Golang template.Indirect函数代码示例

// evalRecursive visit the given value recursively and push all of them to result
func (j *JSONPath) evalRecursive(input []reflect.Value, node *RecursiveNode) ([]reflect.Value, error) {
	result := []reflect.Value{}
	for _, value := range input {
		results := []reflect.Value{}
		value, isNil := template.Indirect(value)
		if isNil {
			continue
		}

		kind := value.Kind()
		if kind == reflect.Struct {
			for i := 0; i < value.NumField(); i++ {
				results = append(results, value.Field(i))
			}
		} else if kind == reflect.Map {
			for _, key := range value.MapKeys() {
				results = append(results, value.MapIndex(key))
			}
		} else if kind == reflect.Array || kind == reflect.Slice || kind == reflect.String {
			for i := 0; i < value.Len(); i++ {
				results = append(results, value.Index(i))
			}
		}
		if len(results) != 0 {
			result = append(result, value)
			output, err := j.evalRecursive(results, node)
			if err != nil {
				return result, err
			}
			result = append(result, output...)
		}
	}
	return result, nil
}

// evalWildcard extract all contents of the given value
func (j *JSONPath) evalWildcard(input []reflect.Value, node *WildcardNode) ([]reflect.Value, error) {
	results := []reflect.Value{}
	for _, value := range input {
		value, isNil := template.Indirect(value)
		if isNil {
			continue
		}

		kind := value.Kind()
		if kind == reflect.Struct {
			for i := 0; i < value.NumField(); i++ {
				results = append(results, value.Field(i))
			}
		} else if kind == reflect.Map {
			for _, key := range value.MapKeys() {
				results = append(results, value.MapIndex(key))
			}
		} else if kind == reflect.Array || kind == reflect.Slice || kind == reflect.String {
			for i := 0; i < value.Len(); i++ {
				results = append(results, value.Index(i))
			}
		}
	}
	return results, nil
}

// evalField evaluates filed of struct or key of map.
func (j *JSONPath) evalField(input []reflect.Value, node *FieldNode) ([]reflect.Value, error) {
	results := []reflect.Value{}
	// If there's no input, there's no output
	if len(input) == 0 {
		return results, nil
	}
	for _, value := range input {
		var result reflect.Value
		value, isNil := template.Indirect(value)
		if isNil {
			continue
		}

		if value.Kind() == reflect.Struct {
			var err error
			if result, err = j.findFieldInValue(&value, node); err != nil {
				return nil, err
			}
		} else if value.Kind() == reflect.Map {
			result = value.MapIndex(reflect.ValueOf(node.Value))
		}
		if result.IsValid() {
			results = append(results, result)
		}
	}
	if len(results) == 0 {
		return results, fmt.Errorf("%s is not found", node.Value)
	}
	return results, nil
}

// evalArray evaluates ArrayNode
func (j *JSONPath) evalArray(input []reflect.Value, node *ArrayNode) ([]reflect.Value, error) {
	result := []reflect.Value{}
	for _, value := range input {

		value, isNil := template.Indirect(value)
		if isNil || (value.Kind() != reflect.Array && value.Kind() != reflect.Slice) {
			return input, fmt.Errorf("%v is not array or slice", value.Type())
		}
		params := node.Params
		if !params[0].Known {
			params[0].Value = 0
		}
		if params[0].Value < 0 {
			params[0].Value += value.Len()
		}
		if !params[1].Known {
			params[1].Value = value.Len()
		}

		if params[1].Value < 0 {
			params[1].Value += value.Len()
		}

		if !params[2].Known {
			value = value.Slice(params[0].Value, params[1].Value)
		} else {
			value = value.Slice3(params[0].Value, params[1].Value, params[2].Value)
		}
		for i := 0; i < value.Len(); i++ {
			result = append(result, value.Index(i))
		}
	}
	return result, nil
}

// evalArray evaluates ArrayNode
func (j *JSONPath) evalArray(input []reflect.Value, node *ArrayNode) ([]reflect.Value, error) {
	result := []reflect.Value{}
	for _, value := range input {

		value, isNil := template.Indirect(value)
		if isNil {
			continue
		}
		if value.Kind() != reflect.Array && value.Kind() != reflect.Slice {
			return input, fmt.Errorf("%v is not array or slice", value.Type())
		}
		params := node.Params
		if !params[0].Known {
			params[0].Value = 0
		}
		if params[0].Value < 0 {
			params[0].Value += value.Len()
		}
		if !params[1].Known {
			params[1].Value = value.Len()
		}

		if params[1].Value < 0 {
			params[1].Value += value.Len()
		}

		sliceLength := value.Len()
		if params[1].Value != params[0].Value { // if you're requesting zero elements, allow it through.
			if params[0].Value >= sliceLength {
				return input, fmt.Errorf("array index out of bounds: index %d, length %d", params[0].Value, sliceLength)
			}
			if params[1].Value > sliceLength {
				return input, fmt.Errorf("array index out of bounds: index %d, length %d", params[1].Value-1, sliceLength)
			}
		}

		if !params[2].Known {
			value = value.Slice(params[0].Value, params[1].Value)
		} else {
			value = value.Slice3(params[0].Value, params[1].Value, params[2].Value)
		}
		for i := 0; i < value.Len(); i++ {
			result = append(result, value.Index(i))
		}
	}
	return result, nil
}

// evalField evaluates field of struct or key of map.
func (j *JSONPath) evalField(input []reflect.Value, node *FieldNode) ([]reflect.Value, error) {
	results := []reflect.Value{}
	// If there's no input, there's no output
	if len(input) == 0 {
		return results, nil
	}
	for _, value := range input {
		var result reflect.Value
		value, isNil := template.Indirect(value)
		if isNil {
			continue
		}

		if value.Kind() == reflect.Struct {
			var err error
			if result, err = j.findFieldInValue(&value, node); err != nil {
				return nil, err
			}
		} else if value.Kind() == reflect.Map {
			mapKeyType := value.Type().Key()
			nodeValue := reflect.ValueOf(node.Value)
			// node value type must be convertible to map key type
			if !nodeValue.Type().ConvertibleTo(mapKeyType) {
				return results, fmt.Errorf("%s is not convertible to %s", nodeValue, mapKeyType)
			}
			result = value.MapIndex(nodeValue.Convert(mapKeyType))
		}
		if result.IsValid() {
			results = append(results, result)
		}
	}
	if len(results) == 0 {
		if j.allowMissingKeys {
			return results, nil
		}
		return results, fmt.Errorf("%s is not found", node.Value)
	}
	return results, nil
}

// evalFilter filter array according to FilterNode
func (j *JSONPath) evalFilter(input []reflect.Value, node *FilterNode) ([]reflect.Value, error) {
	results := []reflect.Value{}
	for _, value := range input {
		value, _ = template.Indirect(value)

		if value.Kind() != reflect.Array && value.Kind() != reflect.Slice {
			return input, fmt.Errorf("%v is not array or slice and cannot be filtered", value)
		}
		for i := 0; i < value.Len(); i++ {
			temp := []reflect.Value{value.Index(i)}
			lefts, err := j.evalList(temp, node.Left)

			//case exists
			if node.Operator == "exists" {
				if len(lefts) > 0 {
					results = append(results, value.Index(i))
				}
				continue
			}

			if err != nil {
				return input, err
			}

			var left, right interface{}
			if len(lefts) != 1 {
				return input, fmt.Errorf("can only compare one element at a time")
			}
			left = lefts[0].Interface()

			rights, err := j.evalList(temp, node.Right)
			if err != nil {
				return input, err
			}
			if len(rights) != 1 {
				return input, fmt.Errorf("can only compare one element at a time")
			}
			right = rights[0].Interface()

			pass := false
			switch node.Operator {
			case "<":
				pass, err = template.Less(left, right)
			case ">":
				pass, err = template.Greater(left, right)
			case "==":
				pass, err = template.Equal(left, right)
			case "!=":
				pass, err = template.NotEqual(left, right)
			case "<=":
				pass, err = template.LessEqual(left, right)
			case ">=":
				pass, err = template.GreaterEqual(left, right)
			default:
				return results, fmt.Errorf("unrecognized filter operator %s", node.Operator)
			}
			if err != nil {
				return results, err
			}
			if pass {
				results = append(results, value.Index(i))
			}
		}
	}
	return results, nil
}