diff options
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | Doc/Zsh/expn.yo | 60 | ||||
| -rw-r--r-- | Src/subst.c | 11 | ||||
| -rw-r--r-- | Test/D04parameter.ztst | 14 |
4 files changed, 56 insertions, 36 deletions
diff --git a/ChangeLog b/ChangeLog index 3ba0a6b1d..a68c01534 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2010-11-25 Peter Stephenson <pws@csr.com> + + * 28434: Doc/Zsh/expn.yo, Src/subst.c, Test/D04parameter.ztst: + Make ${NAME:OFFSET} always use zero-offset. + 2010-11-22 Peter Stephenson <pws@csr.com> * 28424: Doc/Zsh/options.yo, Src/options.c, Src/utils.c, @@ -13838,5 +13843,5 @@ ***************************************************** * This is used by the shell to define $ZSH_PATCHLEVEL -* $Revision: 1.5125 $ +* $Revision: 1.5126 $ ***************************************************** diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo index 416d46407..0c26a7ca5 100644 --- a/Doc/Zsh/expn.yo +++ b/Doc/Zsh/expn.yo @@ -588,23 +588,29 @@ remove the non-matched elements). xitem(tt(${)var(name)tt(:)var(offset)tt(})) item(tt(${)var(name)tt(:)var(offset)tt(:)var(length)tt(}))( This syntax gives effects similar to parameter subscripting -in the form tt($)var(name)tt({)var(offset)tt(,)var(end)tt(}) but in -a form compatible with other shells. - -If the variable var(name) is a scalar, substitute the contents -starting from offset var(offset); if var(name) is an array, -substitute elements from element var(offset). If var(length) is -given, substitute that many characters or elements, otherwise the -entire rest of the scalar or array. - -var(offset) is treated similarly to a parameter subscript: -the offset of the first character or element in var(name) -is 0 if the option tt(KSH_ARRAYS) is set, else 1; a negative -subscript counts backwards so that -1 corresponds to the last -character or element. +in the form tt($)var(name)tt({)var(start)tt(,)var(end)tt(}), but is +compatible with other shells; note that both var(offset) and var(length) +are interpreted differently from the components of a subscript. + +If var(offset) is non-negative, then if the variable var(name) is a +scalar substitute the contents starting var(offset) characters from the +first character of the string, and if var(name) is an array substitute +elements starting var(offset) elements from the first element. If +var(length) is given, substitute that many characters or elements, +otherwise the entire rest of the scalar or array. + +A positive var(offset) is always treated as the offset of a character or +element in var(name) from the first character or element of the array +(this is different from native zsh subscript notation). Hence 0 +refers to the first character or element regardless of the setting of +the option tt(KSH_ARRAYS). + +A negative offset counts backwards from the end of the scalar or array, +so that -1 corresponds to the last character or element, and so on. var(length) is always treated directly as a length and hence may not be -negative. +negative. The option tt(MULTIBYTE) is obeyed, i.e. the offset and length +count multibyte characters where appropriate. var(offset) and var(length) undergo the same set of shell substitutions as for scalar assignment; in addition, they are then subject to arithmetic @@ -615,19 +621,29 @@ print ${foo: 1 + 2} print ${foo:$(( 1 + 2))} print ${foo:$(echo 1 + 2)}) -all have the same effect. +all have the same effect, extracting the string starting at the fourth +character of tt($foo) if the substution would otherwise return a scalar, +or the array starting at the fourth element if tt($foo) would return an +array. Note that with the option tt(KSH_ARRAYS) tt($foo) always returns +a scalar (regardless of the use of the offset syntax) and a form +such as tt($foo[*]:3) is required to extract elements of an array named +tt(foo). -Note that if var(offset) is negative, the tt(-) may not appear immediately +If var(offset) is negative, the tt(-) may not appear immediately after the tt(:) as this indicates the -tt(${)var(name)tt(:-)var(word)tt(}) form of substitution; a space +tt(${)var(name)tt(:-)var(word)tt(}) form of substitution. Instead, a space may be inserted before the tt(-). Furthermore, neither var(offset) nor var(length) may begin with an alphabetic character or tt(&) as these are -used to indicate history-style modifiers. +used to indicate history-style modifiers. To substitute a value from a +variable, the recommended approach is to proceed it with a tt($) as this +signifies the intention (parameter substitution can easily be rendered +unreadable); however, as arithmetic substitution is performed, the +expression tt(${var: offs}) does work, retrieving the offset from +tt($offs). For further compatibility with other shells there is a special case -when the tt(KSH_ARRAYS) option is active, as in emulation of -Bourne-style shells. In this case array subscript 0 usually refers to the -first element of the array. However, if the substitution refers to the +for array offset 0. This usually accesses to the +first element of the array. However, if the substitution refers the positional parameter array, e.g. tt($@) or tt($*), then offset 0 instead refers to tt($0), offset 1 refers to tt($1), and so on. In other words, the positional parameter array is effectively extended by diff --git a/Src/subst.c b/Src/subst.c index 12825ff93..031a1affd 100644 --- a/Src/subst.c +++ b/Src/subst.c @@ -1640,7 +1640,7 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int ssub) int subexp; /* * If we're referring to the positional parameters, then - * e.g ${*:1:1} refers to $1 even if KSH_ARRAYS is in effect. + * e.g ${*:1:1} refers to $1. * This is for compatibility. */ int horrible_offset_hack = 0; @@ -2768,16 +2768,15 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int ssub) return NULL; } } - if (!isset(KSHARRAYS) || horrible_offset_hack) { + if (horrible_offset_hack) { /* * As part of the 'orrible hoffset 'ack, * (what hare you? Han 'orrible hoffset 'ack, * sergeant major), if we are given a ksh/bash/POSIX - * style array which includes offset 0, we use - * $0. + * style positional parameter array which includes + * offset 0, we use $0. */ - if (isset(KSHARRAYS) && horrible_offset_hack && - offset == 0 && isarr) { + if (offset == 0 && isarr) { offset_hack_argzero = 1; } else if (offset > 0) { offset--; diff --git a/Test/D04parameter.ztst b/Test/D04parameter.ztst index 46565a121..4bd911e5f 100644 --- a/Test/D04parameter.ztst +++ b/Test/D04parameter.ztst @@ -1268,15 +1268,15 @@ print ${foo:$(echo 3 + 3):`echo 4 - 3`} print ${foo: -1} print ${foo: -10} -0:Bash-style subscripts, scalar ->3456789 +0:Bash-style offsets, scalar >456789 >56789 >6789 ->3 +>789 >4 >5 >6 +>7 >9 >123456789 @@ -1291,15 +1291,15 @@ print ${foo:$(echo 3 + 3):`echo 4 - 3`} print ${foo: -1} print ${foo: -10} -0:Bash-style subscripts, array ->3 4 5 6 7 8 9 +0:Bash-style offsets, array >4 5 6 7 8 9 >5 6 7 8 9 >6 7 8 9 ->3 +>7 8 9 >4 >5 >6 +>7 >9 >1 2 3 4 5 6 7 8 9 @@ -1321,7 +1321,7 @@ echo ${str: -1:1} } testfn -0:Bash-style subscripts, Bourne-style indexing +0:Bash-style offsets, Bourne-style indexing >1 >2 >3 |