Fungsi-fungsi didalam Grule

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Fungsi-fungsi Built-In

Fungsi-fungsi built-in semuanya dapat ditemukan di file ast/BuildInFunctions.go. Saat ini, ia berisi :

MakeTime(year, month, day, hour, minute, second int64) time.Time

MakeTime akan membuat time.Time dengan locale yang lokal.

Penjelasan Argumen

year Angka tahun.
month Angka bulan, Januari = 1.
day Angka tanggal dalam bulan.
hour Angka jam dalam hari dimulai dari 0.
minute Angka menit dalam jam dimulai dari 0.
second Angka detik dalam menit dimulai dari 0.

Mengembalikan

time.Time nilai yang merepresentasikan waktu dimana menggunakan zona waktu lokal.

Contoh

rule SetExpire "Set the expire date for Fact created before 2020" {
    when
       Fact.CreateTime < MakeTime(2020,1,1,0,0,0)
    then
       Fact.ExpireTime = MakeTime(2021,1,1,0,0,0);
}

Changed(variableName string)

Changed akan membuang nilai pada nama variabel yang ter-rekam dalam Working Memory menjadi hilang, sehingga nilai tersebut akan diambil lagi dari konteks data.

Penjelasan Argumen

variableName Nama variabel yang mana nilai yang tercatat dalam working memory akan dibuang.

Contoh

rule SetExpire "Set new expire date" {
    when
        IsZero(Fact.ExpireTime)
    then
        Fact.CalculateExpire(); // this function will internally change the ExpireTime variable
        Changed("Fact.ExpireTime")
}

Now() time.Time

Now fungsi akan membuat nilai time.Time dengan nilai waktu saat fungsi ini dipanggil.

Mengembalikan

time.Time nilai berisi waktu sekarang.

Contoh

rule ResetTime "Reset the lastUpdate time" {
    when
        Fact.LastUpdate < Now()
    then
        Fact.LastUpdate = Now();
}

Log(text string)

Log Akan mengeluarkan sebuah log dengan tingkat "Debug" dari dalam GRL

Penjelasan Argumen

text Teks yang akan dikeluarkan dalam log

Contoh

rule SomeRule "Log candidate name if he is bellow 17 years old" {
    when
        Candidate.Age < 17
    then
        Log("Under aged : " + Candidate.Name);
}

IsNil(i interface{}) bool

IsNil melakukan pemeriksaan apakah nilai dalam argumen adalah nil.

Penjelasan Argumen

i variabel yang akan diperiksa.

Mengembalikan

true Jika argumen berisi nil atau memiliki nilai ptr yang tidak valid.
false Jika argumen bukan nil atau memiliki nilai ptr yang valid.

Contoh

rule CheckEducation "Check candidate's education fact" {
    when
        IsNil(Candidate.Education) == false &&
        Candidate.Education.Grade == "PHD"
    then
        Candidate.Onboard = true;
}

IsZero(i interface{}) bool

IsZero akan memeriksa nilai argumen apakah berstatus Zero. Zero berarti argumen tersebut baru saja dibuat dan belum diberi nilai apapun oleh program (menggunakan nilai default) Ini biasanya berlaku pada beberapa tipe variabel seperti string, int64, uint64, bool, time.Time, etc.

Penjelasan Argumen

i argumen yang akan diperiksa.

Mengembalikan

true Jika argumen berstatus Zero.
false Jika argumen tidak berstatus Zero.

Contoh

rule CheckStartTime "Check device's starting time." {
    when
        IsZero(Device.StartTime) == true
    then
        Device.StartTime = Now();
}

Retract(ruleName string)

Retract akan menarik rule yang disebutkan dari evaluasi di siklus berikutnya. Jika sebuah rule ditarik, maka skop when nya tidak akan dievaluasi. Saat rule engine ini dijalankan kembail dari awal, maka semua rule yang ditarik akan dikembalikan seperti sediakala.

Penjelasan Argumen

ruleName Nama rule yang akan ditarik.

Contoh

rule CheckStartTime "Check device's starting time." salience 1000 {
    when
        IsZero(Device.StartTime) == true
    then
        Device.StartTime = Now();
        Retract("CheckStartTime");
}

GetTimeYear(time time.Time) int

GetTimeYear Akan mengambil nilai tahun dari argumen.

Penjelasan Argumen

time Variabel time.Time

Mengembalikan

Nilai tahun

Contoh

rule StartNewYearProcess "Check if its a new year to restart new FinancialYear." salience 1000 {
    when
        GetTimeYear(Now()) != GL.FinancialYear
    then
        GL.CloseYear(GL.FinancialYear)
}

GetTimeMonth(time time.Time) int

GetTimeMonth Akan mengambil nilai bulan dari argumen.

Penjelasan Argumen

time The time variable

Mengembalikan

Month value of the time. 1 = January.

Contoh

rule StartNewYearProcess "Check if its a new year to restart new FinancialYear." salience 1000 {
    when
        isZero(Process.Month)
    then
        Process.Month = GetTimeMonth(Process.Month);
}

GetTimeDay(time time.Time) int

GetTimeDay Akan mengambil nilai tanggal dari argumen.

Penjelasan Argumen

time The time variable

Mengembalikan

Day of month value of the time.

Contoh

rule GreetEveryDay "Log a greeting every day." salience 1000 {
    when
        Greeting.Day != GetTimeDay(Now())
    then
        Log("Its a new Day !!!")
        Retract("GreetEveryDay")
}

GetTimeHour(time time.Time) int

GetTimeHour Akan mengambil nilai jam dari argumen.

Penjelasan Argumen

time The time variable

Mengembalikan

Hour value of the time. Is between 0 to 23

Contoh

rule DailyCheckBuild "Execute build every 6AM and 6PM." {
    when
        GetTimeHour(Now()) == 6 || GetTimeHour(Now()) == 18
    then
        CiCd.BuildDaily();
        Retract("DailyCheckBuild");
}

GetTimeMinute(time time.Time) int

GetTimeMinute Akan mengambil nilai menit dari argumen.

Penjelasan Argumen

time The time variable

Mengembalikan

Minute value of the time, between 0 to 59

Contoh

rule DailyCheckBuild "Execute build every 6.30AM and 6.30PM." {
    when
        (GetTimeHour(Now()) == 6 || GetTimeHour(Now()) == 18) &&
        GetTimeMinute(Now()) == 30
    then
        CiCd.BuildDaily();
        Retract("DailyCheckBuild");
}

GetTimeSecond(time time.Time) int

GetTimeSecond Akan mengambil nilai detik dari argumen.

Penjelasan Argumen

time The time variable

Mengembalikan

Second value of the time, between 0 to 59

Contoh

rule DailyCheckBuild "Execute build every 6.30AM and 6.30PM." {
    when
        (GetTimeHour(Now()) == 6 || GetTimeHour(Now()) == 18) &&
        GetTimeMinute(Now()) == 30 && GetTimeSecond(Now()) == 0
    then
        CiCd.BuildDaily();
        Retract("DailyCheckBuild");
}

IsTimeBefore(time, before time.Time) bool

IsTimeBefore akan memeriksa apakah sebuah waktu pada argumen 1 itu adalah waktu sebelum nilai waktu pada argumen 2.

Penjelasan Argumen

time The time variable
before Another time variable

Mengembalikan

True if the before time value is before the time value.
False if the before time value is not before the time value.

Contoh

rule PromotionExpireCheck  "Apply a promotion if the promotion's expired date is not due." {
    when
        IsTimeBefore(Now(), Promotion.ExpireDateTime)
    then
        Promotion.Discount = 0.10;
        Retract("PromotionExpireCheck");
}

IsTimeAfter(time, after time.Time) bool

IsTimeAfter akan memeriksa apakah sebuah waktu pada argumen 1 itu adalah waktu sesudah nilai waktu pada argumen 2.

Penjelasan Argumen

time The time variable
after Another time variable

Mengembalikan

True if the after time value is after the time value.
False if the after time value is not after the time value.

Contoh

rule AdditionalTax  "Apply additional tax if purchase after date specified." {
    when
        IsTimeAfter(Purchase.TransactionTime, TaxRegulation.StartSince)
    then
        Purchase.Tax = PurchaseTax + 0.01;
}

TimeFormat(time time.Time, layout string) string

TimeFormat akan mem-format nilai waktu pada argumen sesuai dengan format yang ditentukan pada argumen layout.

Penjelasan Argumen

time The time variable
layout String variable specifying the date format layout.

For layout format, you can read this article

Mengembalikan

String contains the formatted time

Contoh

rule LogPurchaseDate  "Log the purchase date." {
    when
        IsZero(Purchase.TransactionDate) == false
    then
        Log(TimeFormat(Purchase.TransactionDate, "2006-01-02T15:04:05-0700");
}

Complete()

Complete will cause the engine to stop processing further rules in its current cycle. This is useful if you want to terminate further rule evaluation under a set condition.

Contoh

rule DailyCheckBuild "Execute build at 6.30AM and 6.30PM." {
    when
        (GetTimeHour(Now()) == 6 || GetTimeHour(Now()) == 18) &&
        GetTimeMinute(Now()) == 30 && GetTimeSecond(Now()) == 0
    then
        CiCd.BuildDaily();
        Complete();
}

Math Functions

All the functions bellow is a wrapper to their golang math functions. You should read Golang math page to know how to use each function.

Unlike go, you don't have to use the math. prefix to use them in your GRL.

Use them like normal built in function.

when 
    Max(Fact.A, Fact.C, Fact.B) > 10
then
    Fact.X = Acosh(Fact.C);

Max(vals ...float64) float64
Min(vals ...float64) float64
Abs(x float64) float64
Acos(x float64) float64
Acosh(x float64) float64
Asin(x float64) float64
Asinh(x float64) float64
Atan(x float64) float64
Atan2(y, x float64) float64
Atanh(x float64) float64
Cbrt(x float64) float64
Ceil(x float64) float64
Copysign(x, y float64) float64
Cos(x float64) float64
Cosh(x float64) float64
Dim(x, y float64) float64
Erf(x float64) float64
Erfc(x float64) float64
Erfcinv(x float64) float64
Erfinv(x float64) float64
Exp(x float64) float64
Exp2(x float64) float64
Expm1(x float64) float64
Float64bits(f float64) uint64
Float64frombits(b uint64) float64
Floor(x float64) float64
Gamma(x float64) float64
Hypot(p, q float64) float64
Ilogb(x float64) int
IsInf(f float64, sign int64) bool
IsNaN(f float64) (is bool)
J0(x float64) float64
J1(x float64) float64
Jn(n int64, x float64) float64
Ldexp(frac float64, exp int64) float64
MathLog(x float64) float64
Log10(x float64) float64
Log1p(x float64) float64
Log2(x float64) float64
Logb(x float64) float64
Mod(x, y float64) float64
NaN() float64
Pow(x, y float64) float64
Pow10(n int64) float64
Remainder(x, y float64) float64
Round(x float64) float64
RoundToEven(x float64) float64
Signbit(x float64) bool
Sin(x float64) float64
Sinh(x float64) float64
Sqrt(x float64) float64
Tan(x float64) float64
Tanh(x float64) float64
Trunc(x float64) float64

Constant Functions

The following functions can be called from within GRL as long as the receiver value type is correct.

string.Len() int

Len will return string's length.

Mengembalikan

The length of string's receiver

Contoh

rule DoSomething "Do something when string length is sufficient" {
    when
        Fact.Name.Len() > "ATextConstant".Len()
    then
        Fact.DoSomething();
}

string.Compare(string) int

Compare will compare the receiver string to the argument.

Penjelasan Argumen

string The string to compare to

Mengembalikan

< 0 if receiver is less than the argument
0 if receiver is equal to the argument
> 0 if receiver is greater thant the argument

Contoh

rule CompareString "Do something when Fact.Text is greater than A" {
    when
        Fact.Text.Compare("A") > 0
    then
        Fact.DoSomething();
}

string.Contains(string) bool

Contains will check if its argument is contained within the receiver.

Penjelasan Argumen

string The substring to check within the receiver

Mengembalikan

true if the argument string is contained within the receiver.
false if the argument string is not contained within the receiver.

Contoh

rule ContainString "Do something when Fact.Text is contains XXX" {
    when
        Fact.Text.Contains("XXX")
    then
        Fact.DoSomething();
}

string.Count(string) int

Count will count the number of occurences of argument in receiver string.

Penjelasan Argumen

string The substring to count within the receiver

Mengembalikan

number of occurences of the argument in the receiver.

Contoh

rule CountString "Do something when Fact.Text contains 3 occurrences of 'ABC'" {
    when
        Fact.Text.Count("ABC") == 3
    then
        Fact.DoSomething();
}

string.HasPrefix(string) bool

HasPrefix will check if the receiver string has a specific prefix.

Penjelasan Argumen

string The expected prefix.

Mengembalikan

true if the receiver has the argument as its prefix.
false if the receiver does not have the argument as its prefix.

Contoh

rule IsPrefixed "Do something when Fact.Text started with PREF" {
    when
        Fact.Text.HasPrefix("PREF")
    then
        Fact.DoSomething();
}

string.HasSuffix(string) bool

HasSuffix will check if the receiver string has a specific suffix.

Penjelasan Argumen

string The expected suffix.

Mengembalikan

true if the receiver has the argument as its suffix.
false if the receiver does not have the argument as its suffix.

Contoh

rule IsSuffixed "Do something when Fact.Text ends with SUFF" {
    when
        Fact.Text.HasSuffix("SUFF")
    then
        Fact.DoSomething();
}

string.Index(string) int

Index will return the index of the first occurrence of the argument in the receiver string.

Penjelasan Argumen

string The substring to search for.

Mengembalikan

The index value of the first occurrence of the argument.

Contoh

rule IndexCheck "Do something when Fact.Text ABC occurs as specified" {
    when
        Fact.Text.Index("ABC") == "abABCabABC".Index("ABC")
    then
        Fact.DoSomething();
}

string.LastIndex(string) int

LastIndex will return the index of last occurrence of the argument in the receiver string.

Penjelasan Argumen

string The substring to search for.

Mengembalikan

The index of the last occurrence of the argument.

Contoh

rule LastIndexCheck "Do something when Fact.Text ABC occurs in the last position as specified" {
    when
        Fact.Text.LastIndex("ABC") == "abABCabABC".LastIndex("ABC")
    then
        Fact.DoSomething();
}

string.Repeat(int64) string

Repeat will return a string containing n occurrences of the receiver string.

Penjelasan Argumen

int64 the repeat count

Mengembalikan

A new string containing n occurrences of the receiver.

Contoh

rule StringRepeat "Do something when Fact.Text contains ABCABCABC" {
    when
        Fact.Text == "ABC".Repeat(3)
    then
        Fact.DoSomething();
}

string.Replace(old, new string) string

Replace will return a string with all occurrences of old replaced with new.

Penjelasan Argumen

old the substring you wish to have replaced.
new the string you wish to replace all occurrences of old.

Mengembalikan

A string where all instances of old in the receiver have been replaced with new.

Contoh

rule ReplaceString "Do something when Fact.Text contains replaced string" {
    when
        Fact.Text == "ABC123ABC".Replace("123","ABC")
    then
        Fact.DoSomething();
}

string.Split(string) []string

Split will return a string slice whose elements are determined after splitting the receiver by the string token argument. The token will not be present in the resulting slice elements.

Penjelasan Argumen

string the token you wish to use to split the receiver.

Mengembalikan

The string slice containing parts of the original string as split by the token.

Contoh

rule SplitString "Do something when Fact.Text is prefixed by 'ABC,'" {
    when
        Fact.Text.Split(",")[0] == "ABC"
    then
        Fact.DoSomething();
}

string.ToLower() string

ToLower will return a string whose contents are all lower case instances of characters in the receiver.

Mengembalikan

A new string that is a lower-cased version of the receiver.

Contoh

rule LowerText "Do something when Fact.Text is equal to 'abc'" {
    when
        Fact.Text.ToLower() == "Abc".ToLower()
    then
        Fact.DoSomething();
}

string.ToUpper() string

ToUpper will return a string whose contents are all upper case instances of characters in the receiver.

Mengembalikan

A new string that is an upper-cased version of the receiver.

Contoh

rule UpperText "Do something when Fact.Text is equal to 'ABC'" {
    when
        Fact.Text.ToUpper() == "Abc".ToUpper()
    then
        Fact.DoSomething();
}

string.Trim() string

Trim will return a string where the whitespace on either end of the string has been removed.

Mengembalikan

A string with the whitespace removed from the beginning and end.

Contoh

rule TrimText "Do something when Fact.Text is 'ABC'" {
    when
        Fact.Text == "  Abc   ".Trim().ToUpper()
    then
        Fact.DoSomething();
}

string.MatchString() string

MatchString MatchString reports whether the string s contains any match of the regular expression pattern. Similar to golang MatchString

Returns

True if the regexPattern matches the string s
False if the regexPattern doesn't match the string s

Example

rule MatchStringText "Return true when regex pattern matches the string"  {
	when
	  Fact.Text.MatchString("B([a-z]+)ck")
	then
	  Fact.DoSomething();
}

array.Len() int

Len will return the length of the array/slice.

Mengembalikan

The length of array/slice.

Contoh

rule DoSomething "Do something when array length is sufficient" {
    when
        Fact.ChildrenArray.Len() > 2
    then
        Fact.DoSomething();
}

array.Append(val)

Append will append val onto the end of the receiver array.

Penjelasan Argumen

val value to have appended.

Contoh

rule DoSomething "Add a new child when the array has less than 2 children" {
    when
        Fact.ChildrenArray.Len() < 2
    then
        Fact.ChildrenArray.Append(Fact.NewChild());
}

map.Len() int

Len will return map's length.

Mengembalikan

The length of map receiver.

Contoh

rule DoSomething "Do something when map length is sufficient" {
   when
       Fact.ChildrenMap.Len() > 2
   then
       Fact.DoSomething();
}

Menambah Fungsi Sendiri (Custom)

Semua fungsi yang mana bisa dijalankan dari DataContext bisa dijalankan dari dalam skrip rule, baik di dalam skop "When" atau "Then".

Karenanya, anda dapat membuat sebuah fungsi dan menjadikan fungsi ini merupakan milik (method) dari data, maka fungsi/method itu bisa dijalankan dari dalam GRL.

Diasumsikan anda memiliki sebuah struct dengan beberapa fungsi.

type MyPoGo struct {
}

func (p *MyPoGo) GetStringLength(sarg string) int {
    return len(sarg)
}

func (p *MyPoGo) AppendString(aString, subString string) string {
    return sprintf("%s%s", aString, subString)
}

Dan struct tersebut ditambahkan kedalam konteks data

dctx := grule.context.NewDataContext()
dctx.Add("Pogo", &MyPoGo{})

Anda dapat menjalan fungsi-fungsi tadi dalam rule

when
    Pogo.GetStringLength(some.variable) < 100
then
    some.variable = Pogo.AppendString(some.variable, "Groooling");

Argumen-argumen fungsi Variadic

Argumen-argumen Variadic dapat dipergunakan di dalam fungsi.

func (p *MyPoGo) GetLongestString(strs... string) string {
    var longestStr string
    for _, s := range strs {
        if len(s) > len(longestStr) {
            longestStr = s
        }
    }
    return longestStr
}

This function can then be called from within a rule with zero or more values supplied for the variadic argument

when
    Pogo.GetStringLength(some.variable) < 100
then
    some.longest = Pogo.GetLongestString(some.stringA, some.stringB, some.stringC);

Since it is possible to provide zero values to satisfy a variadic argument, they can also be used to simulate optional parameters.

func (p *MyPoGo) AddTax(cost int64, optionalTaxRate... float64) int64 {
    var taxRate float64 = 0.2
    if len(optionalTaxRate) > 0 {
        taxRate = optionalTaxRate[0]
    }
    return cost * (1+taxRate)
}

when
    Pogo.IsTaxApplied() == false
then
    some.cost = Pogo.AddTax(come.cost);

//or

when
    Pogo.IsTaxApplied() == false
then
    some.cost = Pogo.AddTax(come.cost, 0.15);

Important Thing you must know about Custom Function in Grule

When you make your own function to be called from the rule engine, you need to know the following rules.

The function must be visible. The convention for public functions should start with a capital letter. Private functions cannot be executed.
The function must only return 1 type. Returning multiple variables from a function is not supported, the rule execution will fail if there are multiple return variables.
The way number literals are treated in Grule's DRL is such that a decimal will always be taken as an int64 type and a real as float64, thus always consider to define your function arguments and returns from the types int64 and float64 when you work with numbers.

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