Shader: Add support for branching and discard statements

include/Nazara/Shader/Ast/Enums.hpp

@@ -35,16 +35,15 @@ namespace Nz
 		enum class BinaryType
 		{
 			Add,       //< +
-			Subtract,  //< -
-			Multiply,  //< *
-			Divide,    //< /
-
 			CompEq,    //< ==
 			CompGe,    //< >=
 			CompGt,    //< >
 			CompLe,    //< <=
 			CompLt,    //< <
-			CompNe     //< <=
+			CompNe,    //< <=
+			Divide,    //< /
+			Multiply,  //< *
+			Subtract,  //< -
 		};
 
 		enum class BuiltinEntry

include/Nazara/Shader/ShaderLangParser.hpp

@@ -83,6 +83,8 @@ namespace Nz::ShaderLang
 			std::vector<ShaderAst::Attribute> ParseAttributes();
 
 			// Statements
+			ShaderAst::StatementPtr ParseBranchStatement();
+			ShaderAst::StatementPtr ParseDiscardStatement();
 			ShaderAst::StatementPtr ParseExternalBlock(std::vector<ShaderAst::Attribute> attributes = {});
 			std::vector<ShaderAst::StatementPtr> ParseFunctionBody();
 			ShaderAst::StatementPtr ParseFunctionDeclaration(std::vector<ShaderAst::Attribute> attributes = {});
@@ -90,6 +92,7 @@ namespace Nz::ShaderLang
 			ShaderAst::StatementPtr ParseOptionDeclaration();
 			ShaderAst::StatementPtr ParseStructDeclaration(std::vector<ShaderAst::Attribute> attributes = {});
 			ShaderAst::StatementPtr ParseReturnStatement();
+			ShaderAst::StatementPtr ParseSingleStatement();
 			ShaderAst::StatementPtr ParseStatement();
 			std::vector<ShaderAst::StatementPtr> ParseStatementList();
 			ShaderAst::StatementPtr ParseVariableDeclaration();
@@ -126,6 +129,7 @@ namespace Nz::ShaderLang
 			Context* m_context;
 	};
 
+	inline ShaderAst::StatementPtr Parse(const std::string_view& source);
 	inline ShaderAst::StatementPtr Parse(const std::vector<Token>& tokens);
 	NAZARA_SHADER_API ShaderAst::StatementPtr Parse(const std::filesystem::path& sourcePath);
 }

include/Nazara/Shader/ShaderLangParser.inl

@@ -12,6 +12,11 @@ namespace Nz::ShaderLang
 	{
 	}
 
+	inline ShaderAst::StatementPtr Parse(const std::string_view& source)
+	{
+		return Parse(Tokenize(source));
+	}
+
 	inline ShaderAst::StatementPtr Parse(const std::vector<Token>& tokens)
 	{
 		Parser parser;

include/Nazara/Shader/ShaderLangTokenList.hpp

@@ -18,18 +18,21 @@ NAZARA_SHADERLANG_TOKEN(ClosingCurlyBracket)
 NAZARA_SHADERLANG_TOKEN(ClosingSquareBracket)
 NAZARA_SHADERLANG_TOKEN(Colon)
 NAZARA_SHADERLANG_TOKEN(Comma)
+NAZARA_SHADERLANG_TOKEN(Discard)
 NAZARA_SHADERLANG_TOKEN(Divide)
 NAZARA_SHADERLANG_TOKEN(Dot)
 NAZARA_SHADERLANG_TOKEN(Equal)
+NAZARA_SHADERLANG_TOKEN(Else)
+NAZARA_SHADERLANG_TOKEN(EndOfStream)
 NAZARA_SHADERLANG_TOKEN(External)
 NAZARA_SHADERLANG_TOKEN(FloatingPointValue)
-NAZARA_SHADERLANG_TOKEN(EndOfStream)
 NAZARA_SHADERLANG_TOKEN(FunctionDeclaration)
 NAZARA_SHADERLANG_TOKEN(FunctionReturn)
-NAZARA_SHADERLANG_TOKEN(GreatherThan)
+NAZARA_SHADERLANG_TOKEN(GreaterThan)
-NAZARA_SHADERLANG_TOKEN(GreatherThanEqual)
+NAZARA_SHADERLANG_TOKEN(GreaterThanEqual)
 NAZARA_SHADERLANG_TOKEN(IntegerValue)
 NAZARA_SHADERLANG_TOKEN(Identifier)
+NAZARA_SHADERLANG_TOKEN(If)
 NAZARA_SHADERLANG_TOKEN(LessThan)
 NAZARA_SHADERLANG_TOKEN(LessThanEqual)
 NAZARA_SHADERLANG_TOKEN(Let)

src/Nazara/Shader/ShaderLangLexer.cpp

@@ -40,9 +40,12 @@ namespace Nz::ShaderLang
 		ForceCLocale forceCLocale;
 
 		std::unordered_map<std::string, TokenType> reservedKeywords = {
+			{ "discard",    TokenType::Discard },
+			{ "else",       TokenType::Else },
 			{ "external",   TokenType::External },
 			{ "false",      TokenType::BoolFalse },
 			{ "fn",         TokenType::FunctionDeclaration },
+			{ "if",         TokenType::If },
 			{ "let",        TokenType::Let },
 			{ "option",     TokenType::Option },
 			{ "return",     TokenType::Return },
@@ -263,10 +266,10 @@ namespace Nz::ShaderLang
 					if (next == '=')
 					{
 						currentPos++;
-						tokenType = TokenType::GreatherThanEqual;
+						tokenType = TokenType::GreaterThanEqual;
 					}
 					else
-						tokenType = TokenType::GreatherThan;
+						tokenType = TokenType::GreaterThan;
 
 					break;
 				}

src/Nazara/Shader/ShaderLangParser.cpp

@@ -160,7 +160,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			matrixType.type = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return matrixType;
 		}
@@ -174,7 +174,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			matrixType.type = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return matrixType;
 		}
@@ -187,7 +187,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			samplerType.sampledType = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return samplerType;
 		}
@@ -200,7 +200,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			samplerType.sampledType = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return samplerType;
 		}
@@ -212,7 +212,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			uniformType.containedType = ShaderAst::IdentifierType{ ParseIdentifierAsName() };
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return uniformType;
 		}
@@ -225,7 +225,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			vectorType.type = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return vectorType;
 		}
@@ -238,7 +238,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			vectorType.type = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return vectorType;
 		}
@@ -251,7 +251,7 @@ namespace Nz::ShaderLang
 
 			Expect(Advance(), TokenType::LessThan); //< '<'
 			vectorType.type = ParsePrimitiveType();
-			Expect(Advance(), TokenType::GreatherThan); //< '>'
+			Expect(Advance(), TokenType::GreaterThan); //< '>'
 
 			return vectorType;
 		}
@@ -302,9 +302,6 @@ namespace Nz::ShaderLang
 
 	void Parser::RegisterVariable(std::string identifier)
 	{
-		if (IsVariableInScope(identifier))
-			throw DuplicateIdentifier{ ("identifier name " + identifier + " is already taken").c_str() };
-
 		assert(!m_context->scopeSizes.empty());
 		m_context->identifiersInScope.push_back(std::move(identifier));
 	}
@@ -378,6 +375,47 @@ namespace Nz::ShaderLang
 		return attributes;
 	}
 
+	ShaderAst::StatementPtr Parser::ParseBranchStatement()
+	{
+		std::unique_ptr<ShaderAst::BranchStatement> branch = std::make_unique<ShaderAst::BranchStatement>();
+
+		bool first = true;
+		for (;;)
+		{
+			if (!first)
+				Expect(Advance(), TokenType::Else);
+
+			first = false;
+
+			Expect(Advance(), TokenType::If);
+
+			auto& condStatement = branch->condStatements.emplace_back();
+
+			Expect(Advance(), TokenType::OpenParenthesis);
+
+			condStatement.condition = ParseExpression();
+
+			Expect(Advance(), TokenType::ClosingParenthesis);
+
+			condStatement.statement = ParseStatement();
+
+			if (Peek().type != TokenType::Else || Peek(1).type != TokenType::If)
+				break;
+		}
+
+		if (Peek().type == TokenType::Else)
+			branch->elseStatement = ParseStatement();
+
+		return branch;
+	}
+
+	ShaderAst::StatementPtr Parser::ParseDiscardStatement()
+	{
+		Expect(Advance(), TokenType::Discard);
+
+		return ShaderBuilder::Discard();
+	}
+
 	ShaderAst::StatementPtr Parser::ParseExternalBlock(std::vector<ShaderAst::Attribute> attributes)
 	{
 		std::optional<UInt32> blockSetIndex;
@@ -533,8 +571,6 @@ namespace Nz::ShaderLang
 			returnType = ParseType();
 		}
 
-		Expect(Advance(), TokenType::OpenCurlyBracket);
-
 		EnterScope();
 		for (const auto& parameter : parameters)
 			RegisterVariable(parameter.name);
@@ -616,10 +652,10 @@ namespace Nz::ShaderLang
 				case ShaderAst::AttributeType::Option:
 				{
 					if (!func->optionName.empty())
-						throw AttributeError{ "attribute option must be present once" };
+						throw AttributeError{ "attribute opt must be present once" };
 
 					if (!std::holds_alternative<std::string>(arg))
-						throw AttributeError{ "attribute option requires a string parameter" };
+						throw AttributeError{ "attribute opt requires a string parameter" };
 
 					func->optionName = std::get<std::string>(arg);
 					break;
@@ -786,36 +822,58 @@ namespace Nz::ShaderLang
 		return ShaderBuilder::Return(std::move(expr));
 	}
 
-	ShaderAst::StatementPtr Parser::ParseStatement()
+	ShaderAst::StatementPtr Parser::ParseSingleStatement()
 	{
 		const Token& token = Peek();
 
 		ShaderAst::StatementPtr statement;
 		switch (token.type)
 		{
+			case TokenType::Discard:
+				statement = ParseDiscardStatement();
+				Expect(Advance(), TokenType::Semicolon);
+				break;
+
 			case TokenType::Let:
 				statement = ParseVariableDeclaration();
+				Expect(Advance(), TokenType::Semicolon);
 				break;
 
 			case TokenType::Identifier:
 				statement = ShaderBuilder::ExpressionStatement(ParseVariableAssignation());
+				Expect(Advance(), TokenType::Semicolon);
+				break;
+
+			case TokenType::If:
+				statement = ParseBranchStatement();
 				break;
 
 			case TokenType::Return:
 				statement = ParseReturnStatement();
+				Expect(Advance(), TokenType::Semicolon);
 				break;
 
 			default:
 				break;
 		}
 
-		Expect(Advance(), TokenType::Semicolon);
-
 		return statement;
 	}
 
+	ShaderAst::StatementPtr Parser::ParseStatement()
+	{
+		if (Peek().type == TokenType::OpenCurlyBracket)
+			return ShaderBuilder::MultiStatement(ParseStatementList());
+		else
+			return ParseSingleStatement();
+	}
+
 	std::vector<ShaderAst::StatementPtr> Parser::ParseStatementList()
 	{
+		EnterScope();
+
+		Expect(Advance(), TokenType::OpenCurlyBracket);
+
 		std::vector<ShaderAst::StatementPtr> statements;
 		while (Peek().type != TokenType::ClosingCurlyBracket)
 		{
@@ -823,6 +881,8 @@ namespace Nz::ShaderLang
 			statements.push_back(ParseStatement());
 		}
 
+		LeaveScope();
+
 		return statements;
 	}
 
@@ -944,11 +1004,18 @@ namespace Nz::ShaderLang
 			{
 				switch (currentTokenType)
 				{
-					case TokenType::Plus:     binaryType = ShaderAst::BinaryType::Add; break;
+					case TokenType::Divide:           binaryType = ShaderAst::BinaryType::Divide; break;
-					case TokenType::Minus:    binaryType = ShaderAst::BinaryType::Subtract; break;
+					case TokenType::Equal:            binaryType = ShaderAst::BinaryType::CompEq; break;
-					case TokenType::Multiply: binaryType = ShaderAst::BinaryType::Multiply; break;
+					case TokenType::LessThan:         binaryType = ShaderAst::BinaryType::CompLt; break;
-					case TokenType::Divide:   binaryType = ShaderAst::BinaryType::Divide; break;
+					case TokenType::LessThanEqual:    binaryType = ShaderAst::BinaryType::CompLe; break;
-					default: throw UnexpectedToken{};
+					case TokenType::GreaterThan:      binaryType = ShaderAst::BinaryType::CompLt; break;
+					case TokenType::GreaterThanEqual: binaryType = ShaderAst::BinaryType::CompLe; break;
+					case TokenType::Minus:            binaryType = ShaderAst::BinaryType::Subtract; break;
+					case TokenType::Multiply:         binaryType = ShaderAst::BinaryType::Multiply; break;
+					case TokenType::NotEqual:         binaryType = ShaderAst::BinaryType::CompNe; break;
+					case TokenType::Plus:             binaryType = ShaderAst::BinaryType::Add; break;
+					default:
+						throw UnexpectedToken{};
 				}
 			}
 
@@ -1159,12 +1226,18 @@ namespace Nz::ShaderLang
 	{
 		switch (token)
 		{
-			case TokenType::Plus:              return 20;
+			case TokenType::Divide:            return 80;
-			case TokenType::Divide:            return 40;
+			case TokenType::Dot:               return 100;
-			case TokenType::Multiply:          return 40;
+			case TokenType::Equal:             return 50;
-			case TokenType::Minus:             return 20;
+			case TokenType::LessThan:          return 40;
-			case TokenType::Dot:               return 50;
+			case TokenType::LessThanEqual:     return 40;
-			case TokenType::OpenSquareBracket: return 50;
+			case TokenType::GreaterThan:       return 40;
+			case TokenType::GreaterThanEqual:  return 40;
+			case TokenType::Multiply:          return 80;
+			case TokenType::Minus:             return 60;
+			case TokenType::NotEqual:          return 50;
+			case TokenType::Plus:              return 60;
+			case TokenType::OpenSquareBracket: return 100;
 			default: return -1;
 		}
 	}
@@ -1187,6 +1260,6 @@ namespace Nz::ShaderLang
 			return {};
 		}
 
-		return Parse(Tokenize(std::string_view(reinterpret_cast<const char*>(source.data()), source.size())));
+		return Parse(std::string_view(reinterpret_cast<const char*>(source.data()), source.size()));
 	}
 }