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xo-reader2: + SyntaxStateMachine.forward_children method

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Support gc traversal with goal of making ParserStateMachine a gc root
This commit is contained in:
Roland Conybeare 2026-03-24 17:43:45 -04:00
commit 3af72fec64
91 changed files with 626 additions and 39 deletions
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53
include/xo/reader2/ParserStateMachine.hpp
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@ -7,8 +7,8 @@
#include "ParserResult.hpp"
#include "GlobalEnv.hpp"
#include <xo/expression2/DGlobalSymtab.hpp>
#include <xo/expression2/DLocalSymtab.hpp>
#include <xo/expression2/GlobalSymtab.hpp>
#include <xo/expression2/LocalSymtab.hpp>
#include <xo/expression2/DVariable.hpp>
#include <xo/expression2/VarRef.hpp>
#include <xo/tokenizer2/Token.hpp>
@ -38,6 +38,7 @@ namespace xo {
class ParserStateMachine {
public:
using TypeDescr = xo::reflect::TypeDescr;
using ACollector = xo::mm::ACollector;
using AAllocator = xo::mm::AAllocator;
using ArenaConfig = xo::mm::ArenaConfig;
using AGCObject = xo::mm::AGCObject;
@ -66,6 +67,13 @@ namespace xo {
* (e.g. DArenaHashMap for global symtable).
* If not using X1Collector, this can be the
* same as @p expr_alloc.
*
* NOTE:
* When @p expr_alloc supports the Collector facet:
* ParserStateMachine isn't itself in gc-space
* (i.e. isn't expected to belong to @p expr_alloc).
* To update pointers to gc-owned objects, must have forward_children()
* called as part of @p expr_alloc's gc cycle.
**/
ParserStateMachine(const ArenaConfig & config,
const ArenaHashMapConfig & symtab_var_config,
@ -81,6 +89,8 @@ namespace xo {
/** non-trivial dtor for @ref global_symtab_ **/
~ParserStateMachine();
static constexpr bool is_gc_eligible() { return false; }
///@}
/** @defgroup scm-parserstatemachine-accessors accessor methods **/
///@{
@ -90,7 +100,7 @@ namespace xo {
obj<AAllocator> expr_alloc() const noexcept { return expr_alloc_; }
StringTable * stringtable() noexcept { return &stringtable_; }
DGlobalSymtab * global_symtab() const noexcept { return global_symtab_.data(); }
DLocalSymtab * local_symtab() const noexcept { return local_symtab_; }
DLocalSymtab * local_symtab() const noexcept { return local_symtab_.data(); }
DGlobalEnv * global_env() const noexcept { return global_env_.data(); }
const ParserResult & result() const noexcept { return result_; }
@ -175,7 +185,6 @@ namespace xo {
void clear_error_reset();
///@}
/** @defgroup scm-parserstatemachine-inputmethods input methods **/
///@{
@ -339,8 +348,37 @@ namespace xo {
std::string_view sym);
///@}
/** @defgroup scm-parserstatemachine-gcobject-facet gc support **/
///@{
#ifdef OBSOLETE
std::size_t shallow_size() const noexcept;
/** NOTE:
* ParserStateMachine only eligible to be a GC root.
* It's not eligible to reside in gc-owned space
**/
ParserStateMachine * shallow_copy(obj<AAllocator> mm) const noexcept;
std::size_t forward_children(obj<ACollector> gc) noexcept;
#endif
/** update gc-aware exit pointers from this ParserStateMachine **/
void forward_children(obj<ACollector> gc) noexcept;
///@}
private:
#ifdef OBSOLETE
/** @defgroup scm-parserstatemachine-impl-methods implementation methods **/
///@{
/** record gc-mutable state vars so they're updated when gc runs **/
void _add_gc_roots();
///@}
#endif
private:
/** @defgroup scm-parserstatemachine-instance-vars instance variables **/
///@{
/** Table containing interned strings + symbols.
**/
@ -348,6 +386,7 @@ namespace xo {
/** Arena for internal parsing stack.
* Must be owned exclusively because destructively
* modified as parser completes parsing of each sub-expression
*
* Contents will be a stack of ExprState instances
@ -403,7 +442,7 @@ namespace xo {
* if so, along with stringtable_.
* maybe new struct ParserState?
**/
dp<DGlobalSymtab> global_symtab_;
obj<AGCObject,DGlobalSymtab> global_symtab_;
/** symbol table with local bindings.
* non-null during parsing of lambda expressions.
@ -411,7 +450,7 @@ namespace xo {
* Push local symbol table here to remember local params
* during the body of a lambda expression.
**/
DLocalSymtab * local_symtab_ = nullptr;
obj<AGCObject,DLocalSymtab> local_symtab_;
/** global variable bindings (builtin primitives) **/
obj<AGCObject,DGlobalEnv> global_env_;
@ -435,6 +474,8 @@ namespace xo {
/** true to enable debug output **/
bool debug_flag_ = false;
///@}
};
} /*namespace scm*/
} /*namespace xo*/