498 lines
13 KiB
Go
498 lines
13 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package jsonpath
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import (
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"bytes"
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"fmt"
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"io"
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"reflect"
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"strings"
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"k8s.io/kubernetes/third_party/forked/golang/template"
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)
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type JSONPath struct {
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name string
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parser *Parser
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stack [][]reflect.Value //push and pop values in different scopes
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cur []reflect.Value //current scope values
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beginRange int
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inRange int
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endRange int
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allowMissingKeys bool
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}
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func New(name string) *JSONPath {
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return &JSONPath{
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name: name,
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beginRange: 0,
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inRange: 0,
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endRange: 0,
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}
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}
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// AllowMissingKeys allows a caller to specify whether they want an error if a field or map key
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// cannot be located, or simply an empty result. The receiver is returned for chaining.
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func (j *JSONPath) AllowMissingKeys(allow bool) *JSONPath {
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j.allowMissingKeys = allow
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return j
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}
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// Parse parse the given template, return error
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func (j *JSONPath) Parse(text string) (err error) {
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j.parser, err = Parse(j.name, text)
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return
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}
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// Execute bounds data into template and write the result
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func (j *JSONPath) Execute(wr io.Writer, data interface{}) error {
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fullResults, err := j.FindResults(data)
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if err != nil {
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return err
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}
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for ix := range fullResults {
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if err := j.PrintResults(wr, fullResults[ix]); err != nil {
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return err
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}
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}
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return nil
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}
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func (j *JSONPath) FindResults(data interface{}) ([][]reflect.Value, error) {
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if j.parser == nil {
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return nil, fmt.Errorf("%s is an incomplete jsonpath template", j.name)
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}
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j.cur = []reflect.Value{reflect.ValueOf(data)}
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nodes := j.parser.Root.Nodes
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fullResult := [][]reflect.Value{}
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for i := 0; i < len(nodes); i++ {
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node := nodes[i]
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results, err := j.walk(j.cur, node)
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if err != nil {
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return nil, err
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}
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//encounter an end node, break the current block
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if j.endRange > 0 && j.endRange <= j.inRange {
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j.endRange -= 1
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break
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}
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//encounter a range node, start a range loop
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if j.beginRange > 0 {
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j.beginRange -= 1
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j.inRange += 1
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for k, value := range results {
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j.parser.Root.Nodes = nodes[i+1:]
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if k == len(results)-1 {
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j.inRange -= 1
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}
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nextResults, err := j.FindResults(value.Interface())
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if err != nil {
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return nil, err
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}
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fullResult = append(fullResult, nextResults...)
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}
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break
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}
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fullResult = append(fullResult, results)
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}
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return fullResult, nil
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}
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// PrintResults write the results into writer
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func (j *JSONPath) PrintResults(wr io.Writer, results []reflect.Value) error {
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for i, r := range results {
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text, err := j.evalToText(r)
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if err != nil {
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return err
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}
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if i != len(results)-1 {
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text = append(text, ' ')
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}
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if _, err = wr.Write(text); err != nil {
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return err
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}
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}
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return nil
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}
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// walk visits tree rooted at the given node in DFS order
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func (j *JSONPath) walk(value []reflect.Value, node Node) ([]reflect.Value, error) {
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switch node := node.(type) {
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case *ListNode:
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return j.evalList(value, node)
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case *TextNode:
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return []reflect.Value{reflect.ValueOf(node.Text)}, nil
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case *FieldNode:
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return j.evalField(value, node)
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case *ArrayNode:
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return j.evalArray(value, node)
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case *FilterNode:
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return j.evalFilter(value, node)
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case *IntNode:
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return j.evalInt(value, node)
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case *FloatNode:
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return j.evalFloat(value, node)
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case *WildcardNode:
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return j.evalWildcard(value, node)
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case *RecursiveNode:
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return j.evalRecursive(value, node)
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case *UnionNode:
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return j.evalUnion(value, node)
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case *IdentifierNode:
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return j.evalIdentifier(value, node)
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default:
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return value, fmt.Errorf("unexpected Node %v", node)
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}
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}
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// evalInt evaluates IntNode
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func (j *JSONPath) evalInt(input []reflect.Value, node *IntNode) ([]reflect.Value, error) {
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result := make([]reflect.Value, len(input))
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for i := range input {
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result[i] = reflect.ValueOf(node.Value)
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}
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return result, nil
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}
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// evalFloat evaluates FloatNode
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func (j *JSONPath) evalFloat(input []reflect.Value, node *FloatNode) ([]reflect.Value, error) {
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result := make([]reflect.Value, len(input))
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for i := range input {
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result[i] = reflect.ValueOf(node.Value)
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}
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return result, nil
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}
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// evalList evaluates ListNode
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func (j *JSONPath) evalList(value []reflect.Value, node *ListNode) ([]reflect.Value, error) {
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var err error
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curValue := value
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for _, node := range node.Nodes {
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curValue, err = j.walk(curValue, node)
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if err != nil {
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return curValue, err
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}
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}
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return curValue, nil
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}
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// evalIdentifier evaluates IdentifierNode
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func (j *JSONPath) evalIdentifier(input []reflect.Value, node *IdentifierNode) ([]reflect.Value, error) {
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results := []reflect.Value{}
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switch node.Name {
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case "range":
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j.stack = append(j.stack, j.cur)
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j.beginRange += 1
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results = input
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case "end":
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if j.endRange < j.inRange { //inside a loop, break the current block
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j.endRange += 1
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break
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}
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// the loop is about to end, pop value and continue the following execution
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if len(j.stack) > 0 {
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j.cur, j.stack = j.stack[len(j.stack)-1], j.stack[:len(j.stack)-1]
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} else {
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return results, fmt.Errorf("not in range, nothing to end")
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}
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default:
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return input, fmt.Errorf("unrecognized identifier %v", node.Name)
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}
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return results, nil
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}
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// evalArray evaluates ArrayNode
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func (j *JSONPath) evalArray(input []reflect.Value, node *ArrayNode) ([]reflect.Value, error) {
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result := []reflect.Value{}
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for _, value := range input {
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value, isNil := template.Indirect(value)
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if isNil {
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continue
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}
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if value.Kind() != reflect.Array && value.Kind() != reflect.Slice {
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return input, fmt.Errorf("%v is not array or slice", value.Type())
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}
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params := node.Params
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if !params[0].Known {
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params[0].Value = 0
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}
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if params[0].Value < 0 {
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params[0].Value += value.Len()
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}
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if !params[1].Known {
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params[1].Value = value.Len()
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}
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if params[1].Value < 0 {
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params[1].Value += value.Len()
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}
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sliceLength := value.Len()
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if params[1].Value != params[0].Value { // if you're requesting zero elements, allow it through.
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if params[0].Value >= sliceLength {
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return input, fmt.Errorf("array index out of bounds: index %d, length %d", params[0].Value, sliceLength)
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}
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if params[1].Value > sliceLength {
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return input, fmt.Errorf("array index out of bounds: index %d, length %d", params[1].Value-1, sliceLength)
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}
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}
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if !params[2].Known {
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value = value.Slice(params[0].Value, params[1].Value)
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} else {
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value = value.Slice3(params[0].Value, params[1].Value, params[2].Value)
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}
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for i := 0; i < value.Len(); i++ {
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result = append(result, value.Index(i))
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}
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}
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return result, nil
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}
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// evalUnion evaluates UnionNode
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func (j *JSONPath) evalUnion(input []reflect.Value, node *UnionNode) ([]reflect.Value, error) {
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result := []reflect.Value{}
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for _, listNode := range node.Nodes {
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temp, err := j.evalList(input, listNode)
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if err != nil {
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return input, err
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}
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result = append(result, temp...)
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}
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return result, nil
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}
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func (j *JSONPath) findFieldInValue(value *reflect.Value, node *FieldNode) (reflect.Value, error) {
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t := value.Type()
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var inlineValue *reflect.Value
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for ix := 0; ix < t.NumField(); ix++ {
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f := t.Field(ix)
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jsonTag := f.Tag.Get("json")
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parts := strings.Split(jsonTag, ",")
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if len(parts) == 0 {
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continue
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}
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if parts[0] == node.Value {
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return value.Field(ix), nil
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}
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if len(parts[0]) == 0 {
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val := value.Field(ix)
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inlineValue = &val
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}
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}
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if inlineValue != nil {
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if inlineValue.Kind() == reflect.Struct {
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// handle 'inline'
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match, err := j.findFieldInValue(inlineValue, node)
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if err != nil {
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return reflect.Value{}, err
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}
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if match.IsValid() {
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return match, nil
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}
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}
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}
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return value.FieldByName(node.Value), nil
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}
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// evalField evaluates field of struct or key of map.
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func (j *JSONPath) evalField(input []reflect.Value, node *FieldNode) ([]reflect.Value, error) {
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results := []reflect.Value{}
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// If there's no input, there's no output
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if len(input) == 0 {
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return results, nil
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}
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for _, value := range input {
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var result reflect.Value
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value, isNil := template.Indirect(value)
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if isNil {
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continue
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}
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if value.Kind() == reflect.Struct {
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var err error
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if result, err = j.findFieldInValue(&value, node); err != nil {
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return nil, err
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}
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} else if value.Kind() == reflect.Map {
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mapKeyType := value.Type().Key()
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nodeValue := reflect.ValueOf(node.Value)
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// node value type must be convertible to map key type
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if !nodeValue.Type().ConvertibleTo(mapKeyType) {
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return results, fmt.Errorf("%s is not convertible to %s", nodeValue, mapKeyType)
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}
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result = value.MapIndex(nodeValue.Convert(mapKeyType))
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}
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if result.IsValid() {
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results = append(results, result)
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}
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}
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if len(results) == 0 {
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if j.allowMissingKeys {
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return results, nil
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}
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return results, fmt.Errorf("%s is not found", node.Value)
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}
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return results, nil
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}
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// evalWildcard extract all contents of the given value
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func (j *JSONPath) evalWildcard(input []reflect.Value, node *WildcardNode) ([]reflect.Value, error) {
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results := []reflect.Value{}
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for _, value := range input {
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value, isNil := template.Indirect(value)
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if isNil {
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continue
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}
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kind := value.Kind()
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if kind == reflect.Struct {
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for i := 0; i < value.NumField(); i++ {
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results = append(results, value.Field(i))
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}
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} else if kind == reflect.Map {
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for _, key := range value.MapKeys() {
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results = append(results, value.MapIndex(key))
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}
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} else if kind == reflect.Array || kind == reflect.Slice || kind == reflect.String {
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for i := 0; i < value.Len(); i++ {
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results = append(results, value.Index(i))
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}
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}
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}
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return results, nil
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}
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// evalRecursive visit the given value recursively and push all of them to result
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func (j *JSONPath) evalRecursive(input []reflect.Value, node *RecursiveNode) ([]reflect.Value, error) {
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result := []reflect.Value{}
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for _, value := range input {
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results := []reflect.Value{}
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value, isNil := template.Indirect(value)
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if isNil {
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continue
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}
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kind := value.Kind()
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if kind == reflect.Struct {
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for i := 0; i < value.NumField(); i++ {
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results = append(results, value.Field(i))
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}
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} else if kind == reflect.Map {
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for _, key := range value.MapKeys() {
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results = append(results, value.MapIndex(key))
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}
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} else if kind == reflect.Array || kind == reflect.Slice || kind == reflect.String {
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for i := 0; i < value.Len(); i++ {
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results = append(results, value.Index(i))
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}
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}
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if len(results) != 0 {
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result = append(result, value)
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output, err := j.evalRecursive(results, node)
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if err != nil {
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return result, err
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}
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result = append(result, output...)
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}
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}
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return result, nil
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}
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// evalFilter filter array according to FilterNode
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func (j *JSONPath) evalFilter(input []reflect.Value, node *FilterNode) ([]reflect.Value, error) {
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results := []reflect.Value{}
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for _, value := range input {
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value, _ = template.Indirect(value)
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if value.Kind() != reflect.Array && value.Kind() != reflect.Slice {
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return input, fmt.Errorf("%v is not array or slice and cannot be filtered", value)
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}
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for i := 0; i < value.Len(); i++ {
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temp := []reflect.Value{value.Index(i)}
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lefts, err := j.evalList(temp, node.Left)
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//case exists
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if node.Operator == "exists" {
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if len(lefts) > 0 {
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results = append(results, value.Index(i))
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}
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continue
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}
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if err != nil {
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return input, err
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}
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var left, right interface{}
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if len(lefts) != 1 {
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return input, fmt.Errorf("can only compare one element at a time")
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}
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left = lefts[0].Interface()
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rights, err := j.evalList(temp, node.Right)
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if err != nil {
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return input, err
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}
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if len(rights) != 1 {
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return input, fmt.Errorf("can only compare one element at a time")
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}
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right = rights[0].Interface()
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pass := false
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switch node.Operator {
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case "<":
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pass, err = template.Less(left, right)
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case ">":
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pass, err = template.Greater(left, right)
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case "==":
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pass, err = template.Equal(left, right)
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case "!=":
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pass, err = template.NotEqual(left, right)
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case "<=":
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pass, err = template.LessEqual(left, right)
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case ">=":
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pass, err = template.GreaterEqual(left, right)
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default:
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return results, fmt.Errorf("unrecognized filter operator %s", node.Operator)
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}
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if err != nil {
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return results, err
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}
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if pass {
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results = append(results, value.Index(i))
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}
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}
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}
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return results, nil
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}
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// evalToText translates reflect value to corresponding text
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func (j *JSONPath) evalToText(v reflect.Value) ([]byte, error) {
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iface, ok := template.PrintableValue(v)
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if !ok {
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return nil, fmt.Errorf("can't print type %s", v.Type())
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}
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var buffer bytes.Buffer
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fmt.Fprint(&buffer, iface)
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return buffer.Bytes(), nil
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}
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