Added support for javac (with eclipse classpath support for now) (#141)

* A try at javac support for ALE

* Small cleanup: moved '/tmp/java_ale' string into script var

* Fixed Travis-CI build failing on autocmd not being in augroup and stupid omission

* One more fix for Travis-CI

* For some reason, expandtab was not set

* Indentation and removal of header guard.

Used examples from ale_linters/c/gcc.vim and
ale_linters/javascript/eslint.vim for the indentation of string concat blocks.

1 files changed, 102 insertions, 0 deletions

diff --git a/ale_linters/java/javac.vim b/ale_linters/java/javac.vim
new file mode 100644
index 00000000..80986314
--- /dev/null
+++ b/ale_linters/java/javac.vim
@@ -0,0 +1,102 @@
+" Author: farenjihn <farenjihn@gmail.com>
+" Description: Lints java files using javac
+
+let g:loaded_ale_linters_java_javac = 1
+let g:ale_java_javac_classpath = ''
+
+let s:eclipse_classpath = ''
+let s:tmppath = '/tmp/java_ale/'
+
+function! ale_linters#java#javac#Handle(buffer, lines) abort
+    " Look for lines like the following.
+    "
+    " Main.java:13: warning: [deprecation] donaught() in Testclass has been deprecated
+    " Main.java:16: error: ';' expected
+
+    let l:pattern = '^.*\:\(\d\+\):\ \(.*\):\(.*\)$'
+    let l:output = []
+
+    for l:line in a:lines
+        let l:match = matchlist(l:line, l:pattern)
+
+        if len(l:match) == 0
+            continue
+        endif
+
+        call add(l:output, {
+        \   'bufnr': a:buffer,
+        \   'lnum': l:match[1] + 0,
+        \   'vcol': 0,
+        \   'col': 1,
+        \   'text': l:match[2] . ':' . l:match[3],
+        \   'type': l:match[2] ==# 'error' ? 'E' : 'W',
+        \   'nr': -1,
+        \})
+    endfor
+
+    return l:output
+endfunction
+
+function! ale_linters#java#javac#ParseEclipseClasspath()
+    let l:eclipse_classpath = ''
+
+python << EOF
+
+    import xml.etree.ElementTree as ET, vim
+    tree = ET.parse(".classpath")
+    root = tree.getroot()
+
+    classpath = ''
+
+    for child in root:
+        classpath += child.get("path")
+        classpath += ':'
+
+        vim.command("let l:eclipse_classpath = '%s'" % classpath);
+
+# Cannot indent this EOF token as per :h python
+EOF
+
+    return l:eclipse_classpath
+endfunction
+
+function! ale_linters#java#javac#CheckEclipseClasspath()
+    " Eclipse .classpath parsing through python
+    if file_readable('.classpath')
+        let s:eclipse_classpath = ale_linters#java#javac#ParseEclipseClasspath()
+    endif
+endfunction
+
+function! ale_linters#java#javac#GetCommand(buffer)
+    let l:path = s:tmppath . expand('%:p:h')
+    let l:file = expand('%:t')
+    let l:buf = getline(1, '$')
+
+    " Javac cannot compile files from stdin so we move a copy into /tmp instead
+    call mkdir(l:path, 'p')
+    call writefile(l:buf, l:path . '/' . l:file)
+
+    return 'javac '
+    \ . '-Xlint '
+    \ . '-cp ' . s:eclipse_classpath . g:ale_java_javac_classpath . ':. '
+    \ . g:ale_java_javac_options
+    \ . ' ' . l:path . '/' . l:file
+endfunction
+
+function! ale_linters#java#javac#CleanupTmp()
+    call delete(s:tmppath, 'rf')
+endfunction
+
+augroup java_ale_au
+    autocmd! BufEnter *.java call ale_linters#java#javac#CheckEclipseClasspath()
+    autocmd! BufLeave *.java call ale_linters#java#javac#CleanupTmp()
+augroup END
+
+call ale_linters#java#javac#CheckEclipseClasspath()
+call ale#linter#Define('java', {
+\   'name': 'javac',
+\   'output_stream': 'stderr',
+\   'executable': 'javac',
+\   'command_callback': 'ale_linters#java#javac#GetCommand',
+\   'callback': 'ale_linters#java#javac#Handle',
+\})