An IBlockStateMatcher object can be used to match an IBlockState object against a set of requirements or a set of matching blockstates.

It might be required for you to import the package if you encounter any issues (like casting an Array or using the static .create() method), so better be safe than sorry and add the import.
import crafttweaker.block.IBlockStateMatcher;

Every IBlockState is also an IBlockStateMatcher which matches only to itself.

You can use IBlockState's matchBlock() method to create an IBlockStateMatcher that matches any possible blockstate for that block.

There are several methods that return an IBlockStateMatcher

• Using IBlockStateMatcher.create().
• Using the withMatchedValuesForProperty() method on another IBlockStateMatcher.
• OR two IBlockStateMatchers together to get a compound matcher.
• Creating an IBlockState, as all IBlockState objects are IBlockStateMatchers.

When using OR (|) to combine IBlockStateMatchers, the resulting IBlockStateMatcher is no longer tied to one specific underlying block, as it would be with an IBlockState or an IBlockStateMatcher created using the IBlockStateMatcher.create() method. Instead, the matcher matches any blockstate which would have been matched by any of the combined matchers.

Because this blockstate is not tied to a specific block, it is not possible to use the withMatchedValuesForProperty() method to retrieve another IBlockStateMatcher.

static IBlockStateMatcher create(IBlockState... blockStates); Parameters:

• IBlockState... blockStates → Zero or more blockstates to match with this matcher.

Returns an IBlockStateMatcher to match the specified blockstate(s).

• If zero blockStates are supplied, this matcher will never match any blockstates.
• If only one blockstate is supplied in blockStates, the resulting IBlockStateMatcher will match any blockstate of the provided IBlockState's underlying block with any property values accepted as matching. The withMatchedValuesForProperty method can be used to add more specific requirements for the properties.
• If multiple blockStates are supplied, the resulting IBlockStateMatcher is the same as using the OR (|) operator with each of the IBlockStates provided.

boolean matches(IBlockState blockState);
Parameters:

• IBlockState blockState → The blockstate object to match against

Returns a boolean that represents whether the blockstate matched this matcher's requirements.
You can also use A has B that represents A.matches(B).

(These methods are only allowed on non-compound IBlockStateMatcher instances)

 Copy
IBlockStateMatcher withMatchedValuesForProperty(String name, String... values);
List<String> getMatchedValuesForProperty(String name);
Map<String, List<String>> getMatchedProperties();

Parameters:

• String name → The name of the property
• String... values → One or more values that the property of a matching IBlockState may have.

Returns a new IBlockStateMatcher with the same property requirements as this IBlockStateMatcher with the exception of the specified property name, which will now allow any of the specified values as a matching input.

Collection<IBlockState> getMatchingBlockStates(); Returns a collection of every IBlockState with any combination of properties that match this IBlockStateMatcher. This list may contain blockstates that are not possible to get through normal gameplay means. (Ex: IBlockStateMatcher.create(<blockstate:minecraft:log>) will return an IBlockStateMatcher that matches to logs with property axis=none, having bark textures on all 6 sides.)

boolean isCompound()

Does what you'd expect.

ZenGetter commandString

Returns a Bracket Handler expression string, if needed paired with withMatchedValueForProperty() calls.
Keep in mind though, that the returned method calls do not have "" around the parameters.
So if you wanted to copy that result, you'd need to manually add them to the arguments!