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tree-equal

tree-equal Function

Syntax:

tree-equal tree-1 tree-2 &key test test-not → generalized-boolean

Arguments and Values:

tree-1—a tree.

tree-2—a tree.

test—a designator for a function of two arguments that returns a generalized boolean. test-not—a designator for a function of two arguments that returns a generalized boolean. generalized-boolean—a generalized boolean.

Description:

tree-equal tests whether two trees are of the same shape and have the same leaves. tree-equal returns true if tree-1 and tree-2 are both atoms and satisfy the test, or if they are both conses and the car of tree-1 is tree-equal to the car of tree-2 and the cdr of tree-1 is tree-equal to the cdr of tree-2. Otherwise, tree-equal returns false.

tree-equal recursively compares conses but not any other objects that have components.

The first argument to the :test or :test-not function is tree-1 or a car or cdr of tree-1; the second argument is tree-2 or a car or cdr of tree-2.

Examples:

(setq tree1 ’(1 (1 2)) 
      tree2 ’(1 (1 2))) → (1 (1 2)) 
(tree-equal tree1 tree2) → true 
(eql tree1 tree2) → false 
(setq tree1 ’(’a (’b ’c)) 
      tree2 ’(’a (’b ’c))) → (’a (’b ’c)) 
→ ((QUOTE A) ((QUOTE B) (QUOTE C))) 
(tree-equal tree1 tree2 :test ’eq) → true

Exceptional Situations:

The consequences are undefined if both tree-1 and tree-2 are circular.

See Also:

equal, Section 3.6 (Traversal Rules and Side Effects)

Notes:

The :test-not parameter is deprecated.

Expanded Reference: tree-equal​

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