1 // The compiler code necessary to support the env! extension. Eventually this
2 // should all get sucked into either the compiler syntax extension plugin
6 use syntax::ast::{self, Ident, GenericArg};
7 use syntax::ext::base::*;
9 use syntax::ext::build::AstBuilder;
10 use syntax::symbol::{keywords, Symbol};
12 use syntax::tokenstream;
16 pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt,
18 tts: &[tokenstream::TokenTree])
19 -> Box<dyn base::MacResult + 'cx> {
20 let var = match get_single_str_from_tts(cx, sp, tts, "option_env!") {
21 None => return DummyResult::expr(sp),
25 let sp = sp.apply_mark(cx.current_expansion.mark);
26 let e = match env::var(&*var.as_str()) {
28 let lt = cx.lifetime(sp, keywords::StaticLifetime.ident());
29 cx.expr_path(cx.path_all(sp,
31 cx.std_path(&["option", "Option", "None"]),
32 vec![GenericArg::Type(cx.ty_rptr(sp,
33 cx.ty_ident(sp, Ident::from_str("str")),
35 ast::Mutability::Immutable))],
39 cx.expr_call_global(sp,
40 cx.std_path(&["option", "Option", "Some"]),
41 vec![cx.expr_str(sp, Symbol::intern(&s))])
47 pub fn expand_env<'cx>(cx: &'cx mut ExtCtxt,
49 tts: &[tokenstream::TokenTree])
50 -> Box<dyn base::MacResult + 'cx> {
51 let mut exprs = match get_exprs_from_tts(cx, sp, tts) {
52 Some(ref exprs) if exprs.is_empty() => {
53 cx.span_err(sp, "env! takes 1 or 2 arguments");
54 return DummyResult::expr(sp);
56 None => return DummyResult::expr(sp),
57 Some(exprs) => exprs.into_iter(),
60 let var = match expr_to_string(cx, exprs.next().unwrap(), "expected string literal") {
61 None => return DummyResult::expr(sp),
62 Some((v, _style)) => v,
64 let msg = match exprs.next() {
65 None => Symbol::intern(&format!("environment variable `{}` not defined", var)),
67 match expr_to_string(cx, second, "expected string literal") {
68 None => return DummyResult::expr(sp),
69 Some((s, _style)) => s,
74 if exprs.next().is_some() {
75 cx.span_err(sp, "env! takes 1 or 2 arguments");
76 return DummyResult::expr(sp);
79 let e = match env::var(&*var.as_str()) {
81 cx.span_err(sp, &msg.as_str());
84 Ok(s) => cx.expr_str(sp, Symbol::intern(&s)),