Company-mode based auto-completion for QE-modes.

[hongyi-zhao]

QE-modes is a package which supplies the Emacs major-modes for Quantum ESPRESSO. The auto-completion mechanism currently implemented in QE-modes is based on the interactive command triggered by `M-x' as noted here. Considering that the most popular Emacs completion framework is company-mode, which aims to be a modular in-buffer completion. It will pop up a dynamically generated drop-down box containing the appropriate candidates, generated as you type. So I think it would be great if qe-modes can support auto-completion based on company-mode.

Any tips on implementing this feature for qe-modes package would be appreciated.

Regards,
HZ

[dgutov]

I don't really understand how QE-modes work, from the manual.

If you want to have in-buffer completion with Company when using one of those modes, someone should write a backend (or completion function). That sounds like a feature request for the author of QE-modes.

If you want Company to be used for M-x completion (in the minibuffer), it's on my list, though pretty far down.

[yugaego]

I still don't quite understand what you mean.

Hi @hongyi-zhao , see this EmacsWiki article to better understand text vs input completions. The article isn't 100% purely precise and there're plans to support Company in the minibuffer (I believe Dmitry mentioned this wishlist item), but it supposedly might provide you a better understanding.

So I want to implement the in-buffer company completion support for QE-modes, which is the main reason why I ask this question.

Take a look at the contents of the CONTRIBUTING.md for the starting hints and referenced examples: Backends Integration and Guidelines for Third-Party Packages.

[hongyi-zhao]

Take a look at the contents of the CONTRIBUTING.md for the starting hints and referenced examples: Backends Integration and Guidelines for Third-Party Packages.

Thank you for telling me these wonderful guides. I want to add the company-mode official website and this wonderful blog written by Austin Bingham as a supplement.

The ultimate purpose of QE-modes package is to facilitate the generation of Quantum ESPRESSO input files. Therefore, the content to be automatically completed here may not be the same as ordinary automatic completion. Let me use the following example to illustrate some of the technical difficulties that need to be resolved.

&control
   title = ' Water Molecule ',
   calculation = 'cp',
   restart_mode = 'from_scratch',
   ndr = 51,
   ndw = 51,
   nstep  = 100,
   iprint = 100,
   isave  = 100,
   tstress = .TRUE.,
   tprnfor = .TRUE.,
   dt    = 5.0d0,
   etot_conv_thr = 1.d-9,
   ekin_conv_thr = 1.d-4,
   prefix = 'h2o'
   verbosity = 'medium'
/
&system
   ibrav = 14,
   ce
   celldm(1) = 12.0,
   celldm(2) = 1.0,
   celldm(3) = 1.0,
   celldm(4) = 0.0,
   celldm(5) = 0.0,
   celldm(6) = 0.0,
   nat  = 3,
   ntyp = 2,
   nbnd = 4,
   ecutwfc = 80.0,
/
&electrons
   emass = 400.d0,
   emass_cutoff = 2.5d0,
   electron_dynamics = 'damp',
   electron_damping = 0.2
/
&ions
   orthogonalization = 'ortho',
   ion_dynamics = 'none',
   ion_radius(1) = 0.8d0,
   ion_radius(2) = 0.8d0,
/
ATOMIC_SPECIES
   O 16.0d0 O.blyp-mt.UPF
   H 1.00d0 H.blyp-vbc.UPF
ATOMIC_POSITIONS (bohr)
   O     0.0099    0.0099    0.0000  0 0 0
   H     1.8325   -0.2243   -0.0001  1 1 1
   H    -0.2243    1.8325    0.0002  1 1 1

The input file specification of the above example is located here. The main problems I want to solve are:

1. When I try to input one namelist, hinting all possible namelists at the point with drop-down frame; once I select the namelist, say, &CONTROL, then insert it corresponding to the specification as follows, and put the point in the middle of it, denoted by |:

&control
|
/

2. When I try to input one variable with the point located in certain namelist, hinting all possible variables belonging to the given namelist at the point with drop-down frame. Say, for the namelist &control, only the following variables should be used to construct the candidates list:

calculation | title | verbosity | isave | restart_mode | nstep | iprint | tstress | tprnfor | dt | outdir | saverho | prefix | ndr | ndw | tabps | max_seconds | etot_conv_thr | forc_conv_thr | ekin_conv_thr | disk_io | memory | pseudo_dir | tefield

3. When I try to input one CARD, hinting all possible CARDs at the point with drop-down frame; once I select the CARD, say, ATOMIC_SPECIES, then insert it with an example usage of the CARD, say, the following one:

ATOMIC_POSITIONS (bohr)
   O     0.0099    0.0099    0.0000  0 0 0

If no further usage code snippets are available, put the point at the beginning of the next line, denoted by |, as follows:

ATOMIC_SPECIES
|

[dgutov]

Doesn't sound too alien for in-buffer completion: you look around to see in which part of the file you are, and suggest appropriate completions. Implement post-completion action as well, to insert the appropriate additional text together with the completion and move point where you want it to be.

Perhaps creating such files with M-x will remain preferable for you. But it doesn't look incompatible with in-buffer completion.

[hongyi-zhao]

you look around to see in which part of the file you are, and suggest appropriate completions.

Are there any built-in company features for this purpose?

Implement post-completion action as well, to insert the appropriate additional text together with the completion and move point where you want it to be.

Do you mean something similar to annotation and meta as represented here?

Perhaps creating such files with M-x will remain preferable for you. But it doesn't look incompatible with in-buffer completion.

How can I implement both in one code simultaneously?

[dgutov]

Are there any built-in company features for this purpose?

No, that's simply a task people use Elisp for. Try back-to-indentation, looking-at, re-search-backward and related functions.

Do you mean something similar to annotation and meta as represented here?

Yes, but post-completion. See the company-backends docstring for more explanation and the built-in backends for some examples.

How can I implement both in one code simultaneously?

Not sure what kind of answer you are looking for, but maybe try using company-begin-with.