Various improvements to syntax highlighting.

[datanoise]

Look behind regexp patterns are not recommended in syntax files,
especially with the new NFA engine. So we should try to avoid them.
Highlighting of methods, fields, methods, structs and interfaces should
be much faster now.

Consolidated two options g:go_highlight_structs and
g:go_highlight_interfaces into one g:go_highlight_types.

[fatih]

This is a breaking change. Is there a way to not break this? I don't want people change their vimrc for no reason if possible :)

[datanoise]

I agree that is quite unfortunate. I don't see an efficient way to separate parsing of type Name struct from type Name interface. Let me think about it a bit more. Maybe it can be done using syn-region syntax.

On the other hand, why do we need to distinguish these two cases?

[fatih]

It was like that previously. We don't need to distinguish at all, it is just for backwards compatibility. But if you believe that making it backwards compatibility comes with increased complexity, I'm in favor of breaking it, so it means this change would be ok.

[fatih]

Hi @datanoise. Thanks for this wonderful improvement. Is there a way you can split this into separate PR's for each highlight group? It's hard to follow what exactly it changes and you changed a lot of things :)

[datanoise]

Just for the reference with these settings:

let g:go_highlight_functions = 1
let g:go_highlight_methods = 1
let g:go_highlight_fields = 0
let g:go_highlight_structs = 1
let g:go_highlight_interfaces = 1

I get the following syntax profiler report:

  TOTAL      COUNT  MATCH   SLOWEST     AVERAGE   NAME               PATTERN
  0.133099   527    21      0.001681    0.000253  goInterfaceDef     \(type\s\+\)\@<=\w\+\(\s\+interface\s\+{\)\@=
  0.131706   509    3       0.002651    0.000259  goStructDef        \(type\s\+\)\@<=\w\+\(\s\+struct\s\+{\)\@=
  0.129326   536    30      0.001473    0.000241  goFunction         \()\s\+\)\@<=\w\+\((\)\@=
  0.127595   526    20      0.001799    0.000243  goFunction         \(func\s\+\)\@<=\w\+\((\)\@=
  0.068593   520    14      0.000578    0.000132  goInterface        \(.\)\@<=\w\+\({\)\@=
  0.066483   509    3       0.000577    0.000131  goStruct           \(.\)\@<=\w\+\({\)\@=
  0.011295   531    27      0.000125    0.000021  goMethod           \(\.\)\@<=\w\+\((\)\@=
  0.003664   532    45      0.000066    0.000007  goBuiltins         \<\v(append|cap|close|complex|copy|delete|imag|len)\ze\(
  0.003609   508    2       0.000110    0.000007  goBuiltins         \<\v(make|new|panic|print|println|real|recover)\ze\(
  0.003355   506    0       0.000183    0.000007  goImaginaryFloat   \<-\=\.\d\+\%([Ee][-+]\=\d\+\)\=i\>

Same settings but with the patch:

  TOTAL      COUNT  MATCH   SLOWEST     AVERAGE   NAME               PATTERN
  0.004533   448    11      0.000061    0.000010  goTypeConstructor  \<\w\+{
  0.004355   439    2       0.000253    0.000010  goBuiltins         \<\v(make|new|panic|print|println|real|recover)\ze\(
  0.004079   451    33      0.000062    0.000009  goBuiltins         \<\v(append|cap|close|complex|copy|delete|imag|len)\ze\(
  0.003877   437    0       0.000084    0.000009  goImaginaryFloat   \<-\=\.\d\+\%([Ee][-+]\=\d\+\)\=i\>
  0.003741   437    0       0.000068    0.000009  goImaginaryFloat   \<-\=\d\+\.\d*\%([Ee][-+]\=\d\+\)\=i\>
  0.003735   437    0       0.000070    0.000009  goImaginary        \<-\=\d\+[Ee][-+]\=\d\+i\>
  0.003573   437    0       0.000051    0.000008  goFloat            \<-\=\.\d\+\%([Ee][-+]\=\d\+\)\=\>
  0.003555   437    0       0.000051    0.000008  goImaginary        \<-\=\d\+i\>
  0.003504   437    0       0.000054    0.000008  goHexadecimalInt   \<-\=0[xX]\x\+\>
  0.003501   437    0       0.000044    0.000008  goOctalInt         \<-\=0\o\+\>

I only had to replace

let g:go_highlight_structs = 1
let g:go_highlight_interfaces = 1

to

let g:go_highlight_types = 1

[fatih]

Thanks a lot @datanoise I like the improvements. The syntax file really need some love (especially from someone with some regex fu skills). There are many things to do and I don't have the time to tackle all the issues.

[svanharmelen]

@datanoise @fatih I noticed this PR changed some syntax highlighting among which this one:

Before the * would have been red and the received white... I guess this comes from the changes related to g:go_highlight_functions which now also syntax highlights the receiver type next to the function itself. As I did not set g:go_highlight_types I would expect this to not have changed.

Any way/settings I can tweak this so I get the desired behaviour?

[datanoise]

I guess that makes sense. Could you please try this patch?

diff --git a/syntax/go.vim b/syntax/go.vim
index 9dcf004..1fb3f54 100644
--- a/syntax/go.vim
+++ b/syntax/go.vim
@@ -298,7 +298,6 @@ if g:go_highlight_functions != 0
 else
   syn keyword goDeclaration func
 endif
-hi def link     goReceiverType      Type
 hi def link     goFunction          Function

 " Methods;
@@ -320,6 +319,7 @@ if g:go_highlight_types != 0
   syn match goTypeDecl             /\<type\>/ nextgroup=goTypeName skipwhite skipnl
   syn match goTypeName             /\w\+/ contained nextgroup=goDeclType skipwhite skipnl
   syn match goDeclType             /\<interface\|struct\>/ contained skipwhite skipnl
+  hi def link     goReceiverType      Type
 else
   syn keyword goDeclType           struct interface
   syn keyword goDeclaration        type

[svanharmelen]

@datanoise this patch stops highlighting the receiver, but it also (still) stops highlighting the pointer * sign... I assume the g:go_highlight_operators flag (which I have configured) should enable that part of the highlight?

[datanoise]

That is quite more difficult to highlight. We cannot reuse the same goOperator group name to parse the pointer * sign. I had to introduce a new group goPointerOperator for that.

Could you please try this patch? If it works I'll send a pull request.

diff --git a/syntax/go.vim b/syntax/go.vim
index 9dcf004..be581b6 100644
--- a/syntax/go.vim
+++ b/syntax/go.vim
@@ -286,19 +286,22 @@ if g:go_highlight_operators != 0
   syn match goOperator /:=\|||\|<-\|++\|--/
   " match ...
   syn match goOperator /\.\.\./
+
+  hi def link     goPointerOperator   Operator
 endif
 hi def link     goOperator          Operator

 " Functions;
 if g:go_highlight_functions != 0
   syn match goDeclaration       /\<func\>/ nextgroup=goReceiver,goFunction skipwhite skipnl
-  syn match goReceiver /([^),]\+)/ contained nextgroup=goFunction contains=goReceiverType skipwhite skipnl
-  syn match goReceiverType /\(\s\|*\)\w\+)/hs=s+1,he=e-1 contained
+  syn match goReceiver /([^),]\+)/ contained nextgroup=goFunction contains=goReceiverVar skipwhite skipnl
+  syn match goReceiverVar /\w\+/ nextgroup=goPointerOperator,goReceiverType skipwhite skipnl contained
+  syn match goPointerOperator /\*/ nextgroup=goReceiverType contained skipwhite skipnl
+  syn match goReceiverType /\w\+/ contained
   syn match goFunction /\w\+/ contained
 else
   syn keyword goDeclaration func
 endif
-hi def link     goReceiverType      Type
 hi def link     goFunction          Function

 " Methods;
@@ -320,6 +323,7 @@ if g:go_highlight_types != 0
   syn match goTypeDecl             /\<type\>/ nextgroup=goTypeName skipwhite skipnl
   syn match goTypeName             /\w\+/ contained nextgroup=goDeclType skipwhite skipnl
   syn match goDeclType             /\<interface\|struct\>/ contained skipwhite skipnl
+  hi def link     goReceiverType      Type
 else
   syn keyword goDeclType           struct interface
   syn keyword goDeclaration        type

[svanharmelen]

That seems to fix it, thx!

Unfortunately I found another issue:

In the line configure func([]byte) error, byte is not highlighted as a builtin type and error is highlighted as a function instead of a type 😞

[datanoise]

@svanharmelen thanks for the bug reports. I've included the fix to this issue to my pull request.

[svanharmelen]

Thanks! 👍