forked from mirrors/gecko-dev
72 lines
2.2 KiB
Rust
72 lines
2.2 KiB
Rust
use syn::{
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visit_mut::{visit_file_mut, visit_item_mod_mut, VisitMut},
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File, Item, ItemForeignMod, ItemMod,
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};
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pub(super) fn merge_extern_blocks(file: &mut File) {
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Visitor.visit_file_mut(file)
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}
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struct Visitor;
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impl VisitMut for Visitor {
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fn visit_file_mut(&mut self, file: &mut File) {
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visit_items(&mut file.items);
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visit_file_mut(self, file)
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}
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fn visit_item_mod_mut(&mut self, item_mod: &mut ItemMod) {
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if let Some((_, ref mut items)) = item_mod.content {
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visit_items(items);
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}
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visit_item_mod_mut(self, item_mod)
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}
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}
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fn visit_items(items: &mut Vec<Item>) {
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// Keep all the extern blocks in a different `Vec` for faster search.
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let mut extern_blocks = Vec::<ItemForeignMod>::new();
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for item in std::mem::take(items) {
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if let Item::ForeignMod(ItemForeignMod {
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attrs,
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abi,
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brace_token,
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unsafety,
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items: extern_block_items,
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}) = item
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{
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let mut exists = false;
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for extern_block in &mut extern_blocks {
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// Check if there is a extern block with the same ABI and
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// attributes.
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if extern_block.attrs == attrs && extern_block.abi == abi {
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// Merge the items of the two blocks.
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extern_block.items.extend_from_slice(&extern_block_items);
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exists = true;
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break;
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}
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}
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// If no existing extern block had the same ABI and attributes, store
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// it.
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if !exists {
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extern_blocks.push(ItemForeignMod {
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attrs,
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abi,
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brace_token,
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unsafety,
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items: extern_block_items,
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});
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}
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} else {
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// If the item is not an extern block, we don't have to do anything and just
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// push it back.
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items.push(item);
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}
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}
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// Move all the extern blocks alongside the rest of the items.
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for extern_block in extern_blocks {
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items.push(Item::ForeignMod(extern_block));
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}
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}
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