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|
use proc_macro::TokenStream;
use quote::quote;
use syn::{Expr, ExprLit, Ident, Item, ItemMod, Lit, LitStr, parse_macro_input};
#[proc_macro_attribute]
pub fn constants(attr: TokenStream, item: TokenStream) -> TokenStream {
let prefix = parse_macro_input!(attr as LitStr).value();
let mut input_mod = parse_macro_input!(item as ItemMod);
if let Some((_, items)) = &mut input_mod.content {
// Collect functions to generate
let mut generated_functions = Vec::new();
for item in items.iter_mut() {
if let Item::Macro(macro_item) = item {
// Check if it's a c! macro call
if macro_item.mac.path.is_ident("c") {
// Parse macro content
let macro_tokens = macro_item.mac.tokens.clone();
let parsed: syn::Result<Expr> = syn::parse2(macro_tokens);
if let Ok(Expr::Assign(assign)) = parsed {
// Get constant name and value
if let Some((const_name, const_value)) =
extract_const_name_and_value(&assign)
{
// Process constant and generate function
if let Some(func) = process_constant(&prefix, const_name, const_value) {
generated_functions.push(func);
}
}
}
}
}
}
for func in generated_functions {
items.push(Item::Verbatim(func));
}
}
TokenStream::from(quote! { #input_mod })
}
fn extract_const_name_and_value(assign: &syn::ExprAssign) -> Option<(Ident, Box<Expr>)> {
if let Expr::Path(path) = &*assign.left {
if let Some(ident) = path.path.get_ident() {
let const_name = ident.clone();
let const_value = assign.right.clone();
return Some((const_name, const_value));
}
}
None
}
fn process_constant(
prefix: &str,
const_name: Ident,
const_value: Box<Expr>,
) -> Option<proc_macro2::TokenStream> {
if let Expr::Lit(ExprLit {
lit: Lit::Str(lit_str),
..
}) = *const_value
{
let value_str = lit_str.value();
let value_span = lit_str.span();
if value_str.contains('{') && value_str.contains('}') {
let params = extract_placeholder_params(&value_str);
if !params.is_empty() {
// With parameters
Some(generate_function_with_params(
prefix,
&const_name,
&value_str,
¶ms,
value_span,
))
} else {
// Without parameters
Some(generate_function_without_params(
prefix,
&const_name,
&value_str,
))
}
} else {
// Without parameters
Some(generate_function_without_params(
prefix,
&const_name,
&value_str,
))
}
} else {
None
}
}
fn extract_placeholder_params(value_str: &str) -> Vec<String> {
let mut params = Vec::new();
let chars = value_str.chars().collect::<Vec<_>>();
let mut i = 0;
while i < chars.len() {
if chars[i] == '{' {
let start = i;
i += 1;
while i < chars.len() && chars[i] != '}' {
i += 1;
}
if i < chars.len() && chars[i] == '}' {
let param: String = chars[start + 1..i].iter().collect();
if !param.is_empty() {
params.push(param);
}
}
}
i += 1;
}
params
}
fn generate_function_with_params(
prefix: &str,
const_name: &Ident,
value_str: &str,
params: &[String],
value_span: proc_macro2::Span,
) -> proc_macro2::TokenStream {
let fn_name = format!("{}_{}", prefix, const_name.to_string().to_lowercase());
let fn_ident = Ident::new(&fn_name, const_name.span());
// Generate parameter list
let param_idents: Vec<Ident> = params.iter().map(|p| Ident::new(p, value_span)).collect();
let format_args = param_idents.iter().map(|ident| quote! { #ident });
// Generate format! code
let doc_format_vaule = params.join(", ");
let mut doc_format_template = value_str.to_string();
for param in params {
let placeholder = format!("{{{}}}", param);
doc_format_template = doc_format_template.replace(&placeholder, "{}");
}
let doc_format_code = format!(
"format!(\"{}\", {});",
doc_format_template, doc_format_vaule
);
// Replace {xxx} with {} format
let mut format_str = value_str.to_string();
for param in params {
format_str = format_str.replace(&format!("{{{}}}", param), "{}");
}
quote! {
#[doc = "```ignore"]
#[doc = #doc_format_code]
#[doc = "```"]
pub fn #fn_ident(#(#param_idents: &str),*) -> String {
format!(#format_str, #(#format_args),*)
}
}
}
fn generate_function_without_params(
prefix: &str,
const_name: &Ident,
value_str: &str,
) -> proc_macro2::TokenStream {
let fn_name = format!("{}_{}", prefix, const_name.to_string().to_lowercase());
let fn_ident = Ident::new(&fn_name, const_name.span());
quote! {
#[doc = "`"]
#[doc = #value_str]
#[doc = "`"]
pub fn #fn_ident() -> &'static str {
#value_str
}
}
}
|
