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@ -170,10 +170,10 @@ The double quotes will be counted as part of that lexical token.
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As an example:
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\begin{verbatim}
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exten => s,6,GotoIf($[ "${CALLERIDNAME}" : "Privacy Manager" ]?callerid-liar|s|1:s|7)
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exten => s,6,GotoIf($[ "${CALLERID(name)}" : "Privacy Manager" ]?callerid-liar|s|1:s|7)
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\end{verbatim}
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The variable CALLERIDNAME could evaluate to "DELOREAN MOTORS" (with a space)
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The variable CALLERID(name) could evaluate to "DELOREAN MOTORS" (with a space)
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but the above will evaluate to:
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\begin{verbatim}
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@ -197,67 +197,77 @@ evaluate this expression, because it does not match its grammar.
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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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\begin{verbatim}
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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 floating point comparison if both arguments are
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numbers; 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 floating point-valued
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arguments.
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expr1 {*, /, %} expr2
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Return the results of multiplication, floating point division, or
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remainder of arguments.
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- expr1
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Return the result of subtracting expr1 from 0.
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This, the unary minus operator, is right associative, and
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has the same precedence as the ! operator.
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! expr1
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Return the result of a logical complement of expr1.
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In other words, if expr1 is null, 0, an empty string,
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or the string "0", return a 1. Otherwise, return a 0.
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It has the same precedence as the unary minus operator, and
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is also right associative.
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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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Normally, the double quotes wrapping a string are left as part
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of the string. This is disastrous to the : operator. Therefore,
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before the regex match is made, beginning and ending double quote
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characters are stripped from both the pattern and the string.
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expr1 =~ expr2
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Exactly the same as the ':' operator, except that the match is
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not anchored to the beginning of the string. Pardon any similarity
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to seemingly similar operators in other programming languages!
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The ":" and "=~" operators share the same precedence.
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expr1 ? expr2 :: expr3
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Traditional Conditional operator. If expr1 is a number
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\begin{itemize}
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\item \verb!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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\item \verb!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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\item \verb+expr1 {=, >, >=, <, <=, !=} expr2+
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Return the results of floating point comparison if both arguments are
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numbers; 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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\item \verb!expr1 {+, -} expr2!
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Return the results of addition or subtraction of floating point-valued
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arguments.
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\item \verb!expr1 {*, /, %} expr2!
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Return the results of multiplication, floating point division, or
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remainder of arguments.
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\item \verb!- expr1!
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Return the result of subtracting expr1 from 0.
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This, the unary minus operator, is right associative, and
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has the same precedence as the ! operator.
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\item \verb+! expr1+
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Return the result of a logical complement of expr1.
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In other words, if expr1 is null, 0, an empty string,
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or the string "0", return a 1. Otherwise, return a 0.
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It has the same precedence as the unary minus operator, and
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is also right associative.
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\item \verb!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 regular
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expression subexpression `\(...\)', the string corresponing
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to `\textbackslash1' 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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Normally, the double quotes wrapping a string are left as part
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of the string. This is disastrous to the : operator. Therefore,
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before the regex match is made, beginning and ending double quote
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characters are stripped from both the pattern and the string.
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\item \verb!expr1 =~ expr2!
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Exactly the same as the ':' operator, except that the match is
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not anchored to the beginning of the string. Pardon any similarity
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to seemingly similar operators in other programming languages!
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The ":" and "=\~" operators share the same precedence.
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\item \verb!expr1 ? expr2 :: expr3!
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Traditional Conditional operator. If expr1 is a number
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that evaluates to 0 (false), expr3 is result of the this
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expression evaluation. Otherwise, expr2 is the result.
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If expr1 is a string, and evaluates to an empty string,
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@ -267,7 +277,7 @@ with equal precedence are grouped within { } symbols.
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will be the result of the "evaluation" of this
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expression. expr3 will be the result otherwise. This
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operator has the lowest precedence.
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\end{verbatim}
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\end{itemize}
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Parentheses are used for grouping in the usual manner.
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@ -276,7 +286,7 @@ or C derived languages.
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\subsection{Floating Point Numbers}
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In 1.6 and above, we shifted the \$\[...\] expressions to be calculated
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In 1.6 and above, we shifted the \$[...] expressions to be calculated
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via floating point numbers instead of integers. We use 'long double' numbers
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when possible, which provide around 16 digits of precision with 12 byte numbers.
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@ -309,7 +319,7 @@ don't want to preclude it, either.
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Here is a list of the 'builtin' functions in Expr2. All other dialplan functions
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are available by simply calling them (read-only). In other words, you don't need to
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surround function calls in \$\[...\] expressions with \$\{...\}. Don't jump to conclusions,
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surround function calls in \$[...] expressions with \$\{...\}. Don't jump to conclusions,
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though! -- you still need to wrap variable names in curly braces!
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\begin{enumerate}
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@ -338,6 +348,7 @@ If this quotient is 1/2, it is rounded to the nearest even number.
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\subsection{Examples}
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\begin{astlisting}
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\begin{verbatim}
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"One Thousand Five Hundred" =~ "(T[^ ]+)"
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returns: Thousand
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@ -422,10 +433,11 @@ TRUNC(-3.5)
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returns -3.
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\end{verbatim}
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\end{astlisting}
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Of course, all of the above examples use constants, but would work the
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same if any of the numeric or string constants were replaced with a
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variable reference \${CALLERIDNUM}, for instance.
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variable reference \${CALLERID(num)}, for instance.
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\subsection{Numbers Vs. Strings}
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@ -453,7 +465,7 @@ This is designed to be used together with the expression syntax described
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above, eg :
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\begin{verbatim}
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exten => 1,2,GotoIf($[${CALLERID} = 123456]?2|1:3|1)
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exten => 1,2,GotoIf($[${CALLERID(all)} = 123456]?2|1:3|1)
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\end{verbatim}
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Example of use :
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@ -472,7 +484,7 @@ Syntax errors are now output with 3 lines.
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If the extensions.conf file contains a line like:
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\begin{verbatim}
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exten => s,6,GotoIf($[ "${CALLERIDNUM}" = "3071234567" & & "${CALLERIDNAME}" : "Privacy Manager" ]?callerid-liar|s|1:s|7)
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exten => s,6,GotoIf($[ "${CALLERID(num)}" = "3071234567" & & "${CALLERID(name)}" : "Privacy Manager" ]?callerid-liar|s|1:s|7)
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\end{verbatim}
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You may see an error in /var/log/asterisk/messages like this:
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@ -635,7 +647,7 @@ references with '555'. You can override the 555 for variable values,
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by entering in var=val arguments after the filename on the command
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line. So...
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check\_expr /etc/asterisk/extensions.conf CALLERIDNUM=3075551212 DIALSTATUS=TORTURE EXTEN=121
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check\_expr /etc/asterisk/extensions.conf CALLERID(num)=3075551212 DIALSTATUS=TORTURE EXTEN=121
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will substitute any \${CALLERIDNUM} variable references with
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3075551212, any \${DIALSTATUS} variable references with 'TORTURE', and
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@ -644,15 +656,19 @@ going on in the reference, like \${EXTEN:2}, then the override will
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not work. Everything in the \${...} has to match. So, to substitute
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\${EXTEN:2} references, you'd best say:
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check\_expr /etc/asterisk/extensions.conf CALLERIDNUM=3075551212 DIALSTATUS=TORTURE EXTEN:2=121
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check\_expr /etc/asterisk/extensions.conf CALLERID(num)=3075551212 DIALSTATUS=TORTURE EXTEN:2=121
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on stdout, you will see something like:
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OK -- \$[ "\${DIALSTATUS}" = "TORTURE" | "\${DIALSTATUS}" = "DONTCALL" ] at line 416
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\begin{verbatim}
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OK -- $[ "${DIALSTATUS}" = "TORTURE" | "${DIALSTATUS}" = "DONTCALL" ] at line 416
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\end{verbatim}
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In the expr2\_log file that is generated, you will see:
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line 416, evaluation of \$[ "TORTURE" = "TORTURE" | "TORTURE" = "DONTCALL" ] result: 1
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\begin{verbatim}
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line 416, evaluation of $[ "TORTURE" = "TORTURE" | "TORTURE" = "DONTCALL" ] result: 1
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\end{verbatim}
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check\_expr is a very simplistic algorithm, and it is far from being
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guaranteed to work in all cases, but it is hoped that it will be
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@ -712,7 +728,7 @@ ${SYSTEMNAME} * value of the systemname option of asterisk.conf
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\end{verbatim}
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\subsection{Application return values}
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-------------------------
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In Asterisk 1.2, many applications return the result in a variable
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instead of, as in Asterisk 1.0, changing the dial plan priority (+101).
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For the various status values, see each application's help text.
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Russell Bryant
18 years ago