mirror of
https://github.com/binwiederhier/ntfy.git
synced 2024-12-23 02:02:33 +01:00
307 lines
8.7 KiB
Go
307 lines
8.7 KiB
Go
package server
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import (
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"encoding/json"
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"errors"
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"fmt"
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"heckel.io/ntfy/util"
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"regexp"
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"strings"
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"unicode/utf8"
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)
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const (
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actionIDLength = 10
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actionEOF = rune(0)
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actionsMax = 3
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)
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const (
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actionView = "view"
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actionBroadcast = "broadcast"
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actionHTTP = "http"
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)
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var (
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actionsAll = []string{actionView, actionBroadcast, actionHTTP}
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actionsWithURL = []string{actionView, actionHTTP}
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actionsKeyRegex = regexp.MustCompile(`^([-.\w]+)\s*=\s*`)
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)
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type actionParser struct {
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input string
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pos int
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}
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// parseActions parses the actions string as described in https://ntfy.sh/docs/publish/#action-buttons.
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// It supports both a JSON representation (if the string begins with "[", see parseActionsFromJSON),
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// and the "simple" format, which is more human-readable, but harder to parse (see parseActionsFromSimple).
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func parseActions(s string) (actions []*action, err error) {
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// Parse JSON or simple format
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s = strings.TrimSpace(s)
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if strings.HasPrefix(s, "[") {
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actions, err = parseActionsFromJSON(s)
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} else {
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actions, err = parseActionsFromSimple(s)
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}
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if err != nil {
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return nil, err
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}
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// Add ID field, ensure correct uppercase/lowercase
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for i := range actions {
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actions[i].ID = util.RandomString(actionIDLength)
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actions[i].Action = strings.ToLower(actions[i].Action)
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actions[i].Method = strings.ToUpper(actions[i].Method)
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}
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// Validate
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if len(actions) > actionsMax {
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return nil, fmt.Errorf("only %d actions allowed", actionsMax)
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}
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for _, action := range actions {
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if !util.InStringList(actionsAll, action.Action) {
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return nil, fmt.Errorf("parameter 'action' cannot be '%s', valid values are 'view', 'broadcast' and 'http'", action.Action)
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} else if action.Label == "" {
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return nil, fmt.Errorf("parameter 'label' is required")
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} else if util.InStringList(actionsWithURL, action.Action) && action.URL == "" {
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return nil, fmt.Errorf("parameter 'url' is required for action '%s'", action.Action)
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} else if action.Action == actionHTTP && util.InStringList([]string{"GET", "HEAD"}, action.Method) && action.Body != "" {
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return nil, fmt.Errorf("parameter 'body' cannot be set if method is %s", action.Method)
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}
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}
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return actions, nil
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}
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// parseActionsFromJSON converts a JSON array into an array of actions
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func parseActionsFromJSON(s string) ([]*action, error) {
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actions := make([]*action, 0)
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if err := json.Unmarshal([]byte(s), &actions); err != nil {
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return nil, fmt.Errorf("JSON error: %w", err)
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}
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return actions, nil
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}
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// parseActionsFromSimple parses the "simple" actions string (as described in
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// https://ntfy.sh/docs/publish/#action-buttons), into an array of actions.
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//
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// It can parse an actions string like this:
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// view, "Look ma, commas and \"quotes\" too", url=https://..; action=broadcast, ...
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//
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// It works by advancing the position ("pos") through the input string ("input").
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//
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// The parser is heavily inspired by https://go.dev/src/text/template/parse/lex.go (which
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// is described by Rob Pike in this video: https://www.youtube.com/watch?v=HxaD_trXwRE),
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// though it does not use state functions at all.
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//
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// Other resources:
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// https://adampresley.github.io/2015/04/12/writing-a-lexer-and-parser-in-go-part-1.html
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// https://github.com/adampresley/sample-ini-parser/blob/master/services/lexer/lexer/Lexer.go
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// https://github.com/benbjohnson/sql-parser/blob/master/scanner.go
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// https://blog.gopheracademy.com/advent-2014/parsers-lexers/
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func parseActionsFromSimple(s string) ([]*action, error) {
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if !utf8.ValidString(s) {
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return nil, errors.New("invalid utf-8 string")
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}
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parser := &actionParser{
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pos: 0,
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input: s,
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}
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return parser.Parse()
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}
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// Parse loops trough parseAction() until the end of the string is reached
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func (p *actionParser) Parse() ([]*action, error) {
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actions := make([]*action, 0)
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for !p.eof() {
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a, err := p.parseAction()
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if err != nil {
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return nil, err
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}
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actions = append(actions, a)
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}
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return actions, nil
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}
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// parseAction parses the individual sections of an action using parseSection into key/value pairs,
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// and then uses populateAction to interpret the keys/values. The function terminates
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// when EOF or ";" is reached.
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func (p *actionParser) parseAction() (*action, error) {
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a := newAction()
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section := 0
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for {
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key, value, last, err := p.parseSection()
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if err != nil {
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return nil, err
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}
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if err := populateAction(a, section, key, value); err != nil {
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return nil, err
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}
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p.slurpSpaces()
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if last {
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return a, nil
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}
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section++
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}
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}
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// populateAction is the "business logic" of the parser. It applies the key/value
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// pair to the action instance.
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func populateAction(newAction *action, section int, key, value string) error {
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// Auto-expand keys based on their index
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if key == "" && section == 0 {
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key = "action"
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} else if key == "" && section == 1 {
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key = "label"
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} else if key == "" && section == 2 && util.InStringList(actionsWithURL, newAction.Action) {
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key = "url"
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}
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// Validate
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if key == "" {
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return fmt.Errorf("term '%s' unknown", value)
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}
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// Populate
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if strings.HasPrefix(key, "headers.") {
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newAction.Headers[strings.TrimPrefix(key, "headers.")] = value
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} else if strings.HasPrefix(key, "extras.") {
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newAction.Extras[strings.TrimPrefix(key, "extras.")] = value
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} else {
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switch strings.ToLower(key) {
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case "action":
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newAction.Action = value
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case "label":
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newAction.Label = value
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case "clear":
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lvalue := strings.ToLower(value)
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if !util.InStringList([]string{"true", "yes", "1", "false", "no", "0"}, lvalue) {
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return fmt.Errorf("parameter 'clear' cannot be '%s', only boolean values are allowed (true/yes/1/false/no/0)", value)
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}
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newAction.Clear = lvalue == "true" || lvalue == "yes" || lvalue == "1"
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case "url":
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newAction.URL = value
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case "method":
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newAction.Method = value
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case "body":
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newAction.Body = value
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default:
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return fmt.Errorf("key '%s' unknown", key)
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}
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}
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return nil
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}
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// parseSection parses a section ("key=value") and returns a key/value pair. It terminates
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// when EOF or "," is reached.
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func (p *actionParser) parseSection() (key string, value string, last bool, err error) {
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p.slurpSpaces()
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key = p.parseKey()
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r, w := p.peek()
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if isSectionEnd(r) {
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p.pos += w
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last = isLastSection(r)
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return
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} else if r == '"' || r == '\'' {
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value, last, err = p.parseQuotedValue(r)
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return
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}
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value, last = p.parseValue()
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return
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}
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// parseKey uses a regex to determine whether the current position is a key definition ("key =")
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// and returns the key if it is, or an empty string otherwise.
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func (p *actionParser) parseKey() string {
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matches := actionsKeyRegex.FindStringSubmatch(p.input[p.pos:])
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if len(matches) == 2 {
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p.pos += len(matches[0])
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return matches[1]
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}
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return ""
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}
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// parseValue reads the input until EOF, "," or ";" and returns the value string. Unlike parseQuotedValue,
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// this function does not support "," or ";" in the value itself, and spaces in the beginning and end of the
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// string are trimmed.
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func (p *actionParser) parseValue() (value string, last bool) {
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start := p.pos
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for {
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r, w := p.peek()
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if isSectionEnd(r) {
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last = isLastSection(r)
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value = strings.TrimSpace(p.input[start:p.pos])
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p.pos += w
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return
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}
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p.pos += w
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}
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}
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// parseQuotedValue reads the input until it finds an unescaped end quote character ("), and then
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// advances the position beyond the section end. It supports quoting strings using backslash (\).
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func (p *actionParser) parseQuotedValue(quote rune) (value string, last bool, err error) {
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p.pos++
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start := p.pos
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var prev rune
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for {
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r, w := p.peek()
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if r == actionEOF {
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err = fmt.Errorf("unexpected end of input, quote started at position %d", start)
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return
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} else if r == quote && prev != '\\' {
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value = strings.ReplaceAll(p.input[start:p.pos], "\\"+string(quote), string(quote)) // \" -> "
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p.pos += w
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// Advance until section end (after "," or ";")
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p.slurpSpaces()
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r, w := p.peek()
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last = isLastSection(r)
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if !isSectionEnd(r) {
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err = fmt.Errorf("unexpected character '%c' at position %d", r, p.pos)
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return
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}
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p.pos += w
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return
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}
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prev = r
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p.pos += w
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}
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}
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// slurpSpaces reads all space characters and advances the position
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func (p *actionParser) slurpSpaces() {
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for {
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r, w := p.peek()
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if r == actionEOF || !isSpace(r) {
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return
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}
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p.pos += w
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}
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}
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// peek returns the next run and its width
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func (p *actionParser) peek() (rune, int) {
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if p.eof() {
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return actionEOF, 0
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}
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return utf8.DecodeRuneInString(p.input[p.pos:])
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}
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// eof returns true if the end of the input has been reached
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func (p *actionParser) eof() bool {
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return p.pos >= len(p.input)
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}
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func isSpace(r rune) bool {
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return r == ' ' || r == '\t' || r == '\r' || r == '\n'
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}
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func isSectionEnd(r rune) bool {
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return r == actionEOF || r == ';' || r == ','
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}
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func isLastSection(r rune) bool {
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return r == actionEOF || r == ';'
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}
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