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

1 files changed, 100 insertions, 0 deletions

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',
+\})