Refactor moonc and overhaul watchers

- Essentially rewrote both SleepWatcher and InotifyWatcher
- Added test suites for both, including an expanded set of filesystem
  stubs in order to test them in isolation from the underlying
  filesystem
    - The filesystem stubs have their own tests, kek

Improvements as a result of these changes:
- Watch mode will remove "orphaned" .lua output files if/when their
  corresponding .moon input files are deleted
    - But it will not remove .lua files that have no corresponding .moon
      file to begin with, in order to avoid e.g. removing vendored Lua
      modules
- Both Watcher types will properly handle creation of new subdirectories
    - There *shouldn't* be any problematic races with this, although
      inotify's lack of recursive directory watching makes it difficult
      to know for sure
- More of the code is tested, and more of the code now *could* be tested
  (but isn't yet)
- Some bugs were fixed

Downsides:
- Somewhat gnarlier tests
- Moar lines of code

Author: Shados

docs/command_line.md

@@ -116,17 +116,38 @@ files in the same directories.
 $ moonc my_script1.moon my_script2.moon ...
 ```
 
-You can control where the compiled files are put using the `-t` flag, followed
-by a directory.
+You can control where the compiled files are put using the `-t`/`--output-to`
+flag, followed by a directory.
 
 `moonc` can also take a directory as an argument, and it will recursively scan
 for all MoonScript files and compile them.
 
+If you use `-t` and also specify a directory as argument, then similar to
+`rsync`, handling of whether or not directory names are included in the output
+file paths differs depending on whether or not you specify a trailing `/`.
+
+For example, if you have a folder called `src` containing a file `foo.moon`:
+
+```bash
+$ moonc -t out src
+```
+
+Produces the file `out/src/foo.lua`. Alternatively:
+
+```bash
+$ moonc -t out src/
+```
+
+Produces the file `out/foo.lua`. It does not matter whether or not there is a
+trailing `/` on the `--output-to` directory, only on each of the input
+directories specified.
+
 `moonc` can write to standard out by passing the `-p` flag.
 
 The `-w` flag can be used to enable watch mode. `moonc` will stay running, and
 watch for changes to the input files. If any of them change then they will be
-compiled automatically.
+compiled automatically. Watch mode also works in combination with the `-t`
+flag.
 
 A full list of flags can be seen by passing the `-h` or `--help` flag.
 

moonscript/cmd/moonc.lua

@@ -134,43 +134,52 @@ handle_watch_loop = function(opts, output_to, input_paths, prefix_map)
       end
     end
   end
-  local watcher = create_watcher(input_paths)
-  for filename in watcher do
-    local target = output_for(output_to, prefix_map, filename, "file")
+  local watcher = create_watcher(output_to, input_paths, prefix_map)
+  for file_tuple in watcher do
+    local event_type, filename, target, path_type
+    event_type, filename, target, path_type = file_tuple[1], file_tuple[2], file_tuple[3], file_tuple[4]
     if opts.o then
       target = opts.o
     end
     if opts.lint then
-      local lint = require("moonscript.cmd.lint")
-      local success, err = lint.lint_file(filename)
-      if success then
-        io.stderr:write(success .. "\n\n")
-      elseif err then
-        io.stderr:write(filename .. "\n" .. err .. "\n\n")
+      if event_type == "changedfile" then
+        local lint = require("moonscript.cmd.lint")
+        local success, err = lint.lint_file(filename)
+        if success then
+          io.stderr:write(success .. "\n\n")
+        elseif err then
+          io.stderr:write(filename .. "\n" .. err .. "\n\n")
+        end
+      elseif event_type == "removed" then
+        remove_orphaned_output(target, path_type)
       end
     else
-      local success, err = compile_and_write(filename, target)
-      if not success then
-        io.stderr:write(table.concat({
-          "",
-          "Error: " .. filename,
-          err,
-          "\n"
-        }, "\n"))
-      elseif success == "build" then
-        log_msg("Built", filename, "->", target)
+      if event_type == "changedfile" then
+        local success, err = compile_and_write(filename, target)
+        if not success then
+          io.stderr:write(table.concat({
+            "",
+            "Error: " .. filename,
+            err,
+            "\n"
+          }, "\n"))
+        elseif success == "build" then
+          log_msg("Built", filename, "->", target)
+        end
+      elseif event_type == "removed" then
+        remove_orphaned_output(target, path_type)
       end
     end
   end
   return io.stderr:write("\nQuitting...\n")
 end
-create_watcher = function(input_paths)
+create_watcher = function(output_to, input_paths, prefix_map)
   local watchers = require("moonscript.cmd.watchers")
   local watcher
   if watchers.InotifyWatcher:available() then
-    watcher = watchers.InotifyWatcher(input_paths)
+    watcher = watchers.InotifyWatcher(output_to, input_paths, prefix_map)
   else
-    watcher = watchers.SleepWatcher(input_paths)
+    watcher = watchers.SleepWatcher(output_to, input_paths, prefix_map)
   end
   return watcher:each_update()
 end

moonscript/cmd/moonc.moon

@@ -126,44 +126,50 @@ handle_watch_loop = (opts, output_to, input_paths, prefix_map) ->
       else
         log_msg "Error removing file", target, err_string
 
-  watcher = create_watcher input_paths
+  watcher = create_watcher output_to, input_paths, prefix_map
 
-  for filename in watcher
-    target = output_for(output_to, prefix_map, filename, "file")
+  for file_tuple in watcher
+    {event_type, filename, target, path_type} = file_tuple
 
     if opts.o
       target = opts.o
 
     if opts.lint
-      lint = require "moonscript.cmd.lint"
-      success, err = lint.lint_file filename
-      if success
-        io.stderr\write success .. "\n\n"
-      elseif err
-        io.stderr\write filename .. "\n" .. err .. "\n\n"
+      if event_type == "changedfile"
+        lint = require "moonscript.cmd.lint"
+        success, err = lint.lint_file filename
+        if success
+          io.stderr\write success .. "\n\n"
+        elseif err
+          io.stderr\write filename .. "\n" .. err .. "\n\n"
+      elseif event_type == "removed"
+        remove_orphaned_output target, path_type
     else
-      success, err = compile_and_write filename, target
-      if not success
-        io.stderr\write table.concat({
-          "",
-          "Error: " .. filename,
-          err,
-          "\n",
-        }, "\n")
-      elseif success == "build"
-        log_msg "Built", filename, "->", target
+      if event_type == "changedfile"
+        success, err = compile_and_write filename, target
+        if not success
+          io.stderr\write table.concat({
+            "",
+            "Error: " .. filename,
+            err,
+            "\n",
+          }, "\n")
+        elseif success == "build"
+          log_msg "Built", filename, "->", target
+      elseif event_type == "removed"
+        remove_orphaned_output target, path_type
 
   io.stderr\write "\nQuitting...\n"
 
-create_watcher = (input_paths) ->
+create_watcher = (output_to, input_paths, prefix_map) ->
   watchers = require "moonscript.cmd.watchers"
 
   -- TODO cli argument to force sleep watcher (as it is potentially a little
   -- more reliable)
   watcher = if watchers.InotifyWatcher\available!
-    watchers.InotifyWatcher input_paths
+    watchers.InotifyWatcher output_to, input_paths, prefix_map
   else
-    watchers.SleepWatcher input_paths
+    watchers.SleepWatcher output_to, input_paths, prefix_map
 
   return watcher\each_update!