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83 lines
3.1 KiB
C++
83 lines
3.1 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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#ifndef CARBON_TOOLCHAIN_CHECK_FULL_PATTERN_STACK_H_
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#define CARBON_TOOLCHAIN_CHECK_FULL_PATTERN_STACK_H_
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#include "common/array_stack.h"
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#include "common/check.h"
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#include "toolchain/check/lexical_lookup.h"
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#include "toolchain/sem_ir/ids.h"
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namespace Carbon::Check {
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// Stack of full-patterns currently being checked. When a pattern
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// is followed by an explicit initializer, name bindings should not be used
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// within that initializer, although they are usable before it (within the
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// pattern) and after it. This class keeps track of those state transitions.
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// It is structured as a stack to handle situations like a pattern that
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// contains an initializer, or a pattern in a lambda in an expression pattern.
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//
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// TODO: Unify this with Context::pattern_block_stack, or differentiate them
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// more clearly (and consider unifying this with ScopeStack instead).
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class FullPatternStack {
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public:
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explicit FullPatternStack(LexicalLookup* lookup) : lookup_(lookup) {}
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// Marks the possible start of a new full-pattern (i.e. a pattern which occurs
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// in a non-pattern context).
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auto PushFullPattern() -> void { bind_name_stack_.PushArray(); }
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// Marks the start of the initializer for the full-pattern at the top of the
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// stack.
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auto StartPatternInitializer() -> void {
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for (auto& [name_id, inst_id] : bind_name_stack_.PeekArray()) {
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CARBON_CHECK(inst_id == SemIR::InstId::InitTombstone);
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auto& lookup_result = lookup_->Get(name_id);
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if (!lookup_result.empty()) {
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// TODO: find a way to preserve location information, so that we can
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// provide good diagnostics for a redeclaration of `name_id` in
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// the initializer, if that becomes possible.
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std::swap(lookup_result.back().inst_id, inst_id);
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}
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}
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}
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// Marks the end of the initializer for the full-pattern at the top of the
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// stack.
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auto EndPatternInitializer() -> void {
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for (auto& [name_id, inst_id] : bind_name_stack_.PeekArray()) {
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auto& lookup_result = lookup_->Get(name_id);
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if (!lookup_result.empty()) {
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std::swap(lookup_result.back().inst_id, inst_id);
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}
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CARBON_CHECK(inst_id == SemIR::InstId::InitTombstone);
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}
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}
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// Marks the end of checking for the full-pattern at the top of the stack.
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// This cannot be called while processing an initializer for the top
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// pattern.
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auto PopFullPattern() -> void { bind_name_stack_.PopArray(); }
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// Records that `bind_inst_id` was introduced by the full-pattern at the
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// top of the stack.
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auto AddBindName(SemIR::NameId name_id) -> void {
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bind_name_stack_.AppendToTop(
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{.name_id = name_id, .inst_id = SemIR::InstId::InitTombstone});
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}
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private:
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LexicalLookup* lookup_;
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struct LookupEntry {
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SemIR::NameId name_id;
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SemIR::InstId inst_id;
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};
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ArrayStack<LookupEntry> bind_name_stack_;
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};
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} // namespace Carbon::Check
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#endif // CARBON_TOOLCHAIN_CHECK_FULL_PATTERN_STACK_H_
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