Can this tree carry attributes (i.e. symbols, types or positions)? Typically the answer is yes, except for the EmptyTree null object and two special singletons: noSelfType and pendingSuperCall.

The direct child trees of this tree. EmptyTrees are always omitted. Lists are flattened.

Apply pf to each subtree on which the function is defined and collect the results.

Make a copy of this tree, keeping all attributes, except that all positions are focused (so nothing in this tree will be found when searching by position).

Tests whether two trees are structurally equal. Note that == on trees is reference equality.

Is there exists a part of this tree which satisfies predicate p?

Find all subtrees matching predicate p. Same as withFilter

Returns optionally first tree (in a preorder traversal) which satisfies predicate p, or None if none exists.

Do all parts of this tree satisfy predicate p?

Apply f to each subtree

Does this tree represent a definition? (of a method, of a class, etc)

Is this tree one of the empty trees?

Empty trees are: the EmptyTree null object and TypeTree instances that don't carry a type.

The canonical way to test if a Tree represents a term.

The canonical way to test if a Tree represents a type.

The left-hand side of the assignment.

Is this tree not an empty tree?

Provides an alternate if tree is empty

Position of the tree.

The right-hand side of the assignment.

Symbol of the tree.

For most trees symbol is null. In SymTrees, it is overridden and implemented with a var, initialized to NoSymbol.

Trees which are not SymTrees but which carry symbols do so by overriding def symbol to forward it elsewhere. Examples:

Super(qual, _) has qual's symbol, Apply(fun, args) has fun's symbol, TypeApply(fun, args) has fun's symbol, AppliedTypeTree(tpt, args) has tpt's symbol, TypeTree(tpe) has tpe's typeSymbol, if tpe != null.

Type of the tree.

Upon creation most trees have their tpe set to null. Types are typically assigned to trees during typechecking. Some node factory methods set tpe immediately after creation.

When the typechecker encounters a tree with a non-null tpe, it will assume it to be correct and not check it again. This means one has to be careful not to erase the tpe field of subtrees.

Find all subtrees matching predicate p. Same as filter

Obtains string representation of a tree