Question

I am trying to create an own code to allow a client to post something on a pixel matrix.

Here an example of a code:
15e3n:3;geo(386299n283752w):4;delta(16e3n:5;line(20e0n;20e10n;0e10n;color:d);19w55n;rectangle(50w50n;height:100;width:50));88e2n:randomColor()

I want to interpret this using functions like in this case geo, delta, line, rectangle, geo, randomColor. The things that are written between (and )are the parameters, separated by a ;. (15e3n is in this case a position “15 east, 3 north”)

Example:
function(param1:value1;param2:value2;value3;value4);function2(param1:value1)

The functions should be executed and should replace the function with the result like here:

The text 16e13n:3;line(17e13n;19e13n;color:4);15e13n:3 should result in 16e13n:3;17e13n:4;18e13n:4;19e13n:4;15e13n:3. Because the function line with params 17e13n;19e13n;color:4 have the result 17e13n:4;18e13n:4;19e13n:4;that replaced the function in the input.

How can I achieve this? What is the best way? Regex?
Are there existing examples about how to do this?

Now, this looks a bit complicated 🙂

I thank you in advance for getting help on this!

Answer 1

Note: content are not necessary valid PHP script

My suggestion will be:

5e3n:3;geo(386299n283752w):4;delta(16e3n:5;line(20e0n;20e10n;0e10n;color:d);19w55n;rectangle(50w50n;height:100;width:50));88e2n:randomColor()

First implement a parser to separate statements into an array. You can loop every character, hold a counter of brackets and split by ; that is outside brackets, resulting into this array:

array(
    0 => object(prefix => "5e3n", suffix => "3"),
    1 => object(prefix => "geo(386299n283752w)", suffix => "4"),
    2 => object(prefix => "delta(16e3n:5;line(20e0n;20e10n;0e10n;color:d);19w55n;rectangle(50w50n;height:100;width:50))", suffix => ""),
    3 => object(prefix => "88e2n", suffix => "randomColor()")
)

Then extract the function parameters, you may want to use objects…

array(
    0 => object(prefix => "5e3n", suffix => "3"),
    1 => object(
        prefix => (object)func(
            name => "geo",
            params => array(
                0 => "386299n283752w"
            )
        ),
        suffix => "4"),
    ),
    2 => object(
        prefix => (object)func(
            name => "delta",
            params => array(
                0 => "16e3n:5",
                1 => "line(20e0n;20e10n;0e10n;color:d)",
                2 => "19w55n",
                3 => "rectangle(50w50n;height:100;width:50)"
            )
        ),
        suffix => ""
    ),
    3 => object(
        prefix => "88e2n",
        suffix => (object)func(
            name => "randomColor",
            params => array()
        )
    )
)

Do this recursively until all functions deep inside are extracted.

Then from the depth, process the functions by replacing a (object)func block into the resulting string, by a switch block that do appropriate action according to the name, for example:

function processFunc($func){
    switch($func->name){
        case "randomColor":
            return selectRandomColor();
        /* ... */
    }
}

will process this:

(object)func(
    name => "randomColor",
    params => array()
)

into this:

"blueColor"

Then at the end you will end up a single array which the contents, for example (not directly matching above):

array(
    0 => object(prefix => "5e3n", suffix => "3"),
    1 => object(prefix => "6e2n", suffix => "4"),
    2 => object(prefix => "88e2n", suffix => "")
)

Then re-combine them into a resulting string.

I am not going to write a full script for you, but here’s an idea of how to deal with it. This may not be complete though, but by thinking a bit you should be able to complete it.