136 lines
4.9 KiB
Text
136 lines
4.9 KiB
Text
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GENERAL ENCHANCEMENTS TO EXTENSION LOGIC :
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QUOTING:
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exten => s,5,BackGround,blabla
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The parameter (blabla) can be quoted ("blabla"). In this case, a
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comma does not terminate the field.
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Also, characters special to variable substitution, expression evaluation, etc
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(see below), can be quoted. For example, to literally use a $ on the
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string "$1231", quote it with a preceeding \. Special characters that must
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be quoted to be used, are [ ] $ " \. (to write \ itself, use \\).
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VARIABLES:
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Parameter strings can include variables. Variable names are arbitrary strings.
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They are stored in the respective channel structure.
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To set a variable to a particular value, do :
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;exten => 1,2,SetVar,varname=value
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You can substitute the value of a variable everywhere using ${variablename}.
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For example, to stringwise append $lala to $blabla and store result in $koko,
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do:
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;exten => 1,2,SetVar,koko=${blabla}${lala}
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There are also the following special variables:
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${CALLERID} Caller ID
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${EXTEN} Current extension
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${CONTEXT} Current context
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${PRIORITY} Current priority
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There are two reference modes - reference by value and reference by name.
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To refer to a variable with its name (as an argument to a function that
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requires a variable), just write the name. To refer to the variable's value,
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enclose it inside ${}. For example, SetVar takes as the first argument
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(before the =) a variable name, so:
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;exten => 1,2,SetVar,koko=lala
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;exten => 1,3,SetVar,${koko}=blabla
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stores to the variable "koko" the value "lala" and to variable "lala" the
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value "blabla".
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In fact, everything contained ${here} is just replaced with the value of
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the variable "here".
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EXPRESSIONS:
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Everything contained inside a bracket pair prefixed by a $ (like $[this]) is
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considered as an expression and it is evaluated. Evaluation works similar to
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(but is done on a later stage than) variable substitution: the expression
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(including the square brackets) is replaced by the result of the expression
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evaluation. The arguments and operands of the expression MUST BE separated
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with spaces (take care NOT to leave ANY spaces between opening and closing
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square brackets and the first and last arguments).
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For example, after the sequence:
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exten => 1,1,SetVar,"lala=$[1 + 2]";
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exten => 1,2,SetVar,"koko=$[2 * ${lala}]";
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the value of variable koko is "6".
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Operators are listed below in order of increasing precedence. Operators
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with equal precedence are grouped within { } symbols.
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expr1 | expr2
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Return the evaluation of expr1 if it is neither an empty string
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nor zero; otherwise, returns the evaluation of expr2.
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expr1 & expr2
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Return the evaluation of expr1 if neither expression evaluates to
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an empty string or zero; otherwise, returns zero.
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expr1 {=, >, >=, <, <=, !=} expr2
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Return the results of integer comparison if both arguments are
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integers; otherwise, returns the results of string comparison
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using the locale-specific collation sequence. The result of each
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comparison is 1 if the specified relation is true, or 0 if the
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relation is false.
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expr1 {+, -} expr2
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Return the results of addition or subtraction of integer-valued
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arguments.
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expr1 {*, /, %} expr2
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Return the results of multiplication, integer division, or
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remainder of integer-valued arguments.
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expr1 : expr2
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The `:' operator matches expr1 against expr2, which must be a
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regular expression. The regular expression is anchored to the
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beginning of the string with an implicit `^'.
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If the match succeeds and the pattern contains at least one regu-
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lar expression subexpression `\(...\)', the string correspond-
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ing to `\1' is returned; otherwise the matching operator
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returns the number of characters matched. If the match fails and
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the pattern contains a regular expression subexpression the null
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string is returned; otherwise 0.
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Parentheses are used for grouping in the usual manner.
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The parser must be parsed with bison (bison is REQUIRED - yacc cannot
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produce pure parsers, which are reentrant)
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CONDITIONALS
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There is one conditional operator - the conditional goto :
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;exten => 1,2,gotoif,condition?label1:label2
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If condition is true go to label1, else go to label2. Labels are interpreted
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exactly as in the normal goto command.
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"condition" is just a string. If the string is empty or "0", the condition
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is considered to be false, if it's anything else, the condition is true.
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This is designed to be used together with the expression syntax described
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above, eg :
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exten => 1,2,gotoif,$[${CALLERID} = 123456]?2|1:3|1
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Example of use :
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exten => s,2,SetVar,"vara=1"
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exten => s,3,SetVar,"varb=$[${vara} + 2]"
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exten => s,4,SetVar,"varc=$[${varb} * 2]"
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exten => s,5,GotoIf,"$[${varc} = 6]?99|1:s|6";
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