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package jmespath
import (
"errors"
"reflect"
)
// IsFalse determines if an object is false based on the JMESPath spec.
// JMESPath defines false values to be any of:
// - An empty string array, or hash.
// - The boolean value false.
// - nil
func isFalse(value interface{}) bool {
switch v := value.(type) {
case bool:
return !v
case []interface{}:
return len(v) == 0
case map[string]interface{}:
return len(v) == 0
case string:
return len(v) == 0
case nil:
return true
}
// Try the reflection cases before returning false.
rv := reflect.ValueOf(value)
switch rv.Kind() {
case reflect.Struct:
// A struct type will never be false, even if
// all of its values are the zero type.
return false
case reflect.Slice, reflect.Map:
return rv.Len() == 0
case reflect.Ptr:
if rv.IsNil() {
return true
}
// If it's a pointer type, we'll try to deref the pointer
// and evaluate the pointer value for isFalse.
element := rv.Elem()
return isFalse(element.Interface())
}
return false
}
// ObjsEqual is a generic object equality check.
// It will take two arbitrary objects and recursively determine
// if they are equal.
func objsEqual(left interface{}, right interface{}) bool {
return reflect.DeepEqual(left, right)
}
// SliceParam refers to a single part of a slice.
// A slice consists of a start, a stop, and a step, similar to
// python slices.
type sliceParam struct {
N int
Specified bool
}
// Slice supports [start:stop:step] style slicing that's supported in JMESPath.
func slice(slice []interface{}, parts []sliceParam) ([]interface{}, error) {
computed, err := computeSliceParams(len(slice), parts)
if err != nil {
return nil, err
}
start, stop, step := computed[0], computed[1], computed[2]
result := []interface{}{}
if step > 0 {
for i := start; i < stop; i += step {
result = append(result, slice[i])
}
} else {
for i := start; i > stop; i += step {
result = append(result, slice[i])
}
}
return result, nil
}
func computeSliceParams(length int, parts []sliceParam) ([]int, error) {
var start, stop, step int
if !parts[2].Specified {
step = 1
} else if parts[2].N == 0 {
return nil, errors.New("Invalid slice, step cannot be 0")
} else {
step = parts[2].N
}
var stepValueNegative bool
if step < 0 {
stepValueNegative = true
} else {
stepValueNegative = false
}
if !parts[0].Specified {
if stepValueNegative {
start = length - 1
} else {
start = 0
}
} else {
start = capSlice(length, parts[0].N, step)
}
if !parts[1].Specified {
if stepValueNegative {
stop = -1
} else {
stop = length
}
} else {
stop = capSlice(length, parts[1].N, step)
}
return []int{start, stop, step}, nil
}
func capSlice(length int, actual int, step int) int {
if actual < 0 {
actual += length
if actual < 0 {
if step < 0 {
actual = -1
} else {
actual = 0
}
}
} else if actual >= length {
if step < 0 {
actual = length - 1
} else {
actual = length
}
}
return actual
}
// ToArrayNum converts an empty interface type to a slice of float64.
// If any element in the array cannot be converted, then nil is returned
// along with a second value of false.
func toArrayNum(data interface{}) ([]float64, bool) {
// Is there a better way to do this with reflect?
if d, ok := data.([]interface{}); ok {
result := make([]float64, len(d))
for i, el := range d {
item, ok := el.(float64)
if !ok {
return nil, false
}
result[i] = item
}
return result, true
}
return nil, false
}
// ToArrayStr converts an empty interface type to a slice of strings.
// If any element in the array cannot be converted, then nil is returned
// along with a second value of false. If the input data could be entirely
// converted, then the converted data, along with a second value of true,
// will be returned.
func toArrayStr(data interface{}) ([]string, bool) {
// Is there a better way to do this with reflect?
if d, ok := data.([]interface{}); ok {
result := make([]string, len(d))
for i, el := range d {
item, ok := el.(string)
if !ok {
return nil, false
}
result[i] = item
}
return result, true
}
return nil, false
}
func isSliceType(v interface{}) bool {
if v == nil {
return false
}
return reflect.TypeOf(v).Kind() == reflect.Slice
}
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