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input.go
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input.go
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// Copyright 2022 Snyk Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package legacyiac
import (
"container/list"
"strconv"
"strings"
)
type ParsedMsg struct {
ResourceID string
ResourceType string
// Optional, replaced by defaultResourceNamespace if empty
ResourceNamespace string
Path []interface{}
}
type Input interface {
Raw() interface{}
ParseMsg(msg string) ParsedMsg
}
type parsePathState int
const (
inIdentifier parsePathState = iota
inBracket
inSingleQuote
inDoubleQuote
inEscape
parsePathError
)
type stateStack struct {
stack *list.List
}
func (s *stateStack) pop() parsePathState {
state := s.stack.Front()
if state == nil {
return parsePathError
}
return s.stack.Remove(state).(parsePathState)
}
func (s *stateStack) push(state parsePathState) {
s.stack.PushFront(state)
}
func (s *stateStack) peek() parsePathState {
state := s.stack.Front()
if state == nil {
return parsePathError
}
return state.Value.(parsePathState)
}
func newStateStack(init parsePathState) *stateStack {
stack := &stateStack{
stack: list.New(),
}
stack.push(init)
return stack
}
func parsePath(msg string) []interface{} {
// Trim off 'input' path element if it exists
msg = strings.TrimPrefix(msg, "input.")
path := []interface{}{}
buf := []rune{}
consumeBuf := func() {
s := string(buf)
if s == "" {
return
}
if i, err := strconv.Atoi(s); err == nil {
path = append(path, i)
} else {
path = append(path, s)
}
buf = []rune{}
}
stack := newStateStack(inIdentifier)
for _, char := range msg {
state := stack.peek()
if state == parsePathError {
break
}
switch char {
case '.':
switch state {
case inIdentifier:
consumeBuf()
case inEscape:
buf = append(buf, char)
stack.pop()
default:
buf = append(buf, char)
}
case '[':
switch state {
case inIdentifier, inBracket:
consumeBuf()
stack.push(inBracket)
case inEscape:
buf = append(buf, char)
stack.pop()
default:
buf = append(buf, char)
}
case ']':
switch state {
case inIdentifier:
stack.push(parsePathError)
case inEscape:
buf = append(buf, char)
stack.pop()
case inBracket:
consumeBuf()
stack.pop()
default:
buf = append(buf, char)
}
case '"':
switch state {
case inSingleQuote:
buf = append(buf, char)
case inEscape:
buf = append(buf, char)
stack.pop()
case inDoubleQuote:
consumeBuf()
stack.pop()
default:
stack.push(inDoubleQuote)
}
case '\'':
switch state {
case inDoubleQuote:
buf = append(buf, char)
case inEscape:
buf = append(buf, char)
stack.pop()
case inSingleQuote:
consumeBuf()
stack.pop()
default:
stack.push(inSingleQuote)
}
case '\\':
switch state {
case inEscape:
buf = append(buf, char)
stack.pop()
default:
stack.push(inEscape)
}
default:
buf = append(buf, char)
}
}
consumeBuf()
return path
}