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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
import re
import sys
def read_keyword_list(filename):
macro_pat = re.compile(r"^\s*macro\(([^,]+), *[^,]+, *[^\)]+\)\s*\\?$")
keyword_list = []
index = 0
with open(filename, 'r') as f:
for line in f:
m = macro_pat.search(line)
if m:
keyword_list.append((index, m.group(1)))
index += 1
assert(len(keyword_list) != 0)
return keyword_list
def line(opt, s):
opt['output'].write('{}{}\n'.format(' ' * opt['indent_level'], s))
def indent(opt):
opt['indent_level'] += 1
def dedent(opt):
opt['indent_level'] -= 1
def span_and_count_at(keyword_list, column):
assert(len(keyword_list) != 0);
chars_dict = {}
for index, keyword in keyword_list:
chars_dict[ord(keyword[column])] = True
chars = sorted(chars_dict.keys())
return chars[-1] - chars[0] + 1, len(chars)
def optimal_switch_column(opt, keyword_list, columns, unprocessed_columns):
assert(len(keyword_list) != 0);
assert(unprocessed_columns != 0);
min_count = 0
min_span = 0
min_count_index = 0
min_span_index = 0
for index in range(0, unprocessed_columns):
span, count = span_and_count_at(keyword_list, columns[index])
assert(span != 0)
if span == 1:
assert(count == 1)
return 1, True
assert(count != 1)
if index == 0 or min_span > span:
min_span = span
min_span_index = index
if index == 0 or min_count > count:
min_count = count
min_count_index = index
if min_count <= opt['use_if_threshold']:
return min_count_index, True
return min_span_index, False
def split_list_per_column(keyword_list, column):
assert(len(keyword_list) != 0);
column_dict = {}
for item in keyword_list:
index, keyword = item
per_column = column_dict.setdefault(keyword[column], [])
per_column.append(item)
return sorted(column_dict.items(), key=lambda (char, keyword): ord(char))
def generate_letter_switch(opt, unprocessed_columns, keyword_list,
columns=None):
assert(len(keyword_list) != 0);
if not columns:
columns = range(0, unprocessed_columns)
if len(keyword_list) == 1:
index, keyword = keyword_list[0]
if unprocessed_columns == 0:
line(opt, 'JSKW_GOT_MATCH({}) /* {} */'.format(index, keyword))
return
if unprocessed_columns > opt['char_tail_test_threshold']:
line(opt, 'JSKW_TEST_GUESS({}) /* {} */'.format(index, keyword))
return
conds = []
for column in columns[0:unprocessed_columns]:
quoted = repr(keyword[column])
conds.append('JSKW_AT({})=={}'.format(column, quoted))
line(opt, 'if ({}) {{'.format(' && '.join(conds)))
indent(opt)
line(opt, 'JSKW_GOT_MATCH({}) /* {} */'.format(index, keyword))
dedent(opt)
line(opt, '}')
line(opt, 'JSKW_NO_MATCH()')
return
assert(unprocessed_columns != 0);
optimal_column_index, use_if = optimal_switch_column(opt, keyword_list,
columns,
unprocessed_columns)
optimal_column = columns[optimal_column_index]
# Make a copy to avoid breaking passed list.
columns = columns[:]
columns[optimal_column_index] = columns[unprocessed_columns - 1]
list_per_column = split_list_per_column(keyword_list, optimal_column)
if not use_if:
line(opt, 'switch (JSKW_AT({})) {{'.format(optimal_column))
for char, keyword_list_per_column in list_per_column:
quoted = repr(char)
if use_if:
line(opt, 'if (JSKW_AT({}) == {}) {{'.format(optimal_column,
quoted))
else:
line(opt, ' case {}:'.format(quoted))
indent(opt)
generate_letter_switch(opt, unprocessed_columns - 1,
keyword_list_per_column, columns)
dedent(opt)
if use_if:
line(opt, '}')
if not use_if:
line(opt, '}')
line(opt, 'JSKW_NO_MATCH()')
def split_list_per_length(keyword_list):
assert(len(keyword_list) != 0);
length_dict = {}
for item in keyword_list:
index, keyword = item
per_length = length_dict.setdefault(len(keyword), [])
per_length.append(item)
return sorted(length_dict.items(), key=lambda (length, keyword): length)
def generate_switch(opt, keyword_list):
assert(len(keyword_list) != 0);
line(opt, '/*')
line(opt, ' * Generating switch for the list of {} entries:'.format(len(keyword_list)))
for index, keyword in keyword_list:
line(opt, ' * {}'.format(keyword))
line(opt, ' */')
list_per_length = split_list_per_length(keyword_list)
use_if = False
if len(list_per_length) < opt['use_if_threshold']:
use_if = True
if not use_if:
line(opt, 'switch (JSKW_LENGTH()) {')
for length, keyword_list_per_length in list_per_length:
if use_if:
line(opt, 'if (JSKW_LENGTH() == {}) {{'.format(length))
else:
line(opt, ' case {}:'.format(length))
indent(opt)
generate_letter_switch(opt, length, keyword_list_per_length)
dedent(opt)
if use_if:
line(opt, '}')
if not use_if:
line(opt, '}')
line(opt, 'JSKW_NO_MATCH()')
def main(output, keywords_h):
keyword_list = read_keyword_list(keywords_h)
opt = {
'indent_level': 1,
'use_if_threshold': 3,
'char_tail_test_threshold': 4,
'output': output
}
generate_switch(opt, keyword_list)
if __name__ == '__main__':
main(sys.stdout, *sys.argv[1:])
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