Developer(s) | Rich Salz |
---|---|
Type | Pattern matching |
wildmat is a pattern matching library developed by Rich Salz. Based on the wildcard syntax already used in the Bourne shell, wildmat provides a uniform mechanism for matching patterns across applications with simpler syntax than that typically offered by regular expressions. Patterns are implicitly anchored at the beginning and end of each string when testing for a match.
In June 2019, Rich Salz released the original version of the now-defunct library on GitHub under a public domain dedication. [1]
There are five pattern matching operations other than a strict one-to-one match between the pattern and the source to be checked for a match.
wildmat is most commonly seen in NNTP implementations such as Salz's own INN, also in unrelated software such as GNU tar and Transmission. GNU tar replaced wildmat with the POSIX fnmatch glob matcher in September 1992. The early version contained a potential out-of-bound access on unclosed [. [2]
The original byte oriented wildmat implementation is unable to handle multibyte character sets, and poses problems when the text being searched may contain multiple incompatible character sets. A simplified version of wildmat oriented toward UTF-8 encoding has been developed by the IETF NNTP working group. It is a part of RFC 3977 (section 4), the 2006 standard for NNTP.
In the newer INN which supports UTF-8, a "uwildmat" was added which supports all the features of wildmat. This 2000 rewrite, performed by Russ Allbery, fixes the OOB in the original implementation. Tightly-wound C loops were written out into smaller statements. [3] [4]
Rsync includes a GPLv3-licensed wildmat descendant known as wildmatch, modified by Wayne Davison. The Git version control system imports and makes use of it. It does not support UTF-8, but has the OOB fixed and has additional support for character classes and star globs (** for arbitrary-depth). [5]
A regular expression is a sequence of characters that specifies a search pattern. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. It is a technique developed in theoretical computer science and formal language theory.
rn is a news client written by Larry Wall and originally released in 1984. It was one of the first newsreaders to take full advantage of character-addressable CRT terminals. Previous newsreaders, such as readnews, were mostly line-oriented and designed for use on the printing terminals which were common on the early Unix minicomputers where the Usenet software and network originated. Later variants of the original rn program included rrn, trn, and strn.
In software, a wildcard character is a kind of placeholder represented by a single character, such as an asterisk, which can be interpreted as a number of literal characters or an empty string. It is often used in file searches so the full name need not be typed.
The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects. This pattern is used to:
Almquist shell is a lightweight Unix shell originally written by Kenneth Almquist in the late 1980s. Initially a clone of the System V.4 variant of the Bourne shell, it replaced the original Bourne shell in the BSD versions of Unix released in the early 1990s.
A news server is a collection of software used to handle Usenet articles. It may also refer to a computer itself which is primarily or solely used for handling Usenet. Access to Usenet is only available through news server provider.
A string literal or anonymous string is a type of literal in programming for the representation of a string value within the source code of a computer program. Most often in modern languages this is a quoted sequence of characters, as in x = "foo"
, where "foo"
is a string literal with value foo
– the quotes are not part of the value, and one must use a method such as escape sequences to avoid the problem of delimiter collision and allow the delimiters themselves to be embedded in a string. However, there are numerous alternate notations for specifying string literals, particularly more complicated cases, and the exact notation depends on the individual programming language in question. Nevertheless, there are some general guidelines that most modern programming languages follow.
An email address identifies an email box to which messages are delivered. While early messaging systems used a variety of formats for addressing, today, email addresses follow a set of specific rules originally standardized by the Internet Engineering Task Force (IETF) in the 1980s, and updated by RFC 5322 and 6854. The term email address in this article refers to addr-spec in RFC 5322, not to address or mailbox; i.e., a raw address without a display-name.
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In computer programming, glob patterns specify sets of filenames with wildcard characters. For example, the Unix Bash shell command mv *.txt textfiles/
moves all files with names ending in .txt
from the current directory to the directory textfiles
. Here, *
is a wildcard standing for "any string of characters" and *.txt
is a glob pattern. The other common wildcard is the question mark (?
), which stands for one character. For example, mv ?.txt shorttextfiles/
will move all files named with a single character followed by .txt
from the current directory to directory shorttextfiles
, while ??.txt
would match all files whose name consists of 2 characters followed by .txt
.
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is a command-line utility that locates files based on some user-specified criteria and then applies some requested action on each matched object.
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In computer science, the Krauss wildcard-matching algorithm is a pattern matching algorithm. Based on the wildcard syntax in common use, e.g. in the Microsoft Windows command-line interface, the algorithm provides a non-recursive mechanism for matching patterns in software applications, based on syntax simpler than that typically offered by regular expressions.
In computer science, an algorithm for matching wildcards is useful in comparing text strings that may contain wildcard syntax. Common uses of these algorithms include command-line interfaces, e.g. the Bourne shell or Microsoft Windows command-line or text editor or file manager, as well as the interfaces for some search engines and databases. Wildcard matching is a subset of the problem of matching regular expressions and string matching in general.
Might not be robust in face of malformed patterns; e.g., "foo[a-" could cause a segmentation violation.