Operators

NAME

operators - List of operators in Sncode.

DESCRIPTION

The following operators are supported in Sncode:

• Numerical operators
• Increment/decrement operators
• Assignment operators
• Relational operators for numbers
• Relational operators for strings
• Regular expressions
• String concatenation
• Unary minus
• Logical operators
• Binary operators
• File operators

All operators works will all type of variables: - undefined - integer - double - string - null - associative array - array - boolean.

Each operators as is own set of rules for the conversion unless casting is used.

For numerical operators, undefined and null values are considered equal to 0 whereas boolean values are treated as 1 when true and 0 when false.

For string operators, undefined and null values are treated as an empty string whereas boolean values are treated as "true" when true and "false" when false.

Here is the order for operators precedence:

1. + - .+
2. * /
3. % **
4. | & ^
5. << >>
6. = -= = /= %= *= .= &= |= ^= <⇐ >>=
7. - (unary minus)
8. ~ (not)
9. ? :
10. ()
11. . []

Numerical operators

Usage:

a = b + c;

a = b / c;// if b and c are integer, the result a will be an integer. If one of operands is double, a will be double.

Examples

// Modulo example
r = 5 % 3;
// r = 2

lncrement/decrement operators

Example

// Init example
a = 5; 
// Post increment
b = a++; // a=6 b=5 
// Pre increment
c = ++a; // a=7 c=7
// Post decrement 
d = a--; // a=6 d=7
// Pre decrement 
e = --a; //a=5 e=5

Assignment operators

These operators assign a value to their left operand based on the value of their right operand.

Usage:

a = 1;
a += 2; // a now equals 3

Relational operators for numbers

< <= > >= != <> <⇒

• < : less than
• > : greater than
• <= : less or equal
• >= : greater or uqual
• <=> : compare (WARNING: This operator triggers an error if your script is feeded through an include() sncode function)

• -1 if less than
• 0 if equal
• 1 if greater than

• == : equal
• != : not equal

Example

1 <=> 1; // 0 
1 <=> 2; // -1 
2 <=> 1; // 1

Relational operators for strings

lt -- less than. Compare the length of 2 strings

le -- less. Compare the length of 2 strings

gt -- greater than. Compare the length of 2 strings

ge -- greater. Compare the length of 2 strings

eq -- equal

ne -- not equal

cmp -- compare two string but return -1, 0, or 1.

st -- check is the first string start with the second string. "/usr/local/website" st "/usr" return true; "/usr/local/website" st ".usr" return false

ns -- check is the first string not start with the second string. "/usr/local/website" ns "/usr" return false; "/usr/local/website" ns ".usr" return true

Regular expressions

Usage:

if "2016-01-01" =~ "^(?P\d\d\d\d)-(?P\d\d)-(?P\d\d)$" then

To retrieve the groups, use the getre() function.

Regular expressions support special flags to alter their behavior:

Usage:

if "2016" =~:iasm "^(?P\d\d\d\d)$" then

For more details, please consult the PCRE Documentation.

String concatenation

Example

s1 = "1 str"; 
s1 .+= " more"; 
// s1 = "1 str more" 

Unary minus

-

Logical operators

Usage:

if !a || (a && b) then // if a is false or both variables are true

Example

// Example 1
if false || true then;// always true 

// Example 2
a = true; 
if !a then // always false

In Sncode, logical operators rely on lazy evaluation, which means that in both of these cases, the function fact won't even be called:

if 0 && fact(1) then // 0 means false so we don't need to go further

and 

if 1 || fact(1) then // 1 means true so we don't need to go further

Binary operators

~(not) |(or) &(and) ^(xor) <<(left shift) >>(right shift)

File operators

Usage:

if -e "/path/to/file.txt" then

If the path starts with a /, it is automatically prefixed with the path to the root directory. Otherwise, it is prefixed with the path of the current script.

EXAMPLES

// -e folder/file example
if -e "/extenso/module/sed/core" then
    "core folder exists";
endif

// WARNING -e False positive!
// If your path is an absolute path, it will through a false positive even though the folder/file doesn't exists!
if -e "/usr/local/website/my_site/whatever/does/not/exists" then
    "This path does not exists but -e throughs `true`!";
endif

AUTHOR

Written by Pierre Laplante <laplante@sednove.com>, Jean-Georges Guenard, <jg@sednove.com>