mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 21:50:14 +01:00
Geoff Romer
d71f5b1784
This enables the interpreter logic to express its intent more directly, especially in the common cases, and enables us to get rid of ValAction. It's also a step toward simplifying and encapsulating `state->stack`.
136 lines
3.5 KiB
C++
136 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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#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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class Action {
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public:
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enum class Kind {
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LValAction,
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ExpressionAction,
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PatternAction,
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StatementAction,
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};
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Action(const Value&) = delete;
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Action& operator=(const Value&) = delete;
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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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auto Pos() const -> int { return pos; }
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// Results from a subexpression.
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auto Results() const -> const std::vector<const Value*>& { return results; }
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void IncrementPos() { ++pos; }
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void AddResult(const Value* result) { results.push_back(result); }
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void Clear() {
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pos = 0;
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results.clear();
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}
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// Returns the enumerator corresponding to the most-derived type of this
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// object.
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auto Tag() const -> Kind { return tag; }
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static void PrintList(const Stack<Ptr<Action>>& ls, llvm::raw_ostream& out);
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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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protected:
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// Constructs an Action. `tag` must be the enumerator corresponding to the
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// most-derived type being constructed.
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explicit Action(Kind tag) : tag(tag) {}
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private:
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int pos = 0;
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std::vector<const Value*> results;
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const Kind tag;
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};
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class LValAction : public Action {
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public:
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explicit LValAction(const Expression* exp)
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: Action(Kind::LValAction), exp(exp) {}
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static auto classof(const Action* action) -> bool {
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return action->Tag() == Kind::LValAction;
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}
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auto Exp() const -> const Expression* { return exp; }
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private:
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const Expression* exp;
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};
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class ExpressionAction : public Action {
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public:
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explicit ExpressionAction(const Expression* exp)
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: Action(Kind::ExpressionAction), exp(exp) {}
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static auto classof(const Action* action) -> bool {
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return action->Tag() == Kind::ExpressionAction;
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}
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auto Exp() const -> const Expression* { return exp; }
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private:
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const Expression* exp;
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};
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class PatternAction : public Action {
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public:
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explicit PatternAction(const Pattern* pat)
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: Action(Kind::PatternAction), pat(pat) {}
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static auto classof(const Action* action) -> bool {
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return action->Tag() == Kind::PatternAction;
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}
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auto Pat() const -> const Pattern* { return pat; }
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private:
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const Pattern* pat;
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};
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class StatementAction : public Action {
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public:
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explicit StatementAction(const Statement* stmt)
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: Action(Kind::StatementAction), stmt(stmt) {}
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static auto classof(const Action* action) -> bool {
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return action->Tag() == Kind::StatementAction;
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}
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auto Stmt() const -> const Statement* { return stmt; }
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private:
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const Statement* stmt;
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};
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} // namespace Carbon
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#endif // EXECUTABLE_SEMANTICS_INTERPRETER_ACTION_H_
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