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xo-expression: + Expression::get_free_variables()

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This commit is contained in:
Roland Conybeare 2024-07-01 16:50:17 -04:00
commit b7db7c5454
7 changed files with 59 additions and 0 deletions
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14
include/xo/expression/Apply.hpp
View file

@ -36,6 +36,20 @@ namespace xo {
const ref::rp<Expression> & fn() const { return fn_; }
const std::vector<ref::rp<Expression>> & argv() const { return argv_; }
virtual std::set<std::string> get_free_variables() const override {
std::set<std::string> retval = fn_->get_free_variables();
for (const auto & arg : argv_) {
std::set<std::string> arg_free_set
= arg->get_free_variables();
for (const auto & name : arg_free_set)
retval.insert(name);
}
return retval;
}
virtual std::size_t visit_preorder(VisitFn visitor_fn) override {
std::size_t n = 1;

4
include/xo/expression/ConstantInterface.hpp
View file

@ -36,6 +36,10 @@ namespace xo {
// ----- Expression -----
virtual std::set<std::string> get_free_variables() const override {
return std::set<std::string>();
}
virtual void attach_envs(ref::brw<Environment> /*p*/) override {}

6
include/xo/expression/Expression.hpp
View file

@ -45,6 +45,12 @@ namespace xo {
exprtype extype() const { return extype_; }
TypeDescr valuetype() const { return valuetype_; }
/** find free named variables in this expression.
* comprises the set of names that don't match formal parameters in
* enclosing lambdas.
**/
virtual std::set<std::string> get_free_variables() const = 0;
/** visit each Expression node in this AST,
* and invoke @p fn for each.
* Returns the number of nodes visited.

15
include/xo/expression/IfExpr.hpp
View file

@ -40,6 +40,21 @@ namespace xo {
// ----- Expression -----
virtual std::set<std::string> get_free_variables() const override {
std::set<std::string> retval = test_->get_free_variables();
std::set<std::string> free_vars;
free_vars = when_true_->get_free_variables();
for (const auto & s : free_vars)
retval.insert(s);
free_vars = when_false_->get_free_variables();
for (const auto & s : free_vars)
retval.insert(s);
return retval;
}
virtual std::size_t visit_preorder(VisitFn visitor_fn) override {
std::size_t n = 1;

10
include/xo/expression/Lambda.hpp
View file

@ -49,6 +49,16 @@ namespace xo {
// ----- Expression -----
virtual std::set<std::string> get_free_variables() const override {
std::set<std::string> retval = body_->get_free_variables();
/* but remove formals. */
for (const auto & var : local_env_->argv())
retval.erase(var->name());
return retval;
}
virtual std::size_t visit_preorder(VisitFn visitor_fn) override {
std::size_t n = 1;

4
include/xo/expression/PrimitiveInterface.hpp
View file

@ -48,6 +48,10 @@ namespace xo {
// ----- Expression -----
virtual std::set<std::string> get_free_variables() const override {
return std::set<std::string>();
}
virtual std::size_t visit_preorder(VisitFn visitor_fn) override {
visitor_fn(this);
return 1;

6
include/xo/expression/Variable.hpp
View file

@ -31,6 +31,12 @@ namespace xo {
const std::string & name() const { return name_; }
virtual std::set<std::string> get_free_variables() const override {
std::set<std::string> retval;
retval.insert(this->name_);
return retval;
}
virtual std::size_t visit_preorder(VisitFn visitor_fn) override {
visitor_fn(this);
return 1;