-Add Expression class, used to evaluate expressions

-Added expression evaluation to EditorSpinSlider, fixes #20813, fixes #18932

3 files changed, 2445 insertions, 0 deletions

diff --git a/core/math/expression.cpp b/core/math/expression.cpp
new file mode 100644
index 0000000000..c6276151fc
--- /dev/null
+++ b/core/math/expression.cpp
@@ -0,0 +1,2120 @@
+#include "expression.h"
+
+#include "class_db.h"
+#include "func_ref.h"
+#include "io/marshalls.h"
+#include "math_funcs.h"
+#include "os/os.h"
+#include "reference.h"
+#include "variant_parser.h"
+
+const char *Expression::func_name[Expression::FUNC_MAX] = {
+	"sin",
+	"cos",
+	"tan",
+	"sinh",
+	"cosh",
+	"tanh",
+	"asin",
+	"acos",
+	"atan",
+	"atan2",
+	"sqrt",
+	"fmod",
+	"fposmod",
+	"floor",
+	"ceil",
+	"round",
+	"abs",
+	"sign",
+	"pow",
+	"log",
+	"exp",
+	"is_nan",
+	"is_inf",
+	"ease",
+	"decimals",
+	"stepify",
+	"lerp",
+	"inverse_lerp",
+	"range_lerp",
+	"dectime",
+	"randomize",
+	"randi",
+	"randf",
+	"rand_range",
+	"seed",
+	"rand_seed",
+	"deg2rad",
+	"rad2deg",
+	"linear2db",
+	"db2linear",
+	"polar2cartesian",
+	"cartesian2polar",
+	"wrapi",
+	"wrapf",
+	"max",
+	"min",
+	"clamp",
+	"nearest_po2",
+	"weakref",
+	"funcref",
+	"convert",
+	"typeof",
+	"type_exists",
+	"char",
+	"str",
+	"print",
+	"printerr",
+	"printraw",
+	"var2str",
+	"str2var",
+	"var2bytes",
+	"bytes2var",
+	"color_named",
+};
+
+Expression::BuiltinFunc Expression::find_function(const String &p_string) {
+
+	for (int i = 0; i < FUNC_MAX; i++) {
+		if (p_string == func_name[i])
+			return BuiltinFunc(i);
+	}
+
+	return FUNC_MAX;
+}
+
+String Expression::get_func_name(BuiltinFunc p_func) {
+
+	ERR_FAIL_INDEX_V(p_func, FUNC_MAX, String());
+	return func_name[p_func];
+}
+
+int Expression::get_func_argument_count(BuiltinFunc p_func) {
+
+	switch (p_func) {
+
+		case MATH_RANDOMIZE:
+		case MATH_RAND:
+		case MATH_RANDF:
+			return 0;
+		case MATH_SIN:
+		case MATH_COS:
+		case MATH_TAN:
+		case MATH_SINH:
+		case MATH_COSH:
+		case MATH_TANH:
+		case MATH_ASIN:
+		case MATH_ACOS:
+		case MATH_ATAN:
+		case MATH_SQRT:
+		case MATH_FLOOR:
+		case MATH_CEIL:
+		case MATH_ROUND:
+		case MATH_ABS:
+		case MATH_SIGN:
+		case MATH_LOG:
+		case MATH_EXP:
+		case MATH_ISNAN:
+		case MATH_ISINF:
+		case MATH_DECIMALS:
+		case MATH_SEED:
+		case MATH_RANDSEED:
+		case MATH_DEG2RAD:
+		case MATH_RAD2DEG:
+		case MATH_LINEAR2DB:
+		case MATH_DB2LINEAR:
+		case LOGIC_NEAREST_PO2:
+		case OBJ_WEAKREF:
+		case TYPE_OF:
+		case TEXT_CHAR:
+		case TEXT_STR:
+		case TEXT_PRINT:
+		case TEXT_PRINTERR:
+		case TEXT_PRINTRAW:
+		case VAR_TO_STR:
+		case STR_TO_VAR:
+		case VAR_TO_BYTES:
+		case BYTES_TO_VAR:
+		case TYPE_EXISTS:
+			return 1;
+		case MATH_ATAN2:
+		case MATH_FMOD:
+		case MATH_FPOSMOD:
+		case MATH_POW:
+		case MATH_EASE:
+		case MATH_STEPIFY:
+		case MATH_RANDOM:
+		case MATH_POLAR2CARTESIAN:
+		case MATH_CARTESIAN2POLAR:
+		case LOGIC_MAX:
+		case LOGIC_MIN:
+		case FUNC_FUNCREF:
+		case TYPE_CONVERT:
+		case COLORN:
+			return 2;
+		case MATH_LERP:
+		case MATH_INVERSE_LERP:
+		case MATH_DECTIME:
+		case MATH_WRAP:
+		case MATH_WRAPF:
+		case LOGIC_CLAMP:
+			return 3;
+		case MATH_RANGE_LERP:
+			return 5;
+		case FUNC_MAX: {
+		}
+	}
+	return 0;
+}
+
+#define VALIDATE_ARG_NUM(m_arg)                                          \
+	if (!p_inputs[m_arg]->is_num()) {                                    \
+		r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT; \
+		r_error.argument = m_arg;                                        \
+		r_error.expected = Variant::REAL;                                \
+		return;                                                          \
+	}
+
+void Expression::exec_func(BuiltinFunc p_func, const Variant **p_inputs, Variant *r_return, Variant::CallError &r_error, String &r_error_str) {
+
+	switch (p_func) {
+		case MATH_SIN: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::sin((double)*p_inputs[0]);
+		} break;
+		case MATH_COS: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::cos((double)*p_inputs[0]);
+		} break;
+		case MATH_TAN: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::tan((double)*p_inputs[0]);
+		} break;
+		case MATH_SINH: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::sinh((double)*p_inputs[0]);
+		} break;
+		case MATH_COSH: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::cosh((double)*p_inputs[0]);
+		} break;
+		case MATH_TANH: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::tanh((double)*p_inputs[0]);
+		} break;
+		case MATH_ASIN: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::asin((double)*p_inputs[0]);
+		} break;
+		case MATH_ACOS: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::acos((double)*p_inputs[0]);
+		} break;
+		case MATH_ATAN: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::atan((double)*p_inputs[0]);
+		} break;
+		case MATH_ATAN2: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::atan2((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_SQRT: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::sqrt((double)*p_inputs[0]);
+		} break;
+		case MATH_FMOD: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::fmod((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_FPOSMOD: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::fposmod((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_FLOOR: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::floor((double)*p_inputs[0]);
+		} break;
+		case MATH_CEIL: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::ceil((double)*p_inputs[0]);
+		} break;
+		case MATH_ROUND: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::round((double)*p_inputs[0]);
+		} break;
+		case MATH_ABS: {
+
+			if (p_inputs[0]->get_type() == Variant::INT) {
+
+				int64_t i = *p_inputs[0];
+				*r_return = ABS(i);
+			} else if (p_inputs[0]->get_type() == Variant::REAL) {
+
+				real_t r = *p_inputs[0];
+				*r_return = Math::abs(r);
+			} else {
+
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::REAL;
+			}
+		} break;
+		case MATH_SIGN: {
+
+			if (p_inputs[0]->get_type() == Variant::INT) {
+
+				int64_t i = *p_inputs[0];
+				*r_return = i < 0 ? -1 : (i > 0 ? +1 : 0);
+			} else if (p_inputs[0]->get_type() == Variant::REAL) {
+
+				real_t r = *p_inputs[0];
+				*r_return = r < 0.0 ? -1.0 : (r > 0.0 ? +1.0 : 0.0);
+			} else {
+
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::REAL;
+			}
+		} break;
+		case MATH_POW: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::pow((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_LOG: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::log((double)*p_inputs[0]);
+		} break;
+		case MATH_EXP: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::exp((double)*p_inputs[0]);
+		} break;
+		case MATH_ISNAN: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::is_nan((double)*p_inputs[0]);
+		} break;
+		case MATH_ISINF: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::is_inf((double)*p_inputs[0]);
+		} break;
+		case MATH_EASE: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::ease((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_DECIMALS: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::step_decimals((double)*p_inputs[0]);
+		} break;
+		case MATH_STEPIFY: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::stepify((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_LERP: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			*r_return = Math::lerp((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2]);
+		} break;
+		case MATH_INVERSE_LERP: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			*r_return = Math::inverse_lerp((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2]);
+		} break;
+		case MATH_RANGE_LERP: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			VALIDATE_ARG_NUM(3);
+			VALIDATE_ARG_NUM(4);
+			*r_return = Math::range_lerp((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2], (double)*p_inputs[3], (double)*p_inputs[4]);
+		} break;
+		case MATH_DECTIME: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			*r_return = Math::dectime((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2]);
+		} break;
+		case MATH_RANDOMIZE: {
+			Math::randomize();
+
+		} break;
+		case MATH_RAND: {
+			*r_return = Math::rand();
+		} break;
+		case MATH_RANDF: {
+			*r_return = Math::randf();
+		} break;
+		case MATH_RANDOM: {
+
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			*r_return = Math::random((double)*p_inputs[0], (double)*p_inputs[1]);
+		} break;
+		case MATH_SEED: {
+
+			VALIDATE_ARG_NUM(0);
+			uint64_t seed = *p_inputs[0];
+			Math::seed(seed);
+
+		} break;
+		case MATH_RANDSEED: {
+
+			VALIDATE_ARG_NUM(0);
+			uint64_t seed = *p_inputs[0];
+			int ret = Math::rand_from_seed(&seed);
+			Array reta;
+			reta.push_back(ret);
+			reta.push_back(seed);
+			*r_return = reta;
+
+		} break;
+		case MATH_DEG2RAD: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::deg2rad((double)*p_inputs[0]);
+		} break;
+		case MATH_RAD2DEG: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::rad2deg((double)*p_inputs[0]);
+		} break;
+		case MATH_LINEAR2DB: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::linear2db((double)*p_inputs[0]);
+		} break;
+		case MATH_DB2LINEAR: {
+
+			VALIDATE_ARG_NUM(0);
+			*r_return = Math::db2linear((double)*p_inputs[0]);
+		} break;
+		case MATH_POLAR2CARTESIAN: {
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			double r = *p_inputs[0];
+			double th = *p_inputs[1];
+			*r_return = Vector2(r * Math::cos(th), r * Math::sin(th));
+		} break;
+		case MATH_CARTESIAN2POLAR: {
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			double x = *p_inputs[0];
+			double y = *p_inputs[1];
+			*r_return = Vector2(Math::sqrt(x * x + y * y), Math::atan2(y, x));
+		} break;
+		case MATH_WRAP: {
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			*r_return = Math::wrapi((int64_t)*p_inputs[0], (int64_t)*p_inputs[1], (int64_t)*p_inputs[2]);
+		} break;
+		case MATH_WRAPF: {
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			*r_return = Math::wrapf((double)*p_inputs[0], (double)*p_inputs[1], (double)*p_inputs[2]);
+		} break;
+		case LOGIC_MAX: {
+
+			if (p_inputs[0]->get_type() == Variant::INT && p_inputs[1]->get_type() == Variant::INT) {
+
+				int64_t a = *p_inputs[0];
+				int64_t b = *p_inputs[1];
+				*r_return = MAX(a, b);
+			} else {
+				VALIDATE_ARG_NUM(0);
+				VALIDATE_ARG_NUM(1);
+
+				real_t a = *p_inputs[0];
+				real_t b = *p_inputs[1];
+
+				*r_return = MAX(a, b);
+			}
+
+		} break;
+		case LOGIC_MIN: {
+
+			if (p_inputs[0]->get_type() == Variant::INT && p_inputs[1]->get_type() == Variant::INT) {
+
+				int64_t a = *p_inputs[0];
+				int64_t b = *p_inputs[1];
+				*r_return = MIN(a, b);
+			} else {
+				VALIDATE_ARG_NUM(0);
+				VALIDATE_ARG_NUM(1);
+
+				real_t a = *p_inputs[0];
+				real_t b = *p_inputs[1];
+
+				*r_return = MIN(a, b);
+			}
+		} break;
+		case LOGIC_CLAMP: {
+
+			if (p_inputs[0]->get_type() == Variant::INT && p_inputs[1]->get_type() == Variant::INT && p_inputs[2]->get_type() == Variant::INT) {
+
+				int64_t a = *p_inputs[0];
+				int64_t b = *p_inputs[1];
+				int64_t c = *p_inputs[2];
+				*r_return = CLAMP(a, b, c);
+			} else {
+				VALIDATE_ARG_NUM(0);
+				VALIDATE_ARG_NUM(1);
+				VALIDATE_ARG_NUM(2);
+
+				real_t a = *p_inputs[0];
+				real_t b = *p_inputs[1];
+				real_t c = *p_inputs[2];
+
+				*r_return = CLAMP(a, b, c);
+			}
+		} break;
+		case LOGIC_NEAREST_PO2: {
+
+			VALIDATE_ARG_NUM(0);
+			int64_t num = *p_inputs[0];
+			*r_return = next_power_of_2(num);
+		} break;
+		case OBJ_WEAKREF: {
+
+			if (p_inputs[0]->get_type() != Variant::OBJECT) {
+
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::OBJECT;
+
+				return;
+			}
+
+			if (p_inputs[0]->is_ref()) {
+
+				REF r = *p_inputs[0];
+				if (!r.is_valid()) {
+
+					return;
+				}
+
+				Ref<WeakRef> wref = memnew(WeakRef);
+				wref->set_ref(r);
+				*r_return = wref;
+			} else {
+				Object *obj = *p_inputs[0];
+				if (!obj) {
+
+					return;
+				}
+				Ref<WeakRef> wref = memnew(WeakRef);
+				wref->set_obj(obj);
+				*r_return = wref;
+			}
+
+		} break;
+		case FUNC_FUNCREF: {
+
+			if (p_inputs[0]->get_type() != Variant::OBJECT) {
+
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::OBJECT;
+
+				return;
+			}
+			if (p_inputs[1]->get_type() != Variant::STRING && p_inputs[1]->get_type() != Variant::NODE_PATH) {
+
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 1;
+				r_error.expected = Variant::STRING;
+
+				return;
+			}
+
+			Ref<FuncRef> fr = memnew(FuncRef);
+
+			fr->set_instance(*p_inputs[0]);
+			fr->set_function(*p_inputs[1]);
+
+			*r_return = fr;
+
+		} break;
+		case TYPE_CONVERT: {
+
+			VALIDATE_ARG_NUM(1);
+			int type = *p_inputs[1];
+			if (type < 0 || type >= Variant::VARIANT_MAX) {
+
+				r_error_str = RTR("Invalid type argument to convert(), use TYPE_* constants.");
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::INT;
+				return;
+
+			} else {
+
+				*r_return = Variant::construct(Variant::Type(type), p_inputs, 1, r_error);
+			}
+		} break;
+		case TYPE_OF: {
+
+			*r_return = p_inputs[0]->get_type();
+
+		} break;
+		case TYPE_EXISTS: {
+
+			*r_return = ClassDB::class_exists(*p_inputs[0]);
+
+		} break;
+		case TEXT_CHAR: {
+
+			CharType result[2] = { *p_inputs[0], 0 };
+
+			*r_return = String(result);
+
+		} break;
+		case TEXT_STR: {
+
+			String str = *p_inputs[0];
+
+			*r_return = str;
+
+		} break;
+		case TEXT_PRINT: {
+
+			String str = *p_inputs[0];
+			print_line(str);
+
+		} break;
+
+		case TEXT_PRINTERR: {
+
+			String str = *p_inputs[0];
+
+			//str+="\n";
+			print_error(str);
+
+		} break;
+		case TEXT_PRINTRAW: {
+			String str = *p_inputs[0];
+
+			//str+="\n";
+			OS::get_singleton()->print("%s", str.utf8().get_data());
+
+		} break;
+		case VAR_TO_STR: {
+
+			String vars;
+			VariantWriter::write_to_string(*p_inputs[0], vars);
+			*r_return = vars;
+		} break;
+		case STR_TO_VAR: {
+
+			if (p_inputs[0]->get_type() != Variant::STRING) {
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::STRING;
+
+				return;
+			}
+
+			VariantParser::StreamString ss;
+			ss.s = *p_inputs[0];
+
+			String errs;
+			int line;
+			Error err = VariantParser::parse(&ss, *r_return, errs, line);
+
+			if (err != OK) {
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::STRING;
+				*r_return = "Parse error at line " + itos(line) + ": " + errs;
+				return;
+			}
+
+		} break;
+		case VAR_TO_BYTES: {
+
+			PoolByteArray barr;
+			int len;
+			Error err = encode_variant(*p_inputs[0], NULL, len);
+			if (err) {
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::NIL;
+				r_error_str = "Unexpected error encoding variable to bytes, likely unserializable type found (Object or RID).";
+				return;
+			}
+
+			barr.resize(len);
+			{
+				PoolByteArray::Write w = barr.write();
+				encode_variant(*p_inputs[0], w.ptr(), len);
+			}
+			*r_return = barr;
+		} break;
+		case BYTES_TO_VAR: {
+
+			if (p_inputs[0]->get_type() != Variant::POOL_BYTE_ARRAY) {
+				r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+				r_error.argument = 0;
+				r_error.expected = Variant::POOL_BYTE_ARRAY;
+
+				return;
+			}
+
+			PoolByteArray varr = *p_inputs[0];
+			Variant ret;
+			{
+				PoolByteArray::Read r = varr.read();
+				Error err = decode_variant(ret, r.ptr(), varr.size(), NULL);
+				if (err != OK) {
+					r_error_str = RTR("Not enough bytes for decoding bytes, or invalid format.");
+					r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
+					r_error.argument = 0;
+					r_error.expected = Variant::POOL_BYTE_ARRAY;
+					return;
+				}
+			}
+
+			*r_return = ret;
+
+		} break;
+		case COLORN: {
+
+			VALIDATE_ARG_NUM(1);
+
+			Color color = Color::named(*p_inputs[0]);
+			color.a = *p_inputs[1];
+
+			*r_return = String(color);
+
+		} break;
+		default: {}
+	}
+}
+
+////////
+
+Error Expression::_get_token(Token &r_token) {
+
+	while (true) {
+#define GET_CHAR() (str_ofs >= expression.length() ? 0 : expression[str_ofs++])
+
+		CharType cchar = GET_CHAR();
+		if (cchar == 0) {
+			r_token.type = TK_EOF;
+			return OK;
+		}
+
+		switch (cchar) {
+
+			case 0: {
+				r_token.type = TK_EOF;
+				return OK;
+			} break;
+			case '{': {
+
+				r_token.type = TK_CURLY_BRACKET_OPEN;
+				return OK;
+			};
+			case '}': {
+
+				r_token.type = TK_CURLY_BRACKET_CLOSE;
+				return OK;
+			};
+			case '[': {
+
+				r_token.type = TK_BRACKET_OPEN;
+				return OK;
+			};
+			case ']': {
+
+				r_token.type = TK_BRACKET_CLOSE;
+				return OK;
+			};
+			case '(': {
+
+				r_token.type = TK_PARENTHESIS_OPEN;
+				return OK;
+			};
+			case ')': {
+
+				r_token.type = TK_PARENTHESIS_CLOSE;
+				return OK;
+			};
+			case ',': {
+
+				r_token.type = TK_COMMA;
+				return OK;
+			};
+			case ':': {
+
+				r_token.type = TK_COLON;
+				return OK;
+			};
+			case '.': {
+
+				r_token.type = TK_PERIOD;
+				return OK;
+			};
+			case '$': {
+
+				r_token.type = TK_INPUT;
+				int index = 0;
+				do {
+					if (expression[str_ofs] < '0' || expression[str_ofs] > '9') {
+						_set_error("Expected number after '$'");
+						r_token.type = TK_ERROR;
+						return ERR_PARSE_ERROR;
+					}
+					index *= 10;
+					index += expression[str_ofs] - '0';
+					str_ofs++;
+
+				} while (expression[str_ofs] >= '0' && expression[str_ofs] <= '9');
+
+				r_token.value = index;
+				return OK;
+			};
+			case '=': {
+
+				cchar = GET_CHAR();
+				if (cchar == '=') {
+					r_token.type = TK_OP_EQUAL;
+				} else {
+					_set_error("Expected '='");
+					r_token.type = TK_ERROR;
+					return ERR_PARSE_ERROR;
+				}
+				return OK;
+			};
+			case '!': {
+
+				if (expression[str_ofs] == '=') {
+					r_token.type = TK_OP_NOT_EQUAL;
+					str_ofs++;
+				} else {
+					r_token.type = TK_OP_NOT;
+				}
+				return OK;
+			};
+			case '>': {
+
+				if (expression[str_ofs] == '=') {
+					r_token.type = TK_OP_GREATER_EQUAL;
+					str_ofs++;
+				} else if (expression[str_ofs] == '>') {
+					r_token.type = TK_OP_SHIFT_RIGHT;
+					str_ofs++;
+				} else {
+					r_token.type = TK_OP_GREATER;
+				}
+				return OK;
+			};
+			case '<': {
+
+				if (expression[str_ofs] == '=') {
+					r_token.type = TK_OP_LESS_EQUAL;
+					str_ofs++;
+				} else if (expression[str_ofs] == '<') {
+					r_token.type = TK_OP_SHIFT_LEFT;
+					str_ofs++;
+				} else {
+					r_token.type = TK_OP_LESS;
+				}
+				return OK;
+			};
+			case '+': {
+				r_token.type = TK_OP_ADD;
+				return OK;
+			};
+			case '-': {
+				r_token.type = TK_OP_SUB;
+				return OK;
+			};
+			case '/': {
+				r_token.type = TK_OP_DIV;
+				return OK;
+			};
+			case '*': {
+				r_token.type = TK_OP_MUL;
+				return OK;
+			};
+			case '%': {
+				r_token.type = TK_OP_MOD;
+				return OK;
+			};
+			case '&': {
+
+				if (expression[str_ofs] == '&') {
+					r_token.type = TK_OP_AND;
+					str_ofs++;
+				} else {
+					r_token.type = TK_OP_BIT_AND;
+				}
+				return OK;
+			};
+			case '|': {
+
+				if (expression[str_ofs] == '|') {
+					r_token.type = TK_OP_OR;
+					str_ofs++;
+				} else {
+					r_token.type = TK_OP_BIT_OR;
+				}
+				return OK;
+			};
+			case '^': {
+
+				r_token.type = TK_OP_BIT_XOR;
+
+				return OK;
+			};
+			case '~': {
+
+				r_token.type = TK_OP_BIT_INVERT;
+
+				return OK;
+			};
+			case '"': {
+
+				String str;
+				while (true) {
+
+					CharType ch = GET_CHAR();
+
+					if (ch == 0) {
+						_set_error("Unterminated String");
+						r_token.type = TK_ERROR;
+						return ERR_PARSE_ERROR;
+					} else if (ch == '"') {
+						break;
+					} else if (ch == '\\') {
+						//escaped characters...
+
+						CharType next = GET_CHAR();
+						if (next == 0) {
+							_set_error("Unterminated String");
+							r_token.type = TK_ERROR;
+							return ERR_PARSE_ERROR;
+						}
+						CharType res = 0;
+
+						switch (next) {
+
+							case 'b': res = 8; break;
+							case 't': res = 9; break;
+							case 'n': res = 10; break;
+							case 'f': res = 12; break;
+							case 'r': res = 13; break;
+							case 'u': {
+								//hexnumbarh - oct is deprecated
+
+								for (int j = 0; j < 4; j++) {
+									CharType c = GET_CHAR();
+
+									if (c == 0) {
+										_set_error("Unterminated String");
+										r_token.type = TK_ERROR;
+										return ERR_PARSE_ERROR;
+									}
+									if (!((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F'))) {
+
+										_set_error("Malformed hex constant in string");
+										r_token.type = TK_ERROR;
+										return ERR_PARSE_ERROR;
+									}
+									CharType v;
+									if (c >= '0' && c <= '9') {
+										v = c - '0';
+									} else if (c >= 'a' && c <= 'f') {
+										v = c - 'a';
+										v += 10;
+									} else if (c >= 'A' && c <= 'F') {
+										v = c - 'A';
+										v += 10;
+									} else {
+										ERR_PRINT("BUG");
+										v = 0;
+									}
+
+									res <<= 4;
+									res |= v;
+								}
+
+							} break;
+							//case '\"': res='\"'; break;
+							//case '\\': res='\\'; break;
+							//case '/': res='/'; break;
+							default: {
+								res = next;
+								//r_err_str="Invalid escape sequence";
+								//return ERR_PARSE_ERROR;
+							} break;
+						}
+
+						str += res;
+
+					} else {
+						str += ch;
+					}
+				}
+
+				r_token.type = TK_CONSTANT;
+				r_token.value = str;
+				return OK;
+
+			} break;
+			default: {
+
+				if (cchar <= 32) {
+					break;
+				}
+
+				if (cchar >= '0' && cchar <= '9') {
+					//a number
+
+					String num;
+#define READING_SIGN 0
+#define READING_INT 1
+#define READING_DEC 2
+#define READING_EXP 3
+#define READING_DONE 4
+					int reading = READING_INT;
+
+					CharType c = cchar;
+					bool exp_sign = false;
+					bool exp_beg = false;
+					bool is_float = false;
+
+					while (true) {
+
+						switch (reading) {
+							case READING_INT: {
+
+								if (c >= '0' && c <= '9') {
+									//pass
+								} else if (c == '.') {
+									reading = READING_DEC;
+									is_float = true;
+								} else if (c == 'e') {
+									reading = READING_EXP;
+								} else {
+									reading = READING_DONE;
+								}
+
+							} break;
+							case READING_DEC: {
+
+								if (c >= '0' && c <= '9') {
+
+								} else if (c == 'e') {
+									reading = READING_EXP;
+
+								} else {
+									reading = READING_DONE;
+								}
+
+							} break;
+							case READING_EXP: {
+
+								if (c >= '0' && c <= '9') {
+									exp_beg = true;
+
+								} else if ((c == '-' || c == '+') && !exp_sign && !exp_beg) {
+									if (c == '-')
+										is_float = true;
+									exp_sign = true;
+
+								} else {
+									reading = READING_DONE;
+								}
+							} break;
+						}
+
+						if (reading == READING_DONE)
+							break;
+						num += String::chr(c);
+						c = GET_CHAR();
+					}
+
+					str_ofs--;
+
+					r_token.type = TK_CONSTANT;
+
+					if (is_float)
+						r_token.value = num.to_double();
+					else
+						r_token.value = num.to_int();
+					return OK;
+
+				} else if ((cchar >= 'A' && cchar <= 'Z') || (cchar >= 'a' && cchar <= 'z') || cchar == '_') {
+
+					String id;
+					bool first = true;
+
+					while ((cchar >= 'A' && cchar <= 'Z') || (cchar >= 'a' && cchar <= 'z') || cchar == '_' || (!first && cchar >= '0' && cchar <= '9')) {
+
+						id += String::chr(cchar);
+						cchar = GET_CHAR();
+						first = false;
+					}
+
+					str_ofs--; //go back one
+
+					if (id == "in") {
+						r_token.type = TK_OP_IN;
+					} else if (id == "null") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = Variant();
+					} else if (id == "true") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = true;
+					} else if (id == "false") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = false;
+					} else if (id == "PI") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = Math_PI;
+					} else if (id == "TAU") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = Math_TAU;
+					} else if (id == "INF") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = Math_INF;
+					} else if (id == "NAN") {
+						r_token.type = TK_CONSTANT;
+						r_token.value = Math_NAN;
+					} else if (id == "not") {
+						r_token.type = TK_OP_NOT;
+					} else if (id == "or") {
+						r_token.type = TK_OP_OR;
+					} else if (id == "and") {
+						r_token.type = TK_OP_AND;
+					} else if (id == "self") {
+						r_token.type = TK_SELF;
+					} else {
+
+						for (int i = 0; i < Variant::VARIANT_MAX; i++) {
+							if (id == Variant::get_type_name(Variant::Type(i))) {
+								r_token.type = TK_BASIC_TYPE;
+								r_token.value = i;
+								return OK;
+							}
+						}
+
+						BuiltinFunc bifunc = find_function(id);
+						if (bifunc != FUNC_MAX) {
+							r_token.type = TK_BUILTIN_FUNC;
+							r_token.value = bifunc;
+							return OK;
+						}
+
+						r_token.type = TK_IDENTIFIER;
+						r_token.value = id;
+					}
+
+					return OK;
+				} else {
+					_set_error("Unexpected character.");
+					r_token.type = TK_ERROR;
+					return ERR_PARSE_ERROR;
+				}
+			}
+		}
+	}
+
+	r_token.type = TK_ERROR;
+	return ERR_PARSE_ERROR;
+}
+
+const char *Expression::token_name[TK_MAX] = {
+	"CURLY BRACKET OPEN",
+	"CURLY BRACKET CLOSE",
+	"BRACKET OPEN",
+	"BRACKET CLOSE",
+	"PARENTHESIS OPEN",
+	"PARENTHESIS CLOSE",
+	"IDENTIFIER",
+	"BUILTIN FUNC",
+	"SELF",
+	"CONSTANT",
+	"BASIC TYPE",
+	"COLON",
+	"COMMA",
+	"PERIOD",
+	"OP IN",
+	"OP EQUAL",
+	"OP NOT EQUAL",
+	"OP LESS",
+	"OP LESS EQUAL",
+	"OP GREATER",
+	"OP GREATER EQUAL",
+	"OP AND",
+	"OP OR",
+	"OP NOT",
+	"OP ADD",
+	"OP SUB",
+	"OP MUL",
+	"OP DIV",
+	"OP MOD",
+	"OP SHIFT LEFT",
+	"OP SHIFT RIGHT",
+	"OP BIT AND",
+	"OP BIT OR",
+	"OP BIT XOR",
+	"OP BIT INVERT",
+	"OP INPUT",
+	"EOF",
+	"ERROR"
+};
+
+Expression::ENode *Expression::_parse_expression() {
+
+	Vector<ExpressionNode> expression;
+
+	while (true) {
+		//keep appending stuff to expression
+		ENode *expr = NULL;
+
+		Token tk;
+		_get_token(tk);
+		if (error_set)
+			return NULL;
+
+		switch (tk.type) {
+			case TK_CURLY_BRACKET_OPEN: {
+				//a dictionary
+				DictionaryNode *dn = alloc_node<DictionaryNode>();
+
+				while (true) {
+
+					int cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_CURLY_BRACKET_CLOSE) {
+						break;
+					}
+					str_ofs = cofs; //revert
+					//parse an expression
+					ENode *expr = _parse_expression();
+					if (!expr)
+						return NULL;
+					dn->dict.push_back(expr);
+
+					_get_token(tk);
+					if (tk.type != TK_COLON) {
+						_set_error("Expected ':'");
+						return NULL;
+					}
+
+					expr = _parse_expression();
+					if (!expr)
+						return NULL;
+
+					dn->dict.push_back(expr);
+
+					cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_COMMA) {
+						//all good
+					} else if (tk.type == TK_CURLY_BRACKET_CLOSE) {
+						str_ofs = cofs;
+					} else {
+						_set_error("Expected ',' or '}'");
+					}
+				}
+
+				expr = dn;
+			} break;
+			case TK_BRACKET_OPEN: {
+				//an array
+
+				ArrayNode *an = alloc_node<ArrayNode>();
+
+				while (true) {
+
+					int cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_BRACKET_CLOSE) {
+						break;
+					}
+					str_ofs = cofs; //revert
+					//parse an expression
+					ENode *expr = _parse_expression();
+					if (!expr)
+						return NULL;
+					an->array.push_back(expr);
+
+					cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_COMMA) {
+						//all good
+					} else if (tk.type == TK_BRACKET_CLOSE) {
+						str_ofs = cofs;
+					} else {
+						_set_error("Expected ',' or ']'");
+					}
+				}
+
+				expr = an;
+			} break;
+			case TK_PARENTHESIS_OPEN: {
+				//a suexpression
+				ENode *e = _parse_expression();
+				if (error_set)
+					return NULL;
+				_get_token(tk);
+				if (tk.type != TK_PARENTHESIS_CLOSE) {
+					_set_error("Expected ')'");
+					return NULL;
+				}
+
+				expr = e;
+
+			} break;
+			case TK_IDENTIFIER: {
+
+				String identifier = tk.value;
+
+				int cofs = str_ofs;
+				_get_token(tk);
+				if (tk.type == TK_PARENTHESIS_OPEN) {
+					//function call
+					CallNode *func_call = alloc_node<CallNode>();
+					func_call->method = identifier;
+					SelfNode *self_node = alloc_node<SelfNode>();
+					func_call->base = self_node;
+
+					while (true) {
+
+						int cofs = str_ofs;
+						_get_token(tk);
+						if (tk.type == TK_PARENTHESIS_CLOSE) {
+							break;
+						}
+						str_ofs = cofs; //revert
+						//parse an expression
+						ENode *expr = _parse_expression();
+						if (!expr)
+							return NULL;
+
+						func_call->arguments.push_back(expr);
+
+						cofs = str_ofs;
+						_get_token(tk);
+						if (tk.type == TK_COMMA) {
+							//all good
+						} else if (tk.type == TK_PARENTHESIS_CLOSE) {
+							str_ofs = cofs;
+						} else {
+							_set_error("Expected ',' or ')'");
+						}
+					}
+
+					expr = func_call;
+				} else {
+					//named indexing
+					str_ofs = cofs;
+
+					NamedIndexNode *index = alloc_node<NamedIndexNode>();
+					SelfNode *self_node = alloc_node<SelfNode>();
+					index->base = self_node;
+					index->name = identifier;
+					expr = index;
+				}
+			} break;
+			case TK_INPUT: {
+
+				InputNode *input = alloc_node<InputNode>();
+				input->index = tk.value;
+				expr = input;
+			} break;
+			case TK_SELF: {
+
+				SelfNode *self = alloc_node<SelfNode>();
+				expr = self;
+			} break;
+			case TK_CONSTANT: {
+				ConstantNode *constant = alloc_node<ConstantNode>();
+				constant->value = tk.value;
+				expr = constant;
+			} break;
+			case TK_BASIC_TYPE: {
+				//constructor..
+
+				Variant::Type bt = Variant::Type(int(tk.value));
+				_get_token(tk);
+				if (tk.type != TK_PARENTHESIS_OPEN) {
+					_set_error("Expected '('");
+					return NULL;
+				}
+
+				ConstructorNode *constructor = alloc_node<ConstructorNode>();
+				constructor->data_type = bt;
+
+				while (true) {
+
+					int cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_PARENTHESIS_CLOSE) {
+						break;
+					}
+					str_ofs = cofs; //revert
+					//parse an expression
+					ENode *expr = _parse_expression();
+					if (!expr)
+						return NULL;
+
+					constructor->arguments.push_back(expr);
+
+					cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_COMMA) {
+						//all good
+					} else if (tk.type == TK_PARENTHESIS_CLOSE) {
+						str_ofs = cofs;
+					} else {
+						_set_error("Expected ',' or ')'");
+					}
+				}
+
+				expr = constructor;
+
+			} break;
+			case TK_BUILTIN_FUNC: {
+				//builtin function
+
+				_get_token(tk);
+				if (tk.type != TK_PARENTHESIS_OPEN) {
+					_set_error("Expected '('");
+					return NULL;
+				}
+
+				BuiltinFuncNode *bifunc = alloc_node<BuiltinFuncNode>();
+				bifunc->func = BuiltinFunc(int(tk.value));
+
+				while (true) {
+
+					int cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_PARENTHESIS_CLOSE) {
+						break;
+					}
+					str_ofs = cofs; //revert
+					//parse an expression
+					ENode *expr = _parse_expression();
+					if (!expr)
+						return NULL;
+
+					bifunc->arguments.push_back(expr);
+
+					cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_COMMA) {
+						//all good
+					} else if (tk.type == TK_PARENTHESIS_CLOSE) {
+						str_ofs = cofs;
+					} else {
+						_set_error("Expected ',' or ')'");
+					}
+				}
+
+				int expected_args = get_func_argument_count(bifunc->func);
+				if (bifunc->arguments.size() != expected_args) {
+					_set_error("Builtin func '" + get_func_name(bifunc->func) + "' expects " + itos(expected_args) + " arguments.");
+				}
+
+				expr = bifunc;
+
+			} break;
+			case TK_OP_SUB: {
+
+				ExpressionNode e;
+				e.is_op = true;
+				e.op = Variant::OP_NEGATE;
+				expression.push_back(e);
+				continue;
+			} break;
+			case TK_OP_NOT: {
+
+				ExpressionNode e;
+				e.is_op = true;
+				e.op = Variant::OP_NOT;
+				expression.push_back(e);
+				continue;
+			} break;
+
+			default: {
+				_set_error("Expected expression.");
+				return NULL;
+			} break;
+		}
+
+		//before going to operators, must check indexing!
+
+		while (true) {
+			int cofs2 = str_ofs;
+			_get_token(tk);
+			if (error_set)
+				return NULL;
+
+			bool done = false;
+
+			switch (tk.type) {
+				case TK_BRACKET_OPEN: {
+					//value indexing
+
+					IndexNode *index = alloc_node<IndexNode>();
+					index->base = expr;
+
+					ENode *what = _parse_expression();
+					if (!what)
+						return NULL;
+
+					index->index = what;
+
+					_get_token(tk);
+					if (tk.type != TK_BRACKET_CLOSE) {
+						_set_error("Expected ']' at end of index.");
+						return NULL;
+					}
+					expr = index;
+
+				} break;
+				case TK_PERIOD: {
+					//named indexing or function call
+					_get_token(tk);
+					if (tk.type != TK_IDENTIFIER) {
+						_set_error("Expected identifier after '.'");
+						return NULL;
+					}
+
+					StringName identifier = tk.value;
+
+					int cofs = str_ofs;
+					_get_token(tk);
+					if (tk.type == TK_PARENTHESIS_OPEN) {
+						//function call
+						CallNode *func_call = alloc_node<CallNode>();
+						func_call->method = identifier;
+						func_call->base = expr;
+
+						while (true) {
+
+							int cofs = str_ofs;
+							_get_token(tk);
+							if (tk.type == TK_PARENTHESIS_CLOSE) {
+								break;
+							}
+							str_ofs = cofs; //revert
+							//parse an expression
+							ENode *expr = _parse_expression();
+							if (!expr)
+								return NULL;
+
+							func_call->arguments.push_back(expr);
+
+							cofs = str_ofs;
+							_get_token(tk);
+							if (tk.type == TK_COMMA) {
+								//all good
+							} else if (tk.type == TK_PARENTHESIS_CLOSE) {
+								str_ofs = cofs;
+							} else {
+								_set_error("Expected ',' or ')'");
+							}
+						}
+
+						expr = func_call;
+					} else {
+						//named indexing
+						str_ofs = cofs;
+
+						NamedIndexNode *index = alloc_node<NamedIndexNode>();
+						index->base = expr;
+						index->name = identifier;
+						expr = index;
+					}
+
+				} break;
+				default: {
+					str_ofs = cofs2;
+					done = true;
+				} break;
+			}
+
+			if (done)
+				break;
+		}
+
+		//push expression
+		{
+			ExpressionNode e;
+			e.is_op = false;
+			e.node = expr;
+			expression.push_back(e);
+		}
+
+		//ok finally look for an operator
+
+		int cofs = str_ofs;
+		_get_token(tk);
+		if (error_set)
+			return NULL;
+
+		Variant::Operator op = Variant::OP_MAX;
+
+		switch (tk.type) {
+			case TK_OP_IN: op = Variant::OP_IN; break;
+			case TK_OP_EQUAL: op = Variant::OP_EQUAL; break;
+			case TK_OP_NOT_EQUAL: op = Variant::OP_NOT_EQUAL; break;
+			case TK_OP_LESS: op = Variant::OP_LESS; break;
+			case TK_OP_LESS_EQUAL: op = Variant::OP_LESS_EQUAL; break;
+			case TK_OP_GREATER: op = Variant::OP_GREATER; break;
+			case TK_OP_GREATER_EQUAL: op = Variant::OP_GREATER_EQUAL; break;
+			case TK_OP_AND: op = Variant::OP_AND; break;
+			case TK_OP_OR: op = Variant::OP_OR; break;
+			case TK_OP_NOT: op = Variant::OP_NOT; break;
+			case TK_OP_ADD: op = Variant::OP_ADD; break;
+			case TK_OP_SUB: op = Variant::OP_SUBTRACT; break;
+			case TK_OP_MUL: op = Variant::OP_MULTIPLY; break;
+			case TK_OP_DIV: op = Variant::OP_DIVIDE; break;
+			case TK_OP_MOD: op = Variant::OP_MODULE; break;
+			case TK_OP_SHIFT_LEFT: op = Variant::OP_SHIFT_LEFT; break;
+			case TK_OP_SHIFT_RIGHT: op = Variant::OP_SHIFT_RIGHT; break;
+			case TK_OP_BIT_AND: op = Variant::OP_BIT_AND; break;
+			case TK_OP_BIT_OR: op = Variant::OP_BIT_OR; break;
+			case TK_OP_BIT_XOR: op = Variant::OP_BIT_XOR; break;
+			case TK_OP_BIT_INVERT: op = Variant::OP_BIT_NEGATE; break;
+			default: {};
+		}
+
+		if (op == Variant::OP_MAX) { //stop appending stuff
+			str_ofs = cofs;
+			break;
+		}
+
+		//push operator and go on
+		{
+			ExpressionNode e;
+			e.is_op = true;
+			e.op = op;
+			expression.push_back(e);
+		}
+	}
+
+	/* Reduce the set set of expressions and place them in an operator tree, respecting precedence */
+
+	while (expression.size() > 1) {
+
+		int next_op = -1;
+		int min_priority = 0xFFFFF;
+		bool is_unary = false;
+
+		for (int i = 0; i < expression.size(); i++) {
+
+			if (!expression[i].is_op) {
+
+				continue;
+			}
+
+			int priority;
+
+			bool unary = false;
+
+			switch (expression[i].op) {
+
+				case Variant::OP_BIT_NEGATE:
+					priority = 0;
+					unary = true;
+					break;
+				case Variant::OP_NEGATE:
+					priority = 1;
+					unary = true;
+					break;
+
+				case Variant::OP_MULTIPLY: priority = 2; break;
+				case Variant::OP_DIVIDE: priority = 2; break;
+				case Variant::OP_MODULE: priority = 2; break;
+
+				case Variant::OP_ADD: priority = 3; break;
+				case Variant::OP_SUBTRACT: priority = 3; break;
+
+				case Variant::OP_SHIFT_LEFT: priority = 4; break;
+				case Variant::OP_SHIFT_RIGHT: priority = 4; break;
+
+				case Variant::OP_BIT_AND: priority = 5; break;
+				case Variant::OP_BIT_XOR: priority = 6; break;
+				case Variant::OP_BIT_OR: priority = 7; break;
+
+				case Variant::OP_LESS: priority = 8; break;
+				case Variant::OP_LESS_EQUAL: priority = 8; break;
+				case Variant::OP_GREATER: priority = 8; break;
+				case Variant::OP_GREATER_EQUAL: priority = 8; break;
+
+				case Variant::OP_EQUAL: priority = 8; break;
+				case Variant::OP_NOT_EQUAL: priority = 8; break;
+
+				case Variant::OP_IN: priority = 10; break;
+
+				case Variant::OP_NOT:
+					priority = 11;
+					unary = true;
+					break;
+				case Variant::OP_AND: priority = 12; break;
+				case Variant::OP_OR: priority = 13; break;
+
+				default: {
+					_set_error("Parser bug, invalid operator in expression: " + itos(expression[i].op));
+					return NULL;
+				}
+			}
+
+			if (priority < min_priority) {
+				// < is used for left to right (default)
+				// <= is used for right to left
+
+				next_op = i;
+				min_priority = priority;
+				is_unary = unary;
+			}
+		}
+
+		if (next_op == -1) {
+
+			_set_error("Yet another parser bug....");
+			ERR_FAIL_COND_V(next_op == -1, NULL);
+		}
+
+		// OK! create operator..
+		if (is_unary) {
+
+			int expr_pos = next_op;
+			while (expression[expr_pos].is_op) {
+
+				expr_pos++;
+				if (expr_pos == expression.size()) {
+					//can happen..
+					_set_error("Unexpected end of expression...");
+					return NULL;
+				}
+			}
+
+			//consecutively do unary opeators
+			for (int i = expr_pos - 1; i >= next_op; i--) {
+
+				OperatorNode *op = alloc_node<OperatorNode>();
+				op->op = expression[i].op;
+				op->nodes[0] = expression[i + 1].node;
+				op->nodes[1] = NULL;
+				expression.write[i].is_op = false;
+				expression.write[i].node = op;
+				expression.remove(i + 1);
+			}
+
+		} else {
+
+			if (next_op < 1 || next_op >= (expression.size() - 1)) {
+				_set_error("Parser bug...");
+				ERR_FAIL_V(NULL);
+			}
+
+			OperatorNode *op = alloc_node<OperatorNode>();
+			op->op = expression[next_op].op;
+
+			if (expression[next_op - 1].is_op) {
+
+				_set_error("Parser bug...");
+				ERR_FAIL_V(NULL);
+			}
+
+			if (expression[next_op + 1].is_op) {
+				// this is not invalid and can really appear
+				// but it becomes invalid anyway because no binary op
+				// can be followed by a unary op in a valid combination,
+				// due to how precedence works, unaries will always disappear first
+
+				_set_error("Unexpected two consecutive operators.");
+				return NULL;
+			}
+
+			op->nodes[0] = expression[next_op - 1].node; //expression goes as left
+			op->nodes[1] = expression[next_op + 1].node; //next expression goes as right
+
+			//replace all 3 nodes by this operator and make it an expression
+			expression.write[next_op - 1].node = op;
+			expression.remove(next_op);
+			expression.remove(next_op);
+		}
+	}
+
+	return expression[0].node;
+}
+
+bool Expression::_compile_expression() {
+
+	if (!expression_dirty)
+		return error_set;
+
+	if (nodes) {
+		memdelete(nodes);
+		nodes = NULL;
+		root = NULL;
+	}
+
+	error_str = String();
+	error_set = false;
+	str_ofs = 0;
+
+	root = _parse_expression();
+
+	if (error_set) {
+		root = NULL;
+		if (nodes) {
+			memdelete(nodes);
+		}
+		nodes = NULL;
+		return true;
+	}
+
+	expression_dirty = false;
+	return false;
+}
+
+bool Expression::_execute(const Array &p_inputs, Object *p_instance, Expression::ENode *p_node, Variant &r_ret, String &r_error_str) {
+
+	switch (p_node->type) {
+		case Expression::ENode::TYPE_INPUT: {
+
+			const Expression::InputNode *in = static_cast<const Expression::InputNode *>(p_node);
+			if (in->index < 0 || in->index >= p_inputs.size()) {
+				r_error_str = vformat(RTR("Invalid input %i (not passed) in expression"), in->index);
+				return true;
+			}
+			r_ret = p_inputs[in->index];
+		} break;
+		case Expression::ENode::TYPE_CONSTANT: {
+
+			const Expression::ConstantNode *c = static_cast<const Expression::ConstantNode *>(p_node);
+			r_ret = c->value;
+
+		} break;
+		case Expression::ENode::TYPE_SELF: {
+
+			if (!p_instance) {
+				r_error_str = RTR("self can't be used because instance is null (not passed)");
+				return true;
+			}
+			r_ret = p_instance;
+		} break;
+		case Expression::ENode::TYPE_OPERATOR: {
+
+			const Expression::OperatorNode *op = static_cast<const Expression::OperatorNode *>(p_node);
+
+			Variant a;
+			bool ret = _execute(p_inputs, p_instance, op->nodes[0], a, r_error_str);
+			if (ret)
+				return true;
+
+			Variant b;
+
+			if (op->nodes[1]) {
+				bool ret = _execute(p_inputs, p_instance, op->nodes[1], b, r_error_str);
+				if (ret)
+					return true;
+			}
+
+			bool valid = true;
+			Variant::evaluate(op->op, a, b, r_ret, valid);
+			if (!valid) {
+				r_error_str = vformat(RTR("Invalid operands to operator %s, %s and %s."), Variant::get_operator_name(op->op), Variant::get_type_name(a.get_type()), Variant::get_type_name(b.get_type()));
+				return true;
+			}
+
+		} break;
+		case Expression::ENode::TYPE_INDEX: {
+
+			const Expression::IndexNode *index = static_cast<const Expression::IndexNode *>(p_node);
+
+			Variant base;
+			bool ret = _execute(p_inputs, p_instance, index->base, base, r_error_str);
+			if (ret)
+				return true;
+
+			Variant idx;
+
+			ret = _execute(p_inputs, p_instance, index->index, idx, r_error_str);
+			if (ret)
+				return true;
+
+			bool valid;
+			r_ret = base.get(idx, &valid);
+			if (!valid) {
+				r_error_str = vformat(RTR("Invalid index of type %s for base type %s"), Variant::get_type_name(idx.get_type()), Variant::get_type_name(base.get_type()));
+				return true;
+			}
+
+		} break;
+		case Expression::ENode::TYPE_NAMED_INDEX: {
+
+			const Expression::NamedIndexNode *index = static_cast<const Expression::NamedIndexNode *>(p_node);
+
+			Variant base;
+			bool ret = _execute(p_inputs, p_instance, index->base, base, r_error_str);
+			if (ret)
+				return true;
+
+			bool valid;
+			r_ret = base.get_named(index->name, &valid);
+			if (!valid) {
+				r_error_str = vformat(RTR("Invalid named index '%s' for base type "), String(index->name), Variant::get_type_name(base.get_type()));
+				return true;
+			}
+
+		} break;
+		case Expression::ENode::TYPE_ARRAY: {
+			const Expression::ArrayNode *array = static_cast<const Expression::ArrayNode *>(p_node);
+
+			Array arr;
+			arr.resize(array->array.size());
+			for (int i = 0; i < array->array.size(); i++) {
+
+				Variant value;
+				bool ret = _execute(p_inputs, p_instance, array->array[i], value, r_error_str);
+
+				if (ret)
+					return true;
+				arr[i] = value;
+			}
+
+			r_ret = arr;
+
+		} break;
+		case Expression::ENode::TYPE_DICTIONARY: {
+			const Expression::DictionaryNode *dictionary = static_cast<const Expression::DictionaryNode *>(p_node);
+
+			Dictionary d;
+			for (int i = 0; i < dictionary->dict.size(); i += 2) {
+
+				Variant key;
+				bool ret = _execute(p_inputs, p_instance, dictionary->dict[i + 0], key, r_error_str);
+
+				if (ret)
+					return true;
+
+				Variant value;
+				ret = _execute(p_inputs, p_instance, dictionary->dict[i + 1], value, r_error_str);
+				if (ret)
+					return true;
+
+				d[key] = value;
+			}
+
+			r_ret = d;
+		} break;
+		case Expression::ENode::TYPE_CONSTRUCTOR: {
+
+			const Expression::ConstructorNode *constructor = static_cast<const Expression::ConstructorNode *>(p_node);
+
+			Vector<Variant> arr;
+			Vector<const Variant *> argp;
+			arr.resize(constructor->arguments.size());
+			argp.resize(constructor->arguments.size());
+
+			for (int i = 0; i < constructor->arguments.size(); i++) {
+
+				Variant value;
+				bool ret = _execute(p_inputs, p_instance, constructor->arguments[i], value, r_error_str);
+
+				if (ret)
+					return true;
+				arr.write[i] = value;
+				argp.write[i] = &arr[i];
+			}
+
+			Variant::CallError ce;
+			r_ret = Variant::construct(constructor->data_type, (const Variant **)argp.ptr(), argp.size(), ce);
+
+			if (ce.error != Variant::CallError::CALL_OK) {
+				r_error_str = vformat(RTR("Invalid arguments to construct '%s'"), Variant::get_type_name(constructor->data_type));
+				return true;
+			}
+
+		} break;
+		case Expression::ENode::TYPE_BUILTIN_FUNC: {
+
+			const Expression::BuiltinFuncNode *bifunc = static_cast<const Expression::BuiltinFuncNode *>(p_node);
+
+			Vector<Variant> arr;
+			Vector<const Variant *> argp;
+			arr.resize(bifunc->arguments.size());
+			argp.resize(bifunc->arguments.size());
+
+			for (int i = 0; i < bifunc->arguments.size(); i++) {
+
+				Variant value;
+				bool ret = _execute(p_inputs, p_instance, bifunc->arguments[i], value, r_error_str);
+				if (ret)
+					return true;
+				arr.write[i] = value;
+				argp.write[i] = &arr[i];
+			}
+
+			Variant::CallError ce;
+			exec_func(bifunc->func, (const Variant **)argp.ptr(), &r_ret, ce, r_error_str);
+
+			if (ce.error != Variant::CallError::CALL_OK) {
+				r_error_str = "Builtin Call Failed. " + r_error_str;
+				return true;
+			}
+
+		} break;
+		case Expression::ENode::TYPE_CALL: {
+
+			const Expression::CallNode *call = static_cast<const Expression::CallNode *>(p_node);
+
+			Variant base;
+			bool ret = _execute(p_inputs, p_instance, call->base, base, r_error_str);
+
+			if (ret)
+				return true;
+
+			Vector<Variant> arr;
+			Vector<const Variant *> argp;
+			arr.resize(call->arguments.size());
+			argp.resize(call->arguments.size());
+
+			for (int i = 0; i < call->arguments.size(); i++) {
+
+				Variant value;
+				bool ret = _execute(p_inputs, p_instance, call->arguments[i], value, r_error_str);
+
+				if (ret)
+					return true;
+				arr.write[i] = value;
+				argp.write[i] = &arr[i];
+			}
+
+			Variant::CallError ce;
+			r_ret = base.call(call->method, (const Variant **)argp.ptr(), argp.size(), ce);
+
+			if (ce.error != Variant::CallError::CALL_OK) {
+				r_error_str = vformat(RTR("On call to '%s':"), String(call->method));
+				return true;
+			}
+
+		} break;
+	}
+	return false;
+}
+
+Error Expression::parse(const String &p_expression) {
+
+	if (nodes) {
+		memdelete(nodes);
+		nodes = NULL;
+		root = NULL;
+	}
+
+	error_str = String();
+	error_set = false;
+	str_ofs = 0;
+
+	expression = p_expression;
+	root = _parse_expression();
+
+	if (error_set) {
+		root = NULL;
+		if (nodes) {
+			memdelete(nodes);
+		}
+		nodes = NULL;
+		return ERR_INVALID_PARAMETER;
+	}
+
+	return OK;
+}
+
+Variant Expression::execute(Array p_inputs, Object *p_base, bool p_show_error) {
+
+	execution_error = false;
+	Variant output;
+	String error_txt;
+	bool err = _execute(p_inputs, p_base, root, output, error_txt);
+	if (err) {
+		execution_error = true;
+		error_str = error_txt;
+		if (p_show_error) {
+			ERR_EXPLAIN(error_str);
+			ERR_FAIL_V(Variant());
+		}
+	}
+
+	return output;
+}
+
+bool Expression::has_execute_failed() const {
+	return execution_error;
+}
+
+String Expression::get_error_text() const {
+	return error_str;
+}
+
+void Expression::_bind_methods() {
+
+	ClassDB::bind_method(D_METHOD("parse", "expression"), &Expression::parse);
+	ClassDB::bind_method(D_METHOD("execute", "inputs", "base_instance", "show_error"), &Expression::execute, DEFVAL(Array()), DEFVAL(NULL), DEFVAL(true));
+	ClassDB::bind_method(D_METHOD("has_execute_failed"), &Expression::has_execute_failed);
+	ClassDB::bind_method(D_METHOD("get_error_text"), &Expression::get_error_text);
+}
+
+Expression::Expression() {
+	output_type = Variant::NIL;
+	error_set = true;
+	root = NULL;
+	nodes = NULL;
+	sequenced = false;
+	execution_error = false;
+}
+
+Expression::~Expression() {
+
+	if (nodes) {
+		memdelete(nodes);
+	}
+}
diff --git a/core/math/expression.h b/core/math/expression.h
new file mode 100644
index 0000000000..b0de6ca6db
--- /dev/null
+++ b/core/math/expression.h
@@ -0,0 +1,323 @@
+#ifndef EXPRESSION_H
+#define EXPRESSION_H
+
+#include "core/reference.h"
+
+class Expression : public Reference {
+	GDCLASS(Expression, Reference)
+public:
+	enum BuiltinFunc {
+		MATH_SIN,
+		MATH_COS,
+		MATH_TAN,
+		MATH_SINH,
+		MATH_COSH,
+		MATH_TANH,
+		MATH_ASIN,
+		MATH_ACOS,
+		MATH_ATAN,
+		MATH_ATAN2,
+		MATH_SQRT,
+		MATH_FMOD,
+		MATH_FPOSMOD,
+		MATH_FLOOR,
+		MATH_CEIL,
+		MATH_ROUND,
+		MATH_ABS,
+		MATH_SIGN,
+		MATH_POW,
+		MATH_LOG,
+		MATH_EXP,
+		MATH_ISNAN,
+		MATH_ISINF,
+		MATH_EASE,
+		MATH_DECIMALS,
+		MATH_STEPIFY,
+		MATH_LERP,
+		MATH_INVERSE_LERP,
+		MATH_RANGE_LERP,
+		MATH_DECTIME,
+		MATH_RANDOMIZE,
+		MATH_RAND,
+		MATH_RANDF,
+		MATH_RANDOM,
+		MATH_SEED,
+		MATH_RANDSEED,
+		MATH_DEG2RAD,
+		MATH_RAD2DEG,
+		MATH_LINEAR2DB,
+		MATH_DB2LINEAR,
+		MATH_POLAR2CARTESIAN,
+		MATH_CARTESIAN2POLAR,
+		MATH_WRAP,
+		MATH_WRAPF,
+		LOGIC_MAX,
+		LOGIC_MIN,
+		LOGIC_CLAMP,
+		LOGIC_NEAREST_PO2,
+		OBJ_WEAKREF,
+		FUNC_FUNCREF,
+		TYPE_CONVERT,
+		TYPE_OF,
+		TYPE_EXISTS,
+		TEXT_CHAR,
+		TEXT_STR,
+		TEXT_PRINT,
+		TEXT_PRINTERR,
+		TEXT_PRINTRAW,
+		VAR_TO_STR,
+		STR_TO_VAR,
+		VAR_TO_BYTES,
+		BYTES_TO_VAR,
+		COLORN,
+		FUNC_MAX
+	};
+
+	static int get_func_argument_count(BuiltinFunc p_func);
+	static String get_func_name(BuiltinFunc p_func);
+	static void exec_func(BuiltinFunc p_func, const Variant **p_inputs, Variant *r_return, Variant::CallError &r_error, String &r_error_str);
+	static BuiltinFunc find_function(const String &p_string);
+
+private:
+	static const char *func_name[FUNC_MAX];
+
+	struct Input {
+
+		Variant::Type type;
+		String name;
+
+		Input() { type = Variant::NIL; }
+	};
+
+	Vector<Input> inputs;
+	Variant::Type output_type;
+
+	String expression;
+
+	bool sequenced;
+	int str_ofs;
+	bool expression_dirty;
+
+	bool _compile_expression();
+
+	enum TokenType {
+		TK_CURLY_BRACKET_OPEN,
+		TK_CURLY_BRACKET_CLOSE,
+		TK_BRACKET_OPEN,
+		TK_BRACKET_CLOSE,
+		TK_PARENTHESIS_OPEN,
+		TK_PARENTHESIS_CLOSE,
+		TK_IDENTIFIER,
+		TK_BUILTIN_FUNC,
+		TK_SELF,
+		TK_CONSTANT,
+		TK_BASIC_TYPE,
+		TK_COLON,
+		TK_COMMA,
+		TK_PERIOD,
+		TK_OP_IN,
+		TK_OP_EQUAL,
+		TK_OP_NOT_EQUAL,
+		TK_OP_LESS,
+		TK_OP_LESS_EQUAL,
+		TK_OP_GREATER,
+		TK_OP_GREATER_EQUAL,
+		TK_OP_AND,
+		TK_OP_OR,
+		TK_OP_NOT,
+		TK_OP_ADD,
+		TK_OP_SUB,
+		TK_OP_MUL,
+		TK_OP_DIV,
+		TK_OP_MOD,
+		TK_OP_SHIFT_LEFT,
+		TK_OP_SHIFT_RIGHT,
+		TK_OP_BIT_AND,
+		TK_OP_BIT_OR,
+		TK_OP_BIT_XOR,
+		TK_OP_BIT_INVERT,
+		TK_INPUT,
+		TK_EOF,
+		TK_ERROR,
+		TK_MAX
+	};
+
+	static const char *token_name[TK_MAX];
+	struct Token {
+
+		TokenType type;
+		Variant value;
+	};
+
+	void _set_error(const String &p_err) {
+		if (error_set)
+			return;
+		error_str = p_err;
+		error_set = true;
+	}
+
+	Error _get_token(Token &r_token);
+
+	String error_str;
+	bool error_set;
+
+	struct ENode {
+
+		enum Type {
+			TYPE_INPUT,
+			TYPE_CONSTANT,
+			TYPE_SELF,
+			TYPE_OPERATOR,
+			TYPE_INDEX,
+			TYPE_NAMED_INDEX,
+			TYPE_ARRAY,
+			TYPE_DICTIONARY,
+			TYPE_CONSTRUCTOR,
+			TYPE_BUILTIN_FUNC,
+			TYPE_CALL
+		};
+
+		ENode *next;
+
+		Type type;
+
+		ENode() { next = NULL; }
+		virtual ~ENode() {
+			if (next) {
+				memdelete(next);
+			}
+		}
+	};
+
+	struct ExpressionNode {
+
+		bool is_op;
+		union {
+			Variant::Operator op;
+			ENode *node;
+		};
+	};
+
+	ENode *_parse_expression();
+
+	struct InputNode : public ENode {
+
+		int index;
+		InputNode() {
+			type = TYPE_INPUT;
+		}
+	};
+
+	struct ConstantNode : public ENode {
+
+		Variant value;
+		ConstantNode() {
+			type = TYPE_CONSTANT;
+		}
+	};
+
+	struct OperatorNode : public ENode {
+
+		Variant::Operator op;
+
+		ENode *nodes[2];
+
+		OperatorNode() {
+			type = TYPE_OPERATOR;
+		}
+	};
+
+	struct SelfNode : public ENode {
+
+		SelfNode() {
+			type = TYPE_SELF;
+		}
+	};
+
+	struct IndexNode : public ENode {
+		ENode *base;
+		ENode *index;
+
+		IndexNode() {
+			type = TYPE_INDEX;
+		}
+	};
+
+	struct NamedIndexNode : public ENode {
+		ENode *base;
+		StringName name;
+
+		NamedIndexNode() {
+			type = TYPE_NAMED_INDEX;
+		}
+	};
+
+	struct ConstructorNode : public ENode {
+		Variant::Type data_type;
+		Vector<ENode *> arguments;
+
+		ConstructorNode() {
+			type = TYPE_CONSTRUCTOR;
+		}
+	};
+
+	struct CallNode : public ENode {
+		ENode *base;
+		StringName method;
+		Vector<ENode *> arguments;
+
+		CallNode() {
+			type = TYPE_CALL;
+		}
+	};
+
+	struct ArrayNode : public ENode {
+		Vector<ENode *> array;
+		ArrayNode() {
+			type = TYPE_ARRAY;
+		}
+	};
+
+	struct DictionaryNode : public ENode {
+		Vector<ENode *> dict;
+		DictionaryNode() {
+			type = TYPE_DICTIONARY;
+		}
+	};
+
+	struct BuiltinFuncNode : public ENode {
+		BuiltinFunc func;
+		Vector<ENode *> arguments;
+		BuiltinFuncNode() {
+			type = TYPE_BUILTIN_FUNC;
+		}
+	};
+
+	template <class T>
+	T *alloc_node() {
+		T *node = memnew(T);
+		node->next = nodes;
+		nodes = node;
+		return node;
+	}
+
+	ENode *root;
+	ENode *nodes;
+
+	bool execution_error;
+	bool _execute(const Array &p_inputs, Object *p_instance, Expression::ENode *p_node, Variant &r_ret, String &r_error_str);
+
+protected:
+	static void _bind_methods();
+
+public:
+	Error parse(const String &p_expression);
+	Variant execute(Array p_inputs, Object *p_base = NULL, bool p_show_error = true);
+	bool has_execute_failed() const;
+	String get_error_text() const;
+
+	Expression();
+	~Expression();
+};
+
+#endif // EXPRESSION_H
diff --git a/core/register_core_types.cpp b/core/register_core_types.cpp
index 0e7e63dbd8..859015f44b 100644
--- a/core/register_core_types.cpp
+++ b/core/register_core_types.cpp
@@ -54,6 +54,7 @@
 #include "io/tcp_server.h"
 #include "io/translation_loader_po.h"
 #include "math/a_star.h"
+#include "math/expression.h"
 #include "math/triangle_mesh.h"
 #include "os/input.h"
 #include "os/main_loop.h"
@@ -216,6 +217,7 @@ void register_core_singletons() {
 	ClassDB::register_virtual_class<Input>();
 	ClassDB::register_class<InputMap>();
 	ClassDB::register_class<_JSON>();
+	ClassDB::register_class<Expression>();
 
 	Engine::get_singleton()->add_singleton(Engine::Singleton("ProjectSettings", ProjectSettings::get_singleton()));
 	Engine::get_singleton()->add_singleton(Engine::Singleton("IP", IP::get_singleton()));