Add --emit-lua-preserve-columns flag pallene-lang#567

Including test case.

spec/translator_spec.lua

@@ -9,9 +9,13 @@
 local util = require "pallene.util"
 local execution_tests = require "spec.execution_tests"
 
-local function compile(filename, pallene_code)
+local function compile(filename, pallene_code, preserve_columns)
     assert(util.set_file_contents(filename, pallene_code))
-    local cmd = string.format("pallenec %s --emit-lua", util.shell_quote(filename))
+    local flag = "--emit-lua"
+    if preserve_columns then
+        flag = "--emit-lua-preserve-columns"
+    end
+    local cmd = string.format("pallenec %s " .. flag, util.shell_quote(filename))
     local ok, _, _, error_message = util.outputs_of_execute(cmd)
     return ok, error_message
 end
@@ -32,8 +36,8 @@ end)
 -- Translation tests
 --------------------
 
-local function assert_translation(pallene_code, expected)
-    assert(compile("__translation_test__.pln", pallene_code))
+local function assert_translation(pallene_code, expected, preserve_columns)
+    assert(compile("__translation_test__.pln", pallene_code, preserve_columns))
     local contents = assert(util.get_file_contents("__translation_test__.lua"))
     -- The introduction of math.ln in Pallene to workaround single param math.log requires emitted
     -- Lua code to handle this as well. The current workaround injects "math.ln = math.log; " at
@@ -500,6 +504,30 @@ return m
 ]])
     end)
 
+    it("Remove any type annotation (preserving columns)", function ()
+        assert_translation(
+[[
+local m: module = {}
+local xs: {any} = {10, "hello", 3.14}
+
+local function f(x: any, y: any): any
+    return nil as nil
+end
+
+return m
+]],
+[[
+local m         = {}
+local xs        = {10, "hello", 3.14}
+
+local function f(x     , y     )     
+    return nil       
+end
+
+return m
+]], true)
+    end)
+
     it("Remove function shapes", function ()
         assert_translation(
 [[

src/pallene/driver.lua

@@ -149,6 +149,12 @@ end
 local function compile_pln_to_lua(input_ext, output_ext, input_file_name, base_name)
     assert(input_ext == "pln")
 
+    local preserve_columns = false
+    if output_ext == "lua_pc" then
+        preserve_columns = true
+        output_ext = "lua"
+    end
+
     local input, err = driver.load_input(input_file_name)
     if not input then
         return false, { err }
@@ -167,7 +173,7 @@ local function compile_pln_to_lua(input_ext, output_ext, input_file_name, base_n
         return false, errs
     end
 
-    local translation = translator.translate(input, prog_ast)
+    local translation = translator.translate(input, prog_ast, preserve_columns)
 
     assert(util.set_file_contents(base_name .. "." .. output_ext, translation))
     return true, {}
@@ -188,7 +194,7 @@ function driver.compile(argv0, opt_level, input_ext, output_ext, input_file_name
 
     local mod_name = string.gsub(output_base_name, "/", "_")
 
-    if output_ext == "lua" then
+    if output_ext == "lua" or output_ext == "lua_pc" then
         return compile_pln_to_lua(input_ext, output_ext, input_file_name, output_base_name)
     else
         local first_step = step_index[input_ext]  or error("invalid extension")

src/pallene/pallenec.lua

@@ -28,6 +28,10 @@ do
     p:mutex(
         p:flag("--emit-c",    "Generate a .c file instead of an executable"),
         p:flag("--emit-lua",  "Generate a .lua file instead of an executable"),
+        p:flag("--emit-lua-preserve-columns",
+          "Generate a .lua file instead of an executable with"
+          .. "\nthe positions of tokens preserved (useful with"
+          .. "\nLua diagnostics tool source mapping)"),
         p:flag("--compile-c", "Compile a .c file generated by --emit-c"),
         p:flag("--only-check","Check for syntax or type errors, without compiling"),
         p:flag("--print-ir",  "Show the intermediate representation for a program")
@@ -71,6 +75,7 @@ end
 function pallenec.main()
     if     opts.emit_c      then compile("pln", "c")
     elseif opts.emit_lua    then compile("pln", "lua")
+    elseif opts.emit_lua_preserve_columns then compile("pln", "lua_pc")
     elseif opts.compile_c   then compile("c" ,  "so")
     elseif opts.only_check  then do_check()
     elseif opts.print_ir    then do_print_ir()

src/pallene/translator.lua

@@ -30,8 +30,13 @@ local translator = {}
 
 local Translator = util.Class()
 
-function Translator:init(input)
+function Translator:init(input, preserve_columns)
     self.input = input -- string
+    if preserve_columns then
+        self.eraser = " " -- insert a space for each removed character
+    else
+        self.eraser = "" -- insert nothing when removing characters
+    end
     self.last_index = 1 -- integer
     self.partials = {} -- list of strings
     return self
@@ -51,7 +56,7 @@ function Translator:erase_region(start_index, stop_index)
     self:add_previous(start_index - 1)
 
     local region = self.input:sub(start_index, stop_index)
-    local partial = region:gsub("[^\n\r]", "")
+    local partial = region:gsub("[^\n\r]", self.eraser)
     table.insert(self.partials, partial)
 
     self.last_index = stop_index + 1
@@ -65,8 +70,8 @@ function Translator:prepend_compatibility_code()
     self.partials[1] = "math.ln = math.log; " .. self.partials[1]
 end
 
-function translator.translate(input, prog_ast)
-    local instance = Translator.new(input)
+function translator.translate(input, prog_ast, preserve_columns)
+    local instance = Translator.new(input, preserve_columns)
 
     -- Erase all type regions, while preserving comments
     -- As a sanity check, assert that the comment regions are either inside or outside the type