| #!/usr/bin/env python |
| # Copyright (C) 2013 Google Inc. All rights reserved. |
| # |
| # Redistribution and use in source and binary forms, with or without |
| # modification, are permitted provided that the following conditions are |
| # met: |
| # |
| # * Redistributions of source code must retain the above copyright |
| # notice, this list of conditions and the following disclaimer. |
| # * Redistributions in binary form must reproduce the above |
| # copyright notice, this list of conditions and the following disclaimer |
| # in the documentation and/or other materials provided with the |
| # distribution. |
| # * Neither the name of Google Inc. nor the names of its |
| # contributors may be used to endorse or promote products derived from |
| # this software without specific prior written permission. |
| # |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| import io |
| import itertools |
| import re |
| import sys |
| |
| |
| class BadInput(Exception): |
| """Unsupported input has been found.""" |
| |
| |
| class SwitchCase(object): |
| """Represents a CASE block.""" |
| def __init__(self, identifier, block): |
| self.identifier = identifier |
| self.block = block |
| |
| |
| class Optimizer(object): |
| """Generates optimized identifier matching code.""" |
| def __init__(self, output_file, array_variable, length_variable): |
| self.output_file = output_file |
| self.array_variable = array_variable |
| self.length_variable = length_variable |
| |
| def inspect(self, cases): |
| lengths = list(set([len(c.identifier) for c in cases])) |
| lengths.sort() |
| |
| def response(length): |
| self.inspect_array([c for c in cases if len(c.identifier) == length], range(length)) |
| self.write_selection(self.length_variable, lengths, str, response) |
| |
| def score(self, alternatives): |
| return -sum([len(list(count)) ** 2 for _, count in itertools.groupby(sorted(alternatives))]) |
| |
| def choose_selection_pos(self, cases, pending): |
| candidates = [pos for pos in pending if all(alternative.isalpha() for alternative in [c.identifier[pos] for c in cases])] |
| if not candidates: |
| raise BadInput('Case-insensitive switching on non-alphabetic characters not yet implemented') |
| return sorted(candidates, key=lambda pos: self.score([c.identifier[pos] for c in cases]))[0] |
| |
| def inspect_array(self, cases, pending): |
| assert len(cases) >= 1 |
| if pending: |
| common = [pos for pos in pending |
| if len(set([c.identifier[pos] for c in cases])) == 1] |
| if common: |
| identifier = cases[0].identifier |
| for index in xrange(len(common)): |
| if index == 0: |
| self.output_file.write(u'if (LIKELY(') |
| else: |
| self.output_file.write(u' && ') |
| pos = common[index] |
| if identifier[pos].isalpha(): |
| self.output_file.write("(%s[%d] | 0x20) == '%s'" % |
| (self.array_variable, pos, identifier[pos])) |
| else: |
| self.output_file.write("%s[%d] == '%s'" % |
| (self.array_variable, pos, identifier[pos])) |
| self.output_file.write(u')) {\n') |
| next_pending = list(set(pending) - set(common)) |
| next_pending.sort() |
| self.inspect_array(cases, next_pending) |
| self.output_file.write(u'}\n') |
| else: |
| pos = self.choose_selection_pos(cases, pending) |
| next_pending = filter(lambda p: p != pos, pending) |
| |
| alternatives = list(set([c.identifier[pos] for c in cases])) |
| alternatives.sort() |
| |
| def literal(alternative): |
| if isinstance(alternative, int): |
| return str(alternative) |
| else: |
| return "'%s'" % alternative |
| |
| def response(alternative): |
| self.inspect_array([c for c in cases if c.identifier[pos] == alternative], |
| next_pending) |
| |
| expression = '(%s[%d] | 0x20)' % (self.array_variable, pos) |
| self.write_selection(expression, alternatives, literal, response) |
| else: |
| assert len(cases) == 1 |
| for block_line in cases[0].block: |
| self.output_file.write(block_line) |
| |
| def write_selection(self, expression, alternatives, literal, response): |
| if len(alternatives) == 1: |
| self.output_file.write(u'if (LIKELY(%s == %s)) {\n' % (expression, literal(alternatives[0]))) |
| response(alternatives[0]) |
| self.output_file.write(u'}\n') |
| elif len(alternatives) == 2: |
| self.output_file.write(u'if (%s == %s) {\n' % (expression, literal(alternatives[0]))) |
| response(alternatives[0]) |
| self.output_file.write(u'} else if (LIKELY(%s == %s)) {\n' % (expression, literal(alternatives[1]))) |
| response(alternatives[1]) |
| self.output_file.write(u'}\n') |
| else: |
| self.output_file.write('switch (%s) {\n' % expression) |
| for alternative in alternatives: |
| self.output_file.write(u'case %s: {\n' % literal(alternative)) |
| response(alternative) |
| self.output_file.write(u'} break;\n') |
| self.output_file.write(u'}\n') |
| |
| |
| class LineProcessor(object): |
| def process_line(self, line): |
| pass |
| |
| |
| class MainLineProcessor(LineProcessor): |
| """Processes the contents of an input file.""" |
| SWITCH_PATTERN = re.compile(r'\s*SWITCH\s*\((\w*),\s*(\w*)\) \{$') |
| |
| def __init__(self, output_file): |
| self.output_file = output_file |
| |
| def process_line(self, line): |
| match_switch = MainLineProcessor.SWITCH_PATTERN.match(line) |
| if match_switch: |
| array_variable = match_switch.group(1) |
| length_variable = match_switch.group(2) |
| return SwitchLineProcessor(self, self.output_file, array_variable, length_variable) |
| else: |
| self.output_file.write(line) |
| return self |
| |
| |
| class SwitchLineProcessor(LineProcessor): |
| """Processes the contents of a SWITCH block.""" |
| CASE_PATTERN = re.compile(r'\s*CASE\s*\(\"([a-z0-9_\-\(]*)\"\) \{$') |
| CLOSE_BRACE_PATTERN = re.compile(r'\s*\}$') |
| EMPTY_PATTERN = re.compile(r'\s*$') |
| |
| def __init__(self, parent, output_file, array_variable, length_variable): |
| self.parent = parent |
| self.output_file = output_file |
| self.array_variable = array_variable |
| self.length_variable = length_variable |
| self.cases = [] |
| |
| def process_line(self, line): |
| match_case = SwitchLineProcessor.CASE_PATTERN.match(line) |
| match_close_brace = SwitchLineProcessor.CLOSE_BRACE_PATTERN.match(line) |
| match_empty = SwitchLineProcessor.EMPTY_PATTERN.match(line) |
| if match_case: |
| identifier = match_case.group(1) |
| return CaseLineProcessor(self, self.output_file, identifier) |
| elif match_close_brace: |
| Optimizer(self.output_file, self.array_variable, self.length_variable).inspect(self.cases) |
| return self.parent |
| elif match_empty: |
| return self |
| else: |
| raise BadInput('Invalid line within SWITCH: %s' % line) |
| |
| def add_case(self, latest_case): |
| if latest_case.identifier in [c.identifier for c in self.cases]: |
| raise BadInput('Repeated case: %s' % latest_case.identifier) |
| self.cases.append(latest_case) |
| |
| |
| class CaseLineProcessor(LineProcessor): |
| """Processes the contents of a CASE block.""" |
| CLOSE_BRACE_PATTERN = re.compile(r'\s*\}$') |
| BREAK_PATTERN = re.compile(r'break;') |
| |
| def __init__(self, parent, output_file, identifier): |
| self.parent = parent |
| self.output_file = output_file |
| self.identifier = identifier |
| self.block = [] |
| |
| def process_line(self, line): |
| match_close_brace = CaseLineProcessor.CLOSE_BRACE_PATTERN.match(line) |
| match_break = CaseLineProcessor.BREAK_PATTERN.search(line) |
| if match_close_brace: |
| self.parent.add_case(SwitchCase(self.identifier, self.block)) |
| return self.parent |
| elif match_break: |
| raise BadInput('break within CASE not supported: %s' % line) |
| else: |
| self.block.append(line) |
| return self |
| |
| |
| def process_file(input_name, output_name): |
| """Transforms input file into legal C++ source code.""" |
| with io.open(input_name, 'r', -1, 'utf-8') as input_file: |
| with io.open(output_name, 'w', -1, 'utf-8') as output_file: |
| processor = MainLineProcessor(output_file) |
| input_lines = input_file.readlines() |
| for line in input_lines: |
| processor = processor.process_line(line) |
| |
| |
| if __name__ == '__main__': |
| process_file(sys.argv[1], sys.argv[2]) |
