# parsii-ext

**Repository Path**: ltlwill/parsii-ext

## Basic Information

- **Project Name**: parsii-ext
- **Description**: No description available
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2019-09-18
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README


## 原始项目：https://github.com/zonghaishang/parsii-ext
## 本项目基于原始项目改造：
1. 升级 parsii 依赖至4.0版本
2. 修改一元一次方程计算不对的问题，如方程：x = (x*0.2 + x*0.11 + 8.87)，计算结果是错误的，解决方法是将方程式转义为：(x) - (x*0.2 + x*0.11 + 8.87) = 0，即可解决，
	增加了EscapeParser类执行转义，使用时将 原来的：Parser.parse(expStr) 替换为：EscapeParser.parse(expStr) 即可

# parsii-ext
## 扩展parsii, 支持求解一元一次方程
使用Demo
``` java
String function = "x-x*0.06*(0.02+0.03+0.01)=2359207.68"; // expect x = 2367731.51
Expression expression;
try {
    expression = Parser.parse(function);
} catch (ParseException e) {
   throw new RuntimeException("Parse function '" + function + "' fail.", e);
}
BinaryExpr expr = new BinaryExpr(expression);
double x = expr.getValue();
```

### 测试（see com.company.BinaryExprTest）：
``` java
String expr0 = "x - x*0.06*(0.02 + 0.03 + 0.01) = 3638930.77"; // expect x = 3652078.25
String expr1 = "100 - x + 0.06*x = 3638930.77"; // expect x = -3871096.56
String expr2 = "x - x*0.06*(0.02 + 0.03 + 0.01) = 2359207.68"; // expect x = 2367731.51
String expr3 = "x = 100"; // expect x = 100
String expr4 = "x - x*0.06*(0.02 + 0.03 + 0.01) = 8000000000"; // expect x = 8.028904054596548E9
String expr5 = "1 + 2 + 3 * 5"; // expect 18

expect(testExpr(expr0), 3652078.25);
expect(testExpr(expr1), -3871096.56);
expect(testExpr(expr2), 2367731.51);
expect(testExpr(expr3), 100);
expect(testExpr(expr4), 8.028904054596548E9);
expect(testExpr(expr5), 18);

static double testExpr(String expr){
    Scope scope = new Scope();
    Expression expression;
    try {
        expression = Parser.parse(expr, scope);
    } catch (ParseException e) {
        throw new RuntimeException("Parse expr fail. expr: " + expr, e);
    }
    BinaryExpr expr0 = new BinaryExpr(expression);
    return expr0.getValue();
}

static void expect(double actual, double expected){
    MathContext context = new MathContext(2);
    if(new BigDecimal(actual, context).equals(new BigDecimal(expected, context))){
        return;
    }
    throw new RuntimeException("expected '" + expected + "', actual '" + actual + "'");
}
```

## Maven

parsii-ext 在项目pom.xml中引用:

	<dependency>
	    <groupId>com.scireum</groupId>
	    <artifactId>parsii</artifactId>
	    <version>4.0</version> 
	</dependency>
		
    <dependency>
      <groupId>com.efe</groupId>
      <artifactId>parsii-ext</artifactId>
      <version>1.0</version>
    </dependency>