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https://github.com/carbon-language/carbon-lang.git
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Geoff Romer
e022ff106f
Additional miscellaneous cleanup: - Use the term "deallocate" instead of "kill" in function names, for symmetry with "allocate". - Drop an unnecessary memory allocation in `AllocateValue`. - Implement `PrintHeap` in terms of `PrintAddress`, so that dead values are flagged with `!!`.
123 lines
3.9 KiB
C++
123 lines
3.9 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_INTERPRETER_H_
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#define EXECUTABLE_SEMANTICS_INTERPRETER_INTERPRETER_H_
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#include <list>
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#include <utility>
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#include <vector>
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#include "executable_semantics/ast/declaration.h"
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#include "executable_semantics/interpreter/action.h"
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#include "executable_semantics/interpreter/dictionary.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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namespace Carbon {
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using Env = Dictionary<std::string, Address>;
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/***** Scopes *****/
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struct Scope {
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Scope(Env values, std::list<std::string> l)
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: values(values), locals(std::move(l)) {}
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Env values;
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std::list<std::string> locals;
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};
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/***** Frames and State *****/
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// A frame represents either a function call or a delimited continuation.
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struct Frame {
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// The name of the function.
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std::string name;
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// If the frame represents a function call, the bottom scope
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// contains the parameter-argument bindings for this function
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// call. The rest of the scopes contain local variables defined by
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// blocks within the function. The scope at the top of the stack is
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// the current scope and its environment is the one used for looking
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// up the value associated with a variable.
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Stack<Scope*> scopes;
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// The actions that need to be executed in the future of the
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// current function call. The top of the stack is the action
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// that is executed first.
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Stack<Action*> todo;
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// If this frame is the bottom frame of a continuation, then it stores
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// the address of the continuation.
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// Otherwise the `continuation` field is the sentinel UINT_MAX.
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Address continuation;
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// Returns whether this frame is the bottom frame of a continuation.
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auto IsContinuation() -> bool { return continuation != UINT_MAX; }
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Frame(std::string n, Stack<Scope*> s, Stack<Action*> c)
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: name(std::move(std::move(n))),
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scopes(s),
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todo(c),
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continuation(UINT_MAX) {}
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};
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// A Heap represents the abstract machine's dynamically allocated memory.
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class Heap {
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public:
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// Constructs an empty Heap.
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Heap() = default;
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Heap(const Heap&) = delete;
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Heap& operator=(const Heap&) = delete;
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// Returns the value at the given address in the heap after
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// checking that it is alive.
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auto Read(Address a, int line_num) -> const Value*;
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// Writes the given value at the address in the heap after
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// checking that the address is alive.
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auto Write(Address a, const Value* v, int line_num) -> void;
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// Put the given value on the heap and mark it as alive.
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auto AllocateValue(const Value* v) -> Address;
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// Marks the object at this address, and all of its sub-objects, as dead.
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auto Deallocate(Address address) -> void;
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// Print the value at the given address to the stream `out`.
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auto PrintAddress(Address a, std::ostream& out) -> void;
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// Print all the values on the heap to the stream `out`.
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auto PrintHeap(std::ostream& out) -> void;
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private:
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// Signal an error if the address is no longer alive.
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void CheckAlive(Address address, int line_num);
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// Marks all sub-objects of this value as dead.
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void DeallocateSubObjects(const Value* val);
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std::vector<const Value*> values_;
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std::vector<bool> alive_;
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};
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struct State {
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Stack<Frame*> stack;
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Heap heap;
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};
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extern State* state;
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auto PrintFrame(Frame* frame, std::ostream& out) -> void;
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void PrintStack(Stack<Frame*> ls, std::ostream& out);
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void PrintEnv(Env values);
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auto CopyVal(const Value* val, int line_num) -> const Value*;
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auto ToInteger(const Value* v) -> int;
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/***** Interpreters *****/
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auto InterpProgram(std::list<Declaration>* fs) -> int;
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auto InterpExp(Env values, const Expression* e) -> const Value*;
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} // namespace Carbon
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#endif // EXECUTABLE_SEMANTICS_INTERPRETER_INTERPRETER_H_
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