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Fix #3816 loss precision of calculation
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| Based on https://github.com/mnogu/go-calculator |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| package calculator | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "github.com/shopspring/decimal" | ||
| "math" | ||
| ) | ||
|
|
||
| var functions = map[string]interface{}{ | ||
| "abs": math.Abs, | ||
| "acos": math.Acos, | ||
| "acosh": math.Acosh, | ||
| "asin": math.Asin, | ||
| "asinh": math.Asinh, | ||
| "atan": math.Atan, | ||
| "atan2": math.Atan2, | ||
| "atanh": math.Atanh, | ||
| "cbrt": math.Cbrt, | ||
| "ceil": math.Ceil, | ||
| "copysign": math.Copysign, | ||
| "cos": math.Cos, | ||
| "cosh": math.Cosh, | ||
| "dim": math.Dim, | ||
| "erf": math.Erf, | ||
| "erfc": math.Erfc, | ||
| "erfcinv": math.Erfcinv, // Go 1.10+ | ||
| "erfinv": math.Erfinv, // Go 1.10+ | ||
| "exp": math.Exp, | ||
| "exp2": math.Exp2, | ||
| "expm1": math.Expm1, | ||
| "fma": math.FMA, // Go 1.14+ | ||
| "floor": math.Floor, | ||
| "gamma": math.Gamma, | ||
| "hypot": math.Hypot, | ||
| "j0": math.J0, | ||
| "j1": math.J1, | ||
| "log": math.Log, | ||
| "log10": math.Log10, | ||
| "log1p": math.Log1p, | ||
| "log2": math.Log2, | ||
| "logb": math.Logb, | ||
| "max": math.Max, | ||
| "min": math.Min, | ||
| "mod": math.Mod, | ||
| "nan": math.NaN, | ||
| "nextafter": math.Nextafter, | ||
| "pow": math.Pow, | ||
| "remainder": math.Remainder, | ||
| "round": math.Round, // Go 1.10+ | ||
| "roundtoeven": math.RoundToEven, // Go 1.10+ | ||
| "sin": math.Sin, | ||
| "sinh": math.Sinh, | ||
| "sqrt": math.Sqrt, | ||
| "tan": math.Tan, | ||
| "tanh": math.Tanh, | ||
| "trunc": math.Trunc, | ||
| "y0": math.Y0, | ||
| "y1": math.Y1, | ||
| } | ||
|
|
||
| func call(funcName string, args []decimal.Decimal) (decimal.Decimal, error) { | ||
| f, ok := functions[funcName] | ||
| if !ok { | ||
| return decimal.Zero, fmt.Errorf("unknown function %s", funcName) | ||
| } | ||
| switch f := f.(type) { | ||
| case func() float64: | ||
| return decimal.NewFromFloat(f()), nil | ||
| case func(float64) float64: | ||
| return decimal.NewFromFloat(f(args[0].InexactFloat64())), nil | ||
| case func(float64, float64) float64: | ||
| return decimal.NewFromFloat(f(args[0].InexactFloat64(), args[1].InexactFloat64())), nil | ||
| case func(float64, float64, float64) float64: | ||
| return decimal.NewFromFloat(f(args[0].InexactFloat64(), args[1].InexactFloat64(), args[2].InexactFloat64())), nil | ||
| default: | ||
| return decimal.Zero, fmt.Errorf("invalid function %s", funcName) | ||
| } | ||
| } | ||
|
|
||
| func calculate(n *node) (decimal.Decimal, error) { | ||
| switch n.kind { | ||
| case addNode: | ||
| left, err := calculate(n.left) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| right, err := calculate(n.right) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| return left.Add(right), nil | ||
| case subNode: | ||
| left, err := calculate(n.left) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| right, err := calculate(n.right) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| return left.Sub(right), nil | ||
| case mulNode: | ||
| left, err := calculate(n.left) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| right, err := calculate(n.right) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| return left.Mul(right), nil | ||
| case divNode: | ||
| left, err := calculate(n.left) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| right, err := calculate(n.right) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| return left.Div(right), nil | ||
| case numNode: | ||
| return n.val, nil | ||
| case funcNode: | ||
| var args []decimal.Decimal | ||
| for _, arg := range n.args { | ||
| val, err := calculate(arg) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| args = append(args, val) | ||
| } | ||
| return call(n.funcName, args) | ||
| } | ||
| return decimal.Zero, fmt.Errorf("unknown node type: %s", n.kind) | ||
| } | ||
|
|
||
| func Calculate(expr string) (decimal.Decimal, error) { | ||
| tokens, err := tokenize(expr) | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| p := newParser(tokens) | ||
| n, err := p.parse() | ||
| if err != nil { | ||
| return decimal.Zero, err | ||
| } | ||
| return calculate(n) | ||
| } |
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