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extern crate proc_macro;
use std::env;
use syn::punctuated::Punctuated;
use syn::parse::Parser;
use syn::Token;
use proc_macro::TokenStream;
use proc_macro_hack::proc_macro_hack;
use quote::quote;
#[proc_macro_hack]
pub fn dotenv(input: TokenStream) -> TokenStream {
if let Err(err) = dotenv::dotenv() {
if let dotenv::Error::LineParse(ref line) = err {
panic!("Error parsing .env file: {}", line);
} else {
panic!("Error loading .env file: {}", err);
}
}
expand_env(input)
}
fn expand_env(input_raw: TokenStream) -> TokenStream {
let args = <Punctuated<syn::LitStr, Token![,]>>::parse_terminated.parse(input_raw)
.expect("expected macro to be called with a comma-separated list of string literals");
let mut iter = args.iter();
let var_name = match iter.next() {
Some(s) => s.value(),
None => panic!("expected 1 or 2 arguments, found none"),
};
let err_msg = match iter.next() {
Some(lit) => lit.value(),
None => format!("environment variable `{}` not defined", var_name).into(),
};
if iter.next().is_some() {
panic!("expected 1 or 2 arguments, found 3 or more");
}
match env::var(var_name) {
Ok(val) => quote!(#val).into(),
Err(_) => panic!("{}", err_msg),
}
}