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functions.go
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functions.go
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package tick
import (
"errors"
"fmt"
"math"
"strconv"
"time"
)
var ErrNotFloat = errors.New("value is not a float")
// A callable function from within the expression
type Func interface {
Reset()
Call(...interface{}) (interface{}, error)
}
// Lookup for functions
type Funcs map[string]Func
var statelessFuncs Funcs
func init() {
statelessFuncs = make(Funcs)
// Conversion functions
statelessFuncs["bool"] = &boolean{}
statelessFuncs["int"] = &integer{}
statelessFuncs["float"] = &float{}
// Math functions
statelessFuncs["abs"] = newMath1("abs", math.Abs)
statelessFuncs["acos"] = newMath1("acos", math.Acos)
statelessFuncs["acosh"] = newMath1("acosh", math.Acosh)
statelessFuncs["asin"] = newMath1("asin", math.Asin)
statelessFuncs["asinh"] = newMath1("asinh", math.Asinh)
statelessFuncs["atan"] = newMath1("atan", math.Atan)
statelessFuncs["atan2"] = newMath2("atan2", math.Atan2)
statelessFuncs["atanh"] = newMath1("atanh", math.Atanh)
statelessFuncs["cbrt"] = newMath1("cbrt", math.Cbrt)
statelessFuncs["ceil"] = newMath1("ceil", math.Ceil)
statelessFuncs["cos"] = newMath1("cos", math.Cos)
statelessFuncs["cosh"] = newMath1("cosh", math.Cosh)
statelessFuncs["erf"] = newMath1("erf", math.Erf)
statelessFuncs["erfc"] = newMath1("erfc", math.Erfc)
statelessFuncs["exp"] = newMath1("exp", math.Exp)
statelessFuncs["exp2"] = newMath1("exp2", math.Exp2)
statelessFuncs["expm1"] = newMath1("expm1", math.Expm1)
statelessFuncs["floor"] = newMath1("floor", math.Floor)
statelessFuncs["gamma"] = newMath1("gamma", math.Gamma)
statelessFuncs["hypot"] = newMath2("hypot", math.Hypot)
statelessFuncs["j0"] = newMath1("j0", math.J0)
statelessFuncs["j1"] = newMath1("j1", math.J1)
statelessFuncs["jn"] = newMathIF("jn", math.Jn)
statelessFuncs["log"] = newMath1("log", math.Log)
statelessFuncs["log10"] = newMath1("log10", math.Log10)
statelessFuncs["log1p"] = newMath1("log1p", math.Log1p)
statelessFuncs["log2"] = newMath1("log2", math.Log2)
statelessFuncs["logb"] = newMath1("logb", math.Logb)
statelessFuncs["max"] = newMath2("max", math.Max)
statelessFuncs["min"] = newMath2("min", math.Min)
statelessFuncs["mod"] = newMath2("mod", math.Mod)
statelessFuncs["pow"] = newMath2("pow", math.Pow)
statelessFuncs["pow10"] = newMathI("pow10", math.Pow10)
statelessFuncs["sin"] = newMath1("sin", math.Sin)
statelessFuncs["sinh"] = newMath1("sinh", math.Sinh)
statelessFuncs["sqrt"] = newMath1("sqrt", math.Sqrt)
statelessFuncs["tan"] = newMath1("tan", math.Tan)
statelessFuncs["tanh"] = newMath1("tanh", math.Tanh)
statelessFuncs["trunc"] = newMath1("trunc", math.Trunc)
statelessFuncs["y0"] = newMath1("y0", math.Y0)
statelessFuncs["y1"] = newMath1("y1", math.Y1)
statelessFuncs["yn"] = newMathIF("yn", math.Yn)
// Time functions
statelessFuncs["minute"] = &minute{}
statelessFuncs["hour"] = &hour{}
statelessFuncs["weekday"] = &weekday{}
statelessFuncs["day"] = &day{}
statelessFuncs["month"] = &month{}
statelessFuncs["year"] = &year{}
}
// Return set of built-in Funcs
func NewFunctions() Funcs {
funcs := make(Funcs, len(statelessFuncs)+2)
for n, f := range statelessFuncs {
funcs[n] = f
}
// Statefull functions -- need new instance
funcs["sigma"] = &sigma{}
funcs["count"] = &count{}
return funcs
}
type math1Func func(float64) float64
type math1 struct {
name string
f math1Func
}
func newMath1(name string, f math1Func) *math1 {
return &math1{
name: name,
f: f,
}
}
// Converts the value to a boolean
func (m *math1) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New(m.name + " expects exactly one argument")
}
a0, ok := args[0].(float64)
if !ok {
err = fmt.Errorf("cannot pass %T to %s, must be float64", args[0], m.name)
return
}
v = m.f(a0)
return
}
func (m *math1) Reset() {}
type math2Func func(float64, float64) float64
type math2 struct {
name string
f math2Func
}
func newMath2(name string, f math2Func) *math2 {
return &math2{
name: name,
f: f,
}
}
// Converts the value to a boolean
func (m *math2) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 2 {
return 0, errors.New(m.name + " expects exactly two arguments")
}
a0, ok := args[0].(float64)
if !ok {
err = fmt.Errorf("cannot pass %T to %s, must be float64", args[0], m.name)
return
}
a1, ok := args[1].(float64)
if !ok {
err = fmt.Errorf("cannot pass %T to %s, must be float64", args[1], m.name)
return
}
v = m.f(a0, a1)
return
}
func (m *math2) Reset() {}
type mathIFunc func(int) float64
type mathI struct {
name string
f mathIFunc
}
func newMathI(name string, f mathIFunc) *mathI {
return &mathI{
name: name,
f: f,
}
}
// Converts the value to a boolean
func (m *mathI) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New(m.name + " expects exactly two arguments")
}
a0, ok := args[0].(int64)
if !ok {
err = fmt.Errorf("cannot pass %T to %s, must be int64", args[0], m.name)
return
}
v = m.f(int(a0))
return
}
func (m *mathI) Reset() {}
type mathIFFunc func(int, float64) float64
type mathIF struct {
name string
f mathIFFunc
}
func newMathIF(name string, f mathIFFunc) *mathIF {
return &mathIF{
name: name,
f: f,
}
}
// Converts the value to a boolean
func (m *mathIF) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 2 {
return 0, errors.New(m.name + " expects exactly two arguments")
}
a0, ok := args[0].(int64)
if !ok {
err = fmt.Errorf("cannot pass %T to %s as first arg, must be int64", args[0], m.name)
return
}
a1, ok := args[1].(float64)
if !ok {
err = fmt.Errorf("cannot pass %T to %s as second arg, must be float64", args[1], m.name)
return
}
v = m.f(int(a0), a1)
return
}
func (m *mathIF) Reset() {}
type boolean struct {
}
func (*boolean) Reset() {
}
// Converts the value to a boolean
func (*boolean) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("bool expects exactly one argument")
}
switch a := args[0].(type) {
case bool:
v = a
case string:
v, err = strconv.ParseBool(a)
default:
err = fmt.Errorf("cannot convert %T to boolean", a)
}
return
}
type integer struct {
}
func (*integer) Reset() {
}
// Converts the value to a integer
func (*integer) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("integer expects exactly one argument")
}
switch a := args[0].(type) {
case int64:
v = a
case float64:
v = int64(a)
case string:
v, err = strconv.ParseInt(a, 10, 64)
default:
err = fmt.Errorf("cannot convert %T to integer", a)
}
return
}
type float struct {
}
func (*float) Reset() {
}
// Converts the value to a float
func (*float) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("float expects exactly one argument")
}
switch a := args[0].(type) {
case int64:
v = float64(a)
case float64:
v = a
case string:
v, err = strconv.ParseFloat(a, 64)
default:
err = fmt.Errorf("cannot convert %T to float", a)
}
return
}
type count struct {
n int64
}
func (c *count) Reset() {
c.n = 0
}
// Counts the number of values processed.
func (c *count) Call(args ...interface{}) (v interface{}, err error) {
c.n++
return c.n, nil
}
type sigma struct {
mean float64
variance float64
m2 float64
n float64
}
func (s *sigma) Reset() {
s.mean = 0
s.variance = 0
s.m2 = 0
s.n = 0
}
// Computes the number of standard devaitions a given value is from the running mean.
func (s *sigma) Call(args ...interface{}) (interface{}, error) {
if len(args) != 1 {
return 0, errors.New("sigma expects exactly one argument")
}
x, ok := args[0].(float64)
if !ok {
return nil, ErrNotFloat
}
s.n++
delta := x - s.mean
s.mean = s.mean + delta/s.n
s.m2 = s.m2 + delta*(x-s.mean)
s.variance = s.m2 / (s.n - 1)
if s.n < 2 {
return float64(0), nil
}
return math.Abs(x-s.mean) / math.Sqrt(s.variance), nil
}
type minute struct {
}
func (*minute) Reset() {
}
// Return the minute within the hour for the given time, within the range [0,59].
func (*minute) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("minute expects exactly one argument")
}
switch a := args[0].(type) {
case time.Time:
v = int64(a.Minute())
default:
err = fmt.Errorf("cannot convert %T to time.Time", a)
}
return
}
type hour struct {
}
func (*hour) Reset() {
}
// Return the hour within the day for the given time, within the range [0,23].
func (*hour) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("hour expects exactly one argument")
}
switch a := args[0].(type) {
case time.Time:
v = int64(a.Hour())
default:
err = fmt.Errorf("cannot convert %T to time.Time", a)
}
return
}
type weekday struct {
}
func (*weekday) Reset() {
}
// Return the weekday within the week for the given time, within the range [0,6] where 0 is Sunday.
func (*weekday) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("weekday expects exactly one argument")
}
switch a := args[0].(type) {
case time.Time:
v = int64(a.Weekday())
default:
err = fmt.Errorf("cannot convert %T to time.Time", a)
}
return
}
type day struct {
}
func (*day) Reset() {
}
// Return the day within the month for the given time, within the range [1,31] depending on the month.
func (*day) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("day expects exactly one argument")
}
switch a := args[0].(type) {
case time.Time:
v = int64(a.Day())
default:
err = fmt.Errorf("cannot convert %T to time.Time", a)
}
return
}
type month struct {
}
func (*month) Reset() {
}
// Return the month within the year for the given time, within the range [1,12].
func (*month) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("month expects exactly one argument")
}
switch a := args[0].(type) {
case time.Time:
v = int64(a.Month())
default:
err = fmt.Errorf("cannot convert %T to time.Time", a)
}
return
}
type year struct {
}
func (*year) Reset() {
}
// Return the year for the given time.
func (*year) Call(args ...interface{}) (v interface{}, err error) {
if len(args) != 1 {
return 0, errors.New("year expects exactly one argument")
}
switch a := args[0].(type) {
case time.Time:
v = int64(a.Year())
default:
err = fmt.Errorf("cannot convert %T to time.Time", a)
}
return
}