js_util_module Subsystems / components

• Introduction

• Directory

• Description

  • [Interface description](#Interface description)
  • [Instruction for use](#Instruction for use)

• [Related warehouse](#Related warehouse)

Introduction

The interface of util is used for character Textencoder, TextDecoder and HelpFunction module.The TextEncoder represents a text encoder that accepts a string as input, encodes it in UTF-8 format, and outputs UTF-8 byte stream. The TextDecoder interface represents a text decoder. The decoder takes the byte stream as the input and outputs the Stirng string. HelpFunction is mainly used to callback and promise functions, write and output error codes, and format class strings. Encodes all bytes from the specified u8 array into a newly-allocated u8 array using the Base64 encoding scheme or Encodes the specified byte array into a String using the Base64 encoding scheme.Decodes a Base64 encoded String or input u8 array into a newly-allocated u8 array using the Base64 encoding scheme.The rational number is mainly to compare rational numbers and obtain the numerator and denominator.LruBuffer The algorithm replaces the least used data with new data when the buffer space is insufficient. The algorithm derives from the need to access resources: recently accessed data can be Will visit again in the near future. The least accessed data is the least valuable data that should be kicked out of the cache space. The Scope interface is used to describe the valid range of a field. The constructor for the Scope instance is used to create objects with specified lower and upper bounds and require that these objects be comparable

目录

base/compileruntime/js_util_module/
├── Class:TextEncoder                   # TextEncoder class
│   ├──  new TextEncoder()             	# create textencoder object
│   ├──  encode()                      	# encode method
│   ├──  encoding                     	# encoding property
│   └──  encodeInto()                   # encodeInto method
├── Class:TextDecoder                   # TextDecoder class
│   ├──  new TextDecoder()              # create TextDecoder object
│   ├──  decode()             		    # decode method
│   ├──  encoding                      	# encoding property
│   ├──  fatal	                     	# fatal property
│   └──  ignoreBOM                     	# ignoreBOM property
├── printf()			                # printf method
├── getErrorString()			        # getErrorString method
├── callbackWrapper()		            # callbackWrapper method
├── promiseWrapper()		            # promiseWrapper method
├── Class:Base64                        # Base64 class
│   ├──  new Base64()             	    # create Base64 object
│   ├──  encode()                      	# encode method
│   ├──  encodeToString()               # encodeToString method
│   └──  decode()                       # decode method
├── Class:RationalNumber                # RationalNumber class
│   ├──  new RationalNumber()           # create RationalNumber object
│   ├──  CreateRationalFromString()     # CreatRationalFromString method
│   ├──  CompareTo()                    # CompareTo method
│   ├──  Equals()                       # Equals method
│   ├──  Value()                        # Value method
│   ├──  GetCommonDivisor()             # GetCommonDivisor method
│   ├──  GetDenominator()               # GetDenominator method
│   ├──  GetNumerator()                 # GetNumerator method
│   ├──  IsFinite()                     # IsFinite method
│   ├──  IsNaN()                        # IsNaN method
│   ├──  IsZero()                       # IsZero method
│   └──  ToString()                     # ToString method
├── Class:LruBuffer                 	# LruBuffer class
│   ├──  new LruBuffer()                # create RationalNumber object
│   ├──  updateCapacity()               # updateCapacity method
│   ├──  toString()                     # toString method
│   ├──  values()                       # values method
│   ├──  size()                         # size method
│   ├──  capacity()                     # capacity method
│   ├──  clear()                        # clear method
│   ├──  getCreateCount                 # getCreateCount method
│   ├──  getMissCount()                 # getMissCount method
│   ├──  getRemovalCount()              # getRemovalCount method
│   ├──  getMatchCount()                # getMatchCount method
│   ├──  getPutCount()                  # getPutCount method
│   ├──  isEmpty()                      # isEmpty method
│   ├──  get()                          # get method
│   ├──  put()                          # put method
│   ├──  keys()                         # keys method
│   ├──  remove()                       # remove method
│   ├──  afterRemoval()                 # afterRemoval method
│   ├──  contains()                		# contains method
│   ├──  createDefault()                # createDefault method
│   ├──  entries()               		# entries method
│   └──  [Symbol.iterator]()            # Symboliterator method
└── Class:Scope                         # Scope class
    ├── constructor()                   # create Scope object
    ├── toString()                      # toString method
    ├── intersect()                     # intersect method
    ├── intersect()                     # intersect method
    ├── getUpper()                      # getUpper method
    ├── getLower()                      # getLower method
    ├── expand()                        # expand method 
    ├── expand()                        # expand method
    ├── expand()                        # expand method 
    ├── contains()                      # contains method
    ├── contains()                      # contains method
    └── clamp()                         # clamp method 

Description

Interface description

Interface name	Description
readonly encoding : string	Get the encoding format, only UTF-8 is supported.
encode(input : string) : Uint8Array	Input stirng string, encode and output UTF-8 byte stream.
encodeInto(input : string, dest : Uint8Array) : {read : number, written : number}	Enter the stirng string, dest represents the storage location after encoding, and returns an object, read represents the number of characters that have been encoded,and written represents the size of bytes occupied by the encoded characters.
constructor(encoding? : string, options? : {fatal? : boolean, ignoreBOM? : boolean})	Constructor, the first parameter encoding indicates the format of decoding.The second parameter represents some attributes.Fatal in the attribute indicates whether an exception is thrown, and ignoreBOM indicates whether to ignore the bom flag.
readonly encoding : string	Get the set decoding format.
readonly fatal : boolean	Get the setting that throws the exception.
readonly ignoreBOM : boolean	Get whether to ignore the setting of the bom flag.
decode(input : ArrayBuffer	Input the data to be decoded, and solve the corresponding string character string.The first parameter input represents the data to be decoded, and the second parameter options represents a bool flag, which means that additional data will be followed. The default is false.
function printf(format: string, ...args: Object[]): string	The util.format() method returns a formatted string using the first argument as a printf-like format string which can contain zero or more format specifiers.
function getErrorString(errno: number): string	The geterrorstring () method uses a system error number as a parameter to return system error information.
function callbackWrapper(original: Function): (err: Object, value: Object) => void	Takes an async function (or a function that returns a Promise) and returns a function following the error-first callback style, i.e. taking an (err, value) => ... callback as the last argument. In the callback, the first argument will be the rejection reason (or null if the Promise resolved), and the second argument will be the resolved value.
function promiseWrapper(original: (err: Object, value: Object) => void): Object	Takes a function following the common error-first callback style, i.e. taking an (err, value) => ... callback as the last argument, and returns a version that returns promises.
encode(src: Uint8Array): Uint8Array;	Encodes all bytes from the specified u8 array into a newly-allocated u8 array using the Base64 encoding scheme.
encodeToString(src: Uint8Array): string;	Encodes the specified byte array into a String using the Base64 encoding scheme.
decode(src: Uint8Array	string): Uint8Array;
Decodes a Base64 encoded String or input u8 array into a newly-allocated u8 array using the Base64 encoding scheme.
CreateRationalFromString(src: string): Rational	Create a RationalNumber object based on the given string
CompareTo(src: RationalNumber): number	Compare the current RationalNumber object with the given object
Equals(src: object): number	Check if the given object is the same as the current RationalNumber object
Value(): number	Take the current RationalNumber object to an integer value or a floating point value
GetCommonDivisor(arg1: int, arg2: int,): number	Obtain the greatest common divisor of two specified numbers
GetDenominator(): number	Get the denominator of the current RationalNumber object
GetNumerator(): number	Get the numerator of the current RationalNumber object
IsFinite(): bool	Check that the current RationalNumber object is limited
IsNaN(): bool	Check whether the current RationalNumber object represents a non-number (NaN) value
IsZero(): bool	Check whether the current RationalNumber object represents a zero value
ToString(): string	Get the string representation of the current RationalNumber object
updateCapacity(newCapacity:number):void	Updates the buffer capacity to the specified capacity. This exception is thrown if newCapacity is less than or equal to 0
toString():string	Returns the string representation of the object and outputs the string representation of the object
values():V[ ]	Gets a list of all values in the current buffer, and the output returns a list of all values in the current buffer in ascending order, from most recently accessed to least recently accessed
size():number	Gets the total number of values in the current buffer. The output returns the total number of values in the current buffer
capacity():number	Gets the capacity of the current buffer. The output returns the capacity of the current buffer
clear():void	The key value pairs are cleared from the current buffer, after the key value is cleared, the afterRemoval () method is invoked to perform subsequent operations in turn
getCreateCount():number	Get the number of times the returned value of createdefault(), and output the number of times the returned value of createdefault()
getMissCount():number	Get the number of times the query value does not match, and output the number of times the query value does not match
getRemovalCount():number	Gets the number of evictions from the buffer, and outputs the number of evictions from the buffer
getMatchCount​():number	Obtain the number of successful matching of query values, and output the number of successful matching of query values
getPutCount():number	Gets the number of times the value was added to the buffer, and the output returns the number of times the value was added to the buffer
isEmpty():boolean	Checks whether the current buffer is empty and returns true if the current buffer does not contain any values
get(k:key):V / undefined	Indicates the key to query. If the specified key exists in the buffer, the value associated with the key will be returned; Otherwise, undefined is returned
put(K key, V value):V	Adding the key value pair to the buffer and outputting the value associated with the added key; If the key to be added already exists, the original value is returned. If the key or value is empty, this exception is thrown
keys():V[ ]	Get the key list of the value in the current buffer, and the output returns the key list sorted from the most recent access to the least recent access
remove​(k:key):V / undefined	Deletes the specified key and its associated value from the current buffer
afterRemoval(boolean isEvict, K key, V value, V newValue):void	Perform subsequent operations after deleting the value
contains(k:key):boolean	Checks whether the current buffer contains the specified key, and returns true if the buffer contains the specified key
createDefault(k:key):V	If the value of a specific key is not calculated, subsequent operations are performed. The parameter represents the missing key, and the output returns the value associated with the key
entries() : [K,V]	Allows you to iterate over all key / value pairs contained in this object. The keys and values of each pair are objects
Symbol.iterator:[K,V]	Returns a two-dimensional array in the form of key value pairs
constructor(lowerObj: ScopeType, upperObj: ScopeType)	Creates and returns a Scope object that creates a constructor for a scope instance that specifies a lower and upper bound.
toString():string	The stringification method returns a string representation that contains the current range.
intersect(range: Scope): Scope	This method returns the intersection of a given range and the current range.
intersect(lowerObj: ScopeType, upperObj: ScopeType): Scope	Passing in the upper and lower bounds of the given range returns the intersection of the current range and the range specified by the given lower and upper bounds.
getUpper(): ScopeType	Gets the upper bound of the current scope and returns a value of type ScopeType.
getLower(): ScopeType	Gets the lower bound of the current scope and returns a value of type ScopeType.
expand(lowerObj: ScopeType, upperObj: ScopeType): Scope	This method creates and returns a union that includes the current range and a given lower and upper bound.
expand(range: Scope): Scope	This method creates and returns a union that includes the current range and the given range.
expand(value: ScopeType): Scope	This method creates and returns a union that includes the current range and the given value.
contains(value: ScopeType): boolean	Checks whether the given value is included in the current range. If yes, true is returned. Otherwise, false is returned.
contains(range: Scope): boolean	Checks whether the given range is within the current range. Returns true if in, false otherwise.
clamp(value: ScopeType): ScopeType	Clips the specified value to the current range. If the value is less than the lower limit, lowerObj is returned. If the value is greater than the upper limit, upperObj is returned. Returns value if within the current range.

Each specifier in printf is replaced with a converted value from the corresponding parameter. Supported specifiers are:

Stylized character	Style requirements
%s:	String will be used to convert all values except BigInt, Object and -0.
%d:	Number will be used to convert all values except BigInt and Symbol.
%i:	parseInt(value, 10) is used for all values except BigInt and Symbol.
%f:	parseFloat(value) is used for all values expect Symbol.
%j:	JSON. Replaced with the string '[Circular]' if the argument contains circular references.
%o:	Object. A string representation of an object with generic JavaScript object formatting. Similar to util.inspect() with options { showHidden: true, showProxy: true }. This will show the full object including non-enumerable properties and proxies.
%O:	Object. A string representation of an object with generic JavaScript object formatting. Similar to util.inspect() without options. This will show the full object not including non-enumerable properties and proxies.
%c:	CSS. This specifier is ignored and will skip any CSS passed in.
%%:	single percent sign ('%'). This does not consume an argument.

Instruction for use

The use methods of each interface are as follows:

1.readonly encoding()

import util from '@ohos.util'
var textEncoder = new util.TextEncoder();
var getEncoding = textEncoder.encoding();

2.encode()

import util from '@ohos.util'
var textEncoder = new util.TextEncoder();
var result = textEncoder.encode('abc');

3.encodeInto()

import util from '@ohos.util'
var textEncoder = new util.TextEncoder();
var obj = textEncoder.encodeInto('abc', dest);

4.textDecoder()

import util from '@ohos.util'
var textDecoder = new util.textDecoder("utf-16be", {fatal : ture, ignoreBOM : false});

5.readonly encoding()

import util from '@ohos.util'
var textDecoder = new util.textDecoder("utf-16be", {fatal : ture, ignoreBOM : false});
var getEncoding = textDecoder.encoding();

6.readonly fatal()

import util from '@ohos.util'
var textDecoder = new util.textDecoder("utf-16be", {fatal : ture, ignoreBOM : false});
var fatalStr = textDecoder.fatal();

7.readonly ignoreBOM()

import util from '@ohos.util'
var textDecoder = new util.textDecoder("utf-16be", {fatal : ture, ignoreBOM : false});
var ignoreBom = textDecoder.ignoreBOM();

8.decode()

import util from '@ohos.util'
var textDecoder = new util.textDecoder("utf-16be", {fatal : ture, ignoreBOM : false});
var result = textDecoder.decode(input, {stream : true});

9.printf()

import util from '@ohos.util'
var format = "%%%o%%%i%s";
var value =  function aa(){};
var value1 = 1.5;
var value2 = "qwer";
var result = util.printf(format,value,value1,value2);

10.getErrorString()

import util from '@ohos.util'
var errnum = 13;
var result = util.getErrorString(errnum);

11.callbackWrapper()

import util from '@ohos.util'
async function promiseFn() {
    return Promise.resolve('value');
};
var cb = util.callbackWrapper(promiseFn);
cb((err, ret) => {
    expect(err).strictEqual(null);
    expect(ret).strictEqual('value');
})

12.promiseWrapper()

import util from '@ohos.util'
function aysnFun(str1, str2, callback) {
    if (typeof str1 === 'string' && typeof str1 === 'string') {
        callback(null, str1 + str2);
    } else {
        callback('type err');
    }
}
let newPromiseObj = util.promiseWrapper(aysnFun)("Hello", 'World');
newPromiseObj.then(res => {
    expect(res).strictEqual('HelloWorld');
})

13.encode()

import util from '@ohos.util'
var that = new util.Base64();
var array = new Uint8Array([115,49,51]);
var num = 0;
var result = that.encode(array,num);

14.encodeToString()

import util from '@ohos.util'
var that = new util.Base64();
var array = new Uint8Array([115,49,51]);
var num = 0;
var result = that.encodeToString(array,num);

15.decode()

import util from '@ohos.util'
var that = new util.Base64()
var buff = 'czEz';
var num = 0;
var result = that.decode(buff,num);

16.createRationalFromString()

import util from '@ohos.util'
var pro = new util.RationalNumber(0, 0);
var res = pro.createRationalFromString("-1:2");
var result1 = res.value();

17.compareTo()

import util from '@ohos.util'
var pro = new util.RationalNumber(2, 1);
var proc = new util.RationalNumber(3, 4);
var res = pro.compareTo(proc);

18.equals()

import util from '@ohos.util'
var pro = new util.RationalNumber(2, 1);
var proc = new util.RationalNumber(3, 4);
var res = pro.equals(proc);

19.value()

import util from '@ohos.util'
var pro = new util.RationalNumber(2, 1);
var res = pro.value();

20.getCommonDivisor()

import util from '@ohos.util'
var pro = new util.RationalNumber(0, 0);
var res = pro.getCommonDivisor(4, 8);

21.getDenominator()

import util from '@ohos.util'
var pro = new util.RationalNumber(2, 1);
var res = pro.getDenominator();

22.getNumerator()

import util from '@ohos.util'
var pro = new util.RationalNumber(-2, 1);
var res = pro.getNumerator();

23.isFinite()

import util from '@ohos.util'
var pro = new util.RationalNumber(-2, 1);
var res = pro.isFinite();

24.isNaN()

import util from '@ohos.util'
var pro = new util.RationalNumber(-2, 1);
var res = pro.isNaN();

25.isZero()

import util from '@ohos.util'
var pro = new util.RationalNumber(-2, 1);
var res = pro.isZero();

26.toString()

import util from '@ohos.util'
var pro = new util.RationalNumber(-2, 1);
var res = pro.toString();

27.updateCapacity()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.updateCapacity(100);

28.toString()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.get(2);
pro.remove(20);
var temp = pro.toString();

29.values()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.put(2,"anhu");
pro.put("afaf","grfb");
var temp = pro.values();

30.size()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.put(1,8);
var temp = pro.size();

31.capacity()

import util from '@ohos.util'
var pro = new util.LruBuffer();
var temp = pro.capacity();

32.clear()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.clear();

33.getCreatCount()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(1,8);
var temp = pro.getCreatCount();

34.getMissCount()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.get(2)
var temp = pro.getMissCount();

35.getRemovalCount()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.updateCapacity(2);
pro.put(50,22);
var temp = pro.getRemovalCount();

36.getMatchCount

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
pro.get(2);
var temp5 = pro.getMatchCount();

37.getPutCount()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.getPutCount();

38.isEmpty()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.isEmpty();

39.get()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.get(2);

40.put()

import util from '@ohos.util'
var pro = new util.LruBuffer();
var temp = pro.put(2,10);

41.keys()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.keys();

42.remove()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.remove(20);

43.contains()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.contains(20);

44.createDefault()

import util from '@ohos.util'
var pro = new util.LruBuffer();
var trmp = pro .createDefault(50);

45.entries()

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro.put(2,10);
var temp = pro.entries();

46.Symbol.iterator

import util from '@ohos.util'
var pro = new util.LruBuffer();
pro .put(2,10);
var temp = pro[symbol.iterator]();

Construct a new class in the scope interface to implement the compareTo method.

class Temperature {
    constructor(value) {
        this._temp = value;
    }
    compareTo(value) {
        return this._temp >= value.getTemp();
    }
    getTemp() {
        return this._temp;
    }
    toString() {
        return this._temp.toString();
    }
}

47.constructor()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var range = new Scope(tempLower, tempUpper);

48.toString()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var range = new Scope(tempLower, tempUpper);
range.toString() // => [30,40]

49.intersect()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var range = new Scope(tempLower, tempUpper);
var tempMiDF = new Temperature(35);
var tempMidS = new Temperature(39);
var rangeFir = new Scope(tempMiDF, tempMidS);
range.intersect(rangeFir)  // => [35,39]

50.intersect()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var tempMiDF = new Temperature(35);
var tempMidS = new Temperature(39);
var range = new Scope(tempLower, tempUpper);
range.intersect(tempMiDF, tempMidS)  // => [35,39]

51.getUpper()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var range = new Scope(tempLower, tempUpper);
range.getUpper() // => 40

52.getLower()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var range = new Scope(tempLower, tempUpper);
range.getLower() // => 30

53.expand()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var tempMiDF = new Temperature(35);
var tempMidS = new Temperature(39);
var range = new Scope(tempLower, tempUpper);
range.expand(tempMiDF, tempMidS)  // => [30,40]

54.expand()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var tempMiDF = new Temperature(35);
var tempMidS = new Temperature(39);
var range = new Scope(tempLower, tempUpper);
var rangeFir = new Scope(tempMiDF, tempMidS);
range.expand(rangeFir) // => [30,40]

55.expand()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var tempMiDF = new Temperature(35);
var range = new Scope(tempLower, tempUpper);
range.expand(tempMiDF)  // => [30,40]

56.contains()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var tempMiDF = new Temperature(35);
var range = new Scope(tempLower, tempUpper);
range.contains(tempMiDF) // => true

57.contains()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var range = new Scope(tempLower, tempUpper);
var tempLess = new Temperature(20);
var tempMore = new Temperature(45);
var rangeSec = new Scope(tempLess, tempMore);
range.contains(rangeSec) // => true

58.clamp()

var tempLower = new Temperature(30);
var tempUpper = new Temperature(40);
var tempMiDF = new Temperature(35);
var range = new Scope(tempLower, tempUpper);
range.clamp(tempMiDF) // => 35

Related warehouse

js_util_module subsystem

base/compileruntime/js_util_module/