factor/library/platform/native/parse-numbers.factor

! :folding=indent:collapseFolds=1:

! $Id$
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! Copyright (C) 2004 Slava Pestov.
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IN: parser
USE: arithmetic
USE: combinators
USE: errors
USE: kernel
USE: lists
USE: logic
USE: namespaces
USE: stack
USE: strings
USE: words
USE: vocabularies
USE: unparser

! Number parsing

: not-a-number "Not a number" throw ;

: digit> ( ch -- n )
    [
        [ digit? ] [ CHAR: 0 - ]
        [ letter? ] [ CHAR: a - 10 + ]
        [ LETTER? ] [ CHAR: A - 10 + ]
        [ drop t ] [ not-a-number ]
    ] cond ;

: >digit ( n -- ch )
    dup 10 < [ CHAR: 0 + ] [ 10 - CHAR: a + ] ifte ;

: digit ( num digit -- num )
    "base" get swap 2dup > [
        >r * r> +
    ] [
        not-a-number
    ] ifte ;

: (str>integer) ( str -- num )
    0 swap [ digit> digit ] str-each ;

: str>integer ( str -- num )
    #! Parse a string representation of an integer.
    dup str-length 0 = [
        drop not-a-number
    ] [
        dup "-" str-head? dup [
            nip str>integer neg
        ] [
            drop (str>integer)
        ] ifte
    ] ifte ;

: str>ratio ( str -- num )
    dup CHAR: / index-of str//
    swap str>integer swap str>integer / ;

: str>number ( str -- num )
    [
        [ "/" swap str-contains? ] [ str>ratio   ]
        [ "." swap str-contains? ] [ str>float   ]
        [ drop t                 ] [ str>integer ]
    ] cond ;

: parse-number ( str -- num/f )
    [ str>number ] [ [ drop f ] when ] catch ;