diff options
Diffstat (limited to 'Doc/Zsh/expn.yo')
| -rw-r--r-- | Doc/Zsh/expn.yo | 65 |
1 files changed, 63 insertions, 2 deletions
diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo index ccf245367..fa56bc0af 100644 --- a/Doc/Zsh/expn.yo +++ b/Doc/Zsh/expn.yo @@ -869,7 +869,7 @@ can be specified by separating two characters by a `tt(-)'. A `tt(-)' or `tt(])' may be matched by including it as the first character in the list. There are also several named classes of characters, in the form -`tt([:)var(name)(tt:])' with the following meanings: `tt([:alnum:])' +`tt([:)var(name)tt(:])' with the following meanings: `tt([:alnum:])' alphanumeric, `tt([:alpha:])' alphabetic, `tt([:blank:])' space or tab, `tt([:cntrl:])' control character, `tt([:digit:])' decimal @@ -988,12 +988,18 @@ item(I)( Case sensitive: locally negates the effect of tt(i) or tt(l) from that point on. ) +item(tt(a)var(num))( +Approximate matching: var(num) errors are allowed in the string matched by +the pattern. The rules for this are described in the next subsection. +) enditem() For example, the test string tt(fooxx) can be matched by the pattern tt(LPAR()#i)tt(RPAR()FOOXX), but not by tt(LPAR()#l)tt(RPAR()FOOXX), tt(LPAR()#i)tt(RPAR()FOO)tt(LPAR()#I)tt(RPAR()XX) or -tt(LPAR()LPAR()#i)tt(RPAR()FOOX)tt(RPAR()X). +tt(LPAR()LPAR()#i)tt(RPAR()FOOX)tt(RPAR()X). The string +tt(LPAR()#ia2)tt(RPAR()readme) specifies case-insensitive matching of +tt(readme) with up to two errors. When using the ksh syntax for grouping both tt(KSH_GLOB) and tt(EXTENDED_GLOB) must be set and the left parenthesis should be @@ -1004,6 +1010,61 @@ examining whole paths case-insensitively every directory must be searched for all files which match, so that a pattern of the form tt(LPAR()#i)tt(RPAR()/foo/bar/...) is potentially slow. +subsect(Approximate Matching) +When matching approximately, the shell keeps a count of the errors found, +which cannot exceed the number specified in the +tt(LPAR()#a)var(num)tt(RPAR()) flags. Four types of error are recognised: + +startitem() +item(1.)( +Different characters, as in tt(fooxbar) and tt(fooybar). +) +item(2.)( +Transposition of characters, as in tt(banana) and tt(abnana). +) +item(3.)( +A character missing in the target string, as with the pattern tt(road) and +target string tt(rod). +) +item(4.)( +An extra character appearing in the target string, as with tt(stove) +and tt(strove). +) +enditem() + +Thus, the pattern tt(LPAR()#a3)tt(RPAR()abcd) matches tt(dcba), with the +errors occurring by using the first rule twice and the second once, +grouping the string as tt([d][cb][a]) and tt([a][bc][d]). + +Non-literal parts of the pattern must match exactly, including characters +in character ranges: hence tt(LPAR()#a1)tt(RPAR()???) matches strings of +length four, by applying rule 4 to an empty part of the pattern, but not +strings of length three, since all the tt(?) must match. Other characters +which must match exactly are initial dots in filenames (unless the +tt(GLOB_DOTS) option is set), and all slashes in file names, so that +tt(a/bc) is two errors from tt(ab/c) (the slash cannot be transposed with +another character). Similarly, errors are counted separately for +non-contiguous strings in the pattern, so that tt(LPAR()ab|cd)tt(RPAR()ef) +is two errors from tt(aebf). + +When using exclusion via the tt(~) operator, approximate matching is +treated entirely separately for the excluded part and must be activated +separately. Thus, tt(LPAR()#a1)tt(RPAR()README~READ_ME) matches +tt(READ.ME) but not tt(READ_ME), as the trailing tt(READ_ME) is matched +without approximation. However, +tt(LPAR()#a1)tt(RPAR()README~LPAR()#a1)tt(RPAR()READ_ME) +does not match any pattern of the form tt(READ)var(?)tt(ME) as all +such forms are now excluded. + +Apart from exclusions, there is only one overall error count; however, the +maximum errors allowed may be altered locally, and this can be delimited by +grouping. For example, +tt(LPAR()#a1)tt(RPAR()cat)tt(LPAR()LPAR()#a0)tt(RPAR()dog)tt(RPAR()fox) +allows one error in total, which may not occur in the tt(dog) section, and +the pattern +tt(LPAR()#a1)tt(RPAR()cat)tt(LPAR()#a0)tt(RPAR()dog)tt(LPAR()#a1)tt(RPAR()fox) +is equivalent. + subsect(Recursive Globbing) A pathname component of the form `tt(LPAR())var(foo)tt(/RPAR()#)' matches a path consisting of zero or more directories |