PHP parse_str() function allowing passing shorthand array - php

Question

We are accepting strings from templates to a markup engine, which allows for configuration to be passed in a "simple" form.
The engine parses the strings via PHP, using an adapted version of the parse_str() function - so we can parse any combination of the strings below:
config=posts_per_page:"5",default:"No questions yet -- once created they will appear here."&markup->template="{{ questions }}"
gives:
Array(
[config] => Array
(
[posts_per_page] => 5
[default] => No questions yet -- once created they will appear here.
)
[markup] => Array
(
[template] => {{ questions }}
)
)
OR:
config->default=all:"<p class='ml-3'>No members here yet...</p>"
To Get:
Array
[config] => Array
(
[default] => Array
(
[all] => <p class='ml-3'>No members here yet...</p>
)
)
)
Another:
config=>handle:"medium"
Returns:
Array (
[config] => Array
(
[>handle] => medium
)
)
Strings can be passed with spaces ( and multi-line spaces ) and string parameters should be passed between "double quotes" to preserve natural spacing - we run the following preg_replace on the string before it is passed to the parse_str method:
// strip white spaces from data that is not passed inside double quotes ( "data" ) ##
$string = preg_replace( '~"[^"]*"(*SKIP)(*F)|\s+~', "", $string );
So far, so good - until we try to pass a "delimiter" inside a string value, then it is treated literally - for example the following string returns a corrupt array:
config=posts_per_page:"5",default:"No questions yet -- once created, they will appear here."&markup->template="{{ questions }}"
Returns the following array:
Array (
[config] => Array
(
[posts_per_page] => 5
[default] => No questions yet -- once created
[ they will appear here."] =>
)
[markup] => Array
(
[template] => {{ questions }}
)
)
The "," was treated literally and the string was broken into an extra array part.
One simple solution is to create delimiters and operators with a lower chance of conflicting with string values - for example changing "," to "###" - but one important part of the markup used is that it is easy to write and read - it's intended use-case is for front-end developers to pass simple arguments to the template parser - this is one reason we have tried to avoid JSON - which is of course a good fit in terms of passing data, but it's hard to read and write - of course, that statement is subjective and open to opinion :)
Here is the parse_str method:
public static function parse_str( $string = null ) {
// h::log($string);
// delimiters ##
$operator_assign = '=';
$operator_array = '->';
$delimiter_key = ':';
$delimiter_and_property = ',';
$delimiter_and_key = '&';
// check for "=" delimiter ##
if( false === strpos( $string, $operator_assign ) ){
h::log( 'e:>Passed string format does not include asssignment operator "'.$operator_assign.'" -- '.$string );
return false;
}
# result array
$array = [];
# split on outer delimiter
$pairs = explode( $delimiter_and_key, $string );
# loop through each pair
foreach ( $pairs as $i ) {
# split into name and value
list( $key, $value ) = explode( $operator_assign, $i, 2 );
// what about array values ##
// example -- sm:medium, lg:large
if( false !== strpos( $value, $delimiter_key ) ){
// temp array ##
$value_array = [];
// split value into an array at "," ##
$value_pairs = explode( $delimiter_and_property, $value );
// h::log( $value_pairs );
# loop through each pair
foreach ( $value_pairs as $v_pair ) {
// h::log( $v_pair ); // 'sm:medium'
# split into name and value
list( $value_key, $value_value ) = explode( $delimiter_key, $v_pair, 2 );
$value_array[ $value_key ] = $value_value;
}
// check if we have an array ##
if ( is_array( $value_array ) ){
$value = $value_array;
}
}
// $key might be in part__part format, so check ##
if( false !== strpos( $key, $operator_array ) ){
// explode, max 2 parts ##
$md_key = explode( $operator_array, $key, 2 );
# if name already exists
if( isset( $array[ $md_key[0] ][ $md_key[1] ] ) ) {
# stick multiple values into an array
if( is_array( $array[ $md_key[0] ][ $md_key[1] ] ) ) {
$array[ $md_key[0] ][ $md_key[1] ][] = $value;
} else {
$array[ $md_key[0] ][ $md_key[1] ] = array( $array[ $md_key[0] ][ $md_key[1] ], $value );
}
# otherwise, simply stick it in a scalar
} else {
$array[ $md_key[0] ][ $md_key[1] ] = $value;
}
} else {
# if name already exists
if( isset($array[$key]) ) {
# stick multiple values into an array
if( is_array($array[$key]) ) {
$array[$key][] = $value;
} else {
$array[$key] = array($array[$key], $value);
}
# otherwise, simply stick it in a scalar
} else {
$array[$key] = $value;
}
}
}
// h::log( $array );
# return result array
return $array;
}
I will try to skip splitting string between "double quotes" - probably via another regex, but perhaps there are other potential pitfalls waiting that might not make this approach viable long-term - any help glady accepted!

Answer 1

One solution, is to change the following:
from:
$value_pairs = explode( $delimiter_and_property, $value );
to:
$value_pairs = self::quoted_explode( $value, $delimiter_and_property, '"' );
which calls a new method found on another SO answer ( linked in comment block ):
/**
* Regex Escape values
*/
public static function regex_escape( $subject ) {
return str_replace( array( '\\', '^', '-', ']' ), array( '\\\\', '\\^', '\\-', '\\]' ), $subject );
}
/**
* Explode string, while respecting delimiters
*
* #link https://stackoverflow.com/questions/3264775/an-explode-function-that-ignores-characters-inside-quotes/13755505#13755505
*/
public static function quoted_explode( $subject, $delimiter = ',', $quotes = '\"' )
{
$clauses[] = '[^'.self::regex_escape( $delimiter.$quotes ).']';
foreach( str_split( $quotes) as $quote ) {
$quote = self::regex_escape( $quote );
$clauses[] = "[$quote][^$quote]*[$quote]";
}
$regex = '(?:'.implode('|', $clauses).')+';
preg_match_all( '/'.str_replace('/', '\\/', $regex).'/', $subject, $matches );
return $matches[0];
}