"Label" attributes

Allow creating attributes using register_label_attr, and retrieving the array of Names of declarations which have been tagged with such an attribute.

These differ slightly from the built-in "tag attributes" which can be initialized with the syntax:

initialize someName : TagAttribute ← registerTagAttribute `tagName "description"

in that a "tag attribute" can only be put on a declaration at the moment it is declared, and can not be modified by scoping commands.

The "label attributes" constructed here support adding (or locally removing) the attribute either at the moment of declaration, or later.

@[reducible, inline]

abbrev Lean.LabelExtension : Type

An environment extension that just tracks an array of names.

@[reducible, inline]

abbrev Lean.LabelExtensionMap : Type

The collection of all current LabelExtensions, indexed by name.

opaque Lean.labelExtensionMapRef : IO.Ref LabelExtensionMap

Store the current LabelExtensions.

def Lean.mkLabelExt (name : Name := by exact decl_name%) : IO LabelExtension

Helper function for registerLabelAttr.

def Lean.mkLabelAttr (attrName : Name) (attrDescr : String) (ext : LabelExtension) (ref : Name := by exact decl_name%) : IO Unit

Helper function for registerLabelAttr.

def Lean.registerLabelAttr (attrName : Name) (attrDescr : String) (ref : Name := by exact decl_name%) : IO LabelExtension

Construct a new "label attribute", which does nothing except keep track of the names of the declarations with that attribute.

Users will generally use the register_label_attr macro defined below.

def Lean.Parser.Command.registerLabelAttr : ParserDescr

Initialize a new "label" attribute. Declarations tagged with the attribute can be retrieved using Lean.labelled.

def Lean.labelled (attrName : Name) : CoreM (Array Name)

When attrName is an attribute created using register_labelled_attr, return the names of all declarations labelled using that attribute.