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https://github.com/carbon-language/carbon-lang.git
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SlaterLatiao
9106e9239e
This PR implements the `returned var` for the explorer. - Enabled `returned var` and `return var` syntax in lexer and parser. - Split `Return` statement into `ReturnVar` and `ReturnExpression` to distinguish the two types of returns. - Added logic in name resolution, type checking and interpretation to process `returned var` definition and `ReturnVar` statement.
103 lines
3.5 KiB
C++
103 lines
3.5 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "explorer/ast/static_scope.h"
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#include <optional>
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#include "explorer/common/error_builders.h"
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#include "llvm/Support/Error.h"
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namespace Carbon {
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auto StaticScope::Add(const std::string& name, ValueNodeView entity,
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bool usable) -> ErrorOr<Success> {
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auto [it, inserted] = declared_names_.insert({name, {entity, usable}});
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if (!inserted) {
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if (it->second.entity != entity) {
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return CompilationError(entity.base().source_loc())
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<< "Duplicate name `" << name << "` also found at "
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<< it->second.entity.base().source_loc();
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}
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CARBON_CHECK(usable || !it->second.usable)
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<< entity.base().source_loc() << " attempting to mark a usable name `"
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<< name << "` as unusable";
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it->second.usable |= usable;
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}
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return Success();
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}
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void StaticScope::MarkUsable(const std::string& name) {
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auto it = declared_names_.find(name);
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CARBON_CHECK(it != declared_names_.end()) << name << " not found";
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it->second.usable = true;
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}
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auto StaticScope::Resolve(const std::string& name,
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SourceLocation source_loc) const
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-> ErrorOr<ValueNodeView> {
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CARBON_ASSIGN_OR_RETURN(std::optional<ValueNodeView> result,
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TryResolve(name, source_loc));
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if (!result) {
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return CompilationError(source_loc) << "could not resolve '" << name << "'";
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}
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return *result;
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}
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auto StaticScope::TryResolve(const std::string& name,
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SourceLocation source_loc) const
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-> ErrorOr<std::optional<ValueNodeView>> {
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auto it = declared_names_.find(name);
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if (it != declared_names_.end()) {
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if (!it->second.usable) {
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return CompilationError(source_loc)
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<< "'" << name
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<< "' is not usable until after it has been completely declared";
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}
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return std::make_optional(it->second.entity);
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}
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std::optional<ValueNodeView> result;
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for (Nonnull<const StaticScope*> parent : parent_scopes_) {
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CARBON_ASSIGN_OR_RETURN(std::optional<ValueNodeView> parent_result,
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parent->TryResolve(name, source_loc));
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if (parent_result.has_value() && result.has_value() &&
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*parent_result != *result) {
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return CompilationError(source_loc)
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<< "'" << name << "' is ambiguous between "
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<< result->base().source_loc() << " and "
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<< parent_result->base().source_loc();
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}
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result = parent_result;
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}
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return result;
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}
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auto StaticScope::AddReturnedVar(ValueNodeView returned_var_def_view)
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-> ErrorOr<Success> {
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std::optional<ValueNodeView> resolved_returned_var = ResolveReturned();
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if (resolved_returned_var.has_value()) {
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return CompilationError(returned_var_def_view.base().source_loc())
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<< "Duplicate definition of returned var also found at "
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<< resolved_returned_var->base().source_loc();
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}
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returned_var_def_view_ = std::move(returned_var_def_view);
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return Success();
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}
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auto StaticScope::ResolveReturned() const -> std::optional<ValueNodeView> {
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if (returned_var_def_view_.has_value()) {
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return returned_var_def_view_;
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}
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for (Nonnull<const StaticScope*> parent : parent_scopes_) {
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std::optional<ValueNodeView> parent_returned_var =
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parent->ResolveReturned();
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if (parent_returned_var.has_value()) {
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return parent_returned_var;
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}
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}
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return std::nullopt;
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}
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} // namespace Carbon
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