// Match attempts to match the internal constant representations of x and y.
// If the attempt is successful, the result is the values of x and y,
// if necessary converted to have the same internal representation; otherwise
// the results are invalid.
func (x Const) Match(y Const) (u, v Const) {
switch a := x.val.(type) {
case bool:
if _, ok := y.val.(bool); ok {
u, v = x, y
}
case *big.Int:
switch y.val.(type) {
case *big.Int:
u, v = x, y
case *big.Rat:
var z big.Rat
z.SetInt(a)
u, v = Const{&z}, y
case cmplx:
var z big.Rat
z.SetInt(a)
u, v = Const{cmplx{&z, big.NewRat(0, 1)}}, y
}
case *big.Rat:
switch y.val.(type) {
case *big.Int:
v, u = y.Match(x)
case *big.Rat:
u, v = x, y
case cmplx:
u, v = Const{cmplx{a, big.NewRat(0, 0)}}, y
}
case cmplx:
switch y.val.(type) {
case *big.Int, *big.Rat:
v, u = y.Match(x)
case cmplx:
u, v = x, y
}
case string:
if _, ok := y.val.(string); ok {
u, v = x, y
}
default:
panic("unreachable")
}
return
}
func split(turn, maxTurns int, blueDiscsDrawn int, current, result *big.Rat) {
if blueDiscsDrawn > (maxTurns / 2) {
result.Add(result, current)
//fmt.Println(blueDiscsDrawn, current)
return
} else if turn > maxTurns {
return
}
redCurrent := big.NewRat(1, 1)
blueCurrent := big.NewRat(1, 1)
redCurrent.Mul(current, big.NewRat(int64(turn), int64(turn+1)))
blueCurrent.Mul(current, big.NewRat(1, int64(turn+1)))
split(turn+1, maxTurns, blueDiscsDrawn, redCurrent, result)
split(turn+1, maxTurns, blueDiscsDrawn+1, blueCurrent, result)
}
// MakeConst makes an ideal constant from a literal
// token and the corresponding literal string.
func MakeConst(tok token.Token, lit string) Const {
switch tok {
case token.INT:
var x big.Int
_, ok := x.SetString(lit, 0)
assert(ok)
return Const{&x}
case token.FLOAT:
var y big.Rat
_, ok := y.SetString(lit)
assert(ok)
return Const{&y}
case token.IMAG:
assert(lit[len(lit)-1] == 'i')
var im big.Rat
_, ok := im.SetString(lit[0 : len(lit)-1])
assert(ok)
return Const{cmplx{big.NewRat(0, 1), &im}}
case token.CHAR:
assert(lit[0] == '\'' && lit[len(lit)-1] == '\'')
code, _, _, err := strconv.UnquoteChar(lit[1:len(lit)-1], '\'')
assert(err == nil)
return Const{big.NewInt(int64(code))}
case token.STRING:
s, err := strconv.Unquote(lit)
assert(err == nil)
return Const{s}
}
panic("unreachable")
}
func assertProb(t *T, b *Bayesian, expected *big.Rat, word string) {
actual := b.ProbAWhenB(word)
if expected.Cmp(actual) != 0 {
t.Errorf("'%s' should be correlated %v:%v with Grinnell tweets, but was %v:%v\n",
word,
expected.Num(), expected.Denom(),
actual.Num(), actual.Denom())
}
}
// a.convertTo(t) converts the value of the analyzed expression a,
// which must be a constant, ideal number, to a new analyzed
// expression with a constant value of type t.
//
// TODO(austin) Rename to resolveIdeal or something?
func (a *expr) convertTo(t Type) *expr {
if !a.t.isIdeal() {
log.Panicf("attempted to convert from %v, expected ideal", a.t)
}
var rat *big.Rat
// XXX(Spec) The spec says "It is erroneous".
//
// It is an error to assign a value with a non-zero fractional
// part to an integer, or if the assignment would overflow or
// underflow, or in general if the value cannot be represented
// by the type of the variable.
switch a.t {
case IdealFloatType:
rat = a.asIdealFloat()()
if t.isInteger() && !rat.IsInt() {
a.diag("constant %v truncated to integer", rat.FloatString(6))
return nil
}
case IdealIntType:
i := a.asIdealInt()()
rat = new(big.Rat).SetInt(i)
default:
log.Panicf("unexpected ideal type %v", a.t)
}
// Check bounds
if t, ok := t.lit().(BoundedType); ok {
if rat.Cmp(t.minVal()) < 0 {
a.diag("constant %v underflows %v", rat.FloatString(6), t)
return nil
}
if rat.Cmp(t.maxVal()) > 0 {
a.diag("constant %v overflows %v", rat.FloatString(6), t)
return nil
}
}
// Convert rat to type t.
res := a.newExpr(t, a.desc)
switch t := t.lit().(type) {
case *uintType:
n, d := rat.Num(), rat.Denom()
f := new(big.Int).Quo(n, d)
f = f.Abs(f)
v := uint64(f.Int64())
res.eval = func(*Thread) uint64 { return v }
case *intType:
n, d := rat.Num(), rat.Denom()
f := new(big.Int).Quo(n, d)
v := f.Int64()
res.eval = func(*Thread) int64 { return v }
case *idealIntType:
n, d := rat.Num(), rat.Denom()
f := new(big.Int).Quo(n, d)
res.eval = func() *big.Int { return f }
case *floatType:
n, d := rat.Num(), rat.Denom()
v := float64(n.Int64()) / float64(d.Int64())
res.eval = func(*Thread) float64 { return v }
case *idealFloatType:
res.eval = func() *big.Rat { return rat }
default:
log.Panicf("cannot convert to type %T", t)
}
return res
}
func simpRat(x *big.Rat) Obj {
if x.Denom().Cmp(one_Int) == 0 {
return simpBig(x.Num())
}
return wrap(x)
}
func binaryCmplxOp(x cmplx, op token.Token, y cmplx) interface{} {
a, b := x.re, x.im
c, d := y.re, y.im
switch op {
case token.ADD:
// (a+c) + i(b+d)
var re, im big.Rat
re.Add(a, c)
im.Add(b, d)
return cmplx{&re, &im}
case token.SUB:
// (a-c) + i(b-d)
var re, im big.Rat
re.Sub(a, c)
im.Sub(b, d)
return cmplx{&re, &im}
case token.MUL:
// (ac-bd) + i(bc+ad)
var ac, bd, bc, ad big.Rat
ac.Mul(a, c)
bd.Mul(b, d)
bc.Mul(b, c)
ad.Mul(a, d)
var re, im big.Rat
re.Sub(&ac, &bd)
im.Add(&bc, &ad)
return cmplx{&re, &im}
case token.QUO:
// (ac+bd)/s + i(bc-ad)/s, with s = cc + dd
var ac, bd, bc, ad, s big.Rat
ac.Mul(a, c)
bd.Mul(b, d)
bc.Mul(b, c)
ad.Mul(a, d)
s.Add(c.Mul(c, c), d.Mul(d, d))
var re, im big.Rat
re.Add(&ac, &bd)
re.Quo(&re, &s)
im.Sub(&bc, &ad)
im.Quo(&im, &s)
return cmplx{&re, &im}
case token.EQL:
return a.Cmp(c) == 0 && b.Cmp(d) == 0
case token.NEQ:
return a.Cmp(c) != 0 || b.Cmp(d) != 0
}
panic("unreachable")
}
func binaryFloatOp(x *big.Rat, op token.Token, y *big.Rat) interface{} {
var z big.Rat
switch op {
case token.ADD:
return z.Add(x, y)
case token.SUB:
return z.Sub(x, y)
case token.MUL:
return z.Mul(x, y)
case token.QUO:
return z.Quo(x, y)
case token.EQL:
return x.Cmp(y) == 0
case token.NEQ:
return x.Cmp(y) != 0
case token.LSS:
return x.Cmp(y) < 0
case token.LEQ:
return x.Cmp(y) <= 0
case token.GTR:
return x.Cmp(y) > 0
case token.GEQ:
return x.Cmp(y) >= 0
}
panic("unreachable")
}