]> granicus.if.org Git - python/commitdiff
Jeffrey's next installment
authorGuido van Rossum <guido@python.org>
Thu, 17 Jul 1997 22:38:10 +0000 (22:38 +0000)
committerGuido van Rossum <guido@python.org>
Thu, 17 Jul 1997 22:38:10 +0000 (22:38 +0000)
Lib/re.py

index 7ff53caa6a3f745b7ca5b5505b765ae1b5e94427..8509b5f753c31ca09e121c972f1cd2614804c633 100644 (file)
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -15,30 +15,8 @@ MULTILINE = M = 0x02
 DOTALL = S = 0x04
 VERBOSE = X = 0x08
 
-#
-# Initialize syntax table. This information should really come from the
-# syntax table in regexpr.c rather than being duplicated here.
-#
-
-syntax_table = {}
-
-for char in map(chr, range(0, 256)):
-    syntax_table[char] = []
-
-for char in string.lowercase:
-    syntax_table[char].append('word')
-
-for char in string.uppercase:
-    syntax_table[char].append('word')
-
-for char in string.digits:
-    syntax_table[char].append('word')
-    syntax_table[char].append('digit')
-
-for char in string.whitespace:
-    syntax_table[char].append('whitespace')
-
-syntax_table['_'].append('word')
+repetition_operators = ['*', '*?', '+', '+?', '?', '??', '{n}', '{n}?',
+                       '{n,}', '{n,}?', '{n,m}', '{n,m}?']
 
 #
 #
@@ -47,10 +25,11 @@ syntax_table['_'].append('word')
 def valid_identifier(id):
     if len(id) == 0:
        return 0
-    if ('word' not in syntax_table[id[0]]) or ('digit' in syntax_table[id[0]]):
+    if (not reop.syntax_table[id[0]] & reop.word) or \
+       (reop.syntax_table[id[0]] & reop.digit):
        return 0
     for char in id[1:]:
-       if 'word' not in syntax_table[char]:
+       if not reop.syntax_table[char] & reop.word:
            return 0
     return 1
 
@@ -394,7 +373,6 @@ class SyntaxSpec(Instruction):
        self.syntax = syntax
        Instruction.__init__(self, chr(20), 2)
     def assemble(self, postition, labels):
-       # XXX
        return self.opcode + chr(self.syntax)
 
 class NotSyntaxSpec(Instruction):
@@ -403,7 +381,6 @@ class NotSyntaxSpec(Instruction):
        self.syntax = syntax
        Instruction.__init__(self, chr(21), 2)
     def assemble(self, postition, labels):
-       # XXX
        return self.opcode + chr(self.syntax)
 
 class Label(Instruction):
@@ -455,7 +432,7 @@ def assemble(instructions):
 def escape(pattern):
     result = []
     for char in pattern:
-       if 'word' not in syntax_table[char]:
+       if not reop.syntax_table[char] & reop.word:
            result.append('\\')
        result.append(char)
     return string.join(result, '')
@@ -513,12 +490,12 @@ def build_fastmap_aux(code, pos, visited, fastmap):
            return
        elif instruction.name == 'syntaxspec':
            for char in map(chr, range(256)):
-               if instruction.syntax in syntax_table[char]:
+               if reop.syntax_table[char] & instruction.syntax:
                    fastmap.add(char)
            return
        elif instruction.name == 'notsyntaxspec':
            for char in map(chr, range(256)):
-               if instruction.syntax not in syntax_table[char]:
+               if not reop.syntax_table[char] & instruction.syntax:
                    fastmap.add(char)
            return
        elif instruction.name == 'eol':
@@ -570,8 +547,8 @@ def build_fastmap(code, pos=0):
 #
 
 [NORMAL, CHARCLASS, REPLACEMENT] = range(3)
-[CHAR, MEMORY_REFERENCE, SYNTAX, SET, WORD_BOUNDARY, NOT_WORD_BOUNDARY,
BEGINNING_OF_BUFFER, END_OF_BUFFER] = range(8)
+[CHAR, MEMORY_REFERENCE, SYNTAX, NOT_SYNTAX, SET, WORD_BOUNDARY,
NOT_WORD_BOUNDARY, BEGINNING_OF_BUFFER, END_OF_BUFFER] = range(9)
 
 def expand_escape(pattern, index, context=NORMAL):
     if index >= len(pattern):
@@ -646,11 +623,11 @@ def expand_escape(pattern, index, context=NORMAL):
     
     elif pattern[index] == 'w':
        if context == NORMAL:
-           return SYNTAX, 'word', index + 1
+           return SYNTAX, reop.word, index + 1
        elif context == CHARCLASS:
            set = []
-           for char in syntax_table.keys():
-               if 'word' in syntax_table[char]:
+           for char in reop.syntax_table.keys():
+               if reop.syntax_table[char] & reop.word:
                    set.append(char)
            return SET, set, index + 1
        else:
@@ -658,11 +635,11 @@ def expand_escape(pattern, index, context=NORMAL):
        
     elif pattern[index] == 'W':
        if context == NORMAL:
-           return NOT_SYNTAX, 'word', index + 1
+           return NOT_SYNTAX, reop.word, index + 1
        elif context == CHARCLASS:
            set = []
-           for char in syntax_table.keys():
-               if 'word' not in syntax_table[char]:
+           for char in reop.syntax_table.keys():
+               if not reop.syntax_table[char] & reop.word:
                    set.append(char)
            return SET, set, index + 1
        else:
@@ -670,11 +647,11 @@ def expand_escape(pattern, index, context=NORMAL):
        
     elif pattern[index] == 's':
        if context == NORMAL:
-           return SYNTAX, 'whitespace', index + 1
+           return SYNTAX, reop.whitespace, index + 1
        elif context == CHARCLASS:
            set = []
-           for char in syntax_table.keys():
-               if 'whitespace' in syntax_table[char]:
+           for char in reop.syntax_table.keys():
+               if reop.syntax_table[char] & reop.whitespace:
                    set.append(char)
            return SET, set, index + 1
        else:
@@ -682,11 +659,11 @@ def expand_escape(pattern, index, context=NORMAL):
        
     elif pattern[index] == 'S':
        if context == NORMAL:
-           return NOT_SYNTAX, 'whitespace', index + 1
+           return NOT_SYNTAX, reop.whitespace, index + 1
        elif context == CHARCLASS:
            set = []
-           for char in syntax_table.keys():
-               if 'whitespace' not in syntax_table[char]:
+           for char in reop.syntax_table.keys():
+               if not reop.syntax_table[char] & reop.word:
                    set.append(char)
            return SET, set, index + 1
        else:
@@ -694,11 +671,11 @@ def expand_escape(pattern, index, context=NORMAL):
        
     elif pattern[index] == 'd':
        if context == NORMAL:
-           return SYNTAX, 'digit', index + 1
+           return SYNTAX, reop.digit, index + 1
        elif context == CHARCLASS:
            set = []
-           for char in syntax_table.keys():
-               if 'digit' in syntax_table[char]:
+           for char in reop.syntax_table.keys():
+               if reop.syntax_table[char] & reop.digit:
                    set.append(char)
            return SET, set, index + 1
        else:
@@ -706,11 +683,11 @@ def expand_escape(pattern, index, context=NORMAL):
        
     elif pattern[index] == 'D':
        if context == NORMAL:
-           return NOT_SYNTAX, 'digit', index + 1
+           return NOT_SYNTAX, reop.digit, index + 1
        elif context == CHARCLASS:
            set = []
-           for char in syntax_table.keys():
-               if 'digit' not in syntax_table[char]:
+           for char in reop.syntax_table.keys():
+               if not reop.syntax_table[char] & reop.digit:
                    set.append(char)
            return SET, set, index + 1
        else:
@@ -783,29 +760,31 @@ def compile(pattern, flags=0):
     register = 1
     groupindex = {}
     callouts = []
+    lastop = ''
 
-    # preprocess the pattern looking for embedded pattern modifiers
+    # look for embedded pattern modifiers at the beginning of the pattern
 
     index = 0
-    while (index != -1):
-       index = string.find(pattern, '(?', index)
-       if index != -1:
-           index = index + 2
-           if (index < len(pattern)) and (pattern[index] in 'iImMsSxX'):
-               while (index < len(pattern)) and (pattern[index] != ')'):
-                   if pattern[index] in 'iI':
-                       flags = flags | IGNORECASE
-                   elif pattern[index] in 'mM':
-                       flags = flags | MULTILINE
-                   elif pattern[index] in 'sS':
-                       flags = flags | DOTALL
-                   elif pattern[index] in 'xX':
-                       flags = flags | VERBOSE
-                   else:
-                       raise error, 'unknown flag'
-                   index = index + 1
 
-    index = 0
+    if len(pattern) >= 3 and \
+       (pattern[:2] == '(?') and \
+       (pattern[2] in 'iImMsSxX'):
+       index = 2
+       while (index < len(pattern)) and (pattern[index] != ')'):
+           if pattern[index] in 'iI':
+               flags = flags | IGNORECASE
+           elif pattern[index] in 'mM':
+               flags = flags | MULTILINE
+           elif pattern[index] in 'sS':
+               flags = flags | DOTALL
+           elif pattern[index] in 'xX':
+               flags = flags | VERBOSE
+           else:
+               raise error, 'unknown modifier'
+           index = index + 1
+       index = index + 1
+
+    # compile the rest of the pattern
     
     while (index < len(pattern)):
        char = pattern[index]
@@ -815,30 +794,52 @@ def compile(pattern, flags=0):
 
            if escape_type == CHAR:
                stack.append([Exact(value)])
+               lastop = '\\' + value
                
            elif escape_type == MEMORY_REFERENCE:
                if value >= register:
                    raise error, ('cannot reference a register '
                                  'not yet used')
                stack.append([MatchMemory(value)])
+               lastop = '\\1'
                
            elif escape_type == BEGINNING_OF_BUFFER:
                stack.append([BegBuf()])
+               lastop = '\\A'
                
            elif escape_type == END_OF_BUFFER:
                stack.append([EndBuf()])
+               lastop = '\\Z'
                
            elif escape_type == WORD_BOUNDARY:
                stack.append([WordBound()])
+               lastop = '\\b'
                
            elif escape_type == NOT_WORD_BOUNDARY:
                stack.append([NotWordBound()])
+               lastop = '\\B'
                
            elif escape_type == SYNTAX:
                stack.append([SyntaxSpec(value)])
-               
+               if value == reop.word:
+                   lastop = '\\w'
+               elif value == reop.whitespace:
+                   lastop = '\\s'
+               elif value == reop.digit:
+                   lastop = '\\d'
+               else:
+                   lastop = '\\?'
+                   
            elif escape_type == NOT_SYNTAX:
                stack.append([NotSyntaxSpec(value)])
+               if value == reop.word:
+                   lastop = '\\W'
+               elif value == reop.whitespace:
+                   lastop = '\\S'
+               elif value == reop.digit:
+                   lastop = '\\D'
+               else:
+                   lastop = '\\?'
                
            elif escape_type == SET:
                raise error, 'cannot use set escape type here'
@@ -860,7 +861,8 @@ def compile(pattern, flags=0):
                          Label(label)])
            stack.append([Alternation()])
            label = label + 1
-
+           lastop = '|'
+           
        elif char == '(':
            if index >= len(pattern):
                raise error, 'no matching close paren'
@@ -891,6 +893,7 @@ def compile(pattern, flags=0):
                        groupindex[name] = register
                        stack.append([OpenParen(register)])
                        register = register + 1
+                       lastop = '('
 
                    elif pattern[index] == '=':
                        # backreference to symbolic group name
@@ -906,6 +909,7 @@ def compile(pattern, flags=0):
                                          ' has not been used yet')
                        stack.append([MatchMemory(groupindex[name])])
                        index = end + 1
+                       lastop = '(?P=)'
                        
                    elif pattern[index] == '!':
                        # function callout
@@ -920,7 +924,8 @@ def compile(pattern, flags=0):
                            raise error, ('function callout name not listed '
                                          'in callouts dict')
                        stack.append([FunctionCallout(name)])
-
+                       lastop = '(?P!)'
+                       
                    else:
                        raise error, ('unknown Python extension: ' + \
                                      pattern[index])
@@ -929,7 +934,8 @@ def compile(pattern, flags=0):
                    # grouping, but no registers
                    index = index + 1
                    stack.append([OpenParen(-1)])
-
+                   lastop = '('
+                   
                elif pattern[index] == '#':
                    # comment
                    index = index + 1
@@ -937,7 +943,8 @@ def compile(pattern, flags=0):
                    if end == -1:
                        raise error, 'no end to comment'
                    index = end + 1
-
+                   # do not change lastop
+                   
                elif pattern[index] == '=':
                    raise error, ('zero-width positive lookahead '
                                  'assertion is unsupported')
@@ -947,19 +954,16 @@ def compile(pattern, flags=0):
                                  'assertion is unsupported')
 
                elif pattern[index] in 'iImMsSxX':
-                   # ignore embedded pattern modifiers here, they
-                   # have already been taken care of in the
-                   # preprocessing
-                   while (index < len(pattern)) and (pattern[index] != ')'):
-                       index = index + 1
-                   index = index + 1
-                   
+                   raise error, ('embedded pattern modifiers are only '
+                                 'allowed at the beginning of the pattern')
+
                else:
                    raise error, 'unknown extension'
 
            else:
                stack.append([OpenParen(register)])
                register = register + 1
+               lastop = '('
 
        elif char == ')':
            # make one expression out of everything on the stack up to
@@ -991,6 +995,7 @@ def compile(pattern, flags=0):
                       [EndMemory(stack[-1][0].register)]
            del stack[-1]
            stack.append(expr)
+           lastop = ')'
 
        elif char == '{':
            if len(stack) == 0:
@@ -1024,6 +1029,10 @@ def compile(pattern, flags=0):
                    count = count - 1
                del stack[-1]
                stack.append(expr)
+               if minimal:
+                   lastop = '{n}?'
+               else:
+                   lastop = '{n}'
 
            elif len(fields) == 2:
                # {n,} or {n,m}
@@ -1048,6 +1057,7 @@ def compile(pattern, flags=0):
                                stack[-1] + \
                                [Label(label + 1),
                                 FailureJump(label)])
+                       lastop = '{n,}?'
                    else:
                        expr = expr + \
                               ([Label(label),
@@ -1055,6 +1065,7 @@ def compile(pattern, flags=0):
                                stack[-1] +
                                [StarJump(label),
                                 Label(label + 1)])
+                       lastop = '{n,}'
 
                    del stack[-1]
                    stack.append(expr)
@@ -1099,6 +1110,7 @@ def compile(pattern, flags=0):
                            label = label + 2
                        del stack[-1]
                        stack.append(expr)
+                       lastop = '{n,m}?'
                    else:
                        while max > 0:
                            expr = expr + \
@@ -1108,11 +1120,11 @@ def compile(pattern, flags=0):
                        del stack[-1]
                        stack.append(expr + [Label(label)])
                        label = label + 1
+                       lastop = '{n,m}'
 
            else:
                raise error, ('there need to be one or two fields '
                              'in a {} expression')
-           index = end + 1
 
        elif char == '}':
            raise error, 'unbalanced close curly brace'
@@ -1121,9 +1133,13 @@ def compile(pattern, flags=0):
            # Kleene closure
            if len(stack) == 0:
                raise error, '* needs something to repeat'
-           if (stack[-1][0].name == '(') or (stack[-1][0].name == '|'):
+
+           if lastop in ['(', '|']:
                raise error, '* needs something to repeat'
-           registers = registers_used(stack[-1])
+
+           if lastop in repetition_operators:
+               raise error, 'nested repetition operators'
+           
            if (index < len(pattern)) and (pattern[index] == '?'):
                # non-greedy matching
                expr = [Jump(label + 1),
@@ -1132,6 +1148,7 @@ def compile(pattern, flags=0):
                       [Label(label + 1),
                        FailureJump(label)]
                index = index + 1
+               lastop = '*?'
            else:
                # greedy matching
                expr = [Label(label),
@@ -1139,6 +1156,7 @@ def compile(pattern, flags=0):
                       stack[-1] + \
                       [StarJump(label),
                        Label(label + 1)]
+               lastop = '*'
            del stack[-1]
            stack.append(expr)
            label = label + 2
@@ -1148,9 +1166,12 @@ def compile(pattern, flags=0):
            if len(stack) == 0:
                raise error, '+ needs something to repeat'
            
-           if (stack[-1][0].name == '(') or (stack[-1][0].name == '|'):
+           if lastop in ['(', '|']:
                raise error, '+ needs something to repeat'
-           
+
+           if lastop in repetition_operators:
+               raise error, 'nested repetition operators'
+
            if (index < len(pattern)) and (pattern[index] == '?'):
                # non-greedy
                expr = [Label(label)] + \
@@ -1158,6 +1179,8 @@ def compile(pattern, flags=0):
                       [FailureJump(label)]
                label = label + 1
                index = index + 1
+               lastop = '+?'
+               
            else:
                # greedy
                expr = [DummyFailureJump(label + 1),
@@ -1168,12 +1191,24 @@ def compile(pattern, flags=0):
                       [StarJump(label),
                        Label(label + 2)]
                label = label + 3
+               lastop = '+'
+               
            del stack[-1]
            stack.append(expr)
 
        elif char == '?':
            if len(stack) == 0:
                raise error, 'need something to be optional'
+           
+           if len(stack) == 0:
+               raise error, '? needs something to repeat'
+           
+           if lastop in ['(', '|']:
+               raise error, '? needs something to repeat'
+
+           if lastop in repetition_operators:
+               raise error, 'nested repetition operators'
+
            if (index < len(pattern)) and (pattern[index] == '?'):
                # non-greedy matching
                expr = [FailureJump(label),
@@ -1183,12 +1218,16 @@ def compile(pattern, flags=0):
                       [Label(label + 1)]
                label = label + 2
                index = index + 1
+               lastop = '??'
+               
            else:
                # greedy matching
                expr = [FailureJump(label)] + \
                       stack[-1] + \
                       [Label(label)]
                label = label + 1
+               lastop = '?'
+               
            del stack[-1]
            stack.append(expr)
 
@@ -1197,18 +1236,21 @@ def compile(pattern, flags=0):
                stack.append([Set(map(chr, range(256)))])
            else:
                stack.append([AnyChar()])
+           lastop = '.'
 
        elif char == '^':
            if flags & MULTILINE:
                stack.append([Bol()])
            else:
                stack.append([BegBuf()])
+           lastop = '^'
 
        elif char == '$':
            if flags & MULTILINE:
                stack.append([Eol()])
            else:
                stack.append([EndBuf()])
+           lastop = '$'
 
        elif char == '#':
            if flags & VERBOSE:
@@ -1219,12 +1261,15 @@ def compile(pattern, flags=0):
                    index = len(pattern)
                else:
                    index = end + 1
+               # do not change lastop
            else:
                stack.append([Exact(char)])
+               lastop = '#'
 
        elif char in string.whitespace:
            if not (flags & VERBOSE):
                stack.append([Exact(char)])
+               lastop = char
 
        elif char == '[':
            # compile character class
@@ -1343,8 +1388,11 @@ def compile(pattern, flags=0):
                    raise error, 'empty set'
                stack.append([Set(set)])
 
+           lastop = '[]'
+
        else:
            stack.append([Exact(char)])
+           lastop = char
 
     code = []
     while len(stack) > 0: