Sunday afternoon project: bracketed-paste-magic

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

I posted a stub of this function before.  Here's something closer to a
"production" version.

Aside:  I think this is demonstrating a bug in "fc -p"/"fc -P".  Following
a paste that runs bracketed-paste-magic, the immediately preceding history
entry becomes unavailable.  I have to hit enter at the prompt (even a blank
buffer will do) before I can up-history to that entry.  It's not lost, I
just can't move to it.

# --- 8< --- Functions/Zle/bracketed-paste-magic --- 8< ---

# Starting with zsh-5.0.9, ZLE began to recognize the "bracketed paste"
# capability of terminal emulators, that is, the sequences $'\e[200~' to
# start a paste and $'\e[201~' to indicate the end of the pasted text.
# Pastes are handled by the bracketed-paste widget and insert literally
# into the editor buffer rather than being interpreted as keystrokes.
# 
# This disables some common usages where the self-insert widget has been
# replaced in order to accomplish some extra processing.  An example is
# the contributed url-quote-magic widget.  The bracketed-paste-magic
# widget replaces bracketed-paste with a wrapper that re-enables these
# self-insert actions, and other actions as selected by the zstyles
# described below.
# 
# Setup:
#       autoload -Uz bracketed-paste-magic
#       zle -N bracketed-paste bracketed-paste-magic

# The following zstyles may be set to control processing of pasted text.
#
# active-widgets
#  Looked up in the context :bracketed-paste-magic to obtain a list of
#  patterns that match widget names that should be activated during the
#  paste.  All other key sequences are processed as self-insert-unmeta.
#  The default is 'self-*' so any user-defined widgets named with that
#  prefix are active along with the builtin self-insert.  If this style is
#  not set (note: it must be explicitly deleted after loading this
#  function, otherwise it becomes set by default) or has no value, no
#  widgets are active and the pasted text is inserted literally.  If the
#  value includes undefined-key, any unknown sequences are discarded from
#  the pasted text.
#
# inactive-keys
#  This is the inverse of active-widgets, it lists key sequences that
#  always use self-insert-unmeta even when bound to an active-widget.
#  Note that this is a list of literal key sequences, not patterns.
#  This style is in context :bracketed-paste-magic and has no default.
#
# paste-init
# paste-finish
#  Also looked up in the context :bracketed-paste-magic, these styles
#  each are a list of function names.  They are executed in widget
#  context but are called as functions (NOT as widgets with "zle name").
#  They also run in zsh emulation context set by bracketed-paste-magic.
#  As with hooks, the functions are called in order until one of them
#  returns a nonzero exit status.  The parameter PASTED contains the
#  current state of the pasted text, other ZLE parameters are as usual.
#  Although a nonzero status stops each list of functions, it does NOT
#  abort the entire paste operation; use "zle send-break" for that.

# IMPORTANT:  During processing of the paste (after paste-init and
# before paste-finish), BUFFER starts empty and history is restricted,
# so cursor motions etc. may not pass outside of the pasted content.
# However, the paste-init functions have access to the full history and
# the original BUFFER, so they may for example move words from BUFFER
# into PASTED to make those words visible to the active-widgets.

# Establish default values for styles, but only if not already set
zstyle -m :bracketed-paste-magic active-widgets '*' ||
    zstyle ':bracketed-paste-magic' active-widgets 'self-*'

# Helper/example paste-init for exposing a word prefix inside PASTED.
# Useful with url-quote-magic if you have http://... on the line and
# are pasting additional text on the end of the URL.
#
# Usage:
#       zstyle :bracketed-paste-magic paste-init backward-extend-paste
#
# TODO: rewrite this using match-words-by-style
#
backward-extend-paste() {
    : emulate -LR zsh	# Already set by bracketed-paste-magic
    integer bep_mark=$MARK bep_region=$REGION_ACTIVE
    if (( REGION_ACTIVE && MARK < CURSOR )); then
	zle .exchange-point-and-mark
    fi
    if (( CURSOR )); then
	local -a bep_words=( ${(z)LBUFFER} )
	if [[ -n $bep_words[-1] &&  $LBUFFER = *$bep_words[-1] ]]; then
	    PASTED=$bep_words[-1]$PASTED
	    LBUFFER=${LBUFFER%${bep_words[-1]}}
	fi
    fi
    if (( MARK > bep_mark )); then
	zle .exchange-point-and-mark
    fi
    REGION_ACTIVE=$bep_region
}

# Example paste-finish for quoting the pasted text.
#
# Usage e.g.:
#       zstyle :bracketed-paste-magic paste-finish quote-paste
#       zstyle :bracketed-paste-magic:finish quote-style qqq
#
# Using "zstyle -e" to examine $PASTED lets you choose different quotes
# depending on context.
#
# To forcibly turn off numeric prefix quoting, use e.g.:
#       zstyle :bracketed-paste-magic:finish quote-style none
#
quote-paste() {
    : emulate -LR zsh	# Already set by bracketed-paste-magic
    local qstyle
    # If there's a quoting style, be sure .bracketed-paste leaves it alone
    zstyle -s :bracketed-paste-magic:finish quote-style qstyle && NUMERIC=1
    case $qstyle in
	(b) PASTED=${(b)PASTED};;
	(q-) PASTED=${(q-)PASTED};;
	(\\|q) PASTED=${(q)PASTED};;
	(\'|qq) PASTED=${(qq)PASTED};;
	(\"|qqq) PASTED=${(qqq)PASTED};;
	(\$|qqqq) PASTED=${(qqqq)PASTED};;
	(Q) PASTED=${(Q)PASTED};;
    esac
}

# Now the actual function

bracketed-paste-magic() {
    emulate -LR zsh
    local -a bpm_hooks bpm_inactive
    local PASTED bpm_func bpm_active

    # Set PASTED and run the paste-init functions
    zle .bracketed-paste PASTED
    if zstyle -a :bracketed-paste-magic paste-init bpm_hooks; then
	for bpm_func in $bpm_hooks; do
	    if (( $+functions[$bpm_func] )); then
		$bpm_func || break
	    fi
	done
    fi

    # Save context, create a clean slate for the paste
    integer bpm_mark=$MARK bpm_cursor=$CURSOR bpm_region=$REGION_ACTIVE
    integer bpm_numeric=$NUMERIC
    local bpm_buffer=$BUFFER
    fc -p -a /dev/null 0 0
    BUFFER=

    zstyle -a :bracketed-paste-magic inactive-keys bpm_inactive
    if zstyle -s :bracketed-paste-magic active-widgets bpm_active '|'; then
        # There are active widgets.  Reprocess $PASTED as keystrokes.
	NUMERIC=1
	zle -U - $PASTED
	while [[ -n $PASTED ]] && zle .read-command; do
	    PASTED=${PASTED#$KEYS}
	    if [[ $KEYS = ${(~j:|:)${(b)bpm_inactive}} ]]; then
		zle .self-insert-unmeta
	    else
		case $REPLY in
		    (${~bpm_active}) zle $REPLY;;
		    (*) zle .self-insert-unmeta;;
		esac
	    fi
	done
	PASTED=$BUFFER
    fi

    # Restore state
    BUFFER=$bpm_buffer
    MARK=$bpm_mark
    CURSOR=$bpm_cursor
    REGION_ACTIVE=$bpm_region
    NUMERIC=$bpm_numeric
    fc -P

    # PASTED has been updated, run the paste-finish functions
    if zstyle -a :bracketed-paste-magic paste-finish bpm_hooks; then
	for bpm_func in $bpm_hooks; do
	    if (( $+functions[$bpm_func] )); then
		$bpm_func || break
	    fi
	done
    fi

    # Reprocess $PASTED as an actual paste this time
    zle -U - $PASTED$'\e[201~'	# append paste-end marker
    zle .bracketed-paste
    zle .split-undo

    # Arrange to display highlighting if necessary
    if [[ -n ${(M)zle_highlight:#paste:*} ]]; then
	zle -R
	zle .read-command && zle -U - $KEYS
    fi
}

# Handle zsh autoloading conventions
if [[ $zsh_eval_context = *loadautofunc && ! -o kshautoload ]]; then
    bracketed-paste-magic "$@"
fi

-- 
Barton E. Schaefer