validates_timeliness/lib/validates_timeliness/parser.rb
2010-10-11 15:49:01 +11:00

401 lines
13 KiB
Ruby

require 'date'
module ValidatesTimeliness
# A date and time parsing library which allows you to add custom formats using
# simple predefined tokens. This makes it much easier to catalogue and customize
# the formats rather than dealing directly with regular expressions.
#
# Formats can be added or removed to customize the set of valid date or time
# string values.
#
module Parser
mattr_reader :time_expressions, :date_expressions, :datetime_expressions
# Set the threshold value for a two digit year to be considered last century
#
# Default: 30
#
# Example:
# year = '29' is considered 2029
# year = '30' is considered 1930
#
mattr_accessor :ambiguous_year_threshold
self.ambiguous_year_threshold = 30
# Format tokens:
# y = year
# m = month
# d = day
# h = hour
# n = minute
# s = second
# u = micro-seconds
# ampm = meridian (am or pm) with or without dots (e.g. am, a.m, or a.m.)
# _ = optional space
# tz = Timezone abbreviation (e.g. UTC, GMT, PST, EST)
# zo = Timezone offset (e.g. +10:00, -08:00, +1000)
#
# All other characters are considered literal. You can embed regexp in the
# format but no guarantees that it will remain intact. If you avoid the use
# of any token characters and regexp dots or backslashes as special characters
# in the regexp, it may well work as expected. For special characters use
# POSIX character classes for safety.
#
# Repeating tokens:
# x = 1 or 2 digits for unit (e.g. 'h' means an hour can be '9' or '09')
# xx = 2 digits exactly for unit (e.g. 'hh' means an hour can only be '09')
#
# Special Cases:
# yy = 2 or 4 digit year
# yyyy = exactly 4 digit year
# mmm = month long name (e.g. 'Jul' or 'July')
# ddd = Day name of 3 to 9 letters (e.g. Wed or Wednesday)
# u = microseconds matches 1 to 6 digits
#
# Any other invalid combination of repeating tokens will be swallowed up
# by the next lowest length valid repeating token (e.g. yyy will be
# replaced with yy)
mattr_accessor :time_formats
@@time_formats = [
'hh:nn:ss',
'hh-nn-ss',
'h:nn',
'h.nn',
'h nn',
'h-nn',
'h:nn_ampm',
'h.nn_ampm',
'h nn_ampm',
'h-nn_ampm',
'h_ampm'
]
mattr_accessor :date_formats
@@date_formats = [
'yyyy-mm-dd',
'yyyy/mm/dd',
'yyyy.mm.dd',
'm/d/yy',
'd/m/yy',
'm\d\yy',
'd\m\yy',
'd-m-yy',
'dd-mm-yyyy',
'd.m.yy',
'd mmm yy'
]
mattr_accessor :datetime_formats
@@datetime_formats = [
'yyyy-mm-dd hh:nn:ss',
'yyyy-mm-dd h:nn',
'yyyy-mm-dd h:nn_ampm',
'yyyy-mm-dd hh:nn:ss.u',
'm/d/yy h:nn:ss',
'm/d/yy h:nn_ampm',
'm/d/yy h:nn',
'd/m/yy hh:nn:ss',
'd/m/yy h:nn_ampm',
'd/m/yy h:nn',
'dd-mm-yyyy hh:nn:ss',
'dd-mm-yyyy h:nn_ampm',
'dd-mm-yyyy h:nn',
'ddd, dd mmm yyyy hh:nn:ss (zo|tz)', # RFC 822
'ddd mmm d hh:nn:ss zo yyyy', # Ruby time string
'yyyy-mm-ddThh:nn:ssZ', # iso 8601 without zone offset
'yyyy-mm-ddThh:nn:sszo' # iso 8601 with zone offset
]
# All tokens available for format construction. The token array is made of
# regexp and key for format component mapping, if any.
#
mattr_accessor :format_tokens
@@format_tokens = {
'ddd' => [ '\w{3,9}' ],
'dd' => [ '\d{2}', :day ],
'd' => [ '\d{1,2}', :day ],
'mmm' => [ '\w{3,9}', :month ],
'mm' => [ '\d{2}', :month ],
'm' => [ '\d{1,2}', :month ],
'yyyy' => [ '\d{4}', :year ],
'yy' => [ '\d{4}|\d{2}', :year ],
'hh' => [ '\d{2}', :hour ],
'h' => [ '\d{1,2}', :hour ],
'nn' => [ '\d{2}', :min ],
'n' => [ '\d{1,2}', :min ],
'ss' => [ '\d{2}', :sec ],
's' => [ '\d{1,2}', :sec ],
'u' => [ '\d{1,6}', :usec ],
'ampm' => [ '[aApP]\.?[mM]\.?', :meridian ],
'zo' => [ '[+-]\d{2}:?\d{2}', :offset ],
'tz' => [ '[A-Z]{1,4}' ],
'_' => [ '\s?' ]
}
# Component argument values will be passed to the format method if matched in
# the time string. The key should match the key defined in the format tokens.
#
# The array consists of the position the value should be inserted in
# the time array, and the code to place in the time array.
#
# If the position is nil, then the value won't be put in the time array. If the
# code slot is empty, then just the raw value is used.
#
mattr_accessor :format_components
@@format_components = {
:year => [ 0, 'unambiguous_year(year)'],
:month => [ 1, 'month_index(month)'],
:day => [ 2 ],
:hour => [ 3, 'full_hour(hour, meridian ||= nil)'],
:min => [ 4 ],
:sec => [ 5 ],
:usec => [ 6, 'microseconds(usec)'],
:offset => [ 7, 'offset_in_seconds(offset)'],
:meridian => [ nil ]
}
@@type_wrapper = {
:date => [/\A/, nil],
:time => [nil , /\Z/],
:datetime => [/\A/, /\Z/]
}
class << self
def compile_format_expressions
@@time_expressions = compile_formats(@@time_formats)
@@date_expressions = compile_formats(@@date_formats)
@@datetime_expressions = compile_formats(@@datetime_formats)
end
def parse(value, type, options={})
return value unless value.is_a?(String)
time_array = _parse(value, type, options.reverse_merge(:strict => true))
return nil if time_array.nil?
if type == :date
Date.new(*time_array[0..2]) rescue nil
else
make_time(time_array[0..7], options[:timezone_aware])
end
end
def make_time(time_array, timezone_aware=false)
# Enforce strict date part validity which Time class does not
return nil unless Date.valid_civil?(*time_array[0..2])
if timezone_aware
Time.zone.local(*time_array)
else
Time.time_with_datetime_fallback(ValidatesTimeliness.default_timezone, *time_array)
end
rescue ArgumentError, TypeError
nil
end
# Loop through format expressions for type and call the format method on a match.
# Allow pre or post match strings to exist if strict is false. Otherwise wrap
# regexp in start and end anchors.
#
# Returns time array if matches a format, nil otherwise.
#
def _parse(string, type, options={})
options.reverse_merge!(:strict => true)
sets = if options[:format]
options[:strict] = true
[ send("#{type}_expressions").assoc(options[:format]) ]
else
expression_set(type, string)
end
set = sets.find do |format, regexp|
string =~ wrap_regexp(regexp, type, options[:strict])
end
if set
last = options[:include_offset] ? 8 : 7
values = send(:"format_#{set[0]}", *$~[1..last])
values[0..2] = ValidatesTimeliness.dummy_date_for_time_type if type == :time
return values
end
rescue
nil
end
# Delete formats of specified type. Error raised if format not found.
#
def remove_formats(type, *remove_formats)
remove_formats.each do |format|
unless self.send("#{type}_formats").delete(format)
raise "Format #{format} not found in #{type} formats"
end
end
compile_format_expressions
end
# Adds new formats. Must specify format type and can specify a :before
# option to nominate which format the new formats should be inserted in
# front on to take higher precedence.
#
# Error is raised if format already exists or if :before format is not found.
#
def add_formats(type, *add_formats)
formats = self.send("#{type}_formats")
options = {}
options = add_formats.pop if add_formats.last.is_a?(Hash)
before = options[:before]
raise "Format for :before option #{format} was not found." if before && !formats.include?(before)
add_formats.each do |format|
raise "Format #{format} is already included in #{type} formats" if formats.include?(format)
index = before ? formats.index(before) : -1
formats.insert(index, format)
end
compile_format_expressions
end
# Removes formats where the 1 or 2 digit month comes first, to eliminate
# formats which are ambiguous with the European style of day then month.
# The mmm token is ignored as its not ambiguous.
#
def remove_us_formats
us_format_regexp = /\Am{1,2}[^m]/
date_formats.reject! { |format| us_format_regexp =~ format }
datetime_formats.reject! { |format| us_format_regexp =~ format }
compile_format_expressions
end
def full_hour(hour, meridian)
hour = hour.to_i
return hour if meridian.nil?
if meridian.delete('.').downcase == 'am'
raise if hour == 0 || hour > 12
hour == 12 ? 0 : hour
else
hour == 12 ? hour : hour + 12
end
end
def unambiguous_year(year)
if year.length <= 2
century = Time.now.year.to_s[0..1].to_i
century -= 1 if year.to_i >= ambiguous_year_threshold
year = "#{century}#{year.rjust(2,'0')}"
end
year.to_i
end
def month_index(month)
return month.to_i if month.to_i.nonzero?
abbr_month_names.index(month.capitalize) || month_names.index(month.capitalize)
end
def month_names
I18n.t('date.month_names')
end
def abbr_month_names
I18n.t('date.abbr_month_names')
end
def microseconds(usec)
(".#{usec}".to_f * 1_000_000).to_i
end
def offset_in_seconds(offset)
sign = offset =~ /^-/ ? -1 : 1
parts = offset.scan(/\d\d/).map {|p| p.to_f }
parts[1] = parts[1].to_f / 60
(parts[0] + parts[1]) * sign * 3600
end
private
# Generate regular expression from format string
def generate_format_expression(string_format)
format = string_format.dup
format.gsub!(/([\.\\])/, '\\\\\1') # escapes dots and backslashes
found_tokens, token_order = [], []
tokens = format_tokens.keys.sort {|a,b| a.size <=> b.size }.reverse
# Substitute tokens with numbered placeholder
tokens.each do |token|
regexp_str, arg_key = *format_tokens[token]
if format.gsub!(/#{token}/, "%<#{found_tokens.size}>")
regexp_str = "(#{regexp_str})" if arg_key
found_tokens << [regexp_str, arg_key]
end
end
# Replace placeholders with token regexps
format.scan(/%<(\d)>/).each {|token_index|
token_index = token_index.first
token = found_tokens[token_index.to_i]
format.gsub!("%<#{token_index}>", token[0])
token_order << token[1]
}
compile_format_method(token_order.compact, string_format)
Regexp.new(format)
rescue
raise "The following format regular expression failed to compile: #{format}\n from format #{string_format}."
end
# Compiles a format method which maps the regexp capture groups to method
# arguments based on order captured. A time array is built using the argument
# values placed in the position defined by the component.
#
def compile_format_method(components, name)
values = [nil] * 7
components.each do |component|
position, code = *format_components[component]
values[position] = code || "#{component}.to_i" if position
end
class_eval <<-DEF
class << self
define_method(:"format_#{name}") do |#{components.join(',')}|
[#{values.map {|i| i || 'nil' }.join(',')}]
end
end
DEF
end
def compile_formats(formats)
formats.map { |format| [ format, generate_format_expression(format) ] }
end
# Pick expression set and combine date and datetimes for
# datetime attributes to allow date string as datetime
def expression_set(type, string)
case type
when :date
date_expressions
when :time
time_expressions
when :datetime
# gives a speed-up for date string as datetime attributes
if string.length < 11
date_expressions + datetime_expressions
else
datetime_expressions + date_expressions
end
end
end
def wrap_regexp(regexp, type, strict=false)
type = strict ? :datetime : type
/#{@@type_wrapper[type][0]}#{regexp}#{@@type_wrapper[type][1]}/
end
end
end
end
ValidatesTimeliness::Parser.compile_format_expressions