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Feat/float as decimal #1

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merged 9 commits into from
Jul 6, 2024
Merged

Feat/float as decimal #1

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c870b2d
feat: rework float definition using decimal gda impl
amimart Jun 25, 2024
ed8e9d3
feat: allow to parse float
amimart Jun 25, 2024
3b12331
feat: prevent to use float as placeholders
amimart Jun 25, 2024
ad3d119
feat: make unification of float work
amimart Jul 2, 2024
fe1702f
feat: scan float solution as string
amimart Jul 2, 2024
c048876
feat: reimplement arithmetic functors
amimart Jul 2, 2024
f4bc73c
test: update all tests related to floats
amimart Jul 2, 2024
dd60a95
feat: secure integer arithmetic operations
amimart Jul 4, 2024
bf4ef2a
refactor: remove unused var
amimart Jul 4, 2024
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2 changes: 1 addition & 1 deletion engine/atom_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ func TestAtom_Compare(t *testing.T) {
o int
}{
{title: `a > X`, a: NewAtom("a"), t: x, o: 1},
{title: `a > 1.0`, a: NewAtom("a"), t: Float(1), o: 1},
{title: `a > 1.0`, a: NewAtom("a"), t: NewFloatFromInt64(1), o: 1},
{title: `a > 1`, a: NewAtom("a"), t: Integer(1), o: 1},
{title: `a > 'Z'`, a: NewAtom("a"), t: NewAtom("Z"), o: 1},
{title: `a = a`, a: NewAtom("a"), t: NewAtom("a"), o: 0},
Expand Down
50 changes: 25 additions & 25 deletions engine/builtin_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -399,7 +399,7 @@ func TestUnify(t *testing.T) {
y: NewAtom("def"),
}},
{title: `'='(1, 2).`, x: Integer(1), y: Integer(2), ok: false},
{title: `'='(1, 1.0).`, x: Integer(1), y: Float(1), ok: false},
{title: `'='(1, 1.0).`, x: Integer(1), y: NewFloatFromInt64(1), ok: false},
{title: `'='(g(X), f(f(X))).`, x: NewAtom("g").Apply(x), y: NewAtom("f").Apply(NewAtom("f").Apply(x)), ok: false},
{title: `'='(f(X, 1), f(a(X))).`, x: NewAtom("f").Apply(x, Integer(1)), y: NewAtom("f").Apply(NewAtom("a").Apply(x)), ok: false},
{title: `'='(f(X, Y, X), f(a(X), a(Y), Y, 2)).`, x: NewAtom("f").Apply(x, y, x), y: NewAtom("f").Apply(NewAtom("a").Apply(x), NewAtom("a").Apply(y), y, Integer(2)), ok: false},
Expand Down Expand Up @@ -453,7 +453,7 @@ func TestUnifyWithOccursCheck(t *testing.T) {
y: NewAtom("def"),
}},
{title: `unify_with_occurs_check(1, 2).`, x: Integer(1), y: Integer(2), ok: false},
{title: `unify_with_occurs_check(1, 1.0).`, x: Integer(1), y: Float(1), ok: false},
{title: `unify_with_occurs_check(1, 1.0).`, x: Integer(1), y: NewFloatFromInt64(1), ok: false},
{title: `unify_with_occurs_check(g(X), f(f(X))).`, x: NewAtom("g").Apply(x), y: NewAtom("f").Apply(NewAtom("f").Apply(x)), ok: false},
{title: `unify_with_occurs_check(f(X, 1), f(a(X))).`, x: NewAtom("f").Apply(x, Integer(1)), y: NewAtom("f").Apply(NewAtom("a").Apply(x)), ok: false},
{title: `unify_with_occurs_check(f(X, Y, X), f(a(X), a(Y), Y, 2)).`, x: NewAtom("f").Apply(x, y, x), y: NewAtom("f").Apply(NewAtom("a").Apply(x), NewAtom("a").Apply(y), y, Integer(2)), ok: false},
Expand Down Expand Up @@ -515,7 +515,7 @@ func TestTypeVar(t *testing.T) {

func TestTypeFloat(t *testing.T) {
t.Run("float", func(t *testing.T) {
ok, err := TypeFloat(nil, Float(1.0), Success, nil).Force(context.Background())
ok, err := TypeFloat(nil, newFloatFromFloat64Must(1.0), Success, nil).Force(context.Background())
assert.NoError(t, err)
assert.True(t, ok)
})
Expand Down Expand Up @@ -632,15 +632,15 @@ func TestFunctor(t *testing.T) {
x: Integer(1),
y: Integer(0),
}},
{title: `functor(X, 1.1, 0).`, term: x, name: Float(1.1), arity: Integer(0), ok: true, env: map[Variable]Term{
x: Float(1.1),
{title: `functor(X, 1.1, 0).`, term: x, name: newFloatFromFloat64Must(1.1), arity: Integer(0), ok: true, env: map[Variable]Term{
x: newFloatFromFloat64Must(1.1),
}},
{title: `functor([_|_], '.', 2).`, term: Cons(NewVariable(), NewVariable()), name: atomDot, arity: Integer(2), ok: true},
{title: `functor([], [], 0).`, term: atomEmptyList, name: atomEmptyList, arity: Integer(0), ok: true},
{title: `functor(X, Y, 3).`, term: x, name: y, arity: Integer(3), err: InstantiationError(nil)},
{title: `functor(X, foo, N).`, term: x, name: NewAtom("foo"), arity: n, err: InstantiationError(nil)},
{title: `functor(X, foo, a).`, term: x, name: NewAtom("foo"), arity: NewAtom("a"), err: typeError(validTypeInteger, NewAtom("a"), nil)},
{title: `functor(F, 1.5, 1).`, term: f, name: Float(1.5), arity: Integer(1), err: typeError(validTypeAtom, Float(1.5), nil)},
{title: `functor(F, 1.5, 1).`, term: f, name: newFloatFromFloat64Must(1.5), arity: Integer(1), err: typeError(validTypeAtom, newFloatFromFloat64Must(1.5), nil)},
{title: `functor(F, foo(a), 1).`, term: f, name: NewAtom("foo").Apply(NewAtom("a")), arity: Integer(1), err: typeError(validTypeAtomic, NewAtom("foo").Apply(NewAtom("a")), nil)},
// {title: `current_prolog_flag(max_arity, A), X is A + 1, functor(T, foo, X).`}
{title: `Minus_1 is 0 - 1, functor(F, foo, Minus_1).`, term: f, name: NewAtom("foo"), arity: Integer(-1), err: domainError(validDomainNotLessThanZero, Integer(-1), nil)},
Expand Down Expand Up @@ -782,7 +782,7 @@ func TestUniv(t *testing.T) {
{title: "9", term: x, list: PartialList(NewAtom("bar"), NewAtom("foo")), err: typeError(validTypeList, PartialList(NewAtom("bar"), NewAtom("foo")), nil)},
{title: "10", term: x, list: List(foo, NewAtom("bar")), err: InstantiationError(nil)},
{title: "11", term: x, list: List(Integer(3), Integer(1)), err: typeError(validTypeAtom, Integer(3), nil)},
{title: "12", term: x, list: List(Float(1.1), NewAtom("foo")), err: typeError(validTypeAtom, Float(1.1), nil)},
{title: "12", term: x, list: List(newFloatFromFloat64Must(1.1), NewAtom("foo")), err: typeError(validTypeAtom, newFloatFromFloat64Must(1.1), nil)},
{title: "13", term: x, list: List(NewAtom("a").Apply(NewAtom("b")), Integer(1)), err: typeError(validTypeAtom, NewAtom("a").Apply(NewAtom("b")), nil)},
{title: "14", term: x, list: Integer(4), err: typeError(validTypeList, Integer(4), nil)},
{title: "15", term: NewAtom("f").Apply(x), list: List(NewAtom("f"), NewAtom("u").Apply(x)), ok: true, env: map[Variable]Term{
Expand Down Expand Up @@ -2104,8 +2104,8 @@ func TestCompare(t *testing.T) {
order: atomLessThan,
}},
{title: `compare(<, <, <).`, order: atomLessThan, x: atomLessThan, y: atomLessThan, ok: false},
{title: `compare(1+2, 3, 3.0).`, order: atomPlus.Apply(Integer(1), Integer(2)), x: Integer(3), y: Float(3.0), ok: false, err: typeError(validTypeAtom, atomPlus.Apply(Integer(1), Integer(2)), nil)},
{title: `compare(>=, 3, 3.0).`, order: NewAtom(">="), x: Integer(3), y: Float(3.0), ok: false, err: domainError(validDomainOrder, NewAtom(">="), nil)},
{title: `compare(1+2, 3, 3.0).`, order: atomPlus.Apply(Integer(1), Integer(2)), x: Integer(3), y: newFloatFromFloat64Must(3.0), ok: false, err: typeError(validTypeAtom, atomPlus.Apply(Integer(1), Integer(2)), nil)},
{title: `compare(>=, 3, 3.0).`, order: NewAtom(">="), x: Integer(3), y: newFloatFromFloat64Must(3.0), ok: false, err: domainError(validDomainOrder, NewAtom(">="), nil)},

{title: `missing case for >`, order: atomGreaterThan, x: Integer(2), y: Integer(1), ok: true},
}
Expand Down Expand Up @@ -5523,7 +5523,7 @@ func TestAtomLength(t *testing.T) {
}},
{title: "atom_length('scarlet', 5).", atom: NewAtom("scarlet"), length: Integer(5), ok: false},
{title: "atom_length(Atom, 4).", atom: NewVariable(), length: Integer(4), err: InstantiationError(nil)},
{title: "atom_length(1.23, 4).", atom: Float(1.23), length: Integer(4), err: typeError(validTypeAtom, Float(1.23), nil)},
{title: "atom_length(1.23, 4).", atom: newFloatFromFloat64Must(1.23), length: Integer(4), err: typeError(validTypeAtom, newFloatFromFloat64Must(1.23), nil)},
{title: "atom_length(atom, '4').", atom: NewAtom("atom"), length: NewAtom("4"), err: typeError(validTypeInteger, NewAtom("4"), nil)},

// 8.16.1.3 Errors
Expand Down Expand Up @@ -5868,7 +5868,7 @@ func TestNumberChars(t *testing.T) {
t.Run("chars is a partial list", func(t *testing.T) {
chars := NewVariable()

ok, err := NumberChars(nil, Float(23.4), chars, func(env *Env) *Promise {
ok, err := NumberChars(nil, newFloatFromFloat64Must(23.4), chars, func(env *Env) *Promise {
assert.Equal(t, List(NewAtom("2"), NewAtom("3"), atomDot, NewAtom("4")), env.Resolve(chars))
return Bool(true)
}, nil).Force(context.Background())
Expand All @@ -5879,7 +5879,7 @@ func TestNumberChars(t *testing.T) {
t.Run("chars is a list with variables", func(t *testing.T) {
char := NewVariable()

ok, err := NumberChars(nil, Float(23.4), List(char, NewAtom("3"), atomDot, NewAtom("4")), func(env *Env) *Promise {
ok, err := NumberChars(nil, newFloatFromFloat64Must(23.4), List(char, NewAtom("3"), atomDot, NewAtom("4")), func(env *Env) *Promise {
assert.Equal(t, NewAtom("2"), env.Resolve(char))
return Bool(true)
}, nil).Force(context.Background())
Expand All @@ -5892,7 +5892,7 @@ func TestNumberChars(t *testing.T) {
num := NewVariable()

ok, err := NumberChars(nil, num, List(NewAtom("2"), NewAtom("3"), atomDot, NewAtom("4")), func(env *Env) *Promise {
assert.Equal(t, Float(23.4), env.Resolve(num))
assert.Equal(t, newFloatFromFloat64Must(23.4), env.Resolve(num))
return Bool(true)
}, nil).Force(context.Background())
assert.NoError(t, err)
Expand All @@ -5901,13 +5901,13 @@ func TestNumberChars(t *testing.T) {

t.Run("both provided", func(t *testing.T) {
t.Run("3.3", func(t *testing.T) {
ok, err := NumberChars(nil, Float(3.3), List(NewAtom("3"), atomDot, NewAtom("3")), Success, nil).Force(context.Background())
ok, err := NumberChars(nil, newFloatFromFloat64Must(3.3), List(NewAtom("3"), atomDot, NewAtom("3")), Success, nil).Force(context.Background())
assert.NoError(t, err)
assert.True(t, ok)
})

t.Run("3.3E+0", func(t *testing.T) {
ok, err := NumberChars(nil, Float(3.3), List(NewAtom("3"), atomDot, NewAtom("3"), NewAtom("E"), atomPlus, NewAtom("0")), Success, nil).Force(context.Background())
ok, err := NumberChars(nil, newFloatFromFloat64Must(3.3), List(NewAtom("3"), atomDot, NewAtom("3"), NewAtom("E"), atomPlus, NewAtom("0")), Success, nil).Force(context.Background())
assert.NoError(t, err)
assert.True(t, ok)
})
Expand Down Expand Up @@ -6017,10 +6017,10 @@ func TestNumberCodes(t *testing.T) {
l: List(Integer('3'), Integer('3')),
}},
{title: "number_codes(33, [0'3, 0'3]).", number: Integer(33), list: List(Integer('3'), Integer('3')), ok: true},
{title: "number_codes(33.0, L).", number: Float(33.0), list: l, ok: true, env: map[Variable]Term{
{title: "number_codes(33.0, L).", number: newFloatFromFloat64Must(33.0), list: l, ok: true, env: map[Variable]Term{
l: List(Integer('3'), Integer('3'), Integer('.'), Integer('0')),
}},
{title: "number_codes(33.0, [0'3, 0'., 0'3, 0'E, 0'+, 0'0, 0'1]).", number: Float(33.0), list: List(Integer('3'), Integer('.'), Integer('3'), Integer('E'), Integer('+'), Integer('0'), Integer('1')), ok: true},
{title: "number_codes(33.0, [0'3, 0'., 0'3, 0'E, 0'+, 0'0, 0'1]).", number: newFloatFromFloat64Must(33.0), list: List(Integer('3'), Integer('.'), Integer('3'), Integer('E'), Integer('+'), Integer('0'), Integer('1')), ok: true},
{title: "number_codes(A, [0'-, 0'2, 0'5]).", number: a, list: List(Integer('-'), Integer('2'), Integer('5')), ok: true, env: map[Variable]Term{
a: Integer(-25),
}},
Expand All @@ -6034,10 +6034,10 @@ func TestNumberCodes(t *testing.T) {
a: Integer('a'),
}},
{title: "number_codes(A, [0'4, 0'., 0'2]).", number: a, list: List(Integer('4'), Integer('.'), Integer('2')), ok: true, env: map[Variable]Term{
a: Float(4.2),
a: newFloatFromFloat64Must(4.2),
}},
{title: "number_codes(A, [0'4, 0'2, 0'., 0'0, 0'e, 0'-, 0'1]).", number: a, list: List(Integer('4'), Integer('2'), Integer('.'), Integer('0'), Integer('e'), Integer('-'), Integer('1')), ok: true, env: map[Variable]Term{
a: Float(4.2),
a: newFloatFromFloat64Must(4.2),
}},

// 8.16.8.3 Errors
Expand Down Expand Up @@ -7162,8 +7162,8 @@ func TestSucc(t *testing.T) {
})

t.Run("s is neither a variable nor an integer", func(t *testing.T) {
_, err := Succ(nil, NewVariable(), Float(1), Success, nil).Force(context.Background())
assert.Equal(t, typeError(validTypeInteger, Float(1), nil), err)
_, err := Succ(nil, NewVariable(), NewFloatFromInt64(1), Success, nil).Force(context.Background())
assert.Equal(t, typeError(validTypeInteger, NewFloatFromInt64(1), nil), err)
})
})

Expand All @@ -7185,8 +7185,8 @@ func TestSucc(t *testing.T) {
})

t.Run("s is neither a variable nor an integer", func(t *testing.T) {
_, err := Succ(nil, Integer(0), Float(1), Success, nil).Force(context.Background())
assert.Equal(t, typeError(validTypeInteger, Float(1), nil), err)
_, err := Succ(nil, Integer(0), NewFloatFromInt64(1), Success, nil).Force(context.Background())
assert.Equal(t, typeError(validTypeInteger, NewFloatFromInt64(1), nil), err)
})

t.Run("x is negative", func(t *testing.T) {
Expand All @@ -7206,8 +7206,8 @@ func TestSucc(t *testing.T) {
})

t.Run("x is neither a variable nor an integer", func(t *testing.T) {
_, err := Succ(nil, Float(0), NewVariable(), Success, nil).Force(context.Background())
assert.Equal(t, typeError(validTypeInteger, Float(0), nil), err)
_, err := Succ(nil, newFloatFromFloat64Must(0), NewVariable(), Success, nil).Force(context.Background())
assert.Equal(t, typeError(validTypeInteger, newFloatFromFloat64Must(0), nil), err)
})
}

Expand Down
2 changes: 1 addition & 1 deletion engine/compound_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ func TestCompareCompound(t *testing.T) {
o int
}{
{title: `f(a) > X`, x: NewAtom("f").Apply(NewAtom("a")), y: x, o: 1},
{title: `f(a) > 1.0`, x: NewAtom("f").Apply(NewAtom("a")), y: Float(1), o: 1},
{title: `f(a) > 1.0`, x: NewAtom("f").Apply(NewAtom("a")), y: NewFloatFromInt64(1), o: 1},
{title: `f(a) > 1`, x: NewAtom("f").Apply(NewAtom("a")), y: Integer(1), o: 1},
{title: `f(a) > a`, x: NewAtom("f").Apply(NewAtom("a")), y: NewAtom("a"), o: 1}, {title: `f(a) > f('Z')`, x: NewAtom("f").Apply(NewAtom("a")), y: NewAtom("f").Apply(NewAtom("Z")), o: 1},
{title: `f(a) > e(a)`, x: NewAtom("f").Apply(NewAtom("a")), y: NewAtom("e").Apply(NewAtom("a")), o: 1},
Expand Down
10 changes: 10 additions & 0 deletions engine/env.go
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Original file line number Diff line number Diff line change
Expand Up @@ -306,6 +306,16 @@ func (e *Env) unify(x, y Term, occursCheck bool) (*Env, bool) {
switch y := y.(type) {
case Variable:
return e.unify(y, x, occursCheck)
case Float:
if x, ok := x.(Float); ok {
return e, y.Eq(x)
}
return e, false
case Integer:
if x, ok := x.(Integer); ok {
return e, y == x
}
return e, false
default:
return e, x == y
}
Expand Down
114 changes: 101 additions & 13 deletions engine/float.go
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@@ -1,30 +1,89 @@
package engine

import (
"fmt"
"github.com/cockroachdb/apd"
"io"
"strconv"
"strings"
)

// Float is a prolog floating-point number.
type Float float64
// The underlying implementation is not based on floating-point, it's a [GDA](https://speleotrove.com/decimal/)
// compatible implementation to avoid approximation and determinism issues.
// It uses under the hood a decimal128 with 34 precision digits.
type Float struct {
dec *apd.Decimal
}

// The context that must be used for operations on Float.
var decimal128Ctx = apd.Context{
Precision: 34,
MaxExponent: 6144,
MinExponent: -6143,
Traps: apd.DefaultTraps,
}

func NewFloatFromString(s string) (Float, error) {
dec, c, err := decimal128Ctx.NewFromString(s)
if err != nil {
return Float{}, decimalConditionAsErr(c)
}

return Float{dec: dec}, nil
}

func NewFloatFromInt64(i int64) Float {
var dec apd.Decimal
dec.SetInt64(i)

return Float{dec: &dec}
}

func decimalConditionAsErr(flags apd.Condition) error {
e := flags & decimal128Ctx.Traps
if e == 0 {
return exceptionalValueUndefined
}

for m := apd.Condition(1); m > 0; m <<= 1 {
err := e & m
if err == 0 {
continue
}

switch err {
case apd.Overflow:
return exceptionalValueFloatOverflow
case apd.Underflow:
return exceptionalValueUnderflow
case apd.Subnormal:
return exceptionalValueUnderflow
case apd.DivisionByZero:
return exceptionalValueZeroDivisor
default:
return exceptionalValueUndefined
}
}

return exceptionalValueUndefined
}

func (f Float) number() {}

// WriteTerm outputs the Float to an io.Writer.
func (f Float) WriteTerm(w io.Writer, opts *WriteOptions, _ *Env) error {
ew := errWriter{w: w}
openClose := opts.left.name == atomMinus && opts.left.specifier.class() == operatorClassPrefix && f > 0
openClose := opts.left.name == atomMinus && opts.left.specifier.class() == operatorClassPrefix && !f.Negative()

if openClose || (f < 0 && opts.left != operator{}) {
if openClose || (f.Negative() && opts.left != operator{}) {
_, _ = ew.Write([]byte(" "))
}

if openClose {
_, _ = ew.Write([]byte("("))
}

s := strconv.FormatFloat(float64(f), 'g', -1, 64)
s := fmt.Sprintf("%g", f.dec)
if !strings.ContainsRune(s, '.') {
if strings.ContainsRune(s, 'e') {
s = strings.Replace(s, "e", ".0e", 1)
Expand All @@ -51,15 +110,44 @@ func (f Float) Compare(t Term, env *Env) int {
case Variable:
return 1
case Float:
switch {
case f > t:
return 1
case f < t:
return -1
default:
return 0
}
return f.dec.Cmp(t.dec)
default: // Integer, Atom, custom atomic terms, Compound.
return -1
}
}

func (f Float) String() string {
return fmt.Sprintf("%g", f.dec)
}

func (f Float) Negative() bool {
return f.dec.Sign() < 0
}

func (f Float) Positive() bool {
return f.dec.Sign() > 0
}

func (f Float) Zero() bool {
return f.dec.Sign() == 0
}

func (f Float) Eq(other Float) bool {
return f.dec.Cmp(other.dec) == 0
}

func (f Float) Gt(other Float) bool {
return f.dec.Cmp(other.dec) == 1
}

func (f Float) Gte(other Float) bool {
return f.dec.Cmp(other.dec) >= 0
}

func (f Float) Lt(other Float) bool {
return f.dec.Cmp(other.dec) == -1
}

func (f Float) Lte(other Float) bool {
return f.dec.Cmp(other.dec) <= 0
}
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