Parse a list of attribute/values in PHP

Question

Given a string with attribute/value pairs such as

attr1="some text" attr2 = "some other text" attr3= "some weird !@'#$\"=+ text"

the goal is to parse it and output an associative array, in this case:

array('attr1' => 'some text',
      'attr2' => 'some other text',
      'attr3' => 'some weird !@\'#$\"=+ text')

Note the inconsistent spacing around the equal signs, the escaped double quote in the input, and the escaped single quote in the output.

Good to ask that! No, just making up my own syntax to be easy to type on a command line. — dreeves
– dreeves, Commented Oct 22, 2009 at 7:57
"to be easy to type on a command line", then you might be interested in docs.php.net/getopt — VolkerK
– VolkerK, Commented Oct 22, 2009 at 9:31

Bart Kiers · Accepted Answer · 2009-10-22 08:07:14Z

6

Try something like this:

$text = "attr1=\"some text\" attr2 = \"some other text\" attr3= \"some weird !@'#$\\\"=+ text\"";
echo $text;
preg_match_all('/(\S+)\s*=\s*"((?:\\\\.|[^\\"])*)"/', $text, $matches, PREG_SET_ORDER);
print_r($matches);

which produces:

attr1="some text" attr2 = "some other text" attr3= "some weird !@'#$\"=+ text"

Array
(
    [0] => Array
        (
            [0] => attr1="some text"
            [1] => attr1
            [2] => some text
        )

    [1] => Array
        (
            [0] => attr2 = "some other text"
            [1] => attr2
            [2] => some other text
        )

    [2] => Array
        (
            [0] => attr3= "some weird !@'#$\"=+ text"
            [1] => attr3
            [2] => some weird !@'#$\"=+ text
        )

)

And a short explanation:

(\S+)               // match one or more characters other than white space characters
                    // > and store it in group 1
\s*=\s*             // match a '=' surrounded by zero or more white space characters 
"                   // match a double quote
(                   // open group 2
  (?:\\\\.|[^\\"])* //   match zero or more sub strings that are either a backslash
                    //   > followed by any character, or any character other than a
                    //   > backslash
)                   // close group 2
"                   // match a double quote

edited Oct 22, 2009 at 8:07

answered Oct 22, 2009 at 7:53

Bart Kiers

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8 Comments

Gumbo Over a year ago

What about the third example?

Bart Kiers Over a year ago

Yes, I forgot to double escape the backslash (and double check the output). I'm afraid I am sometimes too confident in myself. Thanks.

Amarghosh Over a year ago

Is there any difference between the way php and actionscript, that is ecmascript/js btw, handles regex? Because this regex gave only the first two attrs in actionscript.

Bart Kiers Over a year ago

Next to no experience in ECMA-ish regex flavours, but you might want to try var regex = /(\S+)\s*=\s*"((?:\\.|[^\\"])*)"/g;, or even var regex = /(\S+)\s*=\s*"((?:\\.|[^\"])*)"/g; (not tested!).

Amarghosh Over a year ago

Both works well with all three cases given by OP, but not with a trailing backslash :(

|

Amarghosh · Accepted Answer · 2009-10-22 09:04:11Z

2

EDIT: This regex fails if the value ends in a backslash like attr4="something\\"

I don't know PHP, but since the regex would be essentially the same in any language, this is how I did it in ActionScript:

var text:String = "attr1=\"some text\" attr2 = \"some other text\" attr3= \"some weird !@'#$\\\"=+ text\"";

var regex:RegExp = /\s*(\w+)\s*=\s*(?:"(.*?)(?<!\\)")\s*/g;

var result:Object;
while(result = regex.exec(text))
    trace(result[1] + " is " + result[2]);

And I got the following out put:

attr1 is some text
attr2 is some other text
attr3 is some weird !@'#$\"=+ text

edited Oct 22, 2009 at 9:04

answered Oct 22, 2009 at 8:15

Amarghosh

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2 Comments

Bart Kiers Over a year ago

Just a small nitpick: if the value contains a backslash itself, like attr3 = "\\" (which will likely need escaping too), it won't work with a negative look behind. Of course, that might never happen, the OP didn't mention such corner cases.

Amarghosh Over a year ago

Yeah, you are right. And that's not a nitpick - apparently this fails if the string ends with a backslash - like attr4="something\\"

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