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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@25909 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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Julian Smart
2004-02-22 01:16:32 +00:00
parent 40126b09cc
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46 changed files with 127 additions and 135 deletions
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40
docs/latex/wx/re_syntax.tex
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@@ -10,7 +10,6 @@ pattern that matches certain strings and doesn't match others.
\helpref{wxRegEx}{wxregex}
\subsection{Different Flavors of REs}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -22,11 +21,10 @@ of the traditional {\it egrep}, while BREs are roughly those of the traditional
EREs with some significant extensions.
This manual page primarily describes
AREs. BREs mostly exist for backward compatibility in some old programs;
they will be discussed at the \helpref{end}{wxresynbre}. POSIX EREs are almost an exact subset
of AREs. Features of AREs that are not present in EREs will be indicated.
AREs. BREs mostly exist for backward compatibility in some old programs;
they will be discussed at the \helpref{end}{wxresynbre}. POSIX EREs are almost an exact subset
of AREs. Features of AREs that are not present in EREs will be indicated.
\subsection{Regular Expression Syntax}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -36,16 +34,14 @@ the package written by Henry Spencer, based on the 1003.2 spec and some
(not quite all) of the Perl5 extensions (thanks, Henry!). Much of the description
of regular expressions below is copied verbatim from his manual entry.
An
ARE is one or more {\it branches}, separated by `{\bf $|$}', matching anything that matches
An ARE is one or more {\it branches}, separated by `{\bf $|$}', matching anything that matches
any of the branches.
A branch is zero or more {\it constraints} or {\it quantified
atoms}, concatenated. It matches a match for the first, followed by a match
for the second, etc; an empty branch matches the empty string.
A quantified
atom is an {\it atom} possibly followed by a single {\it quantifier}. Without a quantifier,
A quantified atom is an {\it atom} possibly followed by a single {\it quantifier}. Without a quantifier,
it matches a match for the atom. The quantifiers, and what a so-quantified
atom matches, are:
@@ -89,8 +85,7 @@ a digit, it is the beginning of a {\it bound} (see above)}
character with no other significance, matches that character.}
\end{twocollist}
A {\it constraint}
matches an empty string when specific conditions are met. A constraint may
A {\it constraint} matches an empty string when specific conditions are met. A constraint may
not be followed by a quantifier. The simple constraints are as follows;
some more constraints are described later, under \helpref{Escapes}{wxresynescapes}.
@@ -108,7 +103,6 @@ The lookahead constraints may not contain back references
An RE may not end with `{\bf $\backslash$}'.
\subsection{Bracket Expressions}\label{wxresynbracket}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -219,7 +213,6 @@ by word characters. A word character is an {\it alnum} character or an underscor
({\bf \_}). These special bracket expressions are deprecated; users of AREs should
use constraint escapes instead (see \helpref{Escapes}{wxresynescapes} below).
\subsection{Escapes}\label{wxresynescapes}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -346,7 +339,6 @@ is taken as a back reference if it comes after a suitable subexpression
(i.e. the number is in the legal range for a back reference), and otherwise
is taken as octal.
\subsection{Metasyntax}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -419,7 +411,6 @@ metasyntax extensions is available if the application (or an initial {\bf ***=}
director) has specified that the user's input be treated as a literal string
rather than as an RE.
\subsection{Matching}\label{wxresynmatching}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -440,8 +431,7 @@ atom with other non-greedy quantifiers (including {\bf \{m,n\}?} with {\it m} eq
quantified atom in it which has a preference. An RE consisting of two or
more branches connected by the {\bf $|$} operator prefers longest match.
Subject
to the constraints imposed by the rules for matching the whole RE, subexpressions
Subject to the constraints imposed by the rules for matching the whole RE, subexpressions
also match the longest or shortest possible substrings, based on their
preferences, with subexpressions starting earlier in the RE taking priority
over ones starting later. Note that outer subexpressions thus take priority
@@ -484,7 +474,6 @@ If inverse partial newline-sensitive matching is specified,
this affects {\bf $^$} and {\bf \$} as with newline-sensitive matching, but not {\bf .} and bracket
expressions. This isn't very useful but is provided for symmetry.
\subsection{Limits And Compatibility}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -519,27 +508,23 @@ Henry Spencer's original 1986 {\it regexp} package, still in widespread use,
implemented an early version of today's EREs. There are four incompatibilities between {\it regexp}'s
near-EREs (`RREs' for short) and AREs. In roughly increasing order of significance:
{\itemize
\item
In AREs, {\bf $\backslash$} followed by an alphanumeric character is either an escape or
\item In AREs, {\bf $\backslash$} followed by an alphanumeric character is either an escape or
an error, while in RREs, it was just another way of writing the alphanumeric.
This should not be a problem because there was no reason to write such
a sequence in RREs.
\item%
{\bf \{} followed by a digit in an ARE is the beginning of
\item {\bf \{} followed by a digit in an ARE is the beginning of
a bound, while in RREs, {\bf \{} was always an ordinary character. Such sequences
should be rare, and will often result in an error because following characters
will not look like a valid bound.
\item%
In AREs, {\bf $\backslash$} remains a special character
\item In AREs, {\bf $\backslash$} remains a special character
within `{\bf $[]$}', so a literal {\bf $\backslash$} within {\bf $[]$} must be
written `{\bf $\backslash\backslash$}'. {\bf $\backslash\backslash$} also gives a literal
{\bf $\backslash$} within {\bf $[]$} in RREs, but only truly paranoid programmers routinely doubled
the backslash.
\item%
AREs report the longest/shortest match for the RE, rather
\item AREs report the longest/shortest match for the RE, rather
than the first found in a specified search order. This may affect some RREs
which were written in the expectation that the first match would be reported.
(The careful crafting of RREs to optimize the search order for fast matching
@@ -549,7 +534,6 @@ order was exploited to deliberately find a match which was {\it not} the longes
will need rewriting.)
}
\subsection{Basic Regular Expressions}\label{wxresynbre}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -570,7 +554,6 @@ are available, and {\bf $\backslash<$} and {\bf $\backslash>$} are synonyms
for {\bf $[[:<:]]$} and {\bf $[[:>:]]$} respectively;
no other escapes are available.
\subsection{Regular Expression Character Names}\label{wxresynchars}
\helpref{Syntax of the builtin regular expression library}{wxresyn}
@@ -674,3 +657,4 @@ Note that the character names are case sensitive.
\twocolitem{tilde}{'$~$'}
\twocolitem{DEL}{'$\backslash$177'}
\end{twocollist}