mirror of
https://github.com/carbon-language/carbon-lang.git
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Geoff RomerandJon Meow
6ac3adfa53
`Pattern` is intended to pilot some changes I would like to apply to all our sum types: - The alternatives are expressed as derived classes rather than members of a `std::variant`. - The alternatives are classes in the [style guide sense](https://google.github.io/styleguide/cppguide.html#Structs_vs._Classes), meaning they can have invariants, but can't have public data members. - Creating an object is expressed using a constructor rather than a factory function. - Accessing an alternative is expressed as a cast (using LLVM's RTTI system) rather than `std::get` or a `Get` method. Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
95 lines
2.8 KiB
C++
95 lines
2.8 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 EXECUTABLE_SEMANTICS_INTERPRETER_ACTION_H_
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#define EXECUTABLE_SEMANTICS_INTERPRETER_ACTION_H_
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#include <vector>
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#include "common/ostream.h"
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#include "executable_semantics/ast/expression.h"
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#include "executable_semantics/ast/pattern.h"
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#include "executable_semantics/ast/statement.h"
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#include "executable_semantics/interpreter/stack.h"
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#include "executable_semantics/interpreter/value.h"
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#include "llvm/Support/Compiler.h"
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namespace Carbon {
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enum class ActionKind {
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LValAction,
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ExpressionAction,
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PatternAction,
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StatementAction,
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ValAction,
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};
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struct LValAction {
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static constexpr ActionKind Kind = ActionKind::LValAction;
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const Expression* exp;
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};
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struct ExpressionAction {
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static constexpr ActionKind Kind = ActionKind::ExpressionAction;
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const Expression* exp;
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};
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struct PatternAction {
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static constexpr ActionKind Kind = ActionKind::PatternAction;
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const Pattern* pattern;
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};
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struct StatementAction {
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static constexpr ActionKind Kind = ActionKind::StatementAction;
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const Statement* stmt;
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};
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struct ValAction {
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static constexpr ActionKind Kind = ActionKind::ValAction;
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const Value* val;
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};
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struct Action {
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static auto MakeLValAction(const Expression* e) -> Action*;
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static auto MakeExpressionAction(const Expression* e) -> Action*;
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static auto MakePatternAction(const Pattern* p) -> Action*;
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static auto MakeStatementAction(const Statement* s) -> Action*;
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static auto MakeValAction(const Value* v) -> Action*;
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static void PrintList(const Stack<Action*>& ls, llvm::raw_ostream& out);
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auto GetLValAction() const -> const LValAction&;
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auto GetExpressionAction() const -> const ExpressionAction&;
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auto GetPatternAction() const -> const PatternAction&;
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auto GetStatementAction() const -> const StatementAction&;
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auto GetValAction() const -> const ValAction&;
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void Print(llvm::raw_ostream& out) const;
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LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
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inline auto tag() const -> ActionKind {
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return std::visit([](const auto& t) { return t.Kind; }, value);
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}
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// The position or state of the action. Starts at 0 and goes up to the number
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// of subexpressions.
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//
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// pos indicates how many of the entries in the following `results` vector
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// will be filled in the next time this action is active.
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// For each i < pos, results[i] contains a pointer to a Value.
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int pos = 0;
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// Results from a subexpression.
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std::vector<const Value*> results;
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private:
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std::variant<LValAction, ExpressionAction, PatternAction, StatementAction,
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ValAction>
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value;
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};
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} // namespace Carbon
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#endif // EXECUTABLE_SEMANTICS_INTERPRETER_ACTION_H_
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