interval>literal ( class interval -- literal literal? )

Vocabulary

compiler.tree.propagation.info

Inputs

class	a class
interval	an interval

Outputs

literal	a literal value
literal?	a boolean

Word description

If interval has zero length and the class is sufficiently precise, we can turn it into a literal.

Definition

USING: accessors classes.algebra combinators kernel math
math.intervals sequences ;

IN: compiler.tree.propagation.info

: interval>literal ( class interval -- literal literal? )
    dup special-interval?
    [ 2drop f f ] [
        dup from>> first {
            { [ over interval-length 0 > ] [ 3drop f f ] }
            { [ pick bignum class<= ] [ 2nip >bignum t ] }
            { [ pick integer class<= ] [ 2nip >fixnum t ] }
            {
                [ pick float class<= ]
                [ 2nip [ f f ] [ >float t ] if-zero ]
            }
            [ 3drop f f ]
        } cond
    ] if ;