feat: 引入features的gin路由

lib/eval/evaluate.go

@@ -0,0 +1,111 @@
+package evaluate
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// Parse and caculate expression
+func CalcExpr(expr string, paramValues map[string]any) (float64, error) {
+	// match parameter with ''
+	re := regexp.MustCompile(`'([^']+)'`)
+	matches := re.FindAllStringSubmatch(expr, -1)
+
+	// replace to value
+	for _, match := range matches {
+		paramName := match[1]
+		value, exists := paramValues[paramName]
+		if !exists {
+			return 0, fmt.Errorf("parameter '%s' not found", paramName)
+		}
+
+		expr = strings.Replace(expr, match[0], fmt.Sprintf("%v", value), 1)
+	}
+
+	// expression to evaluate
+	result, err := evalExpr(expr)
+	return result, err
+}
+
+// eval 解析和计算表达式
+func evalExpr(expr string) (float64, error) {
+	//fset := token.NewFileSet()
+	node, err := parser.ParseExpr(expr)
+	if err != nil {
+		return 0, err
+	}
+	return evalNode(node)
+}
+
+// EvaluateExpr 解析并计算给定的表达式
+func EvalExpr(expr string, values map[string]any) (float64, error) {
+	// 解析表达式
+	node, err := parser.ParseExpr(expr)
+	if err != nil {
+		return 0, err
+	}
+
+	// 遍历 AST 并替换变量
+	ast.Inspect(node, func(n ast.Node) bool {
+		if ident, ok := n.(*ast.Ident); ok {
+			if val, ok := values[ident.Name]; ok {
+				// 替换标识符为对应值
+				ident.Name = fmt.Sprintf("%v", val)
+			}
+		}
+		return true
+	})
+
+	// 计算表达式
+	return evalNode(node)
+}
+
+// eval 递归计算 AST 节点
+func evalNode(node ast.Node) (float64, error) {
+	var result float64
+
+	switch n := node.(type) {
+	case *ast.BinaryExpr:
+		left, err := evalNode(n.X)
+		if err != nil {
+			return 0, err
+		}
+		right, err := evalNode(n.Y)
+		if err != nil {
+			return 0, err
+		}
+		switch n.Op {
+		case token.ADD:
+			result = left + right
+		case token.SUB:
+			result = left - right
+		case token.MUL:
+			result = left * right
+		case token.QUO:
+			result = left / right
+		}
+	case *ast.BasicLit:
+		var err error
+		result, err = strconv.ParseFloat(n.Value, 64)
+		if err != nil {
+			return 0, err
+		}
+	case *ast.Ident:
+		val, err := strconv.ParseFloat(n.Name, 64)
+		if err != nil {
+			return 0, fmt.Errorf("unsupported expression: %s", n.Name)
+		}
+		result = val
+	case *ast.ParenExpr:
+		return evalNode(n.X) // 递归评估括号中的表达式
+	default:
+		return 0, fmt.Errorf("unsupported expression: %T", n)
+	}
+
+	return result, nil
+}