Upgrading from 0.18 to 0.19

The Environment and extension framework underwent some major changes in this release. Please read this if you maintain any community extensions or have written custom functionality on top of this library.

PHP support

This library no longer supports PHP 5.6 or 7.0. Feel free to remove support for those from your extensions as well.

HTML attribute escaping

Previously, any attributes passed into an HtmlElement would need to be pre-escaped. This is now done for you so be sure to remove any references to Xml::escape() when applied to attributes.

This does not affect inner contents which may still need pre-escaping of untrusted user input.

Removed classes and interface methods

The getName() method has been removed from several classes:

This method was originally intended for supporting XML rendering, which was never implemented, and will likely define names a bit differently if/when we do add support.

After doing this, the two abstract classes mentioned above had notthing left in them, so those were removed. Any parsers previously extending them should directly implement the corresponding interface instead.

InlineContainer was also removed.

Xml::escape() no longer accepts the deprecated $preserveEntities parameter.

Removed deprecated RegexHelper methods

Several previously-deprecated methods inside of RegexHelper were finally removed. That functionality was made available with static methods and constants, so use those instead.

Parameter and return types

Pretty much every method now uses parameter and return types, including several interfaces. Update your implementations accordingly.

Environment interfaces

We have extracted two interfaces from the Environment class:

As a result, EnvironmentAwareInterface now requires an EnvironmentInterface instead of an Environment, so update your parsers/processors/renderers accordingly.

Block Elements

A few methods from AbstractBlock have been extracted into a new AbstractStringContainerBlock class and corresponding StringContainerInterface interface:

These are used to represent a block which can contain strings of text inside (even if those strings do not contain “inline” elements but just plain text).

To determine how to best upgrade your existing block element classes, look at the value returned by the acceptsLines() method:

Additionally, StringContainerInterface now extends this new StringContainerInterface interface. Just make sure you’ve implemented the change mentioned above and you should be fine.


Extensions work much differently now. In the past, you’d have functions returning an array of things that the Environment would register for you.

The ExtensionInterface was changed to have a single register(ConfigurableEnvironmentInterface $environment) method. You must now manually add() all your parsers, processors, and renderers yourself directly within the environment you are provided. See the changes made to CommonMarkCoreExtension for a good example.

The Environment will still automatically inject the Environment or Configuration for any parsers, processors, and renderers implementing the EnvironmentAwareInterface or ConfigurationAwareInterface - that behavior hasn’t changed.

Adding renderers with short names

Environment::add___Renderer() now requires the fully-qualified class name with namespace as its first argument. Providing just the class name without the namespace will no longer work.

Prioritization of parsers, processors, and renderers

The execution order of these things no longer depends on the order you add them - you can now specific custom priorities when add()ing them to the Environment! The priority can be any integer you want. The default value is 0. All CommonMark Core things will have a priority between -255 and 255. The higher the number, the earlier it will be executed.

Multiple block/inline renderers per class

Thanks to the new prioritization system, we now support multiple renderers for the same block/inline class! The first renderer to return a non-null result will be considered the “winner” and no subsequent renderers will execute for that block/inline. No change should be required for most extensions unless you were using some weird workaround to support multiple renderers yourself.

RegexHelper::isEscapable() no longer accepts null values

In cases where you may have previously passed a null value in, skip the call to this method. The previous behavior was to return false for null values, but null is never escapable so it’s silly to make this call when we know what the result will be.