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condition_grammar.md

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Condition Grammar

Basic Concepts

  • Condition Primitive

    • Basic conditional judgment unit, which defines the primitive of comparison

      req_host_in("www.bfe-networks.com|bfe-networks.com")  # host is one of the configured domains

  • Condition Expression

    • Expression using "and/or/not" to connect condition primitive

      req_host_in("bfe-networks.com") && req_method_in("GET") # domain is bfe-networks.com and HTTP method is "GET"

  • Condition Variable

    • Variable that is defined by Condition Expression

      bfe_host = req_host_in("bfe-networks.com")  # variable bfe_host is defined by condition expression

  • Advanced Condition Expression

    • Expression using "and/or/not" to connect condition primitive and condition variable

    • In advanced condition expression, condition variable is identified by "$" prefix

      $news_host && req_method_in("GET") # match condition variable and HTTP method is "GET"

Condition Primitive Grammar

  • Basic conditional judgment unit, format is shown as follows:

​ FuncName( params )

  • Condition primitive like function definition: FuncName is name of condition primitive; params are input parameters
  • Return value type of Condition Primitive is bool
  • Note: All builtin condition primitives

Condition Expression Grammar

Condition Expression grammar is defined as follows:

  • Priority and combination rule of "&&/||/!" is same as them in C language

  • Expression description

    Condition Expression(CE) -> 
                   CE && CE
                 | CE || CE
                 | ( CE )
                 | ! CE
                 | Condition Primitive

Advanced Condition Expression Grammar

Advanced Condition Expression grammar is defined as follows:

  • Priority and combination rule of "&&/||/!" is same as them in C language

  • Expression description

    Advanced Condition Expression(ACE) -> 
                   ACE && ACE
                 | ACE || ACE
                 | ( ACE)
                 | ! ACE
                 | Condition Primitive
                 | Condition Variable