/
parser.ex
429 lines (348 loc) · 12.3 KB
/
parser.ex
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
defmodule Crontab.CronExpression.Parser do
@moduledoc """
Parse string like `* * * * * *` to a `%Crontab.CronExpression{}`.
"""
alias Crontab.CronExpression
@type result :: {:ok, CronExpression.t()} | {:error, binary}
@specials %{
reboot: %CronExpression{reboot: true},
yearly: %CronExpression{minute: [0], hour: [0], day: [1], month: [1]},
annually: %CronExpression{minute: [0], hour: [0], day: [1], month: [1]},
monthly: %CronExpression{minute: [0], hour: [0], day: [1]},
weekly: %CronExpression{minute: [0], hour: [0], weekday: [0]},
daily: %CronExpression{minute: [0], hour: [0]},
midnight: %CronExpression{minute: [0], hour: [0]},
hourly: %CronExpression{minute: [0]},
minutely: %CronExpression{},
secondly: %CronExpression{extended: true}
}
@intervals [
:minute,
:hour,
:day,
:month,
:weekday,
:year
]
@extended_intervals [:second | @intervals]
@second_values 0..59
@minute_values 0..59
@hour_values 0..23
@day_of_month_values 1..31
@weekday_values %{
MON: 1,
TUE: 2,
WED: 3,
THU: 4,
FRI: 5,
SAT: 6,
SUN: 7
}
# Sunday can be represented by 0 or 7.
@full_weekday_values [0] ++ Map.values(@weekday_values)
@month_values %{
JAN: 1,
FEB: 2,
MAR: 3,
APR: 4,
MAY: 5,
JUN: 6,
JUL: 7,
AUG: 8,
SEP: 9,
OCT: 10,
NOV: 11,
DEC: 12
}
@doc """
Parse string like `* * * * * *` to a `%CronExpression{}`.
## Examples
iex> Crontab.CronExpression.Parser.parse "* * * * *"
{:ok,
%Crontab.CronExpression{day: [:*], hour: [:*], minute: [:*],
month: [:*], weekday: [:*], year: [:*]}}
iex> Crontab.CronExpression.Parser.parse "* * * * *", true
{:ok,
%Crontab.CronExpression{extended: true, day: [:*], hour: [:*], minute: [:*],
month: [:*], weekday: [:*], year: [:*], second: [:*]}}
iex> Crontab.CronExpression.Parser.parse "fooo"
{:error, "Can't parse fooo as minute."}
"""
@spec parse(binary, boolean) :: result
def parse(cron_expression, extended \\ false)
def parse("@" <> identifier, _) do
special(String.downcase(identifier))
end
def parse(cron_expression, true) do
interpret(String.split(cron_expression, " "), @extended_intervals, %CronExpression{
extended: true
})
end
def parse(cron_expression, false) do
interpret(String.split(cron_expression, " "), @intervals, %CronExpression{})
end
@doc """
Parse string like `* * * * * *` to a `%CronExpression{}`.
## Examples
iex> Crontab.CronExpression.Parser.parse! "* * * * *"
%Crontab.CronExpression{day: [:*], hour: [:*], minute: [:*],
month: [:*], weekday: [:*], year: [:*]}
iex> Crontab.CronExpression.Parser.parse! "* * * * *", true
%Crontab.CronExpression{extended: true, day: [:*], hour: [:*], minute: [:*],
month: [:*], weekday: [:*], year: [:*], second: [:*]}
iex> Crontab.CronExpression.Parser.parse! "fooo"
** (RuntimeError) Can't parse fooo as minute.
"""
@spec parse!(binary, boolean) :: CronExpression.t() | no_return
def parse!(cron_expression, extended \\ false) do
case parse(cron_expression, extended) do
{:ok, result} -> result
{:error, error} -> raise error
end
end
@spec interpret([binary], [CronExpression.interval()], CronExpression.t()) ::
{:ok, CronExpression.t()} | {:error, binary}
defp interpret(
[head_format | tail_format],
[head_expression | tail_expression],
cron_expression
) do
conditions = interpret(head_expression, head_format)
case conditions do
{:ok, ok_conditions} ->
patched_cron_expression = Map.put(cron_expression, head_expression, ok_conditions)
interpret(tail_format, tail_expression, patched_cron_expression)
_ ->
conditions
end
end
defp interpret([], _, cron_expression), do: {:ok, cron_expression}
defp interpret(_, [], _), do: {:error, "The Cron Format String contains too many parts."}
@spec interpret(CronExpression.interval(), binary) ::
{:ok, [CronExpression.value()]} | {:error, binary}
defp interpret(interval, format) do
parts = String.split(format, ",")
tokens = Enum.map(parts, fn part -> tokenize(interval, part) end)
if get_failed_token(tokens) do
get_failed_token(tokens)
else
{:ok, Enum.map(tokens, fn {:ok, token} -> token end)}
end
end
@spec get_failed_token([{:error, binary}] | CronExpression.value()) :: {:error, binary} | nil
defp get_failed_token(tokens) do
Enum.find(tokens, fn token ->
case token do
{:error, _} -> true
_ -> false
end
end)
end
@spec tokenize(CronExpression.interval(), binary) ::
{:ok, CronExpression.value()} | {:error, binary}
defp tokenize(_, "*"), do: {:ok, :*}
defp tokenize(interval, other) do
cond do
String.contains?(other, "/") -> tokenize(interval, :complex_divider, other)
Regex.match?(~r/^.+-.+$/, other) -> tokenize(interval, :-, other)
true -> tokenize(interval, :single_value, other)
end
end
@spec tokenize(CronExpression.interval(), :- | :single_value | :complex_divider) ::
{:ok, CronExpression.value()} | {:error, binary}
defp tokenize(interval, :-, whole_string) do
case String.split(whole_string, "-") do
[min, max] ->
case {clean_value(interval, min), clean_value(interval, max)} do
{{:ok, min_value}, {:ok, max_value}} -> {:ok, {:-, min_value, max_value}}
{error = {:error, _}, _} -> error
{_, error = {:error, _}} -> error
end
_ ->
{:error, "Can't parse #{whole_string} as a range."}
end
end
defp tokenize(interval, :single_value, value) do
clean_value(interval, value)
end
defp tokenize(interval, :complex_divider, value) do
[base, divider] = String.split(value, "/")
# Range increments apply only to * or ranges in <start>-<end> format
range_tokenization_result = tokenize(interval, :-, base)
other_tokenization_result = tokenize(interval, base)
integer_divider = Integer.parse(divider, 10)
case {range_tokenization_result, other_tokenization_result, integer_divider} do
# Invalid increment
{_, _, {_clean_divider, remainder}} when remainder != "" ->
{:error, "Can't parse #{divider} as increment."}
# Zero increment
{_, _, {0, ""}} ->
{:error, "Can't parse #{divider} as increment."}
# Found range in <start>-<end> format
{{:ok, clean_base}, _, {clean_divider, ""}} ->
{:ok, {:/, clean_base, clean_divider}}
# Found star (*) range
{{:error, _}, {:ok, :*}, {clean_divider, ""}} ->
{:ok, {:/, :*, clean_divider}}
# No valid range found
{error = {:error, _}, _, _} ->
error
end
end
@spec clean_value(CronExpression.interval(), binary) ::
{:ok, CronExpression.value()} | {:error, binary}
defp clean_value(:second, value) do
clean_integer_within_range(value, "second", @second_values)
end
defp clean_value(:minute, value) do
clean_integer_within_range(value, "minute", @minute_values)
end
defp clean_value(:hour, value) do
clean_integer_within_range(value, "hour", @hour_values)
end
defp clean_value(:weekday, "L"), do: {:ok, 7}
defp clean_value(:weekday, value) do
# Sunday can be represented by 0 or 7
cond do
String.match?(value, ~r/L$/) ->
parse_last_week_day(value)
String.match?(value, ~r/#\d+$/) ->
parse_nth_week_day(value)
true ->
case parse_week_day(value) do
{:ok, number} ->
check_within_range(number, "day of week", @full_weekday_values)
error ->
error
end
end
end
defp clean_value(:month, "L"), do: {:ok, 12}
defp clean_value(:month, value) do
error_message = "Can't parse #{value} as month."
result =
case {fetch_month_value(String.upcase(value)), Integer.parse(value, 10)} do
# No valid month string or integer
{:error, :error} -> {:error, error_message}
# Month specified as string
{{:ok, number}, :error} -> {:ok, number}
# Month specified as integer
{:error, {number, ""}} -> {:ok, number}
# Integer is followed by an unwanted trailing string
{:error, {_number, _remainder}} -> {:error, error_message}
end
case result do
{:ok, number} ->
month_numbers = Map.values(@month_values)
check_within_range(number, "month", month_numbers)
error ->
error
end
end
defp clean_value(:day, "L"), do: {:ok, :L}
defp clean_value(:day, "LW"), do: {:ok, {:W, :L}}
defp clean_value(:day, value) do
if String.match?(value, ~r/W$/) do
day = binary_part(value, 0, byte_size(value) - 1)
case Integer.parse(day, 10) do
{number, ""} ->
case check_within_range(number, "day of month", @day_of_month_values) do
{:ok, number} -> {:ok, {:W, number}}
error -> error
end
:error ->
{:error, "Can't parse " <> value <> " as interval day."}
end
else
clean_integer_within_range(value, "day of month", @day_of_month_values)
end
end
defp clean_value(interval, value) do
case Integer.parse(value, 10) do
{number, ""} ->
{:ok, number}
:error ->
{:error, "Can't parse " <> value <> " as interval " <> Atom.to_string(interval) <> "."}
end
end
@spec clean_integer_within_range(binary, binary, Range.t()) ::
{:ok, CronExpression.value()} | {:error, binary}
defp clean_integer_within_range(value, field_name, valid_values) do
case Integer.parse(value, 10) do
{number, ""} ->
check_within_range(number, field_name, valid_values)
_ ->
{:error, "Can't parse #{value} as #{field_name}."}
end
end
@spec check_within_range(number, binary, Enum.t()) ::
{:ok, CronExpression.value()} | {:error, binary}
defp check_within_range(number, field_name, valid_values) do
if number in valid_values do
{:ok, number}
else
{:error, "Can't parse #{number} as #{field_name}."}
end
end
@spec parse_week_day(binary) :: {:ok, CronExpression.value()} | {:error, binary}
defp parse_week_day(value) do
error_message = "Can't parse #{value} as day of week."
case {fetch_weekday_value(String.upcase(value)), Integer.parse(value, 10)} do
{:error, :error} -> {:error, error_message}
{{:ok, number}, :error} -> {:ok, number}
{:error, {number, ""}} -> {:ok, number}
{:error, {_number, _remainder}} -> {:error, error_message}
end
end
@spec parse_last_week_day(binary) :: {:ok, CronExpression.value()} | {:error, binary}
defp parse_last_week_day(value) do
case parse_week_day(binary_part(value, 0, byte_size(value) - 1)) do
{:ok, value} ->
case check_within_range(value, "day of week", @full_weekday_values) do
{:ok, number} -> {:ok, {:L, number}}
error -> error
end
error = {:error, _} ->
error
end
end
@spec parse_nth_week_day(binary) :: {:ok, CronExpression.value()} | {:error, binary}
defp parse_nth_week_day(value) do
[weekday, n] = String.split(value, "#")
case parse_week_day(weekday) do
{:ok, value} ->
{n_int, ""} = Integer.parse(n)
case check_within_range(value, "day of week", @full_weekday_values) do
{:ok, number} ->
{:ok, {:"#", number, n_int}}
error ->
error
end
error = {:error, _} ->
error
end
end
@spec fetch_weekday_value(binary) :: {:ok, integer} | :error
Enum.map(@weekday_values, fn {weekday, weekday_number} ->
defp fetch_weekday_value(unquote(to_string(weekday))) do
{:ok, unquote(weekday_number)}
end
end)
defp fetch_weekday_value(_), do: :error
@spec fetch_month_value(binary) :: {:ok, integer} | :error
Enum.map(@month_values, fn {month, month_number} ->
defp fetch_month_value(unquote(to_string(month))) do
{:ok, unquote(month_number)}
end
end)
defp fetch_month_value(_), do: :error
@spec special(binary) :: result
Enum.map(@specials, fn {special, special_value} ->
defp special(unquote(to_string(special))) do
{:ok, unquote(Macro.escape(special_value))}
end
end)
defp special(identifier) do
{:error, "Special identifier @#{identifier} is undefined."}
end
end