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xo-expression: + Lambda::layer_var_map

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This commit is contained in:
Roland Conybeare 2024-07-03 15:10:34 -04:00
commit 89043b0d46
2 changed files with 56 additions and 38 deletions
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17
include/xo/expression/Lambda.hpp
View file

@ -9,6 +9,7 @@
#include "FunctionInterface.hpp"
#include "Variable.hpp"
#include "LocalEnv.hpp"
#include <map>
#include <vector>
#include <string>
//#include <cstdint>
@ -73,9 +74,7 @@ namespace xo {
return this;
}
virtual void attach_envs(ref::brw<Environment> p) override {
local_env_->assign_parent(p);
}
virtual void attach_envs(ref::brw<Environment> p) override;
virtual void display(std::ostream & os) const override;
@ -97,7 +96,7 @@ namespace xo {
* Goal is to unify variables that can use the same binding
* path to determine memory location at runtime.
**/
void regularize_layer_vars();
std::map<std::string, ref::rp<Variable>> regularize_layer_vars();
private:
/** lambda name. Initially supporting only form like
@ -118,6 +117,16 @@ namespace xo {
/** free variables for this lambda **/
std::set<std::string> free_var_set_;
/** map giving unique identity to each variable appearing in this layer.
* includes:
* - formal parameters
* - free variables in @ref body_
* excludes:
* - any variables appearing in nested lambdas
* (whether formals or free variables)
**/
std::map<std::string, ref::rp<Variable>> layer_var_map_;
/** established (once) by @ref attach_envs.
*
* @note data dependency on ancestor expressions that don't exist yet

81
src/expression/Lambda.cpp
View file

@ -69,7 +69,7 @@ namespace xo {
return retval;
} /*calc_free_variables*/
void
std::map<std::string, ref::rp<Variable>>
Lambda::regularize_layer_vars()
{
/* regularize local_env+body: make sure exactly one instance
@ -83,42 +83,43 @@ namespace xo {
* Motivation is to unify Variables that would use the same
* binding_path to resolve their runtime location.
*/
{
std::map<std::string, rp<Variable>> var_map;
std::map<std::string, rp<Variable>> var_map;
for (const auto & arg : local_env_->argv()) {
/* each arg name can appear at most once
* in a particular lambda's parameter list
*/
assert(var_map.find(arg->name()) == var_map.end());
for (const auto & arg : local_env_->argv()) {
/* each arg name can appear at most once
* in a particular lambda's parameter list
*/
assert(var_map.find(arg->name()) == var_map.end());
var_map[arg->name()] = arg;
}
body_ = body_->xform_layer
([&var_map](ref::brw<Expression> x) -> ref::rp<Expression>
{
if (x->extype() == exprtype::variable) {
ref::brw<Variable> var = Variable::from(x);
auto ix = var_map.find(var->name());
if (ix == var_map.end()) {
/* add to var_map, copy to ensure Variable
* is unique to layer
*/
var_map[var->name()] = Variable::copy(var);
return var.get();
} else {
/* substitute already-encountered var_map[] member */
return ix->second;
}
} else {
return x.get();
}
});
var_map[arg->name()] = arg;
}
this->body_
= (body_->xform_layer
([&var_map](ref::brw<Expression> x) -> ref::rp<Expression>
{
if (x->extype() == exprtype::variable) {
ref::brw<Variable> var = Variable::from(x);
auto ix = var_map.find(var->name());
if (ix == var_map.end()) {
/* add to var_map, copy to ensure Variable
* not shared with any other layer
*/
var_map[var->name()] = Variable::copy(var);
return var.get();
} else {
/* substitute already-encountered var_map[] member */
return ix->second;
}
} else {
return x.get();
}
}));
return var_map;
} /*regularize_layer_vars*/
Lambda::Lambda(const std::string & name,
@ -141,13 +142,21 @@ namespace xo {
ss << ")";
this->type_str_ = ss.str();
this->free_var_set_ = this->calc_free_variables();
this->regularize_layer_vars();
/* ensure variables are unique within layer for this lambda */
this->layer_var_map_ = this->regularize_layer_vars();
this->free_var_set_ = this->calc_free_variables();
this->body_->attach_envs(local_env_);
} /*ctor*/
void
Lambda::attach_envs(ref::brw<Environment> p) {
local_env_->assign_parent(p);
}
void
Lambda::display(std::ostream & os) const {
os << "<Lambda"