https://github.com/gzyangkui/math-expr-parser

https://github.com/gzyangkui/math-expr-parser

Last synced: 3 days ago
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• Host: GitHub
• URL: https://github.com/gzyangkui/math-expr-parser
• Owner: GZYangKui
• License: apache-2.0
• Created: 2022-06-12T14:57:36.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2022-06-15T14:29:35.000Z (over 2 years ago)
• Last Synced: 2024-11-05T20:11:40.602Z (about 2 months ago)
• Language: Java
• Size: 23.4 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Math-expr-parser

> Mathematical expression calculation based on recursive descent analysis

## Procedural grammar

```

Add ——> Mul | Add + Mul | Add - Mul

Mul ——> Pri | Pri * Mul | Pri / Mul

Pri ——> num | (Add)

```

> Note: Currently only four operations('+'、'-'、'*'、'/') are supported

## Example

```java

import cn.navclub.mexpr.parser.ASTParser;

import cn.navclub.mexpr.parser.model.ASTNode;

public class Test {

    public static void main(String[] args) {

        String expr = "3+2-5*(((1+1)*6*(6+3))*10)+5";

        //Instance math expr parser

        ASTParser parser = new ASTParser(expr);

        //Get math expr abstract syntax tree

        ASTNode node = parser.astNode();

        //Execute abstract syntax tree

        double rs = parser.execute();

        //Output execute result

        System.out.printf("Expr execute result:%d\n",rs);

    }

}

```

+ Execute example code terminal will output:

```shell

  Expr execute result:-5400

```