src/libsyntax_ext/env.rs

   1 // The compiler code necessary to support the env! extension.  Eventually this
   2 // should all get sucked into either the compiler syntax extension plugin
   3 // interface.
   4 //
   5
   6 use syntax::ast::{self, Ident, GenericArg};
   7 use syntax::ext::base::{self, *};
   8 use syntax::symbol::{kw, sym, Symbol};
   9 use syntax_pos::Span;
  10 use syntax::tokenstream::TokenStream;
  11
  12 use std::env;
  13
  14 pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
  15                               sp: Span,
  16                               tts: TokenStream)
  17                               -> Box<dyn base::MacResult + 'cx> {
  18     let var = match get_single_str_from_tts(cx, sp, tts, "option_env!") {
  19         None => return DummyResult::any(sp),
  20         Some(v) => v,
  21     };
  22
  23     let sp = cx.with_def_site_ctxt(sp);
  24     let e = match env::var(&*var.as_str()) {
  25         Err(..) => {
  26             let lt = cx.lifetime(sp, Ident::new(kw::StaticLifetime, sp));
  27             cx.expr_path(cx.path_all(sp,
  28                                      true,
  29                                      cx.std_path(&[sym::option, sym::Option, sym::None]),
  30                                      vec![GenericArg::Type(cx.ty_rptr(sp,
  31                                                      cx.ty_ident(sp,
  32                                                                  Ident::new(sym::str, sp)),
  33                                                      Some(lt),
  34                                                      ast::Mutability::Immutable))],
  35                                      ))
  36         }
  37         Ok(s) => {
  38             cx.expr_call_global(sp,
  39                                 cx.std_path(&[sym::option, sym::Option, sym::Some]),
  40                                 vec![cx.expr_str(sp, Symbol::intern(&s))])
  41         }
  42     };
  43     MacEager::expr(e)
  44 }
  45
  46 pub fn expand_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
  47                        sp: Span,
  48                        tts: TokenStream)
  49                        -> Box<dyn base::MacResult + 'cx> {
  50     let mut exprs = match get_exprs_from_tts(cx, sp, tts) {
  51         Some(ref exprs) if exprs.is_empty() => {
  52             cx.span_err(sp, "env! takes 1 or 2 arguments");
  53             return DummyResult::any(sp);
  54         }
  55         None => return DummyResult::any(sp),
  56         Some(exprs) => exprs.into_iter(),
  57     };
  58
  59     let var = match expr_to_string(cx, exprs.next().unwrap(), "expected string literal") {
  60         None => return DummyResult::any(sp),
  61         Some((v, _style)) => v,
  62     };
  63     let msg = match exprs.next() {
  64         None => Symbol::intern(&format!("environment variable `{}` not defined", var)),
  65         Some(second) => {
  66             match expr_to_string(cx, second, "expected string literal") {
  67                 None => return DummyResult::any(sp),
  68                 Some((s, _style)) => s,
  69             }
  70         }
  71     };
  72
  73     if exprs.next().is_some() {
  74         cx.span_err(sp, "env! takes 1 or 2 arguments");
  75         return DummyResult::any(sp);
  76     }
  77
  78     let e = match env::var(&*var.as_str()) {
  79         Err(_) => {
  80             cx.span_err(sp, &msg.as_str());
  81             return DummyResult::any(sp);
  82         }
  83         Ok(s) => cx.expr_str(sp, Symbol::intern(&s)),
  84     };
  85     MacEager::expr(e)
  86 }