src/librustdoc/passes/propagate_doc_cfg.rs

   1 // Copyright 2017 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 use std::sync::Arc;
  12
  13 use clean::{Crate, Item};
  14 use clean::cfg::Cfg;
  15 use fold::DocFolder;
  16
  17 pub fn propagate_doc_cfg(cr: Crate) -> Crate {
  18     CfgPropagator { parent_cfg: None }.fold_crate(cr)
  19 }
  20
  21 struct CfgPropagator {
  22     parent_cfg: Option<Arc<Cfg>>,
  23 }
  24
  25 impl DocFolder for CfgPropagator {
  26     fn fold_item(&mut self, mut item: Item) -> Option<Item> {
  27         let old_parent_cfg = self.parent_cfg.clone();
  28
  29         let new_cfg = match (self.parent_cfg.take(), item.attrs.cfg.take()) {
  30             (None, None) => None,
  31             (Some(rc), None) | (None, Some(rc)) => Some(rc),
  32             (Some(mut a), Some(b)) => {
  33                 let b = Arc::try_unwrap(b).unwrap_or_else(|rc| Cfg::clone(&rc));
  34                 *Arc::make_mut(&mut a) &= b;
  35                 Some(a)
  36             }
  37         };
  38         self.parent_cfg = new_cfg.clone();
  39         item.attrs.cfg = new_cfg;
  40
  41         let result = self.fold_item_recur(item);
  42         self.parent_cfg = old_parent_cfg;
  43
  44         result
  45     }
  46 }