"Expand Selection" doesn't expand to strings or scopes

I use VScode's "Expand Selection" command a lot to copy strings around, but when I try to use it on Lua strings, it expands the selection a lot more than just the string I'm on.

Actual behavior

Suppose my cursor is inside the word example:

hs.alert(prefix .. " an exam|ple string " .. suffix)

1st call to Expand Selection selects the word:

hs.alert(prefix .. " an example string " .. suffix)

2nd call to Expand Selection selects everything between () instead of the full string:

hs.alert(prefix .. " an example string " .. suffix)

Expected behavior

2nd call to Expand Selection should select just the string:

hs.alert(prefix .. " an example string " .. suffix)

In JavaScript, I noticed it even has two steps for the string, the inner part of the string, then the outer:

alert(prefix + " an example string " + suffix)

alert(prefix + "an example string" + suffix)

alert(prefix + " an example string " + suffix)

That would also work!

Similar scenarios

Scopes are also currently skipped:

local myFunction = function () ret|urn true end

local myFunction = function () return true end <- 1st call selects the word

local myFunction = function () return true end <- expected: 2nd call selects the function scope

local myFunction = function () return true end <- actual: 2nd call selects the line instead

Same for Object.property:

Object.property = true

Object.property = true <- expected

Object.property = true <- actual

首先定位 Expand Selection 的实现，以及覆盖选择扩展的所有测试；该 issue 没有指定具体文件或入口点。重现 Lua 字符串、函数作用域和 Object.property 示例，然后添加覆盖测试，以展示连续扩展会选择预期的构造。