src/libsyntax/ext/env.rs

   1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 /*
  12  * The compiler code necessary to support the env! extension.  Eventually this
  13  * should all get sucked into either the compiler syntax extension plugin
  14  * interface.
  15  */
  16
  17 use ast;
  18 use codemap::Span;
  19 use ext::base::*;
  20 use ext::base;
  21 use ext::build::AstBuilder;
  22 use parse::token;
  23
  24 use std::os;
  25
  26 pub fn expand_option_env(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
  27                          -> Box<base::MacResult> {
  28     let var = match get_single_str_from_tts(cx, sp, tts, "option_env!") {
  29         None => return DummyResult::expr(sp),
  30         Some(v) => v
  31     };
  32
  33     let e = match os::getenv(var.as_slice()) {
  34       None => {
  35           cx.expr_path(cx.path_all(sp,
  36                                    true,
  37                                    vec!(cx.ident_of("std"),
  38                                         cx.ident_of("option"),
  39                                         cx.ident_of("None")),
  40                                    Vec::new(),
  41                                    vec!(cx.ty_rptr(sp,
  42                                                    cx.ty_ident(sp,
  43                                                         cx.ident_of("str")),
  44                                                    Some(cx.lifetime(sp,
  45                                                         cx.ident_of(
  46                                                             "'static").name)),
  47                                                    ast::MutImmutable))))
  48       }
  49       Some(s) => {
  50           cx.expr_call_global(sp,
  51                               vec!(cx.ident_of("std"),
  52                                    cx.ident_of("option"),
  53                                    cx.ident_of("Some")),
  54                               vec!(cx.expr_str(sp,
  55                                                token::intern_and_get_ident(
  56                                           s.as_slice()))))
  57       }
  58     };
  59     MacExpr::new(e)
  60 }
  61
  62 pub fn expand_env(cx: &mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
  63                   -> Box<base::MacResult> {
  64     let exprs = match get_exprs_from_tts(cx, sp, tts) {
  65         Some(ref exprs) if exprs.len() == 0 => {
  66             cx.span_err(sp, "env! takes 1 or 2 arguments");
  67             return DummyResult::expr(sp);
  68         }
  69         None => return DummyResult::expr(sp),
  70         Some(exprs) => exprs
  71     };
  72
  73     let var = match expr_to_string(cx,
  74                                 *exprs.get(0),
  75                                 "expected string literal") {
  76         None => return DummyResult::expr(sp),
  77         Some((v, _style)) => v
  78     };
  79     let msg = match exprs.len() {
  80         1 => {
  81             token::intern_and_get_ident(format!("environment variable `{}` \
  82                                                  not defined",
  83                                                 var).as_slice())
  84         }
  85         2 => {
  86             match expr_to_string(cx, *exprs.get(1), "expected string literal") {
  87                 None => return DummyResult::expr(sp),
  88                 Some((s, _style)) => s
  89             }
  90         }
  91         _ => {
  92             cx.span_err(sp, "env! takes 1 or 2 arguments");
  93             return DummyResult::expr(sp);
  94         }
  95     };
  96
  97     let e = match os::getenv(var.get()) {
  98         None => {
  99             cx.span_err(sp, msg.get());
 100             cx.expr_uint(sp, 0)
 101         }
 102         Some(s) => cx.expr_str(sp, token::intern_and_get_ident(s.as_slice()))
 103     };
 104     MacExpr::new(e)
 105 }