Adding shader preprocessor support

Co-authored-by: TheOrangeDay <6472143+TheOrangeDay@users.noreply.github.com>

1 files changed, 196 insertions, 0 deletions

diff --git a/servers/rendering/shader_preprocessor.h b/servers/rendering/shader_preprocessor.h
new file mode 100644
index 0000000000..1cbab8e36f
--- /dev/null
+++ b/servers/rendering/shader_preprocessor.h
@@ -0,0 +1,196 @@
+/*************************************************************************/
+/*  shader_preprocessor.h                                                */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef SHADER_PREPROCESSOR_H
+#define SHADER_PREPROCESSOR_H
+
+#include "core/string/ustring.h"
+#include "core/templates/list.h"
+#include "core/templates/local_vector.h"
+#include "core/templates/rb_map.h"
+#include "core/templates/rb_set.h"
+#include "core/typedefs.h"
+
+#include "core/io/resource_loader.h"
+#include "core/os/os.h"
+#include "scene/resources/shader.h"
+#include "scene/resources/shader_include.h"
+
+class ShaderPreprocessor {
+private:
+	struct Token {
+		char32_t text;
+		int line;
+
+		Token();
+		Token(char32_t p_text, int p_line);
+	};
+
+	// The real preprocessor that understands basic shader and preprocessor language syntax.
+	class Tokenizer {
+	public:
+		String code;
+		int line;
+		int index;
+		int size;
+		Vector<Token> generated;
+
+	private:
+		void add_generated(const Token &p_t);
+		char32_t next();
+
+	public:
+		int get_line() const;
+		int get_index() const;
+		char32_t peek();
+
+		void get_and_clear_generated(Vector<Token> *r_out);
+		void backtrack(char32_t p_what);
+		LocalVector<Token> advance(char32_t p_what);
+		void skip_whitespace();
+		String get_identifier(bool *r_is_cursor = nullptr, bool p_started = false);
+		String peek_identifier();
+		Token get_token();
+
+		Tokenizer(const String &p_code);
+	};
+
+	class CommentRemover {
+	private:
+		LocalVector<char32_t> stripped;
+		String code;
+		int index;
+		int line;
+		int comment_line_open;
+		int comments_open;
+		int strings_open;
+
+	public:
+		String get_error() const;
+		int get_error_line() const;
+		char32_t peek() const;
+
+		bool advance(char32_t p_what);
+		String strip();
+
+		CommentRemover(const String &p_code);
+	};
+
+	struct Define {
+		Vector<String> arguments;
+		String body;
+	};
+
+	struct SkippedCondition {
+		int start_line = -1;
+		int end_line = -1;
+	};
+
+public:
+	enum CompletionType {
+		COMPLETION_TYPE_NONE,
+		COMPLETION_TYPE_DIRECTIVE,
+		COMPLETION_TYPE_PRAGMA_DIRECTIVE,
+		COMPLETION_TYPE_PRAGMA,
+	};
+
+	struct State {
+		RBMap<String, Define *> defines;
+		Vector<bool> skip_stack_else;
+		int condition_depth = 0;
+		RBSet<String> includes;
+		List<uint64_t> cyclic_include_hashes; // Holds code hash of includes.
+		int include_depth = 0;
+		String current_include;
+		String current_shader_type;
+		int shader_type_pos = -1;
+		String error;
+		int error_line = -1;
+		RBMap<String, Vector<SkippedCondition *>> skipped_conditions;
+		bool disabled = false;
+		CompletionType completion_type = COMPLETION_TYPE_NONE;
+	};
+
+private:
+	String code;
+	LocalVector<char32_t> output;
+	State *state = nullptr;
+	bool state_owner = false;
+
+private:
+	static bool is_char_word(char32_t p_char);
+	static bool is_char_space(char32_t p_char);
+	static bool is_char_end(char32_t p_char);
+	static String vector_to_string(const LocalVector<char32_t> &p_v, int p_start = 0, int p_end = -1);
+	static String tokens_to_string(const LocalVector<Token> &p_tokens);
+
+	void process_directive(Tokenizer *p_tokenizer);
+	void process_define(Tokenizer *p_tokenizer);
+	void process_else(Tokenizer *p_tokenizer);
+	void process_endif(Tokenizer *p_tokenizer);
+	void process_if(Tokenizer *p_tokenizer);
+	void process_ifdef(Tokenizer *p_tokenizer);
+	void process_ifndef(Tokenizer *p_tokenizer);
+	void process_include(Tokenizer *p_tokenizer);
+	void process_pragma(Tokenizer *p_tokenizer);
+	void process_undef(Tokenizer *p_tokenizer);
+
+	void start_branch_condition(Tokenizer *p_tokenizer, bool p_success);
+
+	void expand_output_macros(int p_start, int p_line);
+	Error expand_macros(const String &p_string, int p_line, String &r_result);
+	Error expand_macros(const String &p_string, int p_line, Vector<Pair<String, Define *>> p_defines, String &r_result);
+	Error expand_macros_once(const String &p_line, int p_line_number, Pair<String, Define *> p_define_pair, String &r_expanded);
+	bool find_match(const String &p_string, const String &p_value, int &r_index, int &r_index_start);
+
+	String next_directive(Tokenizer *p_tokenizer, const Vector<String> &p_directives);
+	void add_to_output(const String &p_str);
+	void set_error(const String &p_error, int p_line);
+	bool check_directive_before_type(Tokenizer *p_tokenizer, const String &p_directive);
+
+	static State *create_state();
+	static Define *create_define(const String &p_body);
+
+	void clear();
+
+public:
+	Error preprocess(State *p_state, String &r_result);
+	Error preprocess(String &r_result);
+
+	State *get_state();
+
+	static void get_keyword_list(List<String> *r_keywords, bool p_include_shader_keywords = false);
+	static void get_pragma_list(List<String> *r_pragmas);
+
+	ShaderPreprocessor(const String &p_code);
+	~ShaderPreprocessor();
+};
+
+#endif // SHADER_PREPROCESSOR_H