Refactor regex error handling and parser structure; support Python 3.9 and above

Buba98 · Buba98 · commit 790ee7ec195c · 2024-12-27T23:07:45.000+01:00
diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
 
     steps:
       - uses: actions/checkout@v4
diff --git a/regex_enumerator/parser/regex_parser.py b/regex_enumerator/parser/regex_parser.py
@@ -1,15 +1,5 @@
-from .regex_tree import Alternative, BackReference, CharClass, RegexTree
-
-
-class RegexError(Exception):
-    def __init__(self, regex: str, index: int, message: str):
-        self.regex = regex
-        self.index = index
-        self.message = message
-
-    def __str__(self):
-        caret_line = ' ' * self.index + '^'
-        return f"\n{self.regex}\n{caret_line}\n{self.message}"
+from ..regex_tree import Alternative, BackReference, CharClass, RegexTree
+from ..regex_error import RegexError
 
 
 class RegexParser:
diff --git a/regex_enumerator/parser/regex_parser_legacy.py b/regex_enumerator/parser/regex_parser_legacy.py
@@ -0,0 +1,334 @@
+from ..regex_tree import Alternative, BackReference, CharClass, RegexTree
+from ..regex_error import RegexError
+
+
+class RegexParser:
+    WORDS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_'
+    HEX = '0123456789abcdefABCDEF'
+    DIGITS = '0123456789'
+    SPACES = ' \t\n\r\f\v'
+
+    def __init__(self, regex: str, charset: str, precompute: bool):
+        self.regex = regex
+        self.charset = charset
+        self.precompute = precompute
+
+    def parse(self) -> RegexTree:
+        self.index = 0
+        return self._parseRegex(False)
+
+    def _parseRegex(self, to_close: bool) -> RegexTree:
+        alternatives: list[Alternative] = []
+        elements: list[CharClass | RegexTree | BackReference] = []
+        named_groups: dict[str, RegexTree] = {}
+        ordered_groups: list[RegexTree] = []
+        min_len_group, max_len_group = 1, 1
+
+        while self.index < len(self.regex):
+            char = self.regex[self.index]
+            self.index += 1
+            if char == '(':
+                if self.index < len(self.regex) and self.regex[self.index] == '?':
+                    self.index += 1
+                    if self.index >= len(self.regex):
+                        self._raise_error("Invalid group")
+                    elif self.regex[self.index] == '<':
+                        self.index += 1
+                        name = ''
+                        while self.index < len(self.regex) and self.regex[self.index] != '>':
+                            name += self.regex[self.index]
+                            self.index += 1
+                        if self.index >= len(self.regex) or self.regex[self.index] != '>' or name == '':
+                            self._raise_error("Invalid named group")
+                        self.index += 1
+                        if name in named_groups:
+                            self._raise_error("Duplicate named group")
+                        subTree = self._parseRegex(True)
+                        named_groups[name] = subTree
+                        ordered_groups.append(subTree)
+                    elif self.regex[self.index] == ':':
+                        self.index += 1
+                        subTree = self._parseRegex(True)
+                    else:
+                        self._raise_error("Invalid group")
+                else:
+                    subTree = self._parseRegex(True)
+                    ordered_groups.append(subTree)
+                elements.append(subTree)
+            elif char == ')':
+                if not to_close:
+                    self._raise_error("Unmatched closing parenthesis")
+                min_len_group, max_len_group = self._parseQuantifier()
+                to_close = False
+                break
+            elif char == '|':
+                alternatives.append(Alternative(elements))
+                elements = []
+                named_groups = {}
+                ordered_groups = []
+            elif char == '[':
+                chars = self._parseCharClass()
+                min_len, max_len = self._parseQuantifier()
+                elements.append(
+                    CharClass(chars, min_len, max_len, self.precompute))
+            elif char == '.':
+                chars = list(self.charset)
+                min_len, max_len = self._parseQuantifier()
+                elements.append(
+                    CharClass(chars, min_len, max_len, self.precompute))
+            elif char == '\\':
+                reference = self._parseBackReferenceLookahead()
+                if reference is None:
+                    chars = self._parseEscapeChar()
+                    min_len, max_len = self._parseQuantifier()
+                    elements.append(
+                        CharClass([chars], min_len, max_len, self.precompute))
+                    continue
+                if isinstance(reference, str):
+                    if reference not in named_groups:
+                        self._raise_error("Named back reference not found")
+                    group = named_groups[reference]
+                else:
+                    if reference < 1 or reference > len(ordered_groups):
+                        self._raise_error(
+                            "Positional back reference not found")
+                    group = ordered_groups[reference - 1]
+                min_len, max_len = self._parseQuantifier()
+                reference = BackReference(
+                    group, min_len, max_len, self.precompute)
+                group.add_reference(reference)
+                elements.append(reference)
+            else:
+                min_len, max_len = self._parseQuantifier()
+                elements.append(
+                    CharClass([char], min_len, max_len, self.precompute))
+
+        if to_close:
+            self._raise_error("Unmatched opening parenthesis")
+
+        alternatives.append(Alternative(elements))
+        return RegexTree(alternatives, min_len_group, max_len_group, self.precompute)
+
+    def _parseBackReferenceLookahead(self) -> str | int | None:
+        if len(self.regex) <= self.index:
+            self._raise_error("Incomplete escape sequence")
+
+        char = self.regex[self.index]
+
+        if char == 'k':
+            self.index += 1
+            name = ''
+            if len(self.regex) <= self.index or self.regex[self.index] != '<':
+                self._raise_error("Invalid named back reference")
+            self.index += 1
+            while self.index < len(self.regex) and self.regex[self.index] != '>':
+                name += self.regex[self.index]
+                self.index += 1
+            if len(self.regex) <= self.index or self.regex[self.index] != '>' or name == '':
+                self._raise_error("Invalid named back reference")
+            self.index += 1
+            return name
+        elif char.isdigit():
+            num = int(char)
+            self.index += 1
+            while self.index < len(self.regex) and self.regex[self.index].isdigit():
+                num = num * 10 + int(self.regex[self.index])
+                self.index += 1
+            return num
+
+    def _parseEscapeChar(self) -> str:
+
+        if len(self.regex) <= self.index:
+            self._raise_error("Incomplete escape sequence")
+
+        char = self.regex[self.index]
+        self.index += 1
+
+        if char == 'd':
+            return self.DIGITS
+        elif char == 'D':
+            return ''.join([c for c in self.charset if not c.isdigit()])
+        elif char == 'w':
+            return self.WORDS
+        elif char == 'W':
+            return ''.join([c for c in self.charset if c not in self.WORDS])
+        elif char == 's':
+            return self.SPACES
+        elif char == 'S':
+            return ''.join([c for c in self.charset if c not in self.SPACES])
+        elif char == 't':
+            return '\t'
+        elif char == 'r':
+            return '\r'
+        elif char == 'n':
+            return '\n'
+        elif char == 'v':
+            return '\v'
+        elif char == 'f':
+            return '\f'
+        elif char == 'x':
+            if len(self.regex) < self.index + 1 or self.regex[self.index] not in self.HEX:
+                self._raise_error('Invalid ASCII escape character')
+            if len(self.regex) < self.index + 2 or self.regex[self.index + 1] not in self.HEX:
+                num = int(self.regex[self.index], 16)
+                self.index += 1
+            else:
+                num = int(self.regex[self.index: self.index + 2], 16)
+                self.index += 2
+            if num < 32 or num > 126:
+                self._raise_error(f"Invalid ASCII escape character {num}")
+            return chr(num)
+        elif char == 'u':
+            code = []
+            for _ in range(4):
+                if len(self.regex) <= self.index or self.regex[self.index] not in self.HEX:
+                    self._raise_error("Invalid unicode escape character")
+                code.append(self.regex[self.index])
+                self.index += 1
+            num = int(''.join(code), 16)
+            return chr(num)
+        elif char == 'p' or char == 'P':
+            self._raise_error("Unicode property not supported")
+        else:
+            return char
+
+    def _parseCharClass(self) -> list[str]:
+        chars_list: list[str] = []
+        first_char = None
+        range_divider = False
+        negated = False
+
+        if len(self.regex) <= self.index:
+            self._raise_error("Unclosed character class")
+
+        if self.regex[self.index] == '^':
+            negated = True
+            self.index += 1
+
+        len_regex = len(self.regex)
+
+        while self.index < len_regex and self.regex[self.index] != ']':
+            char = self.regex[self.index]
+            self.index += 1
+
+            if char == '-' and first_char is not None and not range_divider:
+                range_divider = True
+                continue
+            if char == '\\':
+                escape_char = self._parseEscapeChar()
+                if len(escape_char) > 1 or escape_char == '-':
+                    chars_list.append(escape_char)
+                    if range_divider:
+                        chars_list.append('-')
+                        assert first_char is not None
+                        chars_list.append(first_char)
+                    elif first_char is not None:
+                        chars_list.append(first_char)
+                    continue
+                char = escape_char
+
+            if first_char is None:
+                first_char = char
+            elif range_divider:
+                chars_list.extend([chr(c) for c in range(
+                    ord(first_char), ord(char) + 1)])
+                first_char = None
+                range_divider = False
+            else:
+                chars_list.append(first_char)
+                first_char = char
+
+        if len(self.regex) <= self.index or self.regex[self.index] != ']':
+            self._raise_error("Unclosed character class")
+
+        self.index += 1
+
+        if range_divider:
+            chars_list.append('-')
+            assert first_char is not None
+            chars_list.append(first_char)
+        elif first_char is not None:
+            chars_list.append(first_char)
+
+        if negated:
+            chars_list = [
+                c for c in self.charset if c not in ''.join(chars_list)]
+
+        return chars_list
+
+    def _parseQuantifier(self) -> tuple[int, int | None]:
+
+        if len(self.regex) <= self.index:
+            return 1, 1
+
+        char = self.regex[self.index]
+
+        if char == '*':
+            self.index += 1
+            return 0, None
+        elif char == '+':
+            self.index += 1
+            return 1, None
+        elif char == '?':
+            self.index += 1
+            return 0, 1
+        elif char == '{':
+            self.index += 1
+            return self._parseMinMax()
+        else:
+            return 1, 1
+
+    def _parseMinMax(self) -> tuple[int, int | None]:
+        self._skipSpaces()
+
+        min_len = 0
+        if self.index >= len(self.regex) or not self.regex[self.index].isdigit():
+            self._raise_error("Invalid quantifier")
+        while self.index < len(self.regex) and self.regex[self.index].isdigit():
+            min_len = min_len * 10 + int(self.regex[self.index])
+            self.index += 1
+
+        self._skipSpaces()
+
+        if self.index >= len(self.regex):
+            self._raise_error("Invalid quantifier")
+
+        if self.regex[self.index] == '}':
+            self.index += 1
+            return min_len, min_len
+        if self.regex[self.index] != ',':
+            self._raise_error("Invalid quantifier")
+
+        self.index += 1
+        self._skipSpaces()
+
+        if self.index >= len(self.regex) or self.regex[self.index] not in '0123456789}':
+            self._raise_error("Invalid quantifier")
+
+        if self.regex[self.index] == '}':
+            self.index += 1
+            return min_len, None
+
+        max_len = 0
+        while self.index < len(self.regex) and self.regex[self.index].isdigit():
+            max_len = max_len * 10 + int(self.regex[self.index])
+            self.index += 1
+
+        if max_len < min_len:
+            self._raise_error(
+                "Max length cannot be less than min length in quantifier")
+
+        self._skipSpaces()
+
+        if self.index >= len(self.regex) or self.regex[self.index] != '}':
+            self._raise_error("Invalid quantifier")
+        self.index += 1
+
+        return min_len, max_len
+
+    def _skipSpaces(self):
+        while self.index < len(self.regex) and self.regex[self.index] == ' ':
+            self.index += 1
+
+    def _raise_error(self, message: str):
+        raise RegexError(self.regex, self.index, message)
diff --git a/regex_enumerator/regex_enumerator.py b/regex_enumerator/regex_enumerator.py
@@ -1,4 +1,8 @@
-from .regex_parser import RegexParser
+import sys
+if sys.version_info >= (3, 10):
+    from .parser.regex_parser import RegexParser
+else:
+    from .parser.regex_parser_legacy import RegexParser
 from .regex_tree import RegexTree
 
 
diff --git a/regex_enumerator/regex_error.py b/regex_enumerator/regex_error.py
@@ -0,0 +1,9 @@
+class RegexError(Exception):
+    def __init__(self, regex: str, index: int, message: str):
+        self.regex = regex
+        self.index = index
+        self.message = message
+
+    def __str__(self):
+        caret_line = ' ' * self.index + '^'
+        return f"\n{self.regex}\n{caret_line}\n{self.message}"
diff --git a/setup.py b/setup.py
@@ -18,9 +18,9 @@
               'exhaustive matching', 'exhaustive search', 'regex testing', 'regex tools', 'string enumeration', 'data generation'],
     long_description=long_description,
     long_description_content_type="text/markdown",
-    python_requires='>=3.10',
+    python_requires='>=3.9',
     classifiers=[
-        'Programming Language :: Python :: 3.10',
+        'Programming Language :: Python :: 3.9',
         'Operating System :: OS Independent',
         'License :: OSI Approved :: MIT License',
     ],
diff --git a/tests/test_grammar.py b/tests/test_grammar.py
