87 lines
3.1 KiB
Rust
87 lines
3.1 KiB
Rust
// The compiler code necessary to support the env! extension. Eventually this
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// should all get sucked into either the compiler syntax extension plugin
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// interface.
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//
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use syntax::ast::{self, Ident, GenericArg};
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use syntax::ext::base::{self, *};
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use syntax::ext::build::AstBuilder;
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use syntax::symbol::{keywords, Symbol};
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use syntax_pos::Span;
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use syntax::tokenstream;
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use std::env;
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pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
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sp: Span,
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tts: &[tokenstream::TokenTree])
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-> Box<dyn base::MacResult + 'cx> {
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let var = match get_single_str_from_tts(cx, sp, tts, "option_env!") {
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None => return DummyResult::expr(sp),
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Some(v) => v,
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};
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let sp = sp.apply_mark(cx.current_expansion.mark);
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let e = match env::var(&*var.as_str()) {
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Err(..) => {
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let lt = cx.lifetime(sp, keywords::StaticLifetime.ident());
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cx.expr_path(cx.path_all(sp,
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true,
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cx.std_path(&["option", "Option", "None"]),
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vec![GenericArg::Type(cx.ty_rptr(sp,
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cx.ty_ident(sp, Ident::from_str("str")),
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Some(lt),
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ast::Mutability::Immutable))],
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vec![]))
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}
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Ok(s) => {
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cx.expr_call_global(sp,
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cx.std_path(&["option", "Option", "Some"]),
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vec![cx.expr_str(sp, Symbol::intern(&s))])
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}
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};
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MacEager::expr(e)
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}
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pub fn expand_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
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sp: Span,
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tts: &[tokenstream::TokenTree])
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-> Box<dyn base::MacResult + 'cx> {
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let mut exprs = match get_exprs_from_tts(cx, sp, tts) {
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Some(ref exprs) if exprs.is_empty() => {
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cx.span_err(sp, "env! takes 1 or 2 arguments");
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return DummyResult::expr(sp);
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}
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None => return DummyResult::expr(sp),
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Some(exprs) => exprs.into_iter(),
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};
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let var = match expr_to_string(cx, exprs.next().unwrap(), "expected string literal") {
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None => return DummyResult::expr(sp),
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Some((v, _style)) => v,
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};
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let msg = match exprs.next() {
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None => Symbol::intern(&format!("environment variable `{}` not defined", var)),
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Some(second) => {
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match expr_to_string(cx, second, "expected string literal") {
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None => return DummyResult::expr(sp),
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Some((s, _style)) => s,
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}
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}
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};
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if exprs.next().is_some() {
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cx.span_err(sp, "env! takes 1 or 2 arguments");
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return DummyResult::expr(sp);
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}
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let e = match env::var(&*var.as_str()) {
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Err(_) => {
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cx.span_err(sp, &msg.as_str());
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return DummyResult::expr(sp);
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}
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Ok(s) => cx.expr_str(sp, Symbol::intern(&s)),
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};
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MacEager::expr(e)
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}
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