Skip to content

Latest commit

 

History

History
234 lines (161 loc) · 6 KB

CommentsOnMajorModes.org

File metadata and controls

234 lines (161 loc) · 6 KB
Raw

Comments on Syntax Highlighting of major modes

By Anders Lindgren

ABSTRACT

This file contains personal comments on syntax highlighting provided of the major modes of tested the font-lock regression suite. The comment should be taken with a grain of salt, as the author does not have deep knowledge of all major modes this survey covers. Unlike

Major modes:

Part of the Emacs standard distribution

The following table list the major modes of the Emacs distribution this package provides tests for.

  • [X] Ada
  • [ ] antlr
  • [ ] asm
  • [X] autoconf
  • [X] bat
  • [X] C
  • [ ] C++
  • [ ] cfengine
  • [ ] dcl
  • [X] ELisp
  • [X] f90
  • [ ] fortran
  • [ ] icon
  • [ ] idlwave
  • [X] JavaScript (js)
  • [X] JavaScript (js2)
  • [ ] ld
  • [ ] script
  • [ ] Lisp
  • [X] m4
  • [X] Make
  • [ ] MetaFont / MetaPost
  • [ ] mixasm
  • [ ] Modula2
  • [ ] Object Pascal
  • [X] Objective-C
  • [ ] Octave
  • [ ] Pascal
  • [X] Perl
  • [X] CPerl
  • [X] Prolog
  • [X] PostScript
  • [X] Python
  • [X] Ruby
  • [ ] Scheme
  • [ ] Shell script
  • [ ] Simula
  • [ ] SQL (under ComInt)
  • [ ] tcl
  • [ ] Vera
  • [ ] Verilog
  • [ ] VHDL

Non-standard modes

The ambition of this regression suite is to cover a handful of popular packages, not part of the standard Emacs distribution, that do not provide font-lock regression tests by themselves. The following list contains major modes likely to be added. (A complete list of every major mode written for Emacs would be to voluminous.)

  • [ ] Erlang
  • [ ] Haskell

Supported minor modes:

Part of the Emacs standard distribution

  • [X] CWarn
  • [ ] Prettify symbol

Non-standard modes

Personal comments on syntax highlighting in various modes

Ada

Overall, highlighting looks OK.

  • Unlike other modes, numbers are highlighted. Personally, I would like to see this as a mode-independent option, not something implemented in a single mode like Ada.
  • It fails to highlight numbers like “2.9979E18”.
  • It doesn’t highlight variable definitions, like “cLight” in “cLight : CONSTANT Real := 2.9979E18;”.
  • A lot of types are not highlighted, like String and user-defined types.

Autoconf

Extremely sparse highlighting. Looks like it only highlights a few constructs, but leaves underlying shell code unhighlighted.

One, alternative, approach would be to make this a minor mode that could add it’s rules to, say, bash mode. (Or does this feature already exist?)

Bat

Ok, where do we start. This is really, really bad. There is a lot of highlighting but it shows up in the wrong places all of the time.

  • The argument to “echo” should be highlighted as a string.
  • Variables can’t have “_” in them.
  • Variables are not highlighted in strings.
  • Make sure “SET foo=bar” and “SET foo_2=bar” work.
  • “in” should not be highlighted as a keyword when in a file name like “foo.in”

ELisp

Seriously? Emacs is the king of text editors and elisp is its language, and this is the best syntax highlighting we could come up with?

Only a handful of construct are highlighted, like keywords, variable and function names etc.

OK, I might be a bit biased, I’ve written a package that highlights a lot more in lisp packages: variables bound in parameter lists and let expressions. Quoted and backquoted expressions. etc. See https://github.com/Lindydancer/lisp-extra-font-lock for more information.

F90

Overall OK.

  • Complex variable definitions highlight too much. For example, in “real :: a(10), b(5, 5), c(13,15,17), conv1(3,3), conv2(3,3)” everything after the “::” is in font-lock-variable-name-face, including the commas and parentheses.

JavaScript

Standard js-mode

  • It doesn’t highlight doxygen-style comment.

M4

Very simple major mode.

In “aclocal.m4” m4-mode fails to highlight some comments. Neither m4-mode nor autoconf mode highlights the shell script parts of the file.

Suggestion

As M4 is a generic preprocessor, an alternative would be to implement this as a minor mode and use it in addition to the major mode that corresponds to the file being handled.

Make

Emacs does a pretty decent job. It would be nice if shell script code in rules would be highlighted. It’s doable, but hard work.

Objective-C

  • Doesn’t highlight Objective-C method calls (Here comes https://github.com/Lindydancer/objc-font-lock to the rescue.)
  • Mistakes a leading “+” and “-” for a method declaration/definition, even when occurring in the middle of code section.

Perl

Perl mode

  • It seems to explicitly set specific faces like “underline” on some cases. I’m not sure if it’s configurable, but it undermines the idea of themes.

CPerl mode

  • Provides home-brewed system for highlighting end-of-line spaces. It should use show-trailing-whitespace instead.
  • Defines a number of mode-specific faces, which makes life difficult for theme providers.
  • Several rules use “t” as OVERRIDE flag to add additional highlight. This has two problems:
    1. It overwrites things in all contexts, including comments. (Can be fixed by checking syntax-ppss.)
    2. It overwrites all attributes (e.g. foreground and background) even if the overwriting face only contains some attributes. (Can be fixed by using prepend.)

PostScript

Unreadable language, but with better highlighting support life could be a bit better. Example shows line upon line of the following:

932 1156 ln st np 932 1156 mv 975 1156 ln st np 975 1156 mv 1018 1156 ln st np 1018 1156 mv 1056 1156 ln st np 1056 1156 mv 1086 1156 ln st np 1086 1156 mv 1110 1156 ln st np 1110 1156 mv 1131

Maybe highlighting could be used to group things together, visually?

  • Data to the “colorimage” is subject to highlighting, which it shouldn’t. (Maybe highlight is as a string?) See the bell_206.ps example from “fsu”.

Prolog

  • Overwrites comments with things like “foo/4”.
  • Don’t highlight the “is” keyword. (Is “is” a keyword?)
  • Doesn’t seem to be aware of the “foo:bar” syntax. (Is it standard?)

sh TODO

The variables substitution construct $(VAR) is highlighted in comments.

Shell script mode

Strings containing “<<” are treated as heredoc comments.