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/*
* The compiler code necessary to support the #env extension. Eventually this
* should all get sucked into either the compiler syntax extension plugin
* interface.
*/
import std::ivec;
import std::option;
import std::generic_os;
import base::*;
export expand_syntax_ext;
fn expand_syntax_ext(cx: &ext_ctxt, sp: codemap::span, arg: @ast::expr,
body: option::t[str]) -> @ast::expr {
let args: (@ast::expr)[] = alt arg.node {
ast::expr_vec(elts, _, _) { elts }
_ { cx.span_fatal(sp, "#env requires arguments of the form `[...]`.") }
};
if ivec::len[@ast::expr](args) != 1u {
cx.span_fatal(sp, "malformed #env call");
}
// FIXME: if this was more thorough it would manufacture an
// option::t[str] rather than just an maybe-empty string.
let var = expr_to_str(cx, args.(0), "#env requires a string");
alt generic_os::getenv(var) {
option::none. { ret make_new_str(cx, sp, ""); }
option::some(s) { ret make_new_str(cx, sp, s); }
}
}
fn make_new_str(cx: &ext_ctxt, sp: codemap::span, s: str) -> @ast::expr {
ret make_new_lit(cx, sp, ast::lit_str(s, ast::sk_rc));
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//
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