Initial token parser combinator
In an attempt to make our deck serializer more localized, comprehensible, and less error-prone, we introduce a new parser combinator based around string tokens. This replaces the Selection-based intermediary types so that we have a more direct serialization style.
This commit is contained in:
William Casarin
@@ -1,5 +1,8 @@
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mod decks;
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mod migration;
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mod token_parser;
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pub use decks::{load_decks_cache, save_decks_cache, DECKS_CACHE_FILE};
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pub use migration::{deserialize_columns, COLUMNS_FILE};
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pub use token_parser::{ParseError, TokenParser, TokenSerializable};
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177
crates/notedeck_columns/src/storage/token_parser.rs
Normal file
177
crates/notedeck_columns/src/storage/token_parser.rs
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@@ -0,0 +1,177 @@
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use crate::timeline::kind::PubkeySource;
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use enostr::Pubkey;
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#[derive(Debug, Clone)]
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pub struct UnexpectedToken<'fnd, 'exp> {
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pub expected: &'exp str,
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pub found: &'fnd str,
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}
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#[derive(Debug, Clone)]
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pub enum ParseError<'a> {
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/// Not done parsing yet
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Incomplete,
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/// All parsing options failed
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AltAllFailed,
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/// There was some issue decoding the data
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DecodeFailed,
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/// We encountered an unexpected token
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UnexpectedToken(UnexpectedToken<'a, 'static>),
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/// No more tokens
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EOF,
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}
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#[derive(Clone)]
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pub struct TokenParser<'a> {
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tokens: &'a [&'a str],
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index: usize,
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}
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fn _parse_pubkey_src_tokens<'a>(
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parser: &mut TokenParser<'a>,
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) -> Result<PubkeySource, ParseError<'a>> {
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match parser.pull_token() {
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// we handle bare payloads and assume they are explicit pubkey sources
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Ok("explicit") => {
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let hex_str = parser.pull_token()?;
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Pubkey::from_hex(hex_str)
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.map_err(|_| ParseError::DecodeFailed)
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.map(PubkeySource::Explicit)
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}
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Err(ParseError::EOF) | Ok("deck_author") => Ok(PubkeySource::DeckAuthor),
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Ok(hex_payload) => Pubkey::from_hex(hex_payload)
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.map_err(|_| ParseError::DecodeFailed)
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.map(PubkeySource::Explicit),
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Err(e) => Err(e),
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}
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}
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impl<'a> TokenParser<'a> {
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/// alt tries each parser in `routes` until one succeeds.
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/// If all fail, returns `ParseError::AltAllFailed`.
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#[allow(clippy::type_complexity)]
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pub fn alt<R>(
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parser: &mut TokenParser<'a>,
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routes: &[fn(&mut TokenParser<'a>) -> Result<R, ParseError<'a>>],
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) -> Result<R, ParseError<'a>> {
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let start = parser.index;
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for route in routes {
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match route(parser) {
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Ok(r) => return Ok(r), // if success, stop trying more routes
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Err(_) => {
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// revert index & try next route
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parser.index = start;
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}
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}
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}
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// if we tried them all and none succeeded
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Err(ParseError::AltAllFailed)
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}
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pub fn new(tokens: &'a [&'a str]) -> Self {
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let index = 0;
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Self { tokens, index }
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}
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pub fn parse_token(&mut self, expected: &'static str) -> Result<&'a str, ParseError<'a>> {
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let found = self.pull_token()?;
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if found == expected {
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Ok(found)
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} else {
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Err(ParseError::UnexpectedToken(UnexpectedToken {
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expected,
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found,
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}))
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}
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}
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/// “Parse all” meaning: run the provided closure. If it fails, revert
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/// the index.
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pub fn parse_all<R>(
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&mut self,
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parse_fn: impl FnOnce(&mut Self) -> Result<R, ParseError<'a>>,
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) -> Result<R, ParseError<'a>> {
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let start = self.index;
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let result = parse_fn(self);
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// If the parser closure fails, revert the index
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if result.is_err() {
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self.index = start;
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result
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} else if !self.is_eof() {
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Err(ParseError::Incomplete)
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} else {
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result
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}
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}
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pub fn pull_token(&mut self) -> Result<&'a str, ParseError<'a>> {
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let token = self
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.tokens
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.get(self.index)
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.copied()
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.ok_or(ParseError::EOF)?;
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self.index += 1;
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Ok(token)
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}
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pub fn unpop_token(&mut self) {
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if (self.index as isize) - 1 < 0 {
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return;
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}
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self.index -= 1;
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}
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#[inline]
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pub fn tokens(&self) -> &'a [&'a str] {
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let min_index = self.index.min(self.tokens.len());
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&self.tokens[min_index..]
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}
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#[inline]
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pub fn is_eof(&self) -> bool {
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self.tokens().is_empty()
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}
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}
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pub trait TokenSerializable: Sized {
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/// Return a list of serialization plans for a type. We do this for
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/// type safety and assume constructing these types are lightweight
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fn parse<'a>(parser: &mut TokenParser<'a>) -> Result<Self, ParseError<'a>>;
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_column_serialize() {
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use crate::ui::add_column::{AddAlgoRoute, AddColumnRoute};
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{
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let data = &"column:algo_selection:last_per_pubkey"
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.split(":")
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.collect::<Vec<&str>>();
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let mut parser = TokenParser::new(&data);
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let parsed = AddColumnRoute::parse(&mut parser).unwrap();
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let expected = AddColumnRoute::Algo(AddAlgoRoute::LastPerPubkey);
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assert_eq!(expected, parsed)
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}
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{
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let data: &[&str] = &["column"];
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let mut parser = TokenParser::new(data);
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let parsed = AddColumnRoute::parse(&mut parser).unwrap();
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let expected = AddColumnRoute::Base;
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assert_eq!(expected, parsed)
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}
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}
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}
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@@ -11,6 +11,7 @@ use nostrdb::{Ndb, Transaction};
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use crate::{
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login_manager::AcquireKeyState,
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route::Route,
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storage::{ParseError, TokenParser, TokenSerializable},
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timeline::{kind::ListKind, PubkeySource, Timeline, TimelineKind},
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ui::anim::ICON_EXPANSION_MULTIPLE,
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Damus,
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@@ -61,8 +62,9 @@ enum AddColumnOption {
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Individual(PubkeySource),
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}
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#[derive(Clone, Copy, Eq, PartialEq, Debug)]
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#[derive(Clone, Copy, Eq, PartialEq, Debug, Default)]
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pub enum AddAlgoRoute {
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#[default]
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Base,
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LastPerPubkey,
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}
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@@ -78,6 +80,67 @@ pub enum AddColumnRoute {
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ExternalIndividual,
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}
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impl TokenSerializable for AddColumnRoute {
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fn parse<'a>(parser: &mut TokenParser<'a>) -> Result<Self, ParseError<'a>> {
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// all start with column
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parser.parse_token("column")?;
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// if we're done then we have the base
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if parser.is_eof() {
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return Ok(AddColumnRoute::Base);
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}
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TokenParser::alt(
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parser,
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&[
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|p| {
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p.parse_all(|p| {
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p.parse_token("external_notif_selection")?;
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Ok(AddColumnRoute::UndecidedNotification)
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})
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},
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|p| {
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p.parse_all(|p| {
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p.parse_token("external_notif_selection")?;
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Ok(AddColumnRoute::ExternalNotification)
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})
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},
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|p| {
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p.parse_all(|p| {
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p.parse_token("hashtag_selection")?;
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Ok(AddColumnRoute::Hashtag)
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})
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},
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|p| {
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p.parse_all(|p| {
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p.parse_token("algo_selection")?;
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Ok(AddColumnRoute::Algo(AddAlgoRoute::Base))
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})
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},
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|p| {
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p.parse_all(|p| {
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p.parse_token("algo_selection")?;
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p.parse_token("last_per_pubkey")?;
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Ok(AddColumnRoute::Algo(AddAlgoRoute::LastPerPubkey))
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})
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},
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|p| {
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p.parse_all(|p| {
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p.parse_token("individual_selection")?;
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Ok(AddColumnRoute::UndecidedIndividual)
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})
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},
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|p| {
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p.parse_all(|p| {
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p.parse_token("external_individual_selection")?;
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Ok(AddColumnRoute::ExternalIndividual)
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})
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},
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],
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)
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}
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}
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impl AddColumnOption {
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pub fn take_as_response(
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self,
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