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Some clarifications of out-of-range group indexes/names

This commit is contained in:
Guido van Rossum 1998-04-03 20:07:37 +00:00
parent a50547e0c0
commit 791468f731
2 changed files with 20 additions and 10 deletions
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15
Doc/lib/libre.tex
View File

@ -420,7 +420,7 @@ previous match, so \samp{sub('x*', '-', 'abc')} returns \code{'-a-b-c-'}.
If \var{repl} is a string, any backslash escapes in it are processed.
That is, \samp{\e n} is converted to a single newline character,
\samp{\e r} is converted to a linefeed, and so forth. Unknown escapes
such as \samp{\e j} are XXX. Backreferences, such as \samp{\e 6} are
such as \samp{\e j} are left alone. Backreferences, such as \samp{\e 6} are
replaced with the substring matched by group 6 in the pattern.
In addition to character escapes and backreferences as described
@ -521,13 +521,18 @@ Without arguments, \var{group1} defaults to zero (i.e. the whole match
is returned).
If a \var{groupN} argument is zero, the corresponding return value is the
entire matching string; if it is in the inclusive range [1..99], it is
the string matching the the corresponding parenthesized group. If no
such group exists, the corresponding result is
\code{None}.
the string matching the the corresponding parenthesized group. If a
group number is negative or larger than the number of groups defined
in the pattern, an \exception{IndexError} exception is raised.
If a group is contained in a part of the pattern that did not match,
the corresponding result is \code{None}. If a group is contained in a
part of the pattern that matched multiple times, the last match is
returned.
If the regular expression uses the \code{(?P<\var{name}>...)} syntax,
the \var{groupN} arguments may also be strings identifying groups by
their group name.
their group name. If a string argument is not used as a group name in
the pattern, an \exception{IndexError} exception is raised.
A moderately complicated example:

15
Doc/libre.tex
View File

@ -420,7 +420,7 @@ previous match, so \samp{sub('x*', '-', 'abc')} returns \code{'-a-b-c-'}.
If \var{repl} is a string, any backslash escapes in it are processed.
That is, \samp{\e n} is converted to a single newline character,
\samp{\e r} is converted to a linefeed, and so forth. Unknown escapes
such as \samp{\e j} are XXX. Backreferences, such as \samp{\e 6} are
such as \samp{\e j} are left alone. Backreferences, such as \samp{\e 6} are
replaced with the substring matched by group 6 in the pattern.
In addition to character escapes and backreferences as described
@ -521,13 +521,18 @@ Without arguments, \var{group1} defaults to zero (i.e. the whole match
is returned).
If a \var{groupN} argument is zero, the corresponding return value is the
entire matching string; if it is in the inclusive range [1..99], it is
the string matching the the corresponding parenthesized group. If no
such group exists, the corresponding result is
\code{None}.
the string matching the the corresponding parenthesized group. If a
group number is negative or larger than the number of groups defined
in the pattern, an \exception{IndexError} exception is raised.
If a group is contained in a part of the pattern that did not match,
the corresponding result is \code{None}. If a group is contained in a
part of the pattern that matched multiple times, the last match is
returned.
If the regular expression uses the \code{(?P<\var{name}>...)} syntax,
the \var{groupN} arguments may also be strings identifying groups by
their group name.
their group name. If a string argument is not used as a group name in
the pattern, an \exception{IndexError} exception is raised.
A moderately complicated example: