tuple(a, b, c))        } else {            Ok(DynamicSpacingValue::Single(input.parse()?))        }    }} /// Derives the spacing method for the `DynamicSpacing` enum.pub fn derive_spacing(input: TokenStream) -> TokenStream {    let input = parse_macro_input!(input as DynamicSpacingInput);     let spacing_ratios: Vec<_> = input        .values        .iter()        .map(|v| {            let variant = match v {                DynamicSpacingValue::Single(n) => {                    format_ident!("Base{:02}", n.base10_parse::<u32>().unwrap())                }                DynamicSpacingValue::Tuple(_, b, _) => {                    format_ident!("Base{:02}", b.base10_parse::<u32>().unwrap())                }            };            match v {                DynamicSpacingValue::Single(n) => {                    let n = n.base10_parse::<f32>().unwrap();                    quote! {                        DynamicSpacing::#variant => match ThemeSettings::get_global(cx).ui_density {                            UiDensity::Compact => (#n - 4.0).max(0.0) / BASE_REM_SIZE_IN_PX,                            UiDensity::Default => #n / BASE_REM_SIZE_IN_PX,                            UiDensity::Comfortable => (#n + 4.0) / BASE_REM_SIZE_IN_PX,                        }                    }                }                DynamicSpacingValue::Tuple(a, b, c) => {                    let a = a.base10_parse::<f32>().unwrap();                    let b = b.base10_parse::<f32>().unwrap();                    let c = c.base10_parse::<f32>().unwrap();                    quote! {                        DynamicSpacing::#variant => match ThemeSettings::get_global(cx).ui_density {                            UiDensity::Compact => #a / BASE_REM_SIZE_IN_PX,                            UiDensity::Default => #b / BASE_REM_SIZE_IN_PX,                            UiDensity::Comfortable => #c / BASE_REM_SIZE_IN_PX,                        }                    }                }            }        })        .collect();     let (variant_names, doc_strings): (Vec<_>, Vec<_>) = input        .values        .iter()        .map(|v| {            let variant = match v {                DynamicSpacingValue::Single(n) => {                    format_ident!("Base{:02}", n.base10_parse::<u32>().unwrap())                }                DynamicSpacingValue::Tuple(_, b, _) => {                    format_ident!("Base{:02}", b.base10_parse::<u32>().unwrap())                }            };            let doc_string = match v {                DynamicSpacingValue::Single(n) => {                    let n = n.base10_parse::<f32>().unwrap();                    let compact = (n - 4.0).max(0.0);                    let comfortable = n + 4.0;                    format!(                        "`{}px`|`{}px`|`{}px (@16px/rem)` - Scales with the user's rem size.",                        compact, n, comfortable                    )                }                DynamicSpacingValue::Tuple(a, b, c) => {                    let a = a.base10_parse::<f32>().unwrap();                    let b = b.base10_parse::<f32>().unwrap();                    let c = c.base10_parse::<f32>().unwrap();                    format!(                        "`{}px`|`{}px`|`{}px (@16px/rem)` - Scales with the user's rem size.",                        a, b, c                    )                }            };            (quote!(#variant), quote!(#doc_string))        })        .unzip();     let expanded = quote! {        /// A dynamic spacing system that adjusts spacing based on        /// [UiDensity].        ///        /// The number following "Base" refers to the base pixel size        /// at the default rem size and spacing settings.        ///        /// When possible, [DynamicSpacing] should be used over manual        /// or built-in spacing values in places dynamic spacing is needed.        #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]        pub enum DynamicSpacing {            #(                #[doc = #doc_strings]                #variant_names,            )*        }         impl DynamicSpacing {            /// Returns the spacing ratio, should only be used internally.            fn spacing_ratio(&self, cx: &WindowContext) -> f32 {                const BASE_REM_SIZE_IN_PX: f32 = 16.0;                match self {                    #(#spacing_ratios,)*                }            }             /// Returns the spacing value in rems.            pub fn rems(&self, cx: &WindowContext) -> Rems {                rems(self.spacing_ratio(cx))            }             /// Returns the spacing value in pixels.            pub fn px(&self, cx: &WindowContext) -> Pixels {                let ui_font_size_f32: f32 = ThemeSettings::get_global(cx).ui_font_size.into();                px(ui_font_size_f32 * self.spacing_ratio(cx))            }        }    };     TokenStream::from(expanded)}