TrigonometricMode

Math-Engine

使用 Go 实现的数学表达式解析计算引擎库，它小巧，无任何依赖，具有扩展性(比如可以注册自己的函数到引擎中)，比较完整的完成了数学表达式解析执行，包括词法分析、语法分析、构建AST、运行。

go get -u github.com/dengsgo/math-engine

能够处理的表达式样例：

1+127-21+(3-4)*6/2.5(88+(1+8)*6)/2+99123_345_456 * 1.5 - 2 ^ 4-4 * 6 + 2e2 - 1.6e-3sin(pi/2)+cos(45-45*1)+tan(pi/4)99+abs(-1)-ceil(88.8)+floor(88.8)max(min(2^3, 3^2), 10*1.5-7)double(6) + 3double

Demo

Method Support

+-*/%^e()_pisin(x)cos(x)tan(x)cot(x)sec(x)csc(x)abs(x)ceil(x)floor(x)round(x)sqrt(x)cbrt(x)max(x, ...)min(x, ...)noerr(x)double(x)

Usage

你可以直接引用该库嵌入到自己的程序中：

go get -u github.com/dengsgo/math-engine

在代码中引入：

import "github.com/dengsgo/math-engine/engine"

e.g. 1 常规用法： 直接调用解析执行函数 :

import "github.com/dengsgo/math-engine/engine"

func main() {
  s := "1 + 2 * 6 / 4 + (456 - 8 * 9.2) - (2 + 4 ^ 5)"
  // call top level function
  r, err := engine.ParseAndExec(s)
  if err != nil {
    fmt.Println(err)
  }
  fmt.Printf("%s = %v", s, r)
}

e.g. 2 高级用法： 依次调用函数，手动执行 :

import "github.com/dengsgo/math-engine/engine"

func main() {
	s := "1 + 2 * 6 / 4 + (456 - 8 * 9.2) - (2 + 4 ^ 5)"
	exec(s)
}

// call engine
// one by one
func exec(exp string) {
	// input text -> []token
	toks, err := engine.Parse(exp)
	if err != nil {
		fmt.Println("ERROR: " + err.Error())
		return
	}
	// []token -> AST Tree
	ast := engine.NewAST(toks, exp)
	if ast.Err != nil {
		fmt.Println("ERROR: " + ast.Err.Error())
		return
	}
	// AST builder
	ar := ast.ParseExpression()
	if ast.Err != nil {
		fmt.Println("ERROR: " + ast.Err.Error())
		return
	}
	fmt.Printf("ExprAST: %+v\n", ar)
	// AST traversal -> result
	r := engine.ExprASTResult(ar)
	fmt.Println("progressing ...\t", r)
	fmt.Printf("%s = %v\n", exp, r)
}

编译运行，应该可以看到如下输出：

ExprAST: {Op:- Lhs:{Op:+ Lhs:{Op:+ Lhs:{Val:1} Rhs:{Op:/ Lhs:{Op:* Lhs:{Val:2} Rhs:{Val:6}} Rhs:{Val:4}}} Rhs:{Op:- Lhs:{Val:456} Rhs:{Op:* Lhs:{Val:8} Rhs:{Val:9.2}}}} Rhs:{Op:+ Lhs:{Val:2} Rhs:{Op:^ Lhs:{Val:4} Rhs:{Val:5}}}}
progressing ...  -639.6
1+2*6/4+(456-8*9.2)-(2+4^5) = -639.6

TrigonometricMode

RadianModesin(pi/2) = 1

TrigonometricModeRadianModeAngleMode

import "github.com/dengsgo/math-engine/engine"

func main() {
  s := "1 + sin(90)"
  engine.TrigonometricMode = engine.AngleMode
  engine.ParseAndExec(s) // will return 2, nil
  s = "1 + sin(pi/2)"
  engine.TrigonometricMode = engine.RadianMode
  engine.ParseAndExec(s) // will return 2, nil
}

Register Function

math-engine

e.g

  // RegFunction is Top level function
  // the same function name only needs to be registered once.
  // double is register function name.
  // 1 is a number of parameter signatures. should be -1, 0, or a positive integer
  // func(expr ...engine.ExprAST) float64 is your function.
  engine.RegFunction("double", 1, func(expr ...engine.ExprAST) float64 {
    // when argc > 0，you can use the index value directly according to the number of parameters
    // without worrying about crossing the boundary.
    // use ExprASTResult to get the result of the ExprAST structure.
    return engine.ExprASTResult(expr[0]) * 2
  })

double

//exp := "double(6) + 2"
r, err := engine.ParseAndExec("double(6) + 2")
if err != nil {
  panic(err)
}
fmt.Printf("double(6) + 2 = %f\n", r) // will print ： double(6) + 2 = 14.000000

注意事项：

• 注册的函数名只能是英文字母和数字，且必须英文字母开头（区分大小写）;
• 每一个函数名只能且只需注册一次；
• 注册的函数逻辑中如果有 panic ，需要程序自己捕获处理;
• argc=-1，即该函数的参数是可变的，expr 的长度需要开发者自行逻辑判断处理；

Compile

go version 1.12

# Compile Demo
go test
go build
./math-engine

也可以直接下载已编译好的二进制文件，直接运行：

实现细节

TODO

已实现

+-*/%^1.2e71.2e-7()1+2*6/4+(456-8*9.2)-(2+4^5)*2e3+1.2e-2123_456_789sin, cos, tan, cot, sec, cscabs, ceil, floor, sqrt, cbrt, max, min, noerr

input /> 123+89-0.0.9
ERROR: strconv.ParseFloat: parsing "0.0.9": invalid syntax
want '(' or '0-9' but get '0.0.9'
------------
123+89-0.0.9
       ^
------------