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| -rw-r--r-- | README.rst | 132 |
1 files changed, 124 insertions, 8 deletions
@@ -81,8 +81,8 @@ The following example recognises and captures any email like ``[email protected] assert email(email_addr) == True -Building Regex Example ----------------------- +Building Regex Example: Validating 16-bit Hexadecimal Number +------------------------------------------------------------ The following example recognises and captures the value of a 16-bit hexadecimal number like ``0xC0D3``. @@ -94,24 +94,140 @@ The following example recognises and captures the value of a 16-bit hexadecimal expr = ( RegexBuilder() .start_of_input() - .optional().string("0x") + .optional().string("0x") # match an optional "0x" string .capture() - .exactly(4).any_of() - .range("A", "F") - .range("a", "f") - .range("0", "9") + .exactly(4).any_of() # let x = any characters between (a-f, A-F, and 0-9) + .range("A", "F") # now capture exactly 4 such groups of "x" + .range("a", "f") # this will give the match for the number like "C0D3" + .range("0", "9") # which when combined with "0x" becomes a 16-bit hexadecimal number .end() .end() .end_of_input() - .to_regex() + .to_regex() # used to convert to `re` compatible form ) """ Produces the following regular expression: re.compile(^(?:0x)?([A-Fa-f0-9]{4})$) + + Using `to_regex_string()` instead of `to_regex()` at the end + will give the compiled regex string. """ assert expr.match("0xC0D3") + +Building Regex Example: Validating Signed Integer +------------------------------------------------- + +The following example recognises and checks if a number is a valid signed integer or not (eg. ``-45`` or ``+45``). + +.. code-block:: python + + + from edify import RegexBuilder + + # expression for matching any signed integer. compiles to '^[\+\-]{1}\d+$' + expr = ( + RegexBuilder() + .start_of_input() + .exactly(1).any_of() # capture either '+' or '-', exactly once + .char('+') + .char('-') + .end() + .one_or_more().digit() # capture any number of digits + .end_of_input() + .to_regex() + ) + + if expr.match('-69'): + print("Matched") # prints matched + +Building Regex Example: Simple URL Validator +-------------------------------------------- + +The following example checks if a string is a valid url in the form of ``https://www.example.com/path/to/file.ext`` + + +.. code-block:: python + + + from edify import RegexBuilder + + # expression for validating URLs + validate_urls = ( + RegexBuilder() + .optional().string('http://') # look for an optional "http://" + .optional().string('https://') # or "https://" + .one_or_more().any_of() # let x = any characters between (a-z, 0-9, '-', and '.') + .range('a', 'z') # now capture one or more groups of "x" + .range('0', '9') # essentially capturing all url patterns in the form of + .any_of_chars('.-') # xxx.yyyyyyy.abra-cadabra.com + .end() + .at_least(2).any_of() # this is to make sure we get at least 2 characters in + .range('a', 'z') # the end of the string, which would be our domain + .end() + .zero_or_more().any_of() + .range('a', 'z') # same logic as capturing the url in step 1, but now + .range('0', '9') # we are essentially looking for an optional path + .any_of_chars('/.-_%') # and we add some more characters supported in path + .end() + ) + + # compiles to '^(?:http://)?(?:https://)?([a-z0-9\\.]+[a-z]{2,}[a-z0-9/\\.\\-_%]*)$' + expr = ( + RegexBuilder() + .ignore_case() # case does not matter + .subexpression(validate_urls) # directly writing the subexpression works too + .to_regex() # convert to regex finally + ) + + + if expr.match('https://SOMETHING.www.exam-ple.com/path/to/file.txt'): + print("Matched") # prints matched + + +Building Regex Example: Simple Password Validator +------------------------------------------------- +The regular expression below cheks that a password: + +* Has minimum 8 characters in length. +* At least one uppercase English letter. +* At least one lowercase English letter. +* At least one digit. +* At least one special character from ``#?!@$%^&*-``. + +.. code-block:: python + + from edify import RegexBuilder + + # expression for validating passwords - complies to '^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$' + expr = ( + RegexBuilder() + .start_of_input() # asserts position at start of a line + .assert_ahead() # positive look ahead + # matches any character in range 'A' to 'Z' zero and unlimited times, + # as few times as possible, expanding as needed (lazy) - matching at least 1 uppercase character + .zero_or_more_lazy().any_char().range('A', 'Z') + .end() + .assert_ahead() + # at least 1 lowercase character + .zero_or_more_lazy().any_char().range('a', 'z') + .end() + .assert_ahead() + # at least 1 number + .zero_or_more_lazy().any_char().range('0', '9') + .end() + .assert_ahead() + # at least 1 special character present in the list + .zero_or_more_lazy().any_char().any_of_chars('#?!@$%^&*-') + .end() + .at_least(8).any_char() # must be at least 8 characters long + .end_of_input() + .to_regex() + ) + + if expr.match('-Secr3t!'): + print("Matched") # prints matched Further Documentation |