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ApsaraVideo VOD:EdgeScript syntax

Last Updated:May 18, 2023

This topic describes the conventions of annotations, identifiers, data types, variables, operators, clauses, and functions in the EdgeScript syntax.

Note

You must not use double quotation marks (") in ES.

The following table describes the details about the EdgeScript syntax.

Syntax

Rule

Annotations

All annotations must start with a number sign (#). Example: # This is annotation.

Identifier

  • Identifiers are case-sensitive. An identifier can contain letters, digits, and underscores (_). Identifiers cannot start with a digit.
  • All names of built-in variables, custom variables, built-in functions, and custom functions must comply with the identifier conventions.

Data type

  • String

    Literal constants: use a pair of single quotation marks (') to quote a literal constant, for example, 'hello, EdgeScript'.

  • Number

    Literal constants: decimal numbers, for example, 10, -99, or 1.1.

  • BOOLEAN

    Literal constants: true or false.

  • Dictionary
    Literal constants:
    • []: an empty string.
    • ['key1', 'key2', 100]:
      • 1 -> 'key1'
      • 2 -> 'key2'
      • 3 -> 'key3'
    • ['key1' = 'value1', 'key2' = 1000]
      • 'key1' -> 'value1'
      • 'key2' -> 1000

Variable

  • Definition

    A variable is a symbolic name associated with a value that may change.

  • How to use

    • Both built-in and custom variables are referenced by using their names.
      • Reference a built-in variable: host.
      • Reference a custom variable: seckey.
    • To indicate that the variable is a built-in variable, add a dollar sign ($) before the variable name.

      Reference a built-in variable: $host.

    • A custom variable and a built-in variable cannot use the same name.

      For more information about built-in variables, see EdgeScript built-in variables.

Operator

  • =: the assignment operator.
    • Example: seckey = 'ASDLFJ234dxvf34sDF'
    • Example: seckeys = ['key1', 'key2']
  • -: the minus operator.

    Example: inum = -10

  • Built-in functions are used to process different types of data. No additional operators are provided. For more information about built-in functions, see Logical functions.

      • The built-in functions support the following data types:
        • String
        • Number
        • Dictionary
      • Example
        • sval = concat(sval, 'trail')
        • len(arrvar)

Clause

  • Condition clause
    if condition {   
       ...
    }
    
    if condition1 {   
       if conditon2 {
            ...
       }
    }
    
    if condition {
       ...
    } else {
       ...
    }
  • Clause descriptions
    • A condition clause contains the following elements:
      • Literal constant
      • Variable
      • Function call
    • Body
      • The body can be empty.
      • Multiple statements are allowed. Enter only one statement on each line.
    • Statement nesting is allowed.
    • CodingStyle

      The opening brace ({) must follow if condition on the same line.

  • for loop
    a = ['a', 'b', 'c', 'd']
    def for_func () {
        for k, v in a {
            if eq(v, 'c') {
                return true
            }
        }   
    }
    for_func()
    
    ##########################################################################################
    
    a = ['a' = 1, 'b' = 2, 'c' = 3, 'd' = 4, 'e' = 5, 'f' = 6]
    def for_func () {
        for k, v in a {
            if eq(k, 'c') {
                return true
            }
        }   
    }
    for_func()
    
    ##########################################################################################
    
    num = 0
    def for_func () {
        a = [0,1,2,3,4,5,6,7,8,9]
        for k ,v in a {
            b = [0,1,2,3,4,5,6,7,8,9]
            for k1 ,v1 in b {
                c = [0,1,2,3,4,5,6,7,8,9]
                for k2 ,v2 in c {
                    num = add(num, 1)
                    if and(eq(v, 3), eq(v1, 5), eq(v2, 7)) {
                        return true
                    }
                }
            }
        } 
    }
    for_func()
  • Take note of the following limits:
    • For loops are used only to traverse data of the dictionary or array type.
    • Keywords such as break are not supported. We recommend that you use custom functions and use the return keyword to break loops.
    • Statement nesting is allowed.
    • CodingStyle

      The opening brace ({) must follow for... on the same line.

Function

  • Syntax
    def Function name(Parameter list) {
       ...
    }
  • Descriptions
    • Parameter list
      • The parameter list can be empty.
      • Multiple parameters are allowed. Separate parameters with commas (,).
    • Body
      • The body can be empty.
      • Multiple statements are allowed. Enter only one statement on each line.
      • The return values support the return clause.
    • CodingStyle

      The opening brace ({) must follow def Function name(Parameter list) on the same line.

  • Function call

    You must use Function name() to call both built-in and custom functions.

Remarks

You must not use double quotation marks (") in EdgeScript.