pub fn parse<T: Parse>(tokens: TokenStream) -> Result<T>
Expand description
Parse tokens of source code into the chosen syntax tree node.
This is preferred over parsing a string because tokens are able to preserve information about where in the user’s code they were originally written (the “span” of the token), possibly allowing the compiler to produce better error messages.
This function parses a proc_macro::TokenStream
which is the type used for
interop with the compiler in a procedural macro. To parse a
proc_macro2::TokenStream
, use syn::parse2
instead.
This function is available only if Syn is built with both the "parsing"
and
"proc-macro"
features.
Examples
use proc_macro::TokenStream;
use quote::quote;
use syn::DeriveInput;
#[proc_macro_derive(MyMacro)]
pub fn my_macro(input: TokenStream) -> TokenStream {
// Parse the tokens into a syntax tree
let ast: DeriveInput = syn::parse(input).unwrap();
// Build the output, possibly using quasi-quotation
let expanded = quote! {
/* ... */
};
// Convert into a token stream and return it
expanded.into()
}