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Diffstat (limited to 'js/src/frontend/GenerateReservedWords.py')
| -rw-r--r-- | js/src/frontend/GenerateReservedWords.py | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/js/src/frontend/GenerateReservedWords.py b/js/src/frontend/GenerateReservedWords.py new file mode 100644 index 0000000000..078f8bf833 --- /dev/null +++ b/js/src/frontend/GenerateReservedWords.py @@ -0,0 +1,232 @@ +# 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_reserved_word_list(filename, enable_decorators): + macro_pat = re.compile(r"MACRO\(([^,]+), *[^,]+, *[^\)]+\)\s*\\?") + + reserved_word_list = [] + index = 0 + with open(filename, "r") as f: + for line in f: + m = macro_pat.search(line) + if m: + reserved_word = m.group(1) + if reserved_word == "accessor" and not enable_decorators: + continue + reserved_word_list.append((index, reserved_word)) + index += 1 + + assert len(reserved_word_list) != 0 + + return reserved_word_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(reserved_word_list, column): + assert len(reserved_word_list) != 0 + + chars_dict = {} + for index, word in reserved_word_list: + chars_dict[ord(word[column])] = True + + chars = sorted(chars_dict.keys()) + return chars[-1] - chars[0] + 1, len(chars) + + +def optimal_switch_column(opt, reserved_word_list, columns, unprocessed_columns): + assert len(reserved_word_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(reserved_word_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(reserved_word_list, column): + assert len(reserved_word_list) != 0 + + column_dict = {} + for item in reserved_word_list: + index, word = item + per_column = column_dict.setdefault(word[column], []) + per_column.append(item) + + return sorted(column_dict.items()) + + +def generate_letter_switch(opt, unprocessed_columns, reserved_word_list, columns=None): + assert len(reserved_word_list) != 0 + + if not columns: + columns = range(0, unprocessed_columns) + + if len(reserved_word_list) == 1: + index, word = reserved_word_list[0] + + if unprocessed_columns == 0: + line(opt, "JSRW_GOT_MATCH({}) /* {} */".format(index, word)) + return + + if unprocessed_columns > opt["char_tail_test_threshold"]: + line(opt, "JSRW_TEST_GUESS({}) /* {} */".format(index, word)) + return + + conds = [] + for column in columns[0:unprocessed_columns]: + quoted = repr(word[column]) + conds.append("JSRW_AT({})=={}".format(column, quoted)) + + line(opt, "if ({}) {{".format(" && ".join(conds))) + + indent(opt) + line(opt, "JSRW_GOT_MATCH({}) /* {} */".format(index, word)) + dedent(opt) + + line(opt, "}") + line(opt, "JSRW_NO_MATCH()") + return + + assert unprocessed_columns != 0 + + optimal_column_index, use_if = optimal_switch_column( + opt, reserved_word_list, columns, unprocessed_columns + ) + optimal_column = columns[optimal_column_index] + + # Make a copy to avoid breaking passed list. + columns = list(columns) + columns[optimal_column_index] = columns[unprocessed_columns - 1] + + list_per_column = split_list_per_column(reserved_word_list, optimal_column) + + if not use_if: + line(opt, "switch (JSRW_AT({})) {{".format(optimal_column)) + + for char, reserved_word_list_per_column in list_per_column: + quoted = repr(char) + if use_if: + line(opt, "if (JSRW_AT({}) == {}) {{".format(optimal_column, quoted)) + else: + line(opt, " case {}:".format(quoted)) + + indent(opt) + generate_letter_switch( + opt, unprocessed_columns - 1, reserved_word_list_per_column, columns + ) + dedent(opt) + + if use_if: + line(opt, "}") + + if not use_if: + line(opt, "}") + + line(opt, "JSRW_NO_MATCH()") + + +def split_list_per_length(reserved_word_list): + assert len(reserved_word_list) != 0 + + length_dict = {} + for item in reserved_word_list: + index, word = item + per_length = length_dict.setdefault(len(word), []) + per_length.append(item) + + return sorted(length_dict.items()) + + +def generate_switch(opt, reserved_word_list): + assert len(reserved_word_list) != 0 + + line(opt, "/*") + line( + opt, + " * Generating switch for the list of {} entries:".format( + len(reserved_word_list) + ), + ) + for index, word in reserved_word_list: + line(opt, " * {}".format(word)) + line(opt, " */") + + list_per_length = split_list_per_length(reserved_word_list) + + use_if = False + if len(list_per_length) < opt["use_if_threshold"]: + use_if = True + + if not use_if: + line(opt, "switch (JSRW_LENGTH()) {") + + for length, reserved_word_list_per_length in list_per_length: + if use_if: + line(opt, "if (JSRW_LENGTH() == {}) {{".format(length)) + else: + line(opt, " case {}:".format(length)) + + indent(opt) + generate_letter_switch(opt, length, reserved_word_list_per_length) + dedent(opt) + + if use_if: + line(opt, "}") + + if not use_if: + line(opt, "}") + line(opt, "JSRW_NO_MATCH()") + + +def main(output, reserved_words_h, enable_decorators=False): + reserved_word_list = read_reserved_word_list(reserved_words_h, enable_decorators) + + opt = { + "indent_level": 1, + "use_if_threshold": 3, + "char_tail_test_threshold": 4, + "output": output, + } + generate_switch(opt, reserved_word_list) + + +if __name__ == "__main__": + main(sys.stdout, *sys.argv[1:]) |