fix(snippets): fix parsing of ${1:{$2\}} like cases

lua/mini/snippets.lua

@@ -1796,8 +1796,9 @@ H.parse_processors.dollar_tabstop = function(c, s, n)
   local new_node = { text = {} }
   s:add_node(new_node)
   if c == '$' then return s:set_name('dollar') end -- Case of `$1$2` and `$1$a`
-  table.insert(new_node.text, c) -- Case of `$1a`
   s:set_name('text')
+  if c == '\\' then return s:set_in(new_node, 'after_slash', true) end -- Case of `${1:{$2\}}`
+  table.insert(new_node.text, c) -- Case of `$1a`
 end
 
 H.parse_processors.dollar_var = function(c, s, n)
@@ -1806,8 +1807,9 @@ H.parse_processors.dollar_var = function(c, s, n)
   local new_node = { text = {} }
   s:add_node(new_node)
   if c == '$' then return s:set_name('dollar') end -- Case of `$a$b` and `$a$1`
-  table.insert(new_node.text, c) -- Case of `$a-`
   s:set_name('text')
+  if c == '\\' then return s:set_in(new_node, 'after_slash', true) end -- Case of `${AAA:{$1\}}`
+  table.insert(new_node.text, c) -- Case of `$a-`
 end
 
 H.parse_processors.dollar_lbrace = function(c, s, n)

tests/test_snippets.lua

@@ -2490,6 +2490,11 @@ T['parse()']['placeholder'] = function()
 
   eq(parse([[${1:${2:aa\$bb\}cc\\dd}}]]), { { tabstop = '1', placeholder = { { tabstop = '2', placeholder = { { text = [[aa$bb}cc\dd]] } } } } } })
 
+  eq(parse([[${1:{$2\}}]]),   { { tabstop = '1', placeholder = { { text = '{' }, { tabstop = '2' }, { text = '}' } } } })
+  eq(parse([[${aa:{$1\}}]]),  { { var = 'aa',    placeholder = { { text = '{' }, { tabstop = '1' }, { text = '}' } } } })
+  eq(parse([[${1:{$aa\}}]]),  { { tabstop = '1', placeholder = { { text = '{' }, { var = 'aa' },    { text = '}' } } } })
+  eq(parse([[${aa:{$bb\}}]]), { { var = 'aa',    placeholder = { { text = '{' }, { var = 'bb' },    { text = '}' } } } })
+
   -- - Choice
   eq(parse('${1:${2|aa|}}'),    { { tabstop = '1', placeholder = { { tabstop = '2', choices = { 'aa' } } } } })
   eq(parse('${1:${3|aa|}}'),    { { tabstop = '1', placeholder = { { tabstop = '3', choices = { 'aa' } } } } })
@@ -3085,6 +3090,9 @@ T['parse()']['throws informative errors'] = function()
   validate('${1:a bb', 'Placeholder should be closed with "}"')
   validate('${1:${2:a', 'Placeholder should be closed with "}"')
 
+  validate([[${1:{$2\}]], 'Placeholder should be closed with "}"')
+  validate([[${1:{$aa\}]], 'Placeholder should be closed with "}"')
+
   -- - Nested nodes should error according to their rules
   validate('${1:${2?}}', 'Tabstop id should be followed by "}", ":", "|", or "/" not "?"')
   validate('${1:${2?', 'Tabstop id should be followed by "}", ":", "|", or "/" not "?"')