Skip to content

Commit

Permalink
improve automatic type detection at variable assignment time
Browse files Browse the repository at this point in the history 
less error-prone, and now also supports more complex use cases such as loops and destructuring assignments. This was possible by switching the CoffeeScript compiler to a recent contribution by @edemaine at jashkenas/coffeescript#5395
  • Loading branch information
@phil294
phil294 committed Jan 25, 2022
1 parent f65f758 commit c71f458
Show file tree
Hide file tree
Showing 2 changed files with 1 addition and 128 deletions.
2 changes: 1 addition & 1 deletion server/package.json
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
},
"homepage": "https://github.com/phil294/coffeesense/tree/master/server",
"dependencies": {
"coffeescript": "github:edemaine/coffeescript#var-assign",
"jshashes": "^1.0.8",
"typescript": "^4.3.2",
"volatile-map": "^1.0.2"
Expand All @@ -36,7 +37,6 @@
"@types/resolve": "1.20.0",
"@typescript-eslint/eslint-plugin": "^5.9.0",
"@typescript-eslint/parser": "^5.9.0",
"coffeescript": "^2.5.1",
"core-js": "^3.15.1",
"eslint": "^8.6.0",
"fast-glob": "^3.2.5",
Expand Down
127 changes: 0 additions & 127 deletions server/src/services/transpileService.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -130,133 +130,6 @@ function postprocess_js(result: ITranspilationResult) {
// but they do no harm and should go unnoticed
result.js = result.js.replaceAll(/𒐛: 𒐛,?/g, '')

// console.time('var-decl-fix')
//////////////////////////////////////
///////// Modify variable declarations to solve various TS compiler errors:
// Should not be error but is:
// xy = 123 # Error: Variable 'xy' implicitly has type 'any' in some locations where its type cannot be determined.CoffeeSense [TS](7034)
// => xy # Error: Variable 'xy' implicitly has an 'any' type.CoffeeSense [TS](7005)
//////// and
// Should be error but is not:
// a = 1
// a = 'one'
/////// This is because the cs compiler puts variable declarations to the front:
// Translates to:
// var a;
// a = 1;
// a = 'one';
/////// and now `a` is of type `number | string` (https://github.com/microsoft/TypeScript/issues/45369).
// Below is a hacky workaround that should fix these issues in most cases. It moves the
// declaration part (`var`) down to the variable's first implementation position.
// This works only with easy implementations and single-variable array destructuring:
/*
var a, b, c;
a = 1;
[b] = 2;
({c} = 3);
*/
// Shall become:
/*
var c;
let a = 1; // added let
let [b] = 2; // added let
({c} = 3); // unchanged because of surrounding braces
*/
// similarly, array destructors with more than one variable cannot be changed.
// Returns stay untouched (return x = 1) too.
const js_lines = result.js.split('\n')
const js_line_nos = Array.from(Array(js_lines.length).keys())
// Part 1: Determine declaration areas (` var x, y;`)
const js_decl_lines_info = js_line_nos
.map(decl_line_no => {
const match = js_lines[decl_line_no]!.match(/^(\s*)(var )(.+);$/)
if(match) {
const var_decl_infos = match[3]!.split(', ').map(var_name => ({
var_name,
decl_indent: match[1]!.length,
decl_line_no,
}))
return {
decl_line_no,
var_decl_infos,
}
}
return null
})
.filter(Boolean)
// Part 2: For each `var` decl, find fitting first impl statement
// (`x = 1`), if present, and return new line content (`let x = 1`).
// Might as well be `var x = 1` but this helps differentiating/debugging
const js_impl_line_changes = js_decl_lines_info
.map(info => info!.var_decl_infos)
.flat()
.map(({ var_name, decl_indent, decl_line_no }) => {
const js_line_nos_after_decl = js_line_nos.slice(decl_line_no)
for(const impl_line_no of js_line_nos_after_decl) {
const line = js_lines[impl_line_no]!
const impl_whitespace = line.match(/^\s*/)![0]!
const impl_indent = impl_whitespace.length
if(impl_indent < decl_indent)
// Parent block scope. Need to skip this variable then, no impl has been found
// before current block got closed. It is important to stop here, as otherwise
// it might later match an impl from *another* decl of the same var name
return null
const var_impl_text = `${var_name} = `
if(line.substr(impl_indent, var_impl_text.length) === var_impl_text) {
if(impl_indent > decl_indent)
// This is a conditional first value assignment and type can not safely be set
return null
const rest_of_line = line.slice(impl_indent + var_impl_text.length)
return {
var_name,
impl_line_no,
decl_line_no,
new_line_content: `${impl_whitespace}let ${var_impl_text}${rest_of_line}`,
new_let_column: impl_indent,
}
}
}
return null
}).filter(Boolean)
// Part 3: Apply Part 2 changes and update source maps of those lines
for(const change of js_impl_line_changes) {
js_lines[change!.impl_line_no] = change!.new_line_content
const map_columns = result.source_map[change!.impl_line_no]!.columns
const map_current_impl_start = map_columns[change!.new_let_column]!
// Can be null in cases where the variable is not user-set but e.g. a helper
// variable put there by the cs compiler itself and ignored otherwise
if(map_current_impl_start != null) {
map_columns.splice(
change!.new_let_column,
0,
..."let ".split('').map((_, i) => ({
...map_current_impl_start,
column: map_current_impl_start.column + i
})))
for(let i = map_current_impl_start.column + "let ".length; i < map_columns.length + "let ".length; i++) {
if(map_columns[i])
map_columns[i]!.column += "let ".length // or = i
}
}
}
// Part 4: Update decl lines (Part 1). Where no impl lines were found (Part 2),
// keep them. If all were modified, an empty line will be put.
for(const decl_line_info of js_decl_lines_info) {
let new_decl_line = decl_line_info!.var_decl_infos
.filter(decl_info => ! js_impl_line_changes.some(impl_change =>
impl_change!.var_name === decl_info.var_name &&
impl_change!.decl_line_no === decl_info.decl_line_no))
.map(i => i.var_name)
.join(', ')
if(new_decl_line)
// Those that could not be changed
new_decl_line = 'var ' + new_decl_line
js_lines[decl_line_info!.decl_line_no] = new_decl_line
}

result.js = js_lines.join('\n')
// console.timeEnd('var-decl-fix')

/* Prefer object method shorthand */
result.js = result.js.replaceAll(/([a-zA-Z0-9_$]+): (async )?function(\*?)\(/g, (_, func_name, asynk, asterisk) =>
`${asynk || ''}${asterisk}${func_name} (`
Expand Down

0 comments on commit c71f458

Please sign in to comment.