Add prolog swipl linter (#1979)

* add prolog/swipl linter

* use load_files/2 instead of read_term/2

Because it also checks some semantic warnings / errors
not only syntactic warnings / errors.

e.g.:
* singleton warning
* discontiguous warning
* ...

cf. http://www.swi-prolog.org/pldoc/doc_for?object=style_check/1

* support error messages with no line number

    :- module(module_name, [pred/0]).

causes

    ERROR: Exported procedure module_name:pred/0 is not defined

* add test for prolog/swipl handler

* cosmetic fixes

* detect timeout using SIGALRM

* rename g:prolog_swipl_goals to g:prolog_swipl_load

* write doc for prolog/swipl linter

* update toc and README

* fix ignore patterns

5 files changed, 255 insertions, 0 deletions

diff --git a/README.md b/README.md
index f3d616f3..4b6d7663 100644
--- a/README.md
+++ b/README.md
@@ -165,6 +165,7 @@ formatting.
 | PO | [alex](https://github.com/wooorm/alex) !!, [msgfmt](https://www.gnu.org/software/gettext/manual/html_node/msgfmt-Invocation.html), [proselint](http://proselint.com/), [write-good](https://github.com/btford/write-good) |
 | Pod | [alex](https://github.com/wooorm/alex) !!, [proselint](http://proselint.com/), [write-good](https://github.com/btford/write-good) |
 | Pony | [ponyc](https://github.com/ponylang/ponyc) |
+| Prolog | [swipl](https://github.com/SWI-Prolog/swipl-devel) |
 | proto | [protoc-gen-lint](https://github.com/ckaznocha/protoc-gen-lint) |
 | Pug | [pug-lint](https://github.com/pugjs/pug-lint) |
 | Puppet | [languageserver](https://github.com/lingua-pupuli/puppet-editor-services), [puppet](https://puppet.com), [puppet-lint](https://puppet-lint.com) |
diff --git a/ale_linters/prolog/swipl.vim b/ale_linters/prolog/swipl.vim
new file mode 100644
index 00000000..401e52b6
--- /dev/null
+++ b/ale_linters/prolog/swipl.vim
@@ -0,0 +1,100 @@
+" Author: Takuya Fujiwara <tyru.exe@gmail.com>
+" Description: swipl syntax / semantic check for Prolog files
+
+call ale#Set('prolog_swipl_executable', 'swipl')
+call ale#Set('prolog_swipl_load', 'current_prolog_flag(argv, [File]), load_files(File, [sandboxed(true)]), halt.')
+call ale#Set('prolog_swipl_timeout', 3)
+call ale#Set('prolog_swipl_alarm', 'alarm(%t, (%h), _, [])')
+call ale#Set('prolog_swipl_alarm_handler', 'writeln(user_error, "ERROR: Exceeded %t seconds, Please change g:prolog_swipl_timeout to modify the limit."), halt(1)')
+
+function! ale_linters#prolog#swipl#GetCommand(buffer) abort
+    let l:goals = ale#Var(a:buffer, 'prolog_swipl_load')
+    let l:goals = l:goals =~# '^\s*$' ? 'halt' : l:goals
+    let l:timeout = ale#Var(a:buffer, 'prolog_swipl_timeout') + 0
+
+    if l:timeout > 0
+        let l:goals = s:GetAlarm(a:buffer, l:timeout) . ', ' . l:goals
+    endif
+
+    return '%e -g ' . ale#Escape(l:goals) . ' -- %s'
+endfunction
+
+function! s:GetAlarm(buffer, timeout) abort
+    let l:handler = ale#Var(a:buffer, 'prolog_swipl_alarm_handler')
+    let l:handler = s:Subst(l:handler, {'t': a:timeout})
+    let l:alarm = ale#Var(a:buffer, 'prolog_swipl_alarm')
+    let l:alarm = s:Subst(l:alarm, {'t': a:timeout, 'h': l:handler})
+
+    return l:alarm
+endfunction
+
+function! s:Subst(format, vars) abort
+    let l:vars = extend(copy(a:vars), {'%': '%'})
+
+    return substitute(a:format, '%\(.\)', '\=get(l:vars, submatch(1), "")', 'g')
+endfunction
+
+function! ale_linters#prolog#swipl#Handle(buffer, lines) abort
+    let l:pattern = '\v^(ERROR|Warning)+%(:\s*[^:]+:(\d+)%(:(\d+))?)?:\s*(.*)$'
+    let l:output = []
+    let l:i = 0
+
+    while l:i < len(a:lines)
+        let l:match = matchlist(a:lines[l:i], l:pattern)
+
+        if empty(l:match)
+            let l:i += 1
+            continue
+        endif
+
+        let [l:i, l:text] = s:GetErrMsg(l:i, a:lines, l:match[4])
+        let l:item = {
+        \   'lnum': (l:match[2] + 0 ? l:match[2] + 0 : 1),
+        \   'col': l:match[3] + 0,
+        \   'text': l:text,
+        \   'type': (l:match[1] is# 'ERROR' ? 'E' : 'W'),
+        \}
+
+        if !s:Ignore(l:item)
+            call add(l:output, l:item)
+        endif
+    endwhile
+
+    return l:output
+endfunction
+
+" This returns [<next line number>, <error message string>]
+function! s:GetErrMsg(i, lines, text) abort
+    if a:text !~# '^\s*$'
+        return [a:i + 1, a:text]
+    endif
+
+    let l:i = a:i + 1
+    let l:text = []
+
+    while l:i < len(a:lines) && a:lines[l:i] =~# '^\s'
+        call add(l:text, s:Trim(a:lines[l:i]))
+        let l:i += 1
+    endwhile
+
+    return [l:i, join(l:text, '. ')]
+endfunction
+
+function! s:Trim(str) abort
+    return substitute(a:str, '\v^\s+|\s+$', '', 'g')
+endfunction
+
+" Skip sandbox error which is caused by directives
+" because what we want is syntactic or semantic check.
+function! s:Ignore(item) abort
+    return a:item.type is# 'E' &&
+    \      a:item.text =~# '\vNo permission to (call|directive|assert) sandboxed'
+endfunction
+
+call ale#linter#Define('prolog', {
+\   'name': 'swipl',
+\   'output_stream': 'stderr',
+\   'executable_callback': ale#VarFunc('prolog_swipl_executable'),
+\   'command_callback': 'ale_linters#prolog#swipl#GetCommand',
+\   'callback': 'ale_linters#prolog#swipl#Handle',
+\})
diff --git a/doc/ale-prolog.txt b/doc/ale-prolog.txt
new file mode 100644
index 00000000..14062a5a
--- /dev/null
+++ b/doc/ale-prolog.txt
@@ -0,0 +1,56 @@
+===============================================================================
+ALE Prolog Integration                                     *ale-prolog-options*
+
+
+===============================================================================
+swipl                                                        *ale-prolog-swipl*
+
+g:ale_prolog_swipl_executable                   *g:ale_prolog_swipl_executable*
+                                                *b:ale_prolog_swipl_executable*
+  Type: |String|
+  Default: `'swipl'`
+
+  The executable that will be run for the `swipl` linter.
+
+g:ale_prolog_swipl_load                               *g:ale_prolog_swipl_load*
+                                                      *b:ale_prolog_swipl_load*
+  Type: |String|
+  Default: `'current_prolog_flag(argv, [File]), load_files(File, [sandboxed(true)]), halt.'`
+
+  The prolog goals that will be passed to |g:ale_prolog_swipl_executable| with `-g` option.
+
+  It does:
+  1. Takes the first command argument (current file path)
+  2. Checks (syntactic / semantic) problems and output to stderr
+
+  NOTE: `sandboxed(true)` prohibits executing some directives such as 'initialization main'.
+
+g:ale_prolog_swipl_timeout                         *g:ale_prolog_swipl_timeout*
+                                                   *b:ale_prolog_swipl_timeout*
+  Type: |Number|
+  Default: `3`
+
+  Timeout seconds to detect long-running linter.
+  It is done by setting SIGALRM.
+  See |g:ale_prolog_swipl_alarm| and |g:ale_prolog_swipl_alarm_handler|.
+
+g:ale_prolog_swipl_alarm                             *g:ale_prolog_swipl_alarm*
+                                                     *b:ale_prolog_swipl_alarm*
+  Type: |String|
+  Default: `'alarm(%t, (%h), _, [])'`
+
+  The prolog goals to be expected to set SIGALRM.
+  `%t` is replaced by |g:ale_prolog_swipl_timeout|.
+  `%h` is replaced by |g:ale_prolog_swipl_alarm_handler|.
+
+g:ale_prolog_swipl_alarm_handler             *g:ale_prolog_swipl_alarm_handler*
+                                             *b:ale_prolog_swipl_alarm_handler*
+  Type: |String|
+  Default: `'writeln(user_error, "ERROR: Exceeded %t seconds, Please change g:prolog_swipl_timeout to modify the limit."), halt(1)'`
+
+  The prolog goals to be expected that will be run on SIGALRM.
+  `%t` is replaced by |g:ale_prolog_swipl_timeout|.
+
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
diff --git a/doc/ale.txt b/doc/ale.txt
index 66ce8ab1..95110431 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -226,6 +226,8 @@ CONTENTS                                                         *ale-contents*
       write-good..........................|ale-pod-write-good|
     pony..................................|ale-pony-options|
       ponyc...............................|ale-pony-ponyc|
+    prolog................................|ale-prolog-options|
+      swipl...............................|ale-prolog-swipl|
     proto.................................|ale-proto-options|
       protoc-gen-lint.....................|ale-proto-protoc-gen-lint|
     pug...................................|ale-pug-options|
@@ -453,6 +455,7 @@ Notes:
 * PO: `alex`!!, `msgfmt`, `proselint`, `write-good`
 * Pod: `alex`!!, `proselint`, `write-good`
 * Pony: `ponyc`
+* Prolog: `swipl`
 * proto: `protoc-gen-lint`
 * Pug: `pug-lint`
 * Puppet: `languageserver`, `puppet`, `puppet-lint`
diff --git a/test/handler/test_swipl_handler.vader b/test/handler/test_swipl_handler.vader
new file mode 100644
index 00000000..9e425cf6
--- /dev/null
+++ b/test/handler/test_swipl_handler.vader
@@ -0,0 +1,95 @@
+Before:
+  runtime ale_linters/prolog/swipl.vim
+
+After:
+  call ale#linter#Reset()
+
+Execute (The swipl handler should handle oneline warning / error):
+  call ale#test#SetFilename('test.pl')
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 5,
+  \     'col': 1,
+  \     'text': 'Syntax error: Operator expected',
+  \     'type': 'E',
+  \   },
+  \ ],
+  \ ale_linters#prolog#swipl#Handle(bufnr(''), [
+  \   'ERROR: /path/to/test.pl:5:1: Syntax error: Operator expected',
+  \ ])
+
+Execute (The swipl handler should handle a warning / error of two lines):
+  call ale#test#SetFilename('test.pl')
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 9,
+  \     'col': 0,
+  \     'text': 'Singleton variables: [M]',
+  \     'type': 'W',
+  \   },
+  \ ],
+  \ ale_linters#prolog#swipl#Handle(bufnr(''), [
+  \   'Warning: /path/to/test.pl:9:',
+  \   '        Singleton variables: [M]',
+  \ ])
+
+Execute (The swipl handler should join three or more lines with '. '):
+  call ale#test#SetFilename('test.pl')
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 10,
+  \     'col': 0,
+  \     'text': 'Clauses of fib/2 are not together in the source-file. Earlier definition at /path/to/test.pl:7. Current predicate: f/0. Use :- discontiguous fib/2. to suppress this message',
+  \     'type': 'W',
+  \   },
+  \ ],
+  \ ale_linters#prolog#swipl#Handle(bufnr(''), [
+  \   'Warning: /path/to/test.pl:10:',
+  \   '        Clauses of fib/2 are not together in the source-file',
+  \   '          Earlier definition at /path/to/test.pl:7',
+  \   '          Current predicate: f/0',
+  \   '          Use :- discontiguous fib/2. to suppress this message',
+  \ ])
+
+Execute (The swipl handler should ignore warnings / errors 'No permission to call sandboxed ...'):
+  call ale#test#SetFilename('test.pl')
+  AssertEqual
+  \ [],
+  \ ale_linters#prolog#swipl#Handle(bufnr(''), [
+  \   'ERROR: /path/to/test.pl:11:',
+  \   '        No permission to call sandboxed `''$set_predicate_attribute''(_G3416:_G3417,_G3413,_G3414)''',
+  \   '        Reachable from:',
+  \   '                  system:''$set_pattr''(A,B,C,D)',
+  \   '                  system:''$set_pattr''(vimscript:A,B,C)',
+  \   '                  vimscript: (multifile A)',
+  \   'ERROR: /path/to/test.pl:12:',
+  \   '        No permission to call sandboxed `''$set_predicate_attribute''(_G205:_G206,_G202,_G203)''',
+  \   '        Reachable from:',
+  \   '                  system:''$set_pattr''(A,B,C,D)',
+  \   '                  system:''$set_pattr''(vimscript:A,B,C)',
+  \   '                  vimscript: (multifile A)',
+  \   'ERROR: /path/to/test.pl:13:',
+  \   '        No permission to call sandboxed `''$set_predicate_attribute''(_G1808:_G1809,_G1805,_G1806)''',
+  \   '        Reachable from:',
+  \   '                  system:''$set_pattr''(A,B,C,D)',
+  \   '                  system:''$set_pattr''(vimscript:A,B,C)',
+  \   '                  vimscript: (multifile A)',
+  \ ])
+
+Execute (The swipl handler should handle a warning / error with no line number):
+  call ale#test#SetFilename('test.pl')
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 1,
+  \     'col': 0,
+  \     'text': 'Exported procedure module_name:pred/0 is not defined',
+  \     'type': 'E',
+  \   },
+  \ ],
+  \ ale_linters#prolog#swipl#Handle(bufnr(''), [
+  \   'ERROR: Exported procedure module_name:pred/0 is not defined',
+  \ ])