bpstahlman
commented
5 years ago To flesh out several distinct concepts of emit and capture, I've documented 3 candidate "emit" commands, and 2 candidate "capture" commands. Would appreciate feedback from @snoe and others on the usefulness of the proposed commands. If the consensus is that only one command in each set is particularly useful (or one is significantly more useful than the others), perhaps the best approach is to change sexp's current emit/capture to work accordingly. OTOH, if multiple variants are deemed useful, perhaps it makes sense to provide several distinct emit/capture variants; alternatively, a single emit/capture command could be provided, along with an option to configure its behavior.
Note: I'm not overly attached to the proposed names - just needed a way to distinguish between the various commands...
Note: In all of the examples below, | indicates cursor position.
Emit commands
Emit
sexp_emit_head_element
sexp_emit_tail_element
Description: Emit [count] elements from current list, preserving cursor position unless element under cursor is emitted from list, in which case, cursor will be moved to the list bracket. Note: The only difference between this and the original sexp emit is that the original always positions the cursor on list bracket (even when element under cursor is not emitted).
Example:
| Direction | Count | Before | After |
|---|---|---|---|
| tail | 3 | (((foo (a |b c)) d e)) | (((foo (|) a b c) e)) |
| tail | 2 | (((foo (|a b c)) d e)) | (((foo (|a) b c) d e)) |
Note: I can see an argument in favor of removing lists made empty by the emit: e.g., the empty list before a in the 1st example above.
Barf
sexp_barf_head_element
sexp_barf_tail_element
Description: Emit a single element from current list [count] times, preserving cursor position relative to the element beneath it, even when the element under cursor is emitted from the list. Note: This is essentially the snoe PR. It is also closest to emacs paredit behavior, hence the name.
Example:
| Direction | Count | Before | After |
|---|---|---|---|
| tail | 3 | (((foo (a |b c)) d e)) | (((foo (a) |b) c d e)) |
Eject
sexp_eject_head_element
sexp_eject_tail_element
Description: Push element under cursor out of [count] containing forms, pushing any elements in its path. Note: AFAIK, there is no comparable emit command in either vim-sexp or emacs paredit.
Example:
| Direction | Count | Before | After |
|---|---|---|---|
| tail | 3 | (((foo (a |b c)) d e)) | (((foo (a))) |b c d e) |
| head | 2 | (((foo (a |b c)) d e)) | ((foo a |b ((c)) d e)) |
Capture command
Capture
sexp_capture_head_element
sexp_capture_tail_element
Description: Pull [count] elements into the current list from ancestor forms, preserving original cursor position. Note: This command is similar to the original sexp capture, but allows elements to be pulled from lists other than the immediate parent.
Example:
| Direction | Count | Before | After |
|---|---|---|---|
| tail | 3 | (foo ((a |b) (c d)) e f) | (foo ((a |b (c d) e f))) |
| head | 2 | (foo ((a b) (c |d)) e f) | (((foo (a b) c |d)) e f) |
Slurp
sexp_slurp_head_element
sexp_slurp_tail_element
Description: Pull a single element into an ancestor list [count] times, preserving original cursor position. Note: This is essentially the snoe PR. It is also closest to emacs paredit behavior, hence the name.
Example:
| Direction | Count | Before | After |
|---|---|---|---|
| tail | 3 | (foo ((a |b) (c d)) e f) | (foo ((a |b (c d) e)) f) |
snoe
PR for other half of #10.
This change allows you to capture the next (or previous) element into the sibling form containing your cursor. Another way to say it is that capture will recurse up ancestor forms until it finds an element to capture and moves it into that ancestor.
See the issue for more details.
Cheers