php-sdl 2.0

This is an implementation of the Simple Declarative Language (SDL) serialization language for PHP. It has not thing to do with Simple Directmedia Layer. Think of it like XML with less typing:

    greetings {
        greeting "Aloha" where="Hawaii"
        greeting "Hej" where="Sweden"
    }

This is the v2.0 rewrite of php-sdl, and as such some things are not quite working yet. If you are looking for a working but not too extensible parser, install the v1.x branch with composer, composer require noccylabs/sdl:1.*. The current quirks are:

• Not all LiteralTypes are implemented. This is easily done now however, as each type is in its own folder.
• The parser is broken still.
• Not all unit tests have been created.
• Comments can be generated, but not necessarily always parsed.
• Numeric types may lose precision.

Usage

You shouldn't really use this right now. Here is a brief summary of what is working, and what is not. Contributions and improvements are welcome.

Components

Component	Description	Status
Sdl\SdlTag	Creating tag trees	WORKING
Sdl\SdlTag	Encoding tags and children	WORKING
Sdl\SdlTag	Encoding tags with comments	WORKING
Sdl\SdlTag	Tree traversal	WORKING
Sdl\SdlTag	Tests implemented	PARTIAL
Sdl\Parser\SdlParser	Parsing tags and nested tags	WORKING
Sdl\Parser\SdlParser	Parsing tags with comments
Sdl\Parser\SdlParser	Tests implemented	PARTIAL
Sdl\LiteralType\TypeFactory	LiteralType registering	PARTIAL
Sdl\LiteralType\TypeFactory	Tests implemented	PARTIAL
Sdl\LiteralType\*Type	All types implemented	PARTIAL
Sdl\LiteralType\*Type	Tests implemented	PARTIAL
Sdl\Selector\SdlSelector	Selecting with expressions	PARTIAL
Sdl\Selector\SdlSelector	Tests implemented

Functionality

Function	Status
Creating tag trees	WORKING
Encoding tag trees into SDL	WORKING
Parsing SDL into tag trees	PARTIAL
Navigating the tag tree	WORKING
Selecting tags with expressions	PARTIAL
Create LiteralTypes from native PHP variable types	WORKING
Create LiteralTypes from SDL tokens	PARTIAL
Access LiteralTypes as native PHP values	PARTIAL
Encode LiteralTypes into SDL tokens	PARTIAL

Performance

The parser is currently a little slow at reading, but this can probably be optimized somewhat. Either way it offers a tidy alternative to the established serialization formats (XML, JSON and YAML). It is important to remember that the parsers for XML, JSON and YAML are running as native code, while the SDL parser is written in PHP.

That being said, it should be noted that php-sdl is best used with configuration files that are not being requested at an excessive frequency (such as blog posts, routing tables etc.) but rather for f.ex. job configurations, or immediate files (like dumping blogposts into sdl for easy editing and import).

Caching is implemented as it was in the 1.x version of the parser, i.e. the cache file with the parsed tags is placed in the same directory as the SDL-fil being parsed, with an identical filename except prefixed with a dot (.) and suffixed with ".cache". For example "foo.sdl" would be cached as ".foo.sdl.cache". This behaviour might change in the future.

Format	Parser	10000x	Calls/s
SDL	SdlParser::parseString	8.83s	1132.50
XML	DomDocument::loadXml	0.43s	23469.17
JSON	json_decode	0.26s	38640.62
YAML	yaml_parse_file	0.44s	22738.22

Some possible improvements and optimizations include:

• Improvements to the pre-parser optimization routines.
• Rewrite the parser using regular expressions (could be faster, could be slower)

Examples

Generating tag trees

Generating is simple. Get a new root tag with createRoot() and start adding your children. You can use the same fluid programming as you are used to from Symfony2, where all the setX() methods return the current tag, and a call to end() returns the parent node. createChild() is available to create a tag, add it as a child to the current node, and return the newly created child tag.

    use Sdl\SdlTag;
    $tag = SdlTag::createRoot()
        ->createChild("people")
            ->createChild("person")
                ->setValue("John Doe")
                ->setAttribute("sex","male")
                ->end()
            ->end();
    echo $tag->encode();

Values and attributes can be assigned from PHP values, or directly via any of the LiteralType descendants.

    use Sdl\SdlTag;
    use Sdl\LiteralType\SdlBinary;
    $tag = SdlTag::createRoot()
        ->createChild("image")
            ->setValue(new SdlBinary($file))
            ->setAttribute("type","image/jpeg")
            ->end();

Remember to match your calls to end() to make sure you return the root element when you are using the fluid method calls on a new root or non-variable:

    use Sdl\SdlTag;
    $tag = SdlTag::createRoot();
    $tag->createChild("foo")->createChild("bar");
    // $tag will still point to the root even though end() wasn't called.
    $bad = SdlTag::createRoot()->createChild("foo")->createChild("bar");
    // $bad will be pointing to "bar" here, not the root.

You should however be able to get back to the root using getParent() if you ever needed to:

    function root($tag) {
        while(($parent = $tag->getParent())
            $tag = $parent;
        return $tag;
    }

Parsing a file

To parse a file, use the Sdl\Parser\SdlParser class. It offers a few different methods to parse content and return Sdl\SdlTag objects.

    use Sdl\Parser\SdlParser;
    // Parse a file
    $tag = SdlParser::parseFile("basic.sdl");
    // Parse a string
    $tag = SdlParser::parseString($sdl_string);

Encoding tags to SDL

Tags are encoded into SDL using the encode() method. If you need to write it out to a file, use file_put_contents() or any other appropriate method to write out the output from encode().

    use Sdl\SdlTag;
    // Create a new root
    $tag = SdlTag::createRoot();
    // Add two children
    $tag->addChild("foo")->setValuesFromArray([0, 1, 2 ]);
    $tag->addChild("bar")->setValuesFromArray([2, 3, 4 ]);
    // Output the final SDL
    echo $tag->encode();

Navigating children

You can use getAllChildren(), getChildrenByTagName(..) to navigate the tree.

The SdlSelector will provide a more convenient approach to querying the tree with logical expressions.

    use Sdl\Parser\SdlParser;
    $tag = SdlTag::createRoot();
    $tag->createChild("people")
        ->createChild("person")
            ->setValue("John Doe")
            ->setAttribute("sex","male");
    $people = $tag->getChildrenByTagName("people")[0]->getAllChildren();
    echo "Person name: ".$people[0]->getValue()."\n";

    // Enumerate children
    foreach($tag->getAllChildren() as $ctag) {
        printf("Tag: %s\n", $ctag->getTagName());
    }

Queries

Queries make use of Symfony's ExpressionLanguage component to allow complex queries:

    use Sdl\Parser\SdlParser;
    use Sdl\Selector\SdlSelector;

    // Load the data
    $tag = SdlParser::parseFile(__DIR__."/sdl/products.sdl");
    // Create a new selector for the tag
    $tag_sel = new SdlSelector($tag);

    // Execute the query
    $expr = "/productcatalog/product[tag.attr('itemno')=='101-NAIL']";
    $item = $tag_sel->query($expr);

Development

You can run the unit tests using phpunit:

  $ phpunit --bootstrap tests/bootstrap.php tests/src/

Just remember to create the autoloaders etc first using composer:

  $ composer dump-autoload

When contributing code, follow the conventions used elsewhere and send a pull request with your masterpiece. If you're too lazy to fix something yourself, or more likely busy saving the world elsewhere, create an issue so someone else can take care of it.