lib/varstash

   1 ################################################################################
   2 # Stash/unstash support for per-directory variables
   3 #
   4 # Adopted for zsh-autoenv.
   5 #
   6 #   Copyright (c) 2009,2012 Dave Olszewski <cxreg@pobox.com>
   7 #   http://github.com/cxreg/smartcd
   8 #
   9 #   This code is released under GPL v2 and the Artistic License, and
  10 #   may be redistributed under the terms of either.
  11 #
  12 #
  13 #   This library allows you to save the current value of a given environment
  14 #   variable in a temporary location, so that you can modify it, and then
  15 #   later restore its original value.
  16 #
  17 #   Note that you will need to be in the same directory you were in when you
  18 #   stashed in order to successfully unstash.  This is because the temporary
  19 #   variable is derived from your current working directory's path.
  20 #
  21 #   Usage:
  22 #       stash PATH
  23 #       export PATH=/something/else
  24 #       [...]
  25 #       unstash PATH
  26 #
  27 #   Note that this was written for use with, and works very well with,
  28 #   smartcd.  See the documentation there for examples.
  29 #
  30 #   An alternate usage is `autostash' which will trigger autounstash when
  31 #   leaving the directory, if combined with smartcd.  This reduces the amount
  32 #   of explicit configuration you need to provide:
  33 #
  34 #       autostash PATH
  35 #       export PATH=/something/else
  36 #
  37 #   You may also do both operations on line line, leaving only the very succinct
  38 #
  39 #       autostash PATH=/something/else
  40 #
  41 #   If you attempt to stash the same value twice, a warning will be displayed
  42 #   and the second stash will not occur.  To make it happen anyway, pass -f
  43 #   as the first argument to stash.
  44 #
  45 #       $ stash FOO
  46 #       $ stash FOO
  47 #       You have already stashed FOO, please specify "-f" if you want to overwrite another stashed value
  48 #       $ stash -f FOO
  49 #       $
  50 #
  51 #   This rule is a bit different if you are assigning a value and the variable
  52 #   has already been stashed.  In that case, the new value will be assigned, but
  53 #   the stash will not be overwritten.  This allows for non-conflicting chained
  54 #   stash-assign rules.
  55 #
  56 ################################################################################
  57
  58
  59 # Library functions, from smartcd's lib/core/arrays. {{{
  60 function apush() {
  61     local var=$1; shift
  62     eval "$var=(\${$var[@]} \"\$@\")"
  63 }
  64
  65 function alen() {
  66     local var=$1
  67
  68     if [[ -n $var ]]; then
  69         eval "echo \${#$var[@]}"
  70     fi
  71 }
  72
  73 function afirst() {
  74     setopt localoptions && setopt ksharrays
  75     local var=$1
  76
  77     if [[ -n $var ]] && (( $(eval "echo \${#$var[@]}") >= 1 )); then
  78         eval "echo \"\${$var""[0]}\""
  79     fi
  80 }
  81
  82 function ashift() {
  83     setopt localoptions && setopt ksharrays
  84     local var=$1
  85
  86     local _ashift_return=
  87
  88     if [[ -n $var ]] && (( $(eval "echo \${#$var[@]}") >= 1 )); then
  89         eval "_ashift_return=\"\${$var""[0]}\""
  90         eval "$var""[0]=()"
  91
  92         echo "$_ashift_return"
  93     fi
  94 }
  95 # }}}
  96
  97
  98 function stash() {
  99     if [[ $1 == "-f" ]]; then
 100         local force=1; shift
 101     fi
 102
 103     while [[ -n $1 ]]; do
 104         if [[ $1 == "alias" && $2 == *=* ]]; then
 105             shift
 106             local _stashing_alias_assign=1
 107             continue
 108         fi
 109
 110         local stash_expression=$1
 111         local stash_which=${stash_expression%%'='*}
 112         local stash_name=$(_mangle_var $stash_which)
 113
 114         # Extract the value and make it double-quote safe
 115         local stash_value=${stash_expression#*'='}
 116         stash_value=${stash_value//\\/\\\\}
 117         stash_value=${stash_value//\"/\\\"}
 118         stash_value=${stash_value//\`/\\\`}
 119         stash_value=${stash_value//\$/\\\$}
 120
 121         if [[ ( -n "$(eval echo '$__varstash_alias__'$stash_name)"    ||
 122                 -n "$(eval echo '$__varstash_function__'$stash_name)" ||
 123                 -n "$(eval echo '$__varstash_array__'$stash_name)"    ||
 124                 -n "$(eval echo '$__varstash_export__'$stash_name)"   ||
 125                 -n "$(eval echo '$__varstash_variable__'$stash_name)" ||
 126                 -n "$(eval echo '$__varstash_nostash__'$stash_name)" )
 127                 && -z $force ]]; then
 128
 129             if [[ -z $already_stashed && ${already_stashed-_} == "_" ]]; then
 130                 local already_stashed=1
 131             else
 132                 already_stashed=1
 133             fi
 134
 135             if [[ $stash_which == $stash_expression ]]; then
 136                 if [[ -z $run_from_smartcd ]]; then
 137                     echo "You have already stashed $stash_which, please specify \"-f\" if you want to overwrite another stashed value"
 138                 fi
 139
 140                 # Skip remaining work if we're not doing an assignment
 141                 shift
 142                 continue
 143             fi
 144         fi
 145
 146         # Handle any alias that may exist under this name
 147         if [[ -z $already_stashed ]]; then
 148             local alias_def="$(eval alias $stash_which 2>/dev/null)"
 149             if [[ -n $alias_def ]]; then
 150                 alias_def=${alias_def#alias }
 151                 eval "__varstash_alias__$stash_name=\"$alias_def\""
 152                 local stashed=1
 153             fi
 154         fi
 155         if [[ $stash_which != $stash_expression && -n $_stashing_alias_assign ]]; then
 156             eval "alias $stash_which=\"$stash_value\""
 157         fi
 158
 159         # Handle any function that may exist under this name
 160         if [[ -z $already_stashed ]]; then
 161             local function_def="$(declare -f $stash_which)"
 162             if [[ -n $function_def ]]; then
 163                 # make function definition quote-safe.  because we are going to evaluate the
 164                 # source with "echo -e", we need to double-escape the backslashes (so 1 -> 4)
 165                 function_def=${function_def//\\/\\\\\\\\}
 166                 function_def=${function_def//\"/\\\"}
 167                 function_def=${function_def//\`/\\\`}
 168                 function_def=${function_def//\$/\\\$}
 169                 eval "__varstash_function__$stash_name=\"$function_def\""
 170                 local stashed=1
 171             fi
 172         fi
 173
 174         # Handle any variable that may exist under this name
 175         local vartype="$(declare -p $stash_which 2>/dev/null)"
 176         if [[ -n $vartype ]]; then
 177             if [[ -n $ZSH_VERSION ]]; then
 178                 local pattern="typeset"
 179             else
 180                 local pattern="declare"
 181             fi
 182             if [[ $vartype == $pattern" -a"* ]]; then
 183                 # varible is an array
 184                 if [[ -z $already_stashed ]]; then
 185                     eval "__varstash_array__$stash_name=(\"\${$stash_which""[@]}\")"
 186                 fi
 187
 188             elif [[ $vartype == $pattern" -x"* ]]; then
 189                 # variable is exported
 190                 if [[ -z $already_stashed ]]; then
 191                     eval "__varstash_export__$stash_name=\"\$$stash_which\""
 192                 fi
 193                 if [[ $stash_which != $stash_expression && -z $_stashing_alias_assign ]]; then
 194                     eval "export $stash_which=\"$stash_value\""
 195                 fi
 196             else
 197                 # regular variable
 198                 if [[ -z $already_stashed ]]; then
 199                     eval "__varstash_variable__$stash_name=\"\$$stash_which\""
 200                 fi
 201                 if [[ $stash_which != $stash_expression && -z $_stashing_alias_assign ]]; then
 202                     eval "$stash_which=\"$stash_value\""
 203                 fi
 204
 205             fi
 206             local stashed=1
 207         fi
 208
 209         if [[ -z $stashed ]]; then
 210             # Nothing in the variable we're stashing, but make a note that we stashed so we
 211             # do the right thing when unstashing.  Without this, we take no action on unstash
 212
 213             # Zsh bug sometimes caues
 214             # (eval):1: command not found: __varstash_nostash___tmp__home_dolszewski_src_smartcd_RANDOM_VARIABLE=1
 215             # fixed in zsh commit 724fd07a67f, version 4.3.14
 216             if [[ -z $already_stashed ]]; then
 217                 eval "__varstash_nostash__$stash_name=1"
 218             fi
 219
 220             # In the case of a previously unset variable that we're assigning too, export it
 221             if [[ $stash_which != $stash_expression && -z $_stashing_alias_assign ]]; then
 222                 eval "export $stash_which=\"$stash_value\""
 223             fi
 224         fi
 225
 226         shift
 227         unset -v _stashing_alias_assign
 228     done
 229 }
 230
 231 function autostash() {
 232     local run_from_autostash=1
 233     while [[ -n $1 ]]; do
 234         if [[ $1 == "alias" && $2 == *=* ]]; then
 235             shift
 236             local _stashing_alias_assign=1
 237         fi
 238
 239         local already_stashed=
 240         stash "$1"
 241         if [[ -z $already_stashed ]]; then
 242             local autostash_name=$(_mangle_var AUTOSTASH)
 243             local varname=${1%%'='*}
 244             apush $autostash_name "$varname"
 245         fi
 246         shift
 247         unset -v _stashing_alias_assign
 248     done
 249 }
 250
 251 function unstash() {
 252     while [[ -n $1 ]]; do
 253         local unstash_which=$1
 254         if [[ -z $unstash_which ]]; then
 255             continue
 256         fi
 257
 258         local unstash_name=$(_mangle_var $unstash_which)
 259
 260         # This bit is a little tricky.  Here are the rules:
 261         #   1) unstash any alias, function, or variable which matches
 262         #   2) if one or more matches, but not all, delete any that did not
 263         #   3) if none match but nostash is found, delete all
 264         #   4) if none match and nostash not found, do nothing
 265
 266         # Unstash any alias
 267         if [[ -n "$(eval echo \$__varstash_alias__$unstash_name)" ]]; then
 268             eval "alias $(eval echo \$__varstash_alias__$unstash_name)"
 269             unset __varstash_alias__$unstash_name
 270             local unstashed=1
 271             local unstashed_alias=1
 272         fi
 273
 274         # Unstash any function
 275         if [[ -n "$(eval echo \$__varstash_function__$unstash_name)" ]]; then
 276             eval "function $(eval echo -e \"\$__varstash_function__$unstash_name\")"
 277             unset __varstash_function__$unstash_name
 278             local unstashed=1
 279             local unstashed_function=1
 280         fi
 281
 282         # Unstash any variable
 283         if [[ -n "$(declare -p __varstash_array__$unstash_name 2>/dev/null)" ]]; then
 284             eval "$unstash_which=(\"\${__varstash_array__$unstash_name""[@]}\")"
 285             unset __varstash_array__$unstash_name
 286             local unstashed=1
 287             local unstashed_variable=1
 288         elif [[ -n "$(declare -p __varstash_export__$unstash_name 2>/dev/null)" ]]; then
 289             eval "export $unstash_which=\"\$__varstash_export__$unstash_name\""
 290             unset __varstash_export__$unstash_name
 291             local unstashed=1
 292             local unstashed_variable=1
 293         elif [[ -n "$(declare -p __varstash_variable__$unstash_name 2>/dev/null)" ]]; then
 294             # Unset variable first to reset export
 295             unset -v $unstash_which
 296             eval "$unstash_which=\"\$__varstash_variable__$unstash_name\""
 297             unset __varstash_variable__$unstash_name
 298             local unstashed=1
 299             local unstashed_variable=1
 300         fi
 301
 302         # Unset any values which did not exist at time of stash
 303         local nostash="$(eval echo \$__varstash_nostash__$unstash_name)"
 304         unset __varstash_nostash__$unstash_name
 305         if [[ ( -n "$nostash" && -z "$unstashed" ) || ( -n "$unstashed" && -z "$unstashed_alias" ) ]]; then
 306             unalias $unstash_which 2>/dev/null
 307         fi
 308         if [[ ( -n "$nostash" && -z "$unstashed" ) || ( -n "$unstashed" && -z "$unstashed_function" ) ]]; then
 309             unset -f $unstash_which 2>/dev/null
 310         fi
 311         if [[ ( -n "$nostash" && -z "$unstashed" ) || ( -n "$unstashed" && -z "$unstashed_variable" ) ]]; then
 312             # Don't try to unset illegal variable names
 313             # Using substitution to avoid using regex, which might fail to load on Zsh (minimal system).
 314             if [[ ${unstash_which//[^a-zA-Z0-9_]/} == $unstash_which && $unstash_which != [0-9]* ]]; then
 315                 unset -v $unstash_which
 316             fi
 317         fi
 318
 319         shift
 320     done
 321 }
 322
 323 function autounstash() {
 324     # If there is anything in (mangled) variable AUTOSTASH, then unstash it
 325     local autounstash_name=$(_mangle_var AUTOSTASH)
 326     if (( $(alen $autounstash_name) > 0 )); then
 327         local run_from_autounstash=1
 328         while (( $(alen $autounstash_name) > 0 )); do
 329             local autounstash_var=$(afirst $autounstash_name)
 330             ashift $autounstash_name >/dev/null
 331             unstash $autounstash_var
 332         done
 333         unset $autounstash_name
 334     fi
 335 }
 336
 337 function _mangle_var() {
 338     local mangle_var_where="${varstash_dir:-$PWD}"
 339     mangle_var_where=${mangle_var_where//[^A-Za-z0-9]/_}
 340     local mangled_name=${1//[^A-Za-z0-9]/_}
 341     echo "_tmp_${mangle_var_where}_${mangled_name}"
 342 }
 343
 344 # vim: filetype=sh autoindent expandtab shiftwidth=4 softtabstop=4