| #======================================================================= |
| # |
| # Python Lexical Analyser |
| # |
| # Regular Expressions |
| # |
| #======================================================================= |
| |
| import types |
| from sys import maxint as maxint |
| |
| import Errors |
| |
| # |
| # Constants |
| # |
| |
| BOL = 'bol' |
| EOL = 'eol' |
| EOF = 'eof' |
| |
| nl_code = ord('\n') |
| |
| # |
| # Helper functions |
| # |
| |
| def chars_to_ranges(s): |
| """ |
| Return a list of character codes consisting of pairs |
| [code1a, code1b, code2a, code2b,...] which cover all |
| the characters in |s|. |
| """ |
| char_list = list(s) |
| char_list.sort() |
| i = 0 |
| n = len(char_list) |
| result = [] |
| while i < n: |
| code1 = ord(char_list[i]) |
| code2 = code1 + 1 |
| i = i + 1 |
| while i < n and code2 >= ord(char_list[i]): |
| code2 = code2 + 1 |
| i = i + 1 |
| result.append(code1) |
| result.append(code2) |
| return result |
| |
| def uppercase_range(code1, code2): |
| """ |
| If the range of characters from code1 to code2-1 includes any |
| lower case letters, return the corresponding upper case range. |
| """ |
| code3 = max(code1, ord('a')) |
| code4 = min(code2, ord('z') + 1) |
| if code3 < code4: |
| d = ord('A') - ord('a') |
| return (code3 + d, code4 + d) |
| else: |
| return None |
| |
| def lowercase_range(code1, code2): |
| """ |
| If the range of characters from code1 to code2-1 includes any |
| upper case letters, return the corresponding lower case range. |
| """ |
| code3 = max(code1, ord('A')) |
| code4 = min(code2, ord('Z') + 1) |
| if code3 < code4: |
| d = ord('a') - ord('A') |
| return (code3 + d, code4 + d) |
| else: |
| return None |
| |
| def CodeRanges(code_list): |
| """ |
| Given a list of codes as returned by chars_to_ranges, return |
| an RE which will match a character in any of the ranges. |
| """ |
| re_list = [] |
| for i in xrange(0, len(code_list), 2): |
| re_list.append(CodeRange(code_list[i], code_list[i + 1])) |
| return Alt(*re_list) |
| |
| def CodeRange(code1, code2): |
| """ |
| CodeRange(code1, code2) is an RE which matches any character |
| with a code |c| in the range |code1| <= |c| < |code2|. |
| """ |
| if code1 <= nl_code < code2: |
| return Alt(RawCodeRange(code1, nl_code), |
| RawNewline, |
| RawCodeRange(nl_code + 1, code2)) |
| else: |
| return RawCodeRange(code1, code2) |
| |
| # |
| # Abstract classes |
| # |
| |
| class RE(object): |
| """RE is the base class for regular expression constructors. |
| The following operators are defined on REs: |
| |
| re1 + re2 is an RE which matches |re1| followed by |re2| |
| re1 | re2 is an RE which matches either |re1| or |re2| |
| """ |
| |
| nullable = 1 # True if this RE can match 0 input symbols |
| match_nl = 1 # True if this RE can match a string ending with '\n' |
| str = None # Set to a string to override the class's __str__ result |
| |
| def build_machine(self, machine, initial_state, final_state, |
| match_bol, nocase): |
| """ |
| This method should add states to |machine| to implement this |
| RE, starting at |initial_state| and ending at |final_state|. |
| If |match_bol| is true, the RE must be able to match at the |
| beginning of a line. If nocase is true, upper and lower case |
| letters should be treated as equivalent. |
| """ |
| raise NotImplementedError("%s.build_machine not implemented" % |
| self.__class__.__name__) |
| |
| def build_opt(self, m, initial_state, c): |
| """ |
| Given a state |s| of machine |m|, return a new state |
| reachable from |s| on character |c| or epsilon. |
| """ |
| s = m.new_state() |
| initial_state.link_to(s) |
| initial_state.add_transition(c, s) |
| return s |
| |
| def __add__(self, other): |
| return Seq(self, other) |
| |
| def __or__(self, other): |
| return Alt(self, other) |
| |
| def __str__(self): |
| if self.str: |
| return self.str |
| else: |
| return self.calc_str() |
| |
| def check_re(self, num, value): |
| if not isinstance(value, RE): |
| self.wrong_type(num, value, "Plex.RE instance") |
| |
| def check_string(self, num, value): |
| if type(value) != type(''): |
| self.wrong_type(num, value, "string") |
| |
| def check_char(self, num, value): |
| self.check_string(num, value) |
| if len(value) != 1: |
| raise Errors.PlexValueError("Invalid value for argument %d of Plex.%s." |
| "Expected a string of length 1, got: %s" % ( |
| num, self.__class__.__name__, repr(value))) |
| |
| def wrong_type(self, num, value, expected): |
| if type(value) == types.InstanceType: |
| got = "%s.%s instance" % ( |
| value.__class__.__module__, value.__class__.__name__) |
| else: |
| got = type(value).__name__ |
| raise Errors.PlexTypeError("Invalid type for argument %d of Plex.%s " |
| "(expected %s, got %s" % ( |
| num, self.__class__.__name__, expected, got)) |
| |
| # |
| # Primitive RE constructors |
| # ------------------------- |
| # |
| # These are the basic REs from which all others are built. |
| # |
| |
| ## class Char(RE): |
| ## """ |
| ## Char(c) is an RE which matches the character |c|. |
| ## """ |
| |
| ## nullable = 0 |
| |
| ## def __init__(self, char): |
| ## self.char = char |
| ## self.match_nl = char == '\n' |
| |
| ## def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| ## c = self.char |
| ## if match_bol and c != BOL: |
| ## s1 = self.build_opt(m, initial_state, BOL) |
| ## else: |
| ## s1 = initial_state |
| ## if c == '\n' or c == EOF: |
| ## s1 = self.build_opt(m, s1, EOL) |
| ## if len(c) == 1: |
| ## code = ord(self.char) |
| ## s1.add_transition((code, code+1), final_state) |
| ## if nocase and is_letter_code(code): |
| ## code2 = other_case_code(code) |
| ## s1.add_transition((code2, code2+1), final_state) |
| ## else: |
| ## s1.add_transition(c, final_state) |
| |
| ## def calc_str(self): |
| ## return "Char(%s)" % repr(self.char) |
| |
| def Char(c): |
| """ |
| Char(c) is an RE which matches the character |c|. |
| """ |
| if len(c) == 1: |
| result = CodeRange(ord(c), ord(c) + 1) |
| else: |
| result = SpecialSymbol(c) |
| result.str = "Char(%s)" % repr(c) |
| return result |
| |
| class RawCodeRange(RE): |
| """ |
| RawCodeRange(code1, code2) is a low-level RE which matches any character |
| with a code |c| in the range |code1| <= |c| < |code2|, where the range |
| does not include newline. For internal use only. |
| """ |
| nullable = 0 |
| match_nl = 0 |
| range = None # (code, code) |
| uppercase_range = None # (code, code) or None |
| lowercase_range = None # (code, code) or None |
| |
| def __init__(self, code1, code2): |
| self.range = (code1, code2) |
| self.uppercase_range = uppercase_range(code1, code2) |
| self.lowercase_range = lowercase_range(code1, code2) |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| if match_bol: |
| initial_state = self.build_opt(m, initial_state, BOL) |
| initial_state.add_transition(self.range, final_state) |
| if nocase: |
| if self.uppercase_range: |
| initial_state.add_transition(self.uppercase_range, final_state) |
| if self.lowercase_range: |
| initial_state.add_transition(self.lowercase_range, final_state) |
| |
| def calc_str(self): |
| return "CodeRange(%d,%d)" % (self.code1, self.code2) |
| |
| class _RawNewline(RE): |
| """ |
| RawNewline is a low-level RE which matches a newline character. |
| For internal use only. |
| """ |
| nullable = 0 |
| match_nl = 1 |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| if match_bol: |
| initial_state = self.build_opt(m, initial_state, BOL) |
| s = self.build_opt(m, initial_state, EOL) |
| s.add_transition((nl_code, nl_code + 1), final_state) |
| |
| RawNewline = _RawNewline() |
| |
| |
| class SpecialSymbol(RE): |
| """ |
| SpecialSymbol(sym) is an RE which matches the special input |
| symbol |sym|, which is one of BOL, EOL or EOF. |
| """ |
| nullable = 0 |
| match_nl = 0 |
| sym = None |
| |
| def __init__(self, sym): |
| self.sym = sym |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| # Sequences 'bol bol' and 'bol eof' are impossible, so only need |
| # to allow for bol if sym is eol |
| if match_bol and self.sym == EOL: |
| initial_state = self.build_opt(m, initial_state, BOL) |
| initial_state.add_transition(self.sym, final_state) |
| |
| |
| class Seq(RE): |
| """Seq(re1, re2, re3...) is an RE which matches |re1| followed by |
| |re2| followed by |re3|...""" |
| |
| def __init__(self, *re_list): |
| nullable = 1 |
| for i in xrange(len(re_list)): |
| re = re_list[i] |
| self.check_re(i, re) |
| nullable = nullable and re.nullable |
| self.re_list = re_list |
| self.nullable = nullable |
| i = len(re_list) |
| match_nl = 0 |
| while i: |
| i = i - 1 |
| re = re_list[i] |
| if re.match_nl: |
| match_nl = 1 |
| break |
| if not re.nullable: |
| break |
| self.match_nl = match_nl |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| re_list = self.re_list |
| if len(re_list) == 0: |
| initial_state.link_to(final_state) |
| else: |
| s1 = initial_state |
| n = len(re_list) |
| for i in xrange(n): |
| if i < n - 1: |
| s2 = m.new_state() |
| else: |
| s2 = final_state |
| re = re_list[i] |
| re.build_machine(m, s1, s2, match_bol, nocase) |
| s1 = s2 |
| match_bol = re.match_nl or (match_bol and re.nullable) |
| |
| def calc_str(self): |
| return "Seq(%s)" % ','.join(map(str, self.re_list)) |
| |
| |
| class Alt(RE): |
| """Alt(re1, re2, re3...) is an RE which matches either |re1| or |
| |re2| or |re3|...""" |
| |
| def __init__(self, *re_list): |
| self.re_list = re_list |
| nullable = 0 |
| match_nl = 0 |
| nullable_res = [] |
| non_nullable_res = [] |
| i = 1 |
| for re in re_list: |
| self.check_re(i, re) |
| if re.nullable: |
| nullable_res.append(re) |
| nullable = 1 |
| else: |
| non_nullable_res.append(re) |
| if re.match_nl: |
| match_nl = 1 |
| i = i + 1 |
| self.nullable_res = nullable_res |
| self.non_nullable_res = non_nullable_res |
| self.nullable = nullable |
| self.match_nl = match_nl |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| for re in self.nullable_res: |
| re.build_machine(m, initial_state, final_state, match_bol, nocase) |
| if self.non_nullable_res: |
| if match_bol: |
| initial_state = self.build_opt(m, initial_state, BOL) |
| for re in self.non_nullable_res: |
| re.build_machine(m, initial_state, final_state, 0, nocase) |
| |
| def calc_str(self): |
| return "Alt(%s)" % ','.join(map(str, self.re_list)) |
| |
| |
| class Rep1(RE): |
| """Rep1(re) is an RE which matches one or more repetitions of |re|.""" |
| |
| def __init__(self, re): |
| self.check_re(1, re) |
| self.re = re |
| self.nullable = re.nullable |
| self.match_nl = re.match_nl |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| s1 = m.new_state() |
| s2 = m.new_state() |
| initial_state.link_to(s1) |
| self.re.build_machine(m, s1, s2, match_bol or self.re.match_nl, nocase) |
| s2.link_to(s1) |
| s2.link_to(final_state) |
| |
| def calc_str(self): |
| return "Rep1(%s)" % self.re |
| |
| |
| class SwitchCase(RE): |
| """ |
| SwitchCase(re, nocase) is an RE which matches the same strings as RE, |
| but treating upper and lower case letters according to |nocase|. If |
| |nocase| is true, case is ignored, otherwise it is not. |
| """ |
| re = None |
| nocase = None |
| |
| def __init__(self, re, nocase): |
| self.re = re |
| self.nocase = nocase |
| self.nullable = re.nullable |
| self.match_nl = re.match_nl |
| |
| def build_machine(self, m, initial_state, final_state, match_bol, nocase): |
| self.re.build_machine(m, initial_state, final_state, match_bol, |
| self.nocase) |
| |
| def calc_str(self): |
| if self.nocase: |
| name = "NoCase" |
| else: |
| name = "Case" |
| return "%s(%s)" % (name, self.re) |
| |
| # |
| # Composite RE constructors |
| # ------------------------- |
| # |
| # These REs are defined in terms of the primitive REs. |
| # |
| |
| Empty = Seq() |
| Empty.__doc__ = \ |
| """ |
| Empty is an RE which matches the empty string. |
| """ |
| Empty.str = "Empty" |
| |
| def Str1(s): |
| """ |
| Str1(s) is an RE which matches the literal string |s|. |
| """ |
| result = Seq(*tuple(map(Char, s))) |
| result.str = "Str(%s)" % repr(s) |
| return result |
| |
| def Str(*strs): |
| """ |
| Str(s) is an RE which matches the literal string |s|. |
| Str(s1, s2, s3, ...) is an RE which matches any of |s1| or |s2| or |s3|... |
| """ |
| if len(strs) == 1: |
| return Str1(strs[0]) |
| else: |
| result = Alt(*tuple(map(Str1, strs))) |
| result.str = "Str(%s)" % ','.join(map(repr, strs)) |
| return result |
| |
| def Any(s): |
| """ |
| Any(s) is an RE which matches any character in the string |s|. |
| """ |
| #result = apply(Alt, tuple(map(Char, s))) |
| result = CodeRanges(chars_to_ranges(s)) |
| result.str = "Any(%s)" % repr(s) |
| return result |
| |
| def AnyBut(s): |
| """ |
| AnyBut(s) is an RE which matches any character (including |
| newline) which is not in the string |s|. |
| """ |
| ranges = chars_to_ranges(s) |
| ranges.insert(0, -maxint) |
| ranges.append(maxint) |
| result = CodeRanges(ranges) |
| result.str = "AnyBut(%s)" % repr(s) |
| return result |
| |
| AnyChar = AnyBut("") |
| AnyChar.__doc__ = \ |
| """ |
| AnyChar is an RE which matches any single character (including a newline). |
| """ |
| AnyChar.str = "AnyChar" |
| |
| def Range(s1, s2 = None): |
| """ |
| Range(c1, c2) is an RE which matches any single character in the range |
| |c1| to |c2| inclusive. |
| Range(s) where |s| is a string of even length is an RE which matches |
| any single character in the ranges |s[0]| to |s[1]|, |s[2]| to |s[3]|,... |
| """ |
| if s2: |
| result = CodeRange(ord(s1), ord(s2) + 1) |
| result.str = "Range(%s,%s)" % (s1, s2) |
| else: |
| ranges = [] |
| for i in range(0, len(s1), 2): |
| ranges.append(CodeRange(ord(s1[i]), ord(s1[i+1]) + 1)) |
| result = Alt(*ranges) |
| result.str = "Range(%s)" % repr(s1) |
| return result |
| |
| def Opt(re): |
| """ |
| Opt(re) is an RE which matches either |re| or the empty string. |
| """ |
| result = Alt(re, Empty) |
| result.str = "Opt(%s)" % re |
| return result |
| |
| def Rep(re): |
| """ |
| Rep(re) is an RE which matches zero or more repetitions of |re|. |
| """ |
| result = Opt(Rep1(re)) |
| result.str = "Rep(%s)" % re |
| return result |
| |
| def NoCase(re): |
| """ |
| NoCase(re) is an RE which matches the same strings as RE, but treating |
| upper and lower case letters as equivalent. |
| """ |
| return SwitchCase(re, nocase = 1) |
| |
| def Case(re): |
| """ |
| Case(re) is an RE which matches the same strings as RE, but treating |
| upper and lower case letters as distinct, i.e. it cancels the effect |
| of any enclosing NoCase(). |
| """ |
| return SwitchCase(re, nocase = 0) |
| |
| # |
| # RE Constants |
| # |
| |
| Bol = Char(BOL) |
| Bol.__doc__ = \ |
| """ |
| Bol is an RE which matches the beginning of a line. |
| """ |
| Bol.str = "Bol" |
| |
| Eol = Char(EOL) |
| Eol.__doc__ = \ |
| """ |
| Eol is an RE which matches the end of a line. |
| """ |
| Eol.str = "Eol" |
| |
| Eof = Char(EOF) |
| Eof.__doc__ = \ |
| """ |
| Eof is an RE which matches the end of the file. |
| """ |
| Eof.str = "Eof" |
| |
