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/**
** \file escapes/escapes-visitor.hh
** \brief Compute the escapes.
**
** Variables and formals of a function may escape, i.e., be accessed
** by an inner function.
**
** When the semantic analysis finds a declaration of variable or
** formal FOO, it needs to know whether it escapes or not. This
** requires an additional pass, before the semantic analysis, just to
** spot the potential escapes of FOO.
**
** In order to pass the result to the semantic analysis which walks
** across the ast, the most natural and easy solution consists in
** tagging the various VarDec and Field.
**
** Now, how shall we compute the escapes?
** The answer is obvious: we need to walk the ast, searching for variables
** declared then accessed by an inner function.
**
** If a variable is accessed from a nested function
**
** 2è possibilité :
** - Aucune n'échappe
** - Echappe si accessed dans une fonction nestée
** Attention
*/
#pragma once
#include <map>
#include <ast/default-visitor.hh>
#include <ast/non-assert-visitor.hh>
#include <ast/non-object-visitor.hh>
namespace escapes
{
/** \brief Compute the escapes.
**
** The EscapeVisitor is extremely similar to type::TypeChecker:
** in its course of operation it must relate uses to
** definitions. Therefore it will be run after the bind::Binder.
** It also needs auxiliary information about the definitions (their
** depth): a simple map suffices, since scoping issues were handled
** by the bind::Binder.
**
** Note that this EscapesVisitor is mainly doing nothing: it is just
** interested in declaration and uses of variables/formals (and, of
** course, function declaration...). It would be somewhat stupid to
** write all the methods that `do nothing but walk'. This is why we
** will inherit from the non const ast::DefaultVisitor.
**/
class EscapesVisitor
: public ast::DefaultVisitor
, public ast::NonObjectVisitor
, public ast::NonAssertVisitor
{
public:
/// Super class type.
using super_type = ast::DefaultVisitor;
/// Import all the overloaded visit methods.
using super_type::operator();
// FIXME DONE: Some code was deleted here.
void operator()(ast::SimpleVar& e) override;
void operator()(ast::VarDec& e) override;
void operator()(ast::FunctionDec& e) override;
protected:
std::map<ast::VarDec*, size_t> depth_map_;
private:
size_t current_depth_ = 0;
};
} // namespace escapes
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