switch

Another flow control command

Usage

switch [-p] (<expression>)
{
    case(<value>)[:]<command>
    [break]
    case(<value>)[:]<command>
    [break]
    ....
    match(<wildcard_expression>)[:]<command>
    [break]
    ....
    regexp(<regular_expression>)[:]<command>
    [break]
    ....
    case(<value>)[:]<command>
    [break]
    ....
    default[:]<command>
    [break]
}

Description

The switch command is based on the standard C 'switch' keyword. It conditionally executes groups of commands chosen from a larger set of command groups.
First <expression> is evaluated (<expression> is any arithmetic or string expression).
Then the match, regexp, case and default labels are evaluated sequentially in the order of appearance.
case(<value>)[:]<command>
The <value> is evaluated and is compared against the result of <expression>. String comparison is case insensitive.
If <value> is equal to <expression> then <command> is executed. Please note that <command> must be either a single instruction or an instruction block enclosed in braces. During or after <command> execution, if a break statement is encountered the execution of the switch is terminated, otherwise the next label is evaluated.
If the -p (--passthrough) option is enabled, than the switch command will execute all the instructions blocks until a break statement is found.
match(<value>)[:]<command>
The <value> is expected to be a wildcard expression (wildcard characters being * and ?) that is matched in a case insensitive fashion against <expression>.
If a match occurs, the related <command> is executed. The break statement is treated as in the case label.
regexp(<value>)[:]<command>
The <value> is expected to be a complete standard regular expression that is matched in a case insensitive fashion against <expression>.
If a match occurs, the related <command> is executed. The break statement is treated as in the case label.
default[:]<command>
The default label is executed unconditionally if no previous label terminated execution with the break statement.

Switches

-p | --passthrough

Use c-style 'break' flow control

Examples

# Try to change the 1 below to 2 or 3 to see the results

%tmp = 1
switch(%tmp)
{
    case(1):
        echo \%tmp was 1!
    break;
    case(2)
        echo \%tmp was 2!
    break;
    default:
        echo \%tmp was not 1 nor 2: it was %tmp!
    break;
}

# A more complex example: change the 1 in 2 or 3
%tmp = 1
switch(%tmp)
{
    case(1):
        echo \%tmp was 1!
case(2)
        echo \%tmp was 2!
    break;
    default:
        echo \%tmp was either 1 or something different from 2 (%tmp)
    break;
}

# An example of the -p switch
%tmp = 1
switch -p (%tmp)
{
    case(1):
        echo \%tmp was 1!
    case(2)
        echo \%tmp was 1 or 2!
        break;
    default:
        echo \%tmp was not 1 or 2 (%tmp)
    break;
}

# An example with strings
%tmp = "This is a test"
%tmp2 = "This is not a test"
switch(%tmp)
{
    case(%tmp2)
        echo \%tmp == \%tmp2
        break;
    case(%tmp)
    {
        # do not break here
        echo "Yeah... It's stupid... \%tmp == \%tmp :D"
    }
    match("*TEST"):
        echo "Matched *TEST"
    regexp("[a-zA-Z ]*test"):
        echo "Matched [a-zA-Z ]*text"
    regexp("[a-zA-Z ]*not[a-zA-Z ]*"):
        echo "Matched [a-zA-Z ]*not[a-zA-Z ]*"
    default:
        echo This is executed anyway (unless some break was called)
    break;
}

Index, Commands