PATCH: argument splitting (was Re: zsh widget to resolve symlinks)

[Peter Stephenson <pws@xxxxxxx>]

Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx> wrote:
> It occurred to me recently that a generic widget to split the line into
> shell words and whitespace would be extremely useful, making this sort
> of task much easier.  However, I haven't got around to it yet.

Here it is, with a handy example function that makes some simple
replacements on the current shell argument very easy.  I'll commit it on
the main line, but I believe the functions here should run fine in released
versions of 4.2.

The original problem should now reduce to the following code:

  autoload -U modify-current-argument
  modify-current-argument '${(q)$(eval realpath "$ARG")}'

The eval and the (q) are there to try to be careful about quoting,
use of ~'s, etc.

(Some of the other documentation for ZLE functions in the subsection "Widgets"
should really go into "Utility Functions", too.)

Index: Doc/Zsh/contrib.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/contrib.yo,v
retrieving revision 1.64
diff -u -r1.64 contrib.yo
--- Doc/Zsh/contrib.yo	10 Oct 2006 11:24:38 -0000	1.64
+++ Doc/Zsh/contrib.yo	14 Dec 2006 11:07:01 -0000
@@ -1142,6 +1142,60 @@
 )
 enditem()
 
+subsect(Utility Functions)
+
+These functions are useful in constructing widgets.  They
+should be loaded with `tt(autoload -U) var(function)' and called
+as indicated from user-defined widgets.
+
+startitem()
+tindex(split-shell-arguments)
+item(tt(split-shell-arguments))(
+This function splits the line currently being edited into shell arguments
+and whitespace.  The result is stored in the array tt(reply).  The array
+contains all the parts of the line in order, starting with any whitespace
+before the first argument, and finishing with any whitespace after the last
+argument.  Hence (so long as the option tt(KSH_ARRAYS) is not set)
+whitespace is given by odd indices in the array and arguments by
+even indices.  Note that no stripping of quotes is done; joining together
+all the elements of tt(reply) in order is guaranteed to produce the
+original line.
+
+The parameter tt(REPLY) is set to the index of the word in tt(reply) which
+contains the character after the cursor, where the first element has index
+1.  The parameter tt(REPLY2) is set to the index of the character under the
+cursor in that word, where the first character has index 1.
+
+Hence tt(reply), tt(REPLY) and tt(REPLY2) should all be made local to
+the enclosing function.
+
+See the function tt(modify-current-argument), described below, for
+an example of how to call this function.
+)
+tindex(modify-current-argument)
+item(tt(modify-current-argument) var(expr-using-)tt($ARG))(
+This function provides a simple method of allowing user-defined widgets
+to modify the command line argument under the cursor (or immediately to the
+left of the cursor if the cursor is between arguments).  The argument
+should be an expression which when evaluated operates on the shell
+parameter tt(ARG), which will have been set to the command line argument
+under the cursor.  The expression should be suitably quoted to prevent
+it being evaluated too early.
+
+For example, a user-defined widget containing the following code
+converts the characters in the argument under the cursor into all upper
+case:
+
+example(modify-current-word '${(U)ARG}')
+
+The following strips any quoting from the current word (whether backslashes
+or one of the styles of quotes), and replaces it with single quoting
+throughout:
+
+example(modify-current-word '${(qq)${(Q)ARG}}')
+)
+enditem()
+
 subsect(Styles)
 
 The behavior of several of the above widgets can be controlled by the use
Index: Functions/Zle/modify-current-argument
===================================================================
RCS file: Functions/Zle/modify-current-argument
diff -N Functions/Zle/modify-current-argument
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ Functions/Zle/modify-current-argument	14 Dec 2006 11:07:02 -0000
@@ -0,0 +1,51 @@
+# Take an expression suitable for interpolation in double quotes that
+# performs a replacement on the parameter "ARG".  Replaces the
+# shell argument (which may be a quoted string) under or before the
+# cursor with that.  Ensure the expression is suitable quoted.
+#
+# For example, to uppercase the entire shell argument:
+#   modify-current-word '${(U)ARG}'
+# To strip the current quoting from the word (whether backslashes or
+# single, double or dollar quotes) and use single quotes instead:
+#   modify-current-word '${(qq)${(Q)ARG}}'
+
+# Retain most options from the calling function for the eval.
+# Reset some that might confuse things.
+setopt localoptions noksharrays multibyte
+
+local -a reply
+integer REPLY REPLY2
+
+autoload -U split-shell-arguments
+split-shell-arguments
+
+# Can't do this unless there's some text under or left of us.
+(( REPLY < 2 )) && return 1
+
+# Get the index of the word we want.
+if (( REPLY & 1 )); then
+  # Odd position; need previous word.
+  (( REPLY-- ))
+  # Pretend position was just after the end of it.
+  (( REPLY2 = ${#reply[REPLY]} + 1 ))
+fi
+
+# Length of all characters before current.
+# Force use of character (not index) counting and join without IFS.
+integer wordoff="${(cj..)#reply[1,REPLY-1]}"
+
+# Replacement for current word.  This could do anything to ${reply[REPLY]}.
+local ARG="${reply[REPLY]}" repl
+eval repl=\"$1\"
+# New line:  all words before and after current word, with
+# no additional spaces since we've already got the whitespace
+# and the replacement word in the middle.
+BUFFER="${(j..)reply[1,REPLY-1]}${repl}${(j..)reply[REPLY+1,-1]}"
+
+# Keep cursor at same position in replaced word.
+# Redundant here, but useful if $repl changes the length.
+# Limit to the next position after the end of the word.
+integer repmax=$(( ${#repl} + 1 ))
+# Remember CURSOR starts from offset 0 for some reason, so
+# subtract 1 from positions.
+(( CURSOR = wordoff + (REPLY2 > repmax ? repmax : REPLY2) - 1 ))
Index: Functions/Zle/split-shell-arguments
===================================================================
RCS file: Functions/Zle/split-shell-arguments
diff -N Functions/Zle/split-shell-arguments
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ Functions/Zle/split-shell-arguments	14 Dec 2006 11:07:02 -0000
@@ -0,0 +1,58 @@
+# Split a command line into shell arguments and whitespace in $reply.
+# Odd elements (starting from 1) are whitespace, even elements
+# are shell arguments (possibly quoted strings).  Whitespace at
+# start and end is always included in the array but may be an empty string.
+# $REPLY holds NO_KSH_ARRAYS index of current word in $reply.
+# $REPLY2 holds NO_KSH_ARRAYS index of current character in current word.
+# Hence ${reply[$REPLY][$REPLY2]} is the character under the cursor.
+#
+# reply, REPLY, REPLY2 should therefore be local to the enclosing function.
+#
+# The following formula replaces the current shell word, or previous word
+# if the cursor is on whitespace, by uppercasing all characters.
+
+emulate -L zsh
+setopt extendedglob
+
+local -a bufwords lbufwords
+local word
+integer pos=1 cpos=$((CURSOR+1)) opos iword ichar
+
+bufwords=(${(z)BUFFER})
+
+reply=()
+while [[ ${BUFFER[pos]} = [[:space:]] ]]; do
+  (( pos++ ))
+done
+reply+=${BUFFER[1,pos-1]}
+(( cpos < pos )) && (( iword = 1, ichar = cpos ))
+
+for word in "${bufwords[@]}"; do
+  (( opos = pos ))
+  (( pos += ${#word} ))
+  reply+=("$word")
+  if (( iword == 0  &&  cpos < pos )); then
+    (( iword = ${#reply} ))
+    (( ichar = cpos - opos + 1 ))
+  fi
+
+  (( opos = pos ))
+  while [[ ${BUFFER[pos]} = [[:space:]] ]]; do
+    (( pos++ ))
+  done
+  reply+=("${BUFFER[opos,pos-1]}")
+  if (( iword == 0  &&  cpos < pos )); then
+    (( iword = ${#reply} ))
+    (( ichar = cpos - opos + 1 ))
+  fi
+done
+
+if (( iword == 0 )); then
+  # At the end of the line, so off the indexable positions
+  # (but still a valid cursor position).
+  (( REPLY = ${#reply} ))
+  (( REPLY2 = 1 ))
+else
+  (( REPLY = iword ))
+  (( REPLY2 = ichar ))
+fi

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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