在PHP中将多维数组转换为条件表达式

Question

I'm trying to convert an array to condition-like expression string that will be used in the JS Filtrex library. The JS part is irrelevant for this question.

Following is a sample PHP array that I'm trying to work with.

$condition = array(
    'and',
    array(
        array(
            'field' => 'show_image',
            'compare' => '==',
            'value' => 1
        ),
    ),
    array(
        'or',
        array(
            'field' => 'filter',
            'compare' => '!=',
            'value' => 1
        ),
        array(
            'field' => 'align',
            'compare' => '==',
            'value' => 'left'
        )
    )
);

The resulting string will be something like this :

show_image == 1 and ( filter != 1 or align == "left" )

I'm not sold on the array structure so you're free to modify the array as long as it can be extended with more conditions.

Thanks in advance.

Answer 1

You just need to recurse such a structure, and switch according to the first element:

• If it's a string, then treat the remaining arguments as operands/expressions, joined by operator

• For associative arrays, just concat field/compare/value into a string

For example:

function join_expr($opts) {
    if (isset($opts["compare"])) {    // optional ↓↓↓ caretaking of value type(!)
        return "($opts[field] $opts[compare] '$opts[value]')";
    }
    elseif (gettype($opts[0]) == "string") {
        $op = array_shift($opts);
        return join(
            " $op ",
            array_map("join_expr", $opts)   // recurse on operands/subexpressions
        );
    }
    elseif (count($opts) == 1) {   // somewhat redundant
        return "(" . join_expr($opts[0]) . ")";
    }
    else {
        trigger_error("wrong struct");
    }
}