GDScript: Support `%` in shorthand for `get_node`

The `%` is used in scene unique nodes. Now `%` can also be used instead
of `$` for the shorthand, besides being allowed generally anywhere in
the path as the prefix for a node name.

10 files changed, 167 insertions, 70 deletions

diff --git a/modules/gdscript/editor/gdscript_highlighter.cpp b/modules/gdscript/editor/gdscript_highlighter.cpp
index 191568661d..b86e9b386d 100644
--- a/modules/gdscript/editor/gdscript_highlighter.cpp
+++ b/modules/gdscript/editor/gdscript_highlighter.cpp
@@ -387,9 +387,9 @@ Dictionary GDScriptSyntaxHighlighter::_get_line_syntax_highlighting_impl(int p_l
 			in_member_variable = false;
 		}
 
-		if (!in_node_path && in_region == -1 && str[j] == '$') {
+		if (!in_node_path && in_region == -1 && (str[j] == '$' || str[j] == '%')) {
 			in_node_path = true;
-		} else if (in_region != -1 || (is_a_symbol && str[j] != '/')) {
+		} else if (in_region != -1 || (is_a_symbol && str[j] != '/' && str[j] != '%')) {
 			in_node_path = false;
 		}
 
diff --git a/modules/gdscript/gdscript_compiler.cpp b/modules/gdscript/gdscript_compiler.cpp
index 478fafc930..910f94a936 100644
--- a/modules/gdscript/gdscript_compiler.cpp
+++ b/modules/gdscript/gdscript_compiler.cpp
@@ -667,20 +667,8 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 		case GDScriptParser::Node::GET_NODE: {
 			const GDScriptParser::GetNodeNode *get_node = static_cast<const GDScriptParser::GetNodeNode *>(p_expression);
 
-			String node_name;
-			if (get_node->string != nullptr) {
-				node_name += String(get_node->string->value);
-			} else {
-				for (int i = 0; i < get_node->chain.size(); i++) {
-					if (i > 0) {
-						node_name += "/";
-					}
-					node_name += get_node->chain[i]->name;
-				}
-			}
-
 			Vector<GDScriptCodeGenerator::Address> args;
-			args.push_back(codegen.add_constant(NodePath(node_name)));
+			args.push_back(codegen.add_constant(NodePath(get_node->full_path)));
 
 			GDScriptCodeGenerator::Address result = codegen.add_temporary(_gdtype_from_datatype(get_node->get_datatype()));
 
diff --git a/modules/gdscript/gdscript_parser.cpp b/modules/gdscript/gdscript_parser.cpp
index b93fff3914..7367dfca7c 100644
--- a/modules/gdscript/gdscript_parser.cpp
+++ b/modules/gdscript/gdscript_parser.cpp
@@ -2824,51 +2824,97 @@ GDScriptParser::ExpressionNode *GDScriptParser::parse_call(ExpressionNode *p_pre
 }
 
 GDScriptParser::ExpressionNode *GDScriptParser::parse_get_node(ExpressionNode *p_previous_operand, bool p_can_assign) {
-	if (match(GDScriptTokenizer::Token::LITERAL)) {
-		if (previous.literal.get_type() != Variant::STRING) {
-			push_error(R"(Expect node path as string or identifier after "$".)");
+	if (!current.is_node_name() && !check(GDScriptTokenizer::Token::LITERAL) && !check(GDScriptTokenizer::Token::SLASH) && !check(GDScriptTokenizer::Token::PERCENT)) {
+		push_error(vformat(R"(Expected node path as string or identifier after "%s".)", previous.get_name()));
+		return nullptr;
+	}
+
+	if (check(GDScriptTokenizer::Token::LITERAL)) {
+		if (current.literal.get_type() != Variant::STRING) {
+			push_error(vformat(R"(Expected node path as string or identifier after "%s".)", previous.get_name()));
 			return nullptr;
 		}
-		GetNodeNode *get_node = alloc_node<GetNodeNode>();
-		make_completion_context(COMPLETION_GET_NODE, get_node);
-		get_node->string = parse_literal();
-		return get_node;
-	} else if (current.is_node_name()) {
-		GetNodeNode *get_node = alloc_node<GetNodeNode>();
-		int chain_position = 0;
-		do {
-			make_completion_context(COMPLETION_GET_NODE, get_node, chain_position++);
-			if (!current.is_node_name()) {
-				push_error(R"(Expect node path after "/".)");
+	}
+
+	GetNodeNode *get_node = alloc_node<GetNodeNode>();
+
+	// Store the last item in the path so the parser knows what to expect.
+	// Allow allows more specific error messages.
+	enum PathState {
+		PATH_STATE_START,
+		PATH_STATE_SLASH,
+		PATH_STATE_PERCENT,
+		PATH_STATE_NODE_NAME,
+	} path_state = PATH_STATE_START;
+
+	if (previous.type == GDScriptTokenizer::Token::DOLLAR) {
+		// Detect initial slash, which will be handled in the loop if it matches.
+		match(GDScriptTokenizer::Token::SLASH);
+#ifdef DEBUG_ENABLED
+	} else {
+		get_node->use_dollar = false;
+#endif
+	}
+
+	int context_argument = 0;
+
+	do {
+		if (previous.type == GDScriptTokenizer::Token::PERCENT) {
+			if (path_state != PATH_STATE_START && path_state != PATH_STATE_SLASH) {
+				push_error(R"("%" is only valid in the beginning of a node name (either after "$" or after "/"))");
 				return nullptr;
 			}
-			advance();
-			IdentifierNode *identifier = alloc_node<IdentifierNode>();
-			identifier->name = previous.get_identifier();
-			get_node->chain.push_back(identifier);
-		} while (match(GDScriptTokenizer::Token::SLASH));
-		return get_node;
-	} else if (match(GDScriptTokenizer::Token::SLASH)) {
-		GetNodeNode *get_node = alloc_node<GetNodeNode>();
-		IdentifierNode *identifier_root = alloc_node<IdentifierNode>();
-		get_node->chain.push_back(identifier_root);
-		int chain_position = 0;
-		do {
-			make_completion_context(COMPLETION_GET_NODE, get_node, chain_position++);
-			if (!current.is_node_name()) {
-				push_error(R"(Expect node path after "/".)");
+			get_node->full_path += "%";
+
+			path_state = PATH_STATE_PERCENT;
+		} else if (previous.type == GDScriptTokenizer::Token::SLASH) {
+			if (path_state != PATH_STATE_START && path_state != PATH_STATE_NODE_NAME) {
+				push_error(R"("/" is only valid at the beginning of the path or after a node name.)");
 				return nullptr;
 			}
+
+			get_node->full_path += "/";
+
+			path_state = PATH_STATE_SLASH;
+		}
+
+		make_completion_context(COMPLETION_GET_NODE, get_node, context_argument++);
+
+		if (match(GDScriptTokenizer::Token::LITERAL)) {
+			if (previous.literal.get_type() != Variant::STRING) {
+				String previous_token;
+				switch (path_state) {
+					case PATH_STATE_START:
+						previous_token = "$";
+						break;
+					case PATH_STATE_PERCENT:
+						previous_token = "%";
+						break;
+					case PATH_STATE_SLASH:
+						previous_token = "/";
+						break;
+					default:
+						break;
+				}
+				push_error(vformat(R"(Expected node path as string or identifier after "%s".)", previous_token));
+				return nullptr;
+			}
+
+			get_node->full_path += previous.literal.operator String();
+
+			path_state = PATH_STATE_NODE_NAME;
+		} else if (current.is_node_name()) {
 			advance();
-			IdentifierNode *identifier = alloc_node<IdentifierNode>();
-			identifier->name = previous.get_identifier();
-			get_node->chain.push_back(identifier);
-		} while (match(GDScriptTokenizer::Token::SLASH));
-		return get_node;
-	} else {
-		push_error(R"(Expect node path as string or identifier after "$".)");
-		return nullptr;
-	}
+			get_node->full_path += previous.get_identifier();
+
+			path_state = PATH_STATE_NODE_NAME;
+		} else if (!check(GDScriptTokenizer::Token::SLASH) && !check(GDScriptTokenizer::Token::PERCENT)) {
+			push_error(vformat(R"(Unexpected "%s" in node path.)", current.get_name()));
+			return nullptr;
+		}
+	} while (match(GDScriptTokenizer::Token::SLASH) || match(GDScriptTokenizer::Token::PERCENT));
+
+	return get_node;
 }
 
 GDScriptParser::ExpressionNode *GDScriptParser::parse_preload(ExpressionNode *p_previous_operand, bool p_can_assign) {
@@ -3273,7 +3319,7 @@ GDScriptParser::ParseRule *GDScriptParser::get_rule(GDScriptTokenizer::Token::Ty
 		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_FACTOR }, // STAR,
 		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_POWER }, // STAR_STAR,
 		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_FACTOR }, // SLASH,
-		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_FACTOR }, // PERCENT,
+		{ &GDScriptParser::parse_get_node,                  &GDScriptParser::parse_binary_operator,      	PREC_FACTOR }, // PERCENT,
 		// Assignment
 		{ nullptr,                                          &GDScriptParser::parse_assignment,           	PREC_ASSIGNMENT }, // EQUAL,
 		{ nullptr,                                          &GDScriptParser::parse_assignment,           	PREC_ASSIGNMENT }, // PLUS_EQUAL,
@@ -4253,17 +4299,10 @@ void GDScriptParser::TreePrinter::print_function(FunctionNode *p_function, const
 }
 
 void GDScriptParser::TreePrinter::print_get_node(GetNodeNode *p_get_node) {
-	push_text("$");
-	if (p_get_node->string != nullptr) {
-		print_literal(p_get_node->string);
-	} else {
-		for (int i = 0; i < p_get_node->chain.size(); i++) {
-			if (i > 0) {
-				push_text("/");
-			}
-			print_identifier(p_get_node->chain[i]);
-		}
+	if (p_get_node->use_dollar) {
+		push_text("$");
 	}
+	push_text(p_get_node->full_path);
 }
 
 void GDScriptParser::TreePrinter::print_identifier(IdentifierNode *p_identifier) {
diff --git a/modules/gdscript/gdscript_parser.h b/modules/gdscript/gdscript_parser.h
index 96b9a10d3c..e3f8d4b8ba 100644
--- a/modules/gdscript/gdscript_parser.h
+++ b/modules/gdscript/gdscript_parser.h
@@ -749,8 +749,10 @@ public:
 	};
 
 	struct GetNodeNode : public ExpressionNode {
-		LiteralNode *string = nullptr;
-		Vector<IdentifierNode *> chain;
+		String full_path;
+#ifdef DEBUG_ENABLED
+		bool use_dollar = true;
+#endif
 
 		GetNodeNode() {
 			type = GET_NODE;
diff --git a/modules/gdscript/tests/scripts/parser/errors/dollar-assignment-bug-53696.out b/modules/gdscript/tests/scripts/parser/errors/dollar-assignment-bug-53696.out
index b3dc181a22..9fafcb5a64 100644
--- a/modules/gdscript/tests/scripts/parser/errors/dollar-assignment-bug-53696.out
+++ b/modules/gdscript/tests/scripts/parser/errors/dollar-assignment-bug-53696.out
@@ -1,2 +1,2 @@
 GDTEST_PARSER_ERROR
-Expect node path as string or identifier after "$".
+Expected node path as string or identifier after "$".
diff --git a/modules/gdscript/tests/scripts/parser/errors/nothing_after_dollar.out b/modules/gdscript/tests/scripts/parser/errors/nothing_after_dollar.out
index b3dc181a22..9fafcb5a64 100644
--- a/modules/gdscript/tests/scripts/parser/errors/nothing_after_dollar.out
+++ b/modules/gdscript/tests/scripts/parser/errors/nothing_after_dollar.out
@@ -1,2 +1,2 @@
 GDTEST_PARSER_ERROR
-Expect node path as string or identifier after "$".
+Expected node path as string or identifier after "$".
diff --git a/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar.out b/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar.out
index b3dc181a22..9fafcb5a64 100644
--- a/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar.out
+++ b/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar.out
@@ -1,2 +1,2 @@
 GDTEST_PARSER_ERROR
-Expect node path as string or identifier after "$".
+Expected node path as string or identifier after "$".
diff --git a/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar_slash.out b/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar_slash.out
index dcb4ccecb0..3062f0be70 100644
--- a/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar_slash.out
+++ b/modules/gdscript/tests/scripts/parser/errors/wrong_value_after_dollar_slash.out
@@ -1,2 +1,2 @@
 GDTEST_PARSER_ERROR
-Expect node path after "/".
+Expected node path as string or identifier after "/".
diff --git a/modules/gdscript/tests/scripts/parser/features/dollar_and_percent_get_node.gd b/modules/gdscript/tests/scripts/parser/features/dollar_and_percent_get_node.gd
new file mode 100644
index 0000000000..f04f4de08d
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/features/dollar_and_percent_get_node.gd
@@ -0,0 +1,49 @@
+extends Node
+
+func test():
+	var child = Node.new()
+	child.name = "Child"
+	add_child(child)
+	child.owner = self
+
+	var hey = Node.new()
+	hey.name = "Hey"
+	child.add_child(hey)
+	hey.owner = self
+	hey.unique_name_in_owner = true
+
+	var fake_hey = Node.new()
+	fake_hey.name = "Hey"
+	add_child(fake_hey)
+	fake_hey.owner = self
+
+	var sub_child = Node.new()
+	sub_child.name = "SubChild"
+	hey.add_child(sub_child)
+	sub_child.owner = self
+
+	var howdy = Node.new()
+	howdy.name = "Howdy"
+	sub_child.add_child(howdy)
+	howdy.owner = self
+	howdy.unique_name_in_owner = true
+
+	print(hey == $Child/Hey)
+	print(howdy == $Child/Hey/SubChild/Howdy)
+
+	print(%Hey == hey)
+	print($%Hey == hey)
+	print(%"Hey" == hey)
+	print($"%Hey" == hey)
+	print($%"Hey" == hey)
+	print(%Hey/%Howdy == howdy)
+	print($%Hey/%Howdy == howdy)
+	print($"%Hey/%Howdy" == howdy)
+	print($"%Hey"/"%Howdy" == howdy)
+	print(%"Hey"/"%Howdy" == howdy)
+	print($%"Hey"/"%Howdy" == howdy)
+	print($"%Hey"/%"Howdy" == howdy)
+	print(%"Hey"/%"Howdy" == howdy)
+	print($%"Hey"/%"Howdy" == howdy)
+	print(%"Hey/%Howdy" == howdy)
+	print($%"Hey/%Howdy" == howdy)
diff --git a/modules/gdscript/tests/scripts/parser/features/dollar_and_percent_get_node.out b/modules/gdscript/tests/scripts/parser/features/dollar_and_percent_get_node.out
new file mode 100644
index 0000000000..041c4439b0
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/features/dollar_and_percent_get_node.out
@@ -0,0 +1,19 @@
+GDTEST_OK
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true
+true