From eb320acbcdd58dcc5b7be9746363e6d41b6d37ee Mon Sep 17 00:00:00 2001
From: Sara <sara@objectionable.solutions>
Date: Thu, 26 Mar 2026 14:53:21 +0100
Subject: [PATCH] chore: progress on generative grammar

---
 modules/generative_grammar/symbol.cpp | 24 ++++++++++++++++--------
 modules/generative_grammar/symbol.h   |  9 ++++-----
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/modules/generative_grammar/symbol.cpp b/modules/generative_grammar/symbol.cpp
index 3101579e61..41bb56e6c0 100644
--- a/modules/generative_grammar/symbol.cpp
+++ b/modules/generative_grammar/symbol.cpp
@@ -1,6 +1,7 @@
 #include "generative_grammar/symbol.h"
 #include "core/error/error_macros.h"
 #include "core/object/class_db.h"
+#include "core/templates/hash_map.h"
 
 void Symbol::_bind_methods() {
 	BIND_HPROPERTY(Variant::INT, symbol, PROPERTY_HINT_ENUM, Type_hint());
@@ -8,7 +9,7 @@ void Symbol::_bind_methods() {
 }
 
 bool Symbol::is_terminal() const {
-	switch (this->type) {
+	switch (this->symbol) {
 		default:
 			return false;
 	}
@@ -39,11 +40,11 @@ TypedArray<Ref<Symbol>> Symbol::get_children_array() const {
 }
 
 void Rule::_bind_methods() {
-	BIND_HPROPERTY(Variant::OBJECT, match, PROPERTY_HINT_RESOURCE_TYPE, "Symbol");
+	BIND_HPROPERTY(Variant::OBJECT, pattern, PROPERTY_HINT_RESOURCE_TYPE, "Symbol");
 	BIND_HPROPERTY(Variant::OBJECT, result, PROPERTY_HINT_RESOURCE_TYPE, "Symbol");
 }
 
-bool Rule::symbols_match(Ref<Symbol> match, Ref<Symbol> pattern) {
+bool Rule::match_symbols(Ref<Symbol> match, Ref<Symbol> pattern, HashMap<Ref<Symbol>, Ref<Symbol>> &matches) {
 	if (match == pattern) {
 		return true; // reference match or null match
 	}
@@ -57,14 +58,11 @@ bool Rule::symbols_match(Ref<Symbol> match, Ref<Symbol> pattern) {
 	if (match->get_children().size() < pattern->get_children().size()) {
 		return false; // too little children to be able to match
 	}
-	if ((match->get_parent() == nullptr) != (pattern->get_parent() == nullptr)) {
-		return false; // mismatch in existence of incoming edge
-	}
 	// check for matching outgoing edges
 	for (Ref<Symbol> pattern_symbol : pattern->get_children()) {
 		bool match_found{ false };
 		for (Ref<Symbol> match_symbol : match->get_children()) {
-			if (symbols_match(match_symbol, pattern_symbol)) {
+			if (match_symbols(match_symbol, pattern_symbol, matches)) {
 				match_found = true;
 				break;
 			}
@@ -73,8 +71,18 @@ bool Rule::symbols_match(Ref<Symbol> match, Ref<Symbol> pattern) {
 			return false;
 		}
 	}
+	matches.insert(pattern, match);
 	return true;
 }
 
-bool Rule::matches(Ref<Symbol> graph) {
+bool Rule::try_apply(Ref<Symbol> match) {
+	// identify corresponding symbols
+	HashMap<Ref<Symbol>, Ref<Symbol>> symbols{};
+	if (!match_symbols(match, this->pattern, symbols)) {
+		return false;
+	}
+	// clear matching edges
+	for (KeyValue<Ref<Symbol>, Ref<Symbol>> kvp : symbols) {
+	}
+	return true;
 }
diff --git a/modules/generative_grammar/symbol.h b/modules/generative_grammar/symbol.h
index e9450906cc..287ab73010 100644
--- a/modules/generative_grammar/symbol.h
+++ b/modules/generative_grammar/symbol.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "core/io/resource.h"
+#include "core/templates/hash_map.h"
 #include "core/templates/hash_set.h"
 #include "core/variant/type_info.h"
 #include "core/variant/typed_array.h"
@@ -32,18 +33,16 @@ MAKE_TYPE_INFO(Symbol::Type, Variant::INT);
 struct Rule : public Resource {
 	GDCLASS(Rule, Resource);
 	static void _bind_methods();
-	bool symbols_match(Ref<Symbol> match, Ref<Symbol> pattern);
+	bool match_symbols(Ref<Symbol> match, Ref<Symbol> pattern, HashMap<Ref<Symbol>, Ref<Symbol>> &matches);
 
 public:
-	bool matches(Ref<Symbol> graph);
-	void apply(Ref<Symbol> graph);
 	bool try_apply(Ref<Symbol> graph);
 
 private:
-	Ref<Symbol> match{};
+	Ref<Symbol> pattern{};
 	Ref<Symbol> result{};
 
 public:
-	GET_SET_FNS(Ref<Symbol>, match);
+	GET_SET_FNS(Ref<Symbol>, pattern);
 	GET_SET_FNS(Ref<Symbol>, result);
 };