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xo-expression2: upsert global vars works in DDefineSsm

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This commit is contained in:
Roland Conybeare 2026-02-16 19:48:14 -05:00
commit 03847102be
3 changed files with 57 additions and 29 deletions
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11
include/xo/expression2/DGlobalSymtab.hpp
View file

@ -65,13 +65,12 @@ namespace xo {
/** @defgroup scm-globalsymtab-general-methods general methods **/
///@{
/** establish binding for @p sym, with type described by @p typeref,
* replacing existing global (if present) with the same name.
* Use memory from @p mm to create variable-expr
/** update this symtab to associate @p var with @c var->name().
* If there was a previous variable with the same name,
* replace it with @p var.
**/
DVariable * establish_variable(obj<AAllocator> mm,
const DUniqueString * sym,
TypeRef typeref);
void upsert_variable(obj<AAllocator> mm,
DVariable * var);
///@}
/** @defgroup scm-globalsymtab-symboltable-facet symboltable facet **/

1
include/xo/expression2/DVariable.hpp
View file

@ -48,6 +48,7 @@ namespace xo {
Binding path() const { return path_; }
void assign_name(const DUniqueString * name) { this->name_ = name; }
void assign_path(Binding b) { this->path_ = b; }
/** @defgroup scm-variable-expression-facet **/
///@{

94
src/expression2/DGlobalSymtab.cpp
View file

@ -65,6 +65,65 @@ namespace xo {
return var.data();
}
void
DGlobalSymtab::upsert_variable(obj<AAllocator> mm,
DVariable * var)
{
// It's possible there's already a global variable
// with the same name.
//
// For example redefining a variable in an interactive session.
// In this case use the established binding.
//
DVariable * existing = this->lookup_variable(var->name());
if (existing) {
if (existing == var) {
// impossible, but.. noop, right?
return;
}
// adopt the existing binding
var->assign_path(existing->path());
// stash new definition (possibly has different type),
// replacing previous one
//
(*vars_)[existing->path().j_slot()] = obj<AGCObject,DVariable>(var);
} else {
DArray::size_type n = vars_->size();
// NOTE: expansion of var_ array here is moot at present (Feb 2026),
// since the feature isn't yet implemented in ArenaHashMap
/** make sure vars_ has room **/
if (n == vars_->capacity()) {
// DArray is out of room. Reallocate with more capacity
DArray * vars_2x = DArray::copy(mm, vars_, vars_->capacity() * 2);
if (!vars_2x) {
assert(false);
// in any case, we can't make progress
return;
}
this->vars_ = vars_2x;
}
/** now we know binding for var **/
Binding binding = Binding::global(n);
var->assign_path(binding);
// need slot# in .map_ for this unique symbol
(*map_)[var->name()] = binding.j_slot();
vars_->push_back(obj<AGCObject,DVariable>(var));
}
}
#ifdef NOT_USING // don't know if we need this path
DVariable *
DGlobalSymtab::establish_variable(obj<AAllocator> mm,
const DUniqueString * sym,
@ -75,43 +134,12 @@ namespace xo {
if (!var) {
assert(vars_);
DArray::size_type n = vars_->size();
// NOTE: expansion here is moot at present (Feb 2026).
// Not implemented in ArenaHashMap
/** make sure vars_ has room **/
if (n == vars_->capacity()) {
// reallocate with more capacity
DArray * vars_2x = DArray::copy(mm, vars_, vars_->capacity() * 2);
assert(vars_2x);
this->vars_ = vars_2x;
}
/** create new variable **/
Binding binding = Binding::global(n);
var = DVariable::make(mm, sym, typeref, binding);
if (!var) {
// something terribly wrong
assert(false);
return var;
}
assert(map_->size() < map_->capacity());
(*map_)[sym] = binding.j_slot();
bool ok = vars_->push_back(obj<AGCObject,DVariable>(var));
if (!ok)
assert(false);
xxx;
}
return var;
}
#endif
Binding
DGlobalSymtab::lookup_binding(const DUniqueString * sym) const noexcept