mirror of
https://github.com/rclone/rclone.git
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419 lines
10 KiB
Go
419 lines
10 KiB
Go
package jmespath
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import (
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"errors"
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"reflect"
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"unicode"
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"unicode/utf8"
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)
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/* This is a tree based interpreter. It walks the AST and directly
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interprets the AST to search through a JSON document.
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*/
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type treeInterpreter struct {
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fCall *functionCaller
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}
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func newInterpreter() *treeInterpreter {
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interpreter := treeInterpreter{}
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interpreter.fCall = newFunctionCaller()
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return &interpreter
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}
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type expRef struct {
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ref ASTNode
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}
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// Execute takes an ASTNode and input data and interprets the AST directly.
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// It will produce the result of applying the JMESPath expression associated
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// with the ASTNode to the input data "value".
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func (intr *treeInterpreter) Execute(node ASTNode, value interface{}) (interface{}, error) {
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switch node.nodeType {
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case ASTComparator:
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left, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, err
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}
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right, err := intr.Execute(node.children[1], value)
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if err != nil {
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return nil, err
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}
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switch node.value {
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case tEQ:
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return objsEqual(left, right), nil
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case tNE:
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return !objsEqual(left, right), nil
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}
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leftNum, ok := left.(float64)
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if !ok {
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return nil, nil
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}
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rightNum, ok := right.(float64)
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if !ok {
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return nil, nil
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}
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switch node.value {
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case tGT:
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return leftNum > rightNum, nil
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case tGTE:
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return leftNum >= rightNum, nil
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case tLT:
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return leftNum < rightNum, nil
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case tLTE:
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return leftNum <= rightNum, nil
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}
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case ASTExpRef:
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return expRef{ref: node.children[0]}, nil
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case ASTFunctionExpression:
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resolvedArgs := []interface{}{}
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for _, arg := range node.children {
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current, err := intr.Execute(arg, value)
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if err != nil {
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return nil, err
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}
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resolvedArgs = append(resolvedArgs, current)
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}
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return intr.fCall.CallFunction(node.value.(string), resolvedArgs, intr)
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case ASTField:
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if m, ok := value.(map[string]interface{}); ok {
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key := node.value.(string)
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return m[key], nil
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}
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return intr.fieldFromStruct(node.value.(string), value)
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case ASTFilterProjection:
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left, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, nil
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}
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sliceType, ok := left.([]interface{})
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if !ok {
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if isSliceType(left) {
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return intr.filterProjectionWithReflection(node, left)
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}
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return nil, nil
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}
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compareNode := node.children[2]
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collected := []interface{}{}
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for _, element := range sliceType {
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result, err := intr.Execute(compareNode, element)
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if err != nil {
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return nil, err
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}
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if !isFalse(result) {
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current, err := intr.Execute(node.children[1], element)
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if err != nil {
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return nil, err
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}
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if current != nil {
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collected = append(collected, current)
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}
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}
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}
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return collected, nil
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case ASTFlatten:
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left, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, nil
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}
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sliceType, ok := left.([]interface{})
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if !ok {
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// If we can't type convert to []interface{}, there's
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// a chance this could still work via reflection if we're
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// dealing with user provided types.
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if isSliceType(left) {
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return intr.flattenWithReflection(left)
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}
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return nil, nil
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}
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flattened := []interface{}{}
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for _, element := range sliceType {
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if elementSlice, ok := element.([]interface{}); ok {
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flattened = append(flattened, elementSlice...)
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} else if isSliceType(element) {
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reflectFlat := []interface{}{}
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v := reflect.ValueOf(element)
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for i := 0; i < v.Len(); i++ {
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reflectFlat = append(reflectFlat, v.Index(i).Interface())
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}
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flattened = append(flattened, reflectFlat...)
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} else {
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flattened = append(flattened, element)
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}
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}
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return flattened, nil
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case ASTIdentity, ASTCurrentNode:
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return value, nil
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case ASTIndex:
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if sliceType, ok := value.([]interface{}); ok {
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index := node.value.(int)
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if index < 0 {
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index += len(sliceType)
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}
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if index < len(sliceType) && index >= 0 {
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return sliceType[index], nil
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}
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return nil, nil
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}
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// Otherwise try via reflection.
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rv := reflect.ValueOf(value)
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if rv.Kind() == reflect.Slice {
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index := node.value.(int)
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if index < 0 {
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index += rv.Len()
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}
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if index < rv.Len() && index >= 0 {
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v := rv.Index(index)
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return v.Interface(), nil
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}
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}
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return nil, nil
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case ASTKeyValPair:
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return intr.Execute(node.children[0], value)
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case ASTLiteral:
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return node.value, nil
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case ASTMultiSelectHash:
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if value == nil {
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return nil, nil
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}
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collected := make(map[string]interface{})
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for _, child := range node.children {
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current, err := intr.Execute(child, value)
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if err != nil {
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return nil, err
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}
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key := child.value.(string)
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collected[key] = current
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}
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return collected, nil
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case ASTMultiSelectList:
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if value == nil {
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return nil, nil
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}
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collected := []interface{}{}
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for _, child := range node.children {
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current, err := intr.Execute(child, value)
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if err != nil {
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return nil, err
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}
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collected = append(collected, current)
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}
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return collected, nil
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case ASTOrExpression:
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matched, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, err
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}
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if isFalse(matched) {
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matched, err = intr.Execute(node.children[1], value)
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if err != nil {
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return nil, err
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}
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}
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return matched, nil
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case ASTAndExpression:
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matched, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, err
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}
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if isFalse(matched) {
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return matched, nil
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}
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return intr.Execute(node.children[1], value)
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case ASTNotExpression:
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matched, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, err
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}
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if isFalse(matched) {
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return true, nil
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}
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return false, nil
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case ASTPipe:
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result := value
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var err error
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for _, child := range node.children {
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result, err = intr.Execute(child, result)
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if err != nil {
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return nil, err
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}
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}
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return result, nil
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case ASTProjection:
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left, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, err
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}
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sliceType, ok := left.([]interface{})
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if !ok {
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if isSliceType(left) {
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return intr.projectWithReflection(node, left)
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}
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return nil, nil
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}
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collected := []interface{}{}
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var current interface{}
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for _, element := range sliceType {
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current, err = intr.Execute(node.children[1], element)
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if err != nil {
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return nil, err
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}
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if current != nil {
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collected = append(collected, current)
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}
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}
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return collected, nil
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case ASTSubexpression, ASTIndexExpression:
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left, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, err
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}
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return intr.Execute(node.children[1], left)
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case ASTSlice:
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sliceType, ok := value.([]interface{})
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if !ok {
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if isSliceType(value) {
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return intr.sliceWithReflection(node, value)
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}
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return nil, nil
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}
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parts := node.value.([]*int)
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sliceParams := make([]sliceParam, 3)
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for i, part := range parts {
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if part != nil {
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sliceParams[i].Specified = true
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sliceParams[i].N = *part
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}
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}
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return slice(sliceType, sliceParams)
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case ASTValueProjection:
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left, err := intr.Execute(node.children[0], value)
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if err != nil {
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return nil, nil
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}
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mapType, ok := left.(map[string]interface{})
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if !ok {
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return nil, nil
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}
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values := make([]interface{}, len(mapType))
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for _, value := range mapType {
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values = append(values, value)
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}
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collected := []interface{}{}
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for _, element := range values {
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current, err := intr.Execute(node.children[1], element)
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if err != nil {
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return nil, err
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}
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if current != nil {
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collected = append(collected, current)
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}
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}
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return collected, nil
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}
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return nil, errors.New("Unknown AST node: " + node.nodeType.String())
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}
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func (intr *treeInterpreter) fieldFromStruct(key string, value interface{}) (interface{}, error) {
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rv := reflect.ValueOf(value)
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first, n := utf8.DecodeRuneInString(key)
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fieldName := string(unicode.ToUpper(first)) + key[n:]
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if rv.Kind() == reflect.Struct {
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v := rv.FieldByName(fieldName)
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if !v.IsValid() {
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return nil, nil
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}
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return v.Interface(), nil
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} else if rv.Kind() == reflect.Ptr {
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// Handle multiple levels of indirection?
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if rv.IsNil() {
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return nil, nil
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}
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rv = rv.Elem()
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v := rv.FieldByName(fieldName)
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if !v.IsValid() {
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return nil, nil
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}
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return v.Interface(), nil
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}
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return nil, nil
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}
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func (intr *treeInterpreter) flattenWithReflection(value interface{}) (interface{}, error) {
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v := reflect.ValueOf(value)
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flattened := []interface{}{}
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for i := 0; i < v.Len(); i++ {
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element := v.Index(i).Interface()
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if reflect.TypeOf(element).Kind() == reflect.Slice {
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// Then insert the contents of the element
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// slice into the flattened slice,
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// i.e flattened = append(flattened, mySlice...)
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elementV := reflect.ValueOf(element)
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for j := 0; j < elementV.Len(); j++ {
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flattened = append(
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flattened, elementV.Index(j).Interface())
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}
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} else {
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flattened = append(flattened, element)
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}
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}
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return flattened, nil
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}
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func (intr *treeInterpreter) sliceWithReflection(node ASTNode, value interface{}) (interface{}, error) {
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v := reflect.ValueOf(value)
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parts := node.value.([]*int)
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sliceParams := make([]sliceParam, 3)
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for i, part := range parts {
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if part != nil {
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sliceParams[i].Specified = true
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sliceParams[i].N = *part
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}
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}
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final := []interface{}{}
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for i := 0; i < v.Len(); i++ {
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element := v.Index(i).Interface()
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final = append(final, element)
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}
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return slice(final, sliceParams)
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}
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func (intr *treeInterpreter) filterProjectionWithReflection(node ASTNode, value interface{}) (interface{}, error) {
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compareNode := node.children[2]
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collected := []interface{}{}
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v := reflect.ValueOf(value)
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for i := 0; i < v.Len(); i++ {
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element := v.Index(i).Interface()
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result, err := intr.Execute(compareNode, element)
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if err != nil {
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return nil, err
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}
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if !isFalse(result) {
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current, err := intr.Execute(node.children[1], element)
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if err != nil {
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return nil, err
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}
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if current != nil {
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collected = append(collected, current)
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}
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}
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}
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return collected, nil
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}
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func (intr *treeInterpreter) projectWithReflection(node ASTNode, value interface{}) (interface{}, error) {
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collected := []interface{}{}
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v := reflect.ValueOf(value)
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for i := 0; i < v.Len(); i++ {
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element := v.Index(i).Interface()
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result, err := intr.Execute(node.children[1], element)
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if err != nil {
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return nil, err
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}
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if result != nil {
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collected = append(collected, result)
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}
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}
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return collected, nil
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}
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