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// Copyright (C) 2025 Free Software Foundation, Inc.
// This file is part of GCC.
// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.
// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
#include "rust-desugar-question-mark.h"
#include "rust-ast-builder.h"
#include "rust-ast-visitor.h"
namespace Rust {
namespace AST {
DesugarQuestionMark::DesugarQuestionMark () {}
void
DesugarQuestionMark::go (AST::Crate &crate)
{
DesugarQuestionMark::visit (crate);
}
void
DesugarQuestionMark::visit (ExprStmt &stmt)
{
if (stmt.get_expr ().get_expr_kind () == Expr::Kind::ErrorPropagation)
desugar_and_replace (stmt.get_expr_ptr ());
DefaultASTVisitor::visit (stmt);
}
void
DesugarQuestionMark::visit (CallExpr &call)
{
if (call.get_function_expr ().get_expr_kind ()
== Expr::Kind::ErrorPropagation)
desugar_and_replace (call.get_function_expr_ptr ());
for (auto &arg : call.get_params ())
if (arg->get_expr_kind () == Expr::Kind::ErrorPropagation)
desugar_and_replace (arg);
DefaultASTVisitor::visit (call);
}
void
DesugarQuestionMark::visit (LetStmt &stmt)
{
if (stmt.has_init_expr ()
&& stmt.get_init_expr ().get_expr_kind () == Expr::Kind::ErrorPropagation)
desugar_and_replace (stmt.get_init_expr_ptr ());
DefaultASTVisitor::visit (stmt);
}
MatchArm
make_match_arm (std::unique_ptr<Pattern> &&pattern)
{
auto loc = pattern->get_locus ();
auto patterns = std::vector<std::unique_ptr<Pattern>> ();
patterns.emplace_back (std::move (pattern));
return MatchArm (std::move (patterns), loc);
}
MatchCase
ok_case (Builder &builder)
{
auto val = builder.identifier_pattern ("val");
auto patterns = std::vector<std::unique_ptr<Pattern>> ();
patterns.emplace_back (std::move (val));
auto pattern_item = std::unique_ptr<TupleStructItems> (
new TupleStructItemsNoRange (std::move (patterns)));
auto pattern = std::unique_ptr<Pattern> (new TupleStructPattern (
builder.path_in_expression (LangItem::Kind::RESULT_OK),
std::move (pattern_item)));
auto arm = make_match_arm (std::move (pattern));
auto ret_val = builder.identifier ("val");
return MatchCase (std::move (arm), std::move (ret_val));
}
MatchCase
err_case (Builder &builder)
{
auto val = builder.identifier_pattern ("err");
auto patterns = std::vector<std::unique_ptr<Pattern>> ();
patterns.emplace_back (std::move (val));
auto pattern_item = std::unique_ptr<TupleStructItems> (
new TupleStructItemsNoRange (std::move (patterns)));
auto pattern = std::unique_ptr<Pattern> (new TupleStructPattern (
builder.path_in_expression (LangItem::Kind::RESULT_ERR),
std::move (pattern_item)));
auto arm = make_match_arm (std::move (pattern));
auto try_from_err = std::make_unique<PathInExpression> (
builder.path_in_expression (LangItem::Kind::TRY_FROM_ERROR));
auto from_from = std::make_unique<PathInExpression> (
builder.path_in_expression (LangItem::Kind::FROM_FROM));
auto early_return = builder.return_expr (
builder.call (std::move (try_from_err),
builder.call (std::move (from_from),
builder.identifier ("err"))));
return MatchCase (std::move (arm), std::move (early_return));
}
std::unique_ptr<Expr>
DesugarQuestionMark::desugar (ErrorPropagationExpr &expr)
{
auto builder = Builder (expr.get_locus ());
// Try::into_result(<expr>)
auto try_into = std::make_unique<PathInExpression> (
builder.path_in_expression (LangItem::Kind::TRY_INTO_RESULT));
auto call = builder.call (std::move (try_into),
expr.get_propagating_expr ().clone_expr ());
// Ok(val) => val,
auto ok_match_case = ok_case (builder);
// Err(err) => return Try::from_error(From::from(err)),
auto err_match_case = err_case (builder);
auto cases = std::vector<MatchCase> ();
cases.emplace_back (ok_match_case);
cases.emplace_back (err_match_case);
// match <call> {
// <ok_arm>
// <err_arm>
// }
return std::unique_ptr<MatchExpr> (new MatchExpr (std::move (call),
std::move (cases), {}, {},
expr.get_locus ()));
}
void
DesugarQuestionMark::desugar_and_replace (std::unique_ptr<Expr> &ptr)
{
auto original = static_cast<ErrorPropagationExpr &> (*ptr);
auto desugared = desugar (original);
ptr = std::move (desugared);
}
} // namespace AST
} // namespace Rust
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