publish lancet

slice/slice_util.go

@@ -0,0 +1,54 @@
+package slice
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// sliceValue return the reflect value of a slice
+func sliceValue(slice interface{}) reflect.Value {
+	v := reflect.ValueOf(slice)
+	if v.Kind() != reflect.Slice {
+		panic(fmt.Sprintf("Invalid slice type, value of type %T", slice))
+	}
+	return v
+}
+
+// functionValue return the reflect value of a function
+func functionValue(function interface{}) reflect.Value {
+	v := reflect.ValueOf(function)
+	if v.Kind() != reflect.Func {
+		panic(fmt.Sprintf("Invalid function type, value of type %T", function))
+	}
+	return v
+}
+
+// checkSliceCallbackFuncSignature Check func sign :  s :[]type1{} -> func(i int, data type1) type2
+// see https://coolshell.cn/articles/21164.html#%E6%B3%9B%E5%9E%8BMap-Reduce
+func checkSliceCallbackFuncSignature(fn reflect.Value, types ...reflect.Type) bool {
+	//Check it is a function
+	if fn.Kind() != reflect.Func {
+		return false
+	}
+	// NumIn() - returns a function type's input parameter count.
+	// NumOut() - returns a function type's output parameter count.
+	if (fn.Type().NumIn() != len(types)-1) || (fn.Type().NumOut() != 1) {
+		return false
+	}
+	// In() - returns the type of a function type's i'th input parameter.
+	// first input param type should be int
+	if fn.Type().In(0) != reflect.TypeOf(1) {
+		return false
+	}
+	for i := 0; i < len(types)-1; i++ {
+		if fn.Type().In(i) != types[i] {
+			return false
+		}
+	}
+	// Out() - returns the type of a function type's i'th output parameter.
+	outType := types[len(types)-1]
+	if outType != nil && fn.Type().Out(0) != outType {
+		return false
+	}
+	return true
+}