bbe748bd2b
Factor out most of the tag edit logic from the Post class to a new PostEdit class. The PostEdit class contains the logic for parsing tags and metatags from the tag edit string, and for determining which tags were added or removed by the edit. Fixes various bugs caused by not calculating the set of added or removed tags correctly, for example when tag category prefixes were used (e.g. `copy:touhou`) or when the same tag was added and removed in the same edit (e.g. `touhou -touhou`). Fixes #5123: Tag categorization prefixes bypass deprecation check Fixes #5126: Negating a deprecated tag will still cause the warning to show Fixes #3477: Remove tag validator triggering on tag category changes Fixes #4848: newpool: metatag doesn't parse correctly
110 lines
2.9 KiB
Ruby
110 lines
2.9 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
require "strscan"
|
|
|
|
# A StringParser is a wrapper around StringScanner that adds extra
|
|
# helper methods for writing parser-combinator style parsers.
|
|
#
|
|
# @see StringScanner
|
|
# @see https://hmac.dev/posts/2019-05-19-ruby-parser-combinators.html
|
|
class StringParser
|
|
class Error < StandardError; end
|
|
|
|
attr_reader :input
|
|
attr_accessor :state
|
|
private attr_reader :scanner
|
|
|
|
delegate :rest, :eos?, to: :scanner
|
|
|
|
# @param input [String] The string to parse.
|
|
# @param state [Object] An arbitrary piece of user-defined state. Will be
|
|
# rolled back when the parser backtracks or is reset.
|
|
def initialize(input, state: nil)
|
|
@input = input.to_s.clone.freeze
|
|
@state = state
|
|
@scanner = StringScanner.new(@input)
|
|
end
|
|
|
|
# Try to match `pattern`, returning the string if it matched or nil if it didn't.
|
|
#
|
|
# @param pattern [Regexp, String] The pattern to match.
|
|
# @return [String, nil] The matched string, or nil
|
|
def accept(pattern)
|
|
scanner.scan(pattern)
|
|
end
|
|
|
|
# Skip over `pattern`, returning true if it was skipped or false if it wasn't.
|
|
#
|
|
# @param pattern [Regexp, String] The pattern to match.
|
|
# @return [Boolean] True if the pattern was skipped, false otherwise.
|
|
def skip(pattern)
|
|
scanner.scan(pattern) != nil
|
|
end
|
|
|
|
# Try to match `pattern`, returning the string if it matched or raising an Error if it didn't.
|
|
#
|
|
# @param pattern [Regexp, String] The pattern to match.
|
|
# @return [String] The matched string
|
|
# @raise [Error] If the pattern didn't match
|
|
def expect(pattern)
|
|
str = scanner.scan(pattern)
|
|
error("Expected '#{pattern}'; got '#{str}'") if str.nil?
|
|
str
|
|
end
|
|
|
|
# Move the scan pointer back N characters (default: 1)
|
|
#
|
|
# @param n [Integer] The number of characters to move back (default: 1).
|
|
def rewind(n = 1)
|
|
scanner.pos -= n
|
|
end
|
|
|
|
# Raise a parse error.
|
|
#
|
|
# @param message [String] The parse error message.
|
|
# @raise [Error]
|
|
def error(message)
|
|
raise Error, message
|
|
end
|
|
|
|
# Try to parse the given block, backtracking to the previous state if the parse failed.
|
|
def backtrack(&block)
|
|
saved_pos = scanner.pos
|
|
saved_state = state.deep_dup
|
|
error("Unexpected EOS") if scanner.eos?
|
|
yield
|
|
rescue Error
|
|
scanner.pos = saved_pos
|
|
self.state = saved_state
|
|
raise
|
|
end
|
|
|
|
# Parse the block zero or more times, returning an array of parse results.
|
|
def zero_or_more(&block)
|
|
matches = []
|
|
loop do
|
|
matches << backtrack { yield }
|
|
end
|
|
rescue Error
|
|
matches
|
|
end
|
|
|
|
# Parse the block one or more times, returning an array of parse results.
|
|
def one_or_more(&block)
|
|
first = yield
|
|
rest = zero_or_more(&block)
|
|
[first, *rest]
|
|
end
|
|
|
|
# Given a list of parsers, try each in sequence and return the first one that succeeds.
|
|
def one_of(parsers)
|
|
parsers.each do |parser|
|
|
return backtrack { parser.call }
|
|
rescue Error
|
|
next
|
|
end
|
|
|
|
error("expected one of: #{parsers}")
|
|
end
|
|
end
|