Category talk:Wren-rat: Difference between revisions
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→Source code: Now uses Wren S/H lexer.
(Added source code for new 'Wren-rat' module.) |
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===Source code===
import "./trait" for Comparable▼
▲<lang ecmascript>/* Module "rat.wren" */
▲import "/trait" for Comparable
/* Rat represents a rational number as an integral numerator and (non-zero) denominator
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*/
class Rat is Comparable {
static maxSafe { Rat.fromInt(9007199254740991) }▼
// Private helper function to check that 'o' is a suitable type and throw an error otherwise.
// Numbers and numeric strings are returned as rationals.
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if (o is Rat) return o
if (o is Num) return Rat.fromFloat(o)
if (o is String) return
o.contains("/") ? fromRationalString(o) : fromString(o)
Fiber.abort("Argument must either be a rational number, a number or a numeric string.")
}
// Private helper
static gcd_(n, d) {
while (d != 0) {
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// Constants.
static
static
static
static
static
static
static five { Rat.new( 5, 1) }
static six { Rat.new( 6, 1) }
static seven { Rat.new( 7, 1) }
static eight { Rat.new( 8, 1) }
static nine { Rat.new( 9, 1) }
static ten { Rat.new( 10, 1) }
static half { Rat.new( 1, 2) }
static third { Rat.new( 1, 3) }
static quarter { Rat.new( 1, 4) }
static fifth { Rat.new( 1, 5) }
static sixth { Rat.new( 1, 6) }
static seventh { Rat.new( 1, 7) }
static eighth { Rat.new( 1, 8) }
static ninth { Rat.new( 1, 9) }
static tenth { Rat.new( 1, 10) }
// Constructs a new Rat object by passing it a numerator and a denominator.
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_d = d
}
// Convenience method which constructs a new Rat object by passing it just a numerator.
// Constructs a rational number from an integer.
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static fromString(s) {
var n
s = s.trim()
if (!(n = Num.fromString(s))) Fiber.abort("Argument must be a numeric string.")
if (n.isInteger) return Rat.new(n, 1)
return fromDecimalString_(s
}
// Constructs a rational number from a string of the form "n/d".
// Improper fractions are allowed.
static fromRationalString(s) {
s = s.trim()
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return Rat.new(n, d)
}
// Constructs a rational number from a string of the form "i_n/d" where 'i' is an integer.
// Improper and negative fractional parts are allowed.
static fromMixedString(s) {
var ind = s.split("_")
if (ind.count != 2) Fiber.abort("Argument is not a suitable string.")
var nd = fromRationalString(ind[1])
var i = Rat.fromString(ind[0])
var neg = i.isNegative || (i.isZero && ind[0][0] == "-")
return neg ? i - nd : i + nd
}
// Returns the greater of two rational numbers.
static max(r1, r2) { (r1 < r2) ? r2 : r1 }
// Returns the smaller of two rational numbers.
static min(r1, r2) { (r1 < r2) ? r1 : r2 }
// Private helper method to compare two integers.
static compareInts_(i, j) { (i - j).sign }
// Determines whether a Rat object is always shown as such or, if integral, as an integer.
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// Basic properties.
num { _n } // numerator
den { _d } // denominator
ratio { [_n, _d] } // a two element list of the above
isNegative { _n < 0 } // checks if negative
isUnit { _n.abs == 1 } // checks if plus or minus one
isZero { _n == 0 } // checks if zero
// Rounding methods (similar to those in Num class).
ceil { Rat.fromInt(
floor { Rat.fromInt(
truncate { Rat.fromInt(
round { Rat.fromInt(
fraction { this - truncate } // fractional part (same sign as this.num)
// Reciprocal
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-(o) { (o = Rat.check_(o)) && (this + (-o)) }
*(o) { (o = Rat.check_(o)) && Rat.new(_n * o.num, _d * o.den) }
/(o) { (o = Rat.check_(o)) && Rat.new(
%(o) { (o = Rat.check_(o)) && (this
// Computes integral powers.
pow(i) {
if (!((i is Num) && i.isInteger)) Fiber.abort("Argument must be an
if (i == 0) return
var np = _n.pow(i.abs).round
var dp = _d.pow(i.abs).round
return (i > 0) ? Rat.new(np, dp) : Rat.new(dp, np)
}
// Returns the square of the current instance.
square { Rat.new(_n * _n , _d *_d) }
// Other methods.
inc { this + Rat.one } // increment
dec { this - Rat.one } // decrement
abs { (_n >= 0) ?
sign { _n.sign } // sign
// The inherited 'clone' method just returns 'this' as Rat objects are immutable.
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// Compares this Rat with another one to enable comparison operators via Comparable trait.
compare(other) {
if ((other is Num) && other.isInfinity) return -other.sign
other = Rat.check_(other)
if (_d == other.den) return Rat.compareInts_(_n, other.num)
return Rat.compareInts_(_n * other.den, other.num * _d)
}
// As above but compares the absolute values of the Rats.
compareAbs(other) { this.abs.compare(other.abs) }
// Converts the current instance to a Num.
toFloat { _n/_d }
// Converts the current instance to an integer with any fractional part truncated.
toInt { this.toFloat.truncate }
// Returns a string represenation of this instance in the form "i_n/d" where 'i' is an integer.
toMixedString {
var q = _n / _d
var sign = q < 0 ? "-" : ""
q = q.abs.truncate
var r = _n.abs % _d
return sign + q.toString + "_" + r.toString + "/" + _d.toString
}
// Returns the string representation of this Rat object depending on 'showAsInt'.
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static max(a) { a.reduce { |acc, x| (x > acc) ? x : acc } }
static min(a) { a.reduce { |acc, x| (x < acc) ? x : acc } }
}</syntaxhighlight>
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