Function parse_url_stream

codegen/src/util.rs:11–55

Parse url and return url token stream. A URL can be an expression.

(attr: &TokenStream)

/// Parse url and return url token stream.
/// A URL can be an expression.
pub fn parse_url_stream(attr: &TokenStream) -> syn::Result<proc_macro2::TokenStream> {
    let attr_str = attr.to_string();
    if attr_str.is_empty() {
        return Err(syn::Error::new(
            proc_macro2::Span::call_site(),
            "no metadata assign",
        ));
    }

    let attrs = attr_str.split(",");
    let exprs: Vec<&str> = attrs.into_iter().map(|u| u).collect();
    // The default starting expression is the URL.
    if let Some(expr_str) = exprs.first() {
        let expr_str = expr_str.trim();
        let url_expr = syn::parse::<syn::Expr>(TokenStream::from_str(expr_str).unwrap())?;
        let url_stream = parse_url(&url_expr)?;

        // Skip the url.
        for i in 1..exprs.len() {
            let exp_str = exprs[i].trim();
            let url_expr = syn::parse::<syn::Expr>(TokenStream::from_str(exp_str).unwrap())?;

            match url_expr {
                // An assignment path: path = xxx.
                syn::Expr::Assign(assign) => {
                    let left = &assign.left;
                    if let syn::Expr::Path(ref k) = **left {
                        let key = k.path.segments.last().unwrap().ident.to_string();
                        if key == "path" {
                            let right = &assign.right;
                            // Url + path.
                            return Ok(quote!(#url_stream .to_string() + #right));
                        }
                    }
                }
                _ => {}
            }
        }
        return Ok(quote!(#url_stream .to_string()));
    }
    Err(syn::Error::new(
        proc_macro2::Span::call_site(),
        "no metadata assign",
    ))
}

/// Parse and validate the url.
pub fn parse_url(url_expr: &syn::Expr) -> syn::Result<proc_macro2::TokenStream> {