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Revise placement-in expansion to use push/pop_unsafe and move_val_init.

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This commit is contained in:
Felix S. Klock II 2015-06-05 14:21:32 +02:00
parent 866250c6d4
commit d79bbbc4ef
1 changed files with 37 additions and 24 deletions
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61
src/libsyntax/ext/expand.rs
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@ -56,7 +56,7 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
});
}
e.and_then(|ast::Expr {id, node, span}| match node {
return e.and_then(|ast::Expr {id, node, span}| match node {
// expr_mac should really be expr_ext or something; it's the
// entry-point for all syntax extensions.
@ -88,12 +88,11 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
//
// let p = PLACE;
// let mut place = Placer::make_place(p);
// let raw_place = InPlace::pointer(&mut place);
// let value = EXPR;
// unsafe {
// std::ptr::write(raw_place, value);
// let raw_place = Place::pointer(&mut place);
// push_unsafe!({
// std::intrinsics::move_val_init(raw_place, pop_unsafe!( EXPR ));
// InPlace::finalize(place)
// }
// })
let value_span = value_expr.span;
let placer_span = placer.span;
@ -103,17 +102,15 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
let placer_ident = token::gensym_ident("placer");
let agent_ident = token::gensym_ident("place");
let value_ident = token::gensym_ident("value");
let p_ptr_ident = token::gensym_ident("p_ptr");
let placer = fld.cx.expr_ident(span, placer_ident);
let agent = fld.cx.expr_ident(span, agent_ident);
let value = fld.cx.expr_ident(span, value_ident);
let p_ptr = fld.cx.expr_ident(span, p_ptr_ident);
let make_place = ["ops", "Placer", "make_place"];
let place_pointer = ["ops", "Place", "pointer"];
let ptr_write = ["ptr", "write"];
let move_val_init = ["intrinsics", "move_val_init"];
let inplace_finalize = ["ops", "InPlace", "finalize"];
let make_call = |fld: &mut MacroExpander, p, args| {
@ -145,26 +142,23 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
stmt_let(fld, p_ptr_ident, call)
};
// let value = <value_expr>;
let s4 = fld.cx.stmt_let(value_span, false, value_ident, value_expr);
// pop_unsafe!(EXPR));
let pop_unsafe_expr = pop_unsafe_expr(fld.cx, value_expr, value_span);
// unsafe { ptr::write(p_ptr, value); InPlace::finalize(place) }
// push_unsafe!({
// ptr::write(p_ptr, pop_unsafe!(<value_expr>));
// InPlace::finalize(place)
// })
let expr = {
let call_ptr_write = StmtSemi(make_call(
fld, &ptr_write, vec![p_ptr, value]), ast::DUMMY_NODE_ID);
let call_ptr_write = codemap::respan(value_span, call_ptr_write);
let call_move_val_init = StmtSemi(make_call(
fld, &move_val_init, vec![p_ptr, pop_unsafe_expr]), ast::DUMMY_NODE_ID);
let call_move_val_init = codemap::respan(value_span, call_move_val_init);
let call = make_call(fld, &inplace_finalize, vec![agent]);
Some(fld.cx.expr_block(P(ast::Block {
stmts: vec![P(call_ptr_write)],
expr: Some(call),
id: ast::DUMMY_NODE_ID,
rules: ast::UnsafeBlock(ast::CompilerGenerated),
span: span,
})))
Some(push_unsafe_expr(fld.cx, vec![P(call_move_val_init)], call, span))
};
let block = fld.cx.block_all(span, vec![s1, s2, s3, s4], expr);
let block = fld.cx.block_all(span, vec![s1, s2, s3], expr);
fld.cx.expr_block(block)
}
@ -474,7 +468,26 @@ pub fn expand_expr(e: P<ast::Expr>, fld: &mut MacroExpander) -> P<ast::Expr> {
span: span
}, fld))
}
})
});
fn push_unsafe_expr(cx: &mut ExtCtxt, stmts: Vec<P<ast::Stmt>>,
expr: P<ast::Expr>, span: Span)
-> P<ast::Expr> {
let rules = ast::PushUnsafeBlock(ast::CompilerGenerated);
cx.expr_block(P(ast::Block {
rules: rules, span: span, id: ast::DUMMY_NODE_ID,
stmts: stmts, expr: Some(expr),
}))
}
fn pop_unsafe_expr(cx: &mut ExtCtxt, expr: P<ast::Expr>, span: Span)
-> P<ast::Expr> {
let rules = ast::PopUnsafeBlock(ast::CompilerGenerated);
cx.expr_block(P(ast::Block {
rules: rules, span: span, id: ast::DUMMY_NODE_ID,
stmts: vec![], expr: Some(expr),
}))
}
}
/// Expand a (not-ident-style) macro invocation. Returns the result