fix #565

5 files changed, 88 insertions, 26 deletions

diff --git a/changelog.md b/changelog.md
index a73512e7..2ebb2f9e 100644
--- a/changelog.md
+++ b/changelog.md
@@ -3,6 +3,7 @@
 ## 2.0.3
 * `CHG` improve memory usage
 * `FIX` some dialog boxes block the initialization process
+* `FIX` [#565](https://github.com/sumneko/lua-language-server/issues/565)
 
 ## 2.0.2
 `2021-6-23`
diff --git a/script/core/signature.lua b/script/core/signature.lua
index 8de1c374..76189fb7 100644
--- a/script/core/signature.lua
+++ b/script/core/signature.lua
@@ -4,6 +4,7 @@ local vm         = require 'vm'
 local hoverLabel = require 'core.hover.label'
 local hoverDesc  = require 'core.hover.description'
 local guide      = require 'parser.guide'
+local lookback   = require 'core.look-backward'
 
 local function findNearCall(uri, ast, pos)
     local text = files.getText(uri)
@@ -71,7 +72,7 @@ local function makeOneSignature(source, oop, index)
     }
 end
 
-local function makeSignatures(call, pos)
+local function makeSignatures(text, call, pos)
     local node = call.node
     local oop = node.type == 'method'
              or node.type == 'getmethod'
@@ -85,13 +86,26 @@ local function makeSignatures(call, pos)
             end
         end
         for i, arg in ipairs(args) do
-            if arg.start <= pos and arg.finish >= pos then
+            local start =  lookback.findTargetSymbol(text, arg.start - 1, '(')
+                        or lookback.findTargetSymbol(text, arg.start - 1, ',')
+                        or arg.start
+            if start > pos then
+                index = i - 1
+                break
+            end
+            if pos <= arg.finish then
                 index = i
                 break
             end
         end
         if not index then
-            index = #args + 1
+            local backSymbol = lookback.findSymbol(text, pos)
+            if backSymbol == ','
+            or backSymbol == '(' then
+                index = #args + 1
+            else
+                index = #args
+            end
         end
     else
         index = 1
@@ -112,38 +126,18 @@ local function makeSignatures(call, pos)
     return signs
 end
 
-local function isSpace(char)
-    if char == ' '
-    or char == '\n'
-    or char == '\r'
-    or char == '\t' then
-        return true
-    end
-    return false
-end
-
-local function skipSpace(text, offset)
-    for i = offset, 1, -1 do
-        local char = text:sub(i, i)
-        if not isSpace(char) then
-            return i
-        end
-    end
-    return 0
-end
-
 return function (uri, pos)
     local ast = files.getState(uri)
     if not ast then
         return nil
     end
     local text = files.getText(uri)
-    pos = skipSpace(text, pos)
+    pos = lookback.skipSpace(text, pos)
     local call = findNearCall(uri, ast, pos)
     if not call then
         return nil
     end
-    local signs = makeSignatures(call, pos)
+    local signs = makeSignatures(text, call, pos)
     if not signs or #signs == 0 then
         return nil
     end
diff --git a/script/parser/ast.lua b/script/parser/ast.lua
index bd8a66cf..e92e3e16 100644
--- a/script/parser/ast.lua
+++ b/script/parser/ast.lua
@@ -6,6 +6,7 @@ local mathType    = math.type
 local tableRemove = table.remove
 local pairs       = pairs
 local tableSort   = table.sort
+local print       = print
 
 _ENV = nil
 
@@ -1925,6 +1926,17 @@ local Defs = {
                 }
             }
         }
+    end,
+    CallArgSnip = function (name, tailStart, tailSymbol)
+        PushError {
+            type   = 'UNEXPECT_SYMBOL',
+            start  = tailStart,
+            finish = tailStart,
+            info = {
+                symbol = tailSymbol,
+            }
+        }
+        return name
     end
 }
 
diff --git a/script/parser/grammar.lua b/script/parser/grammar.lua
index 01756c2a..2c046f0e 100644
--- a/script/parser/grammar.lua
+++ b/script/parser/grammar.lua
@@ -304,6 +304,13 @@ MustName    <-  Name / DirtyName
 DirtyName   <-  {} -> DirtyName
 ]]
 
+grammar 'DocType' [[
+DocType     <-  (!%nl !')' !',' DocChar)+
+DocChar     <-  '(' (!%nl !')' .)+ ')'?
+            /   '<' (!%nl !'>' .)+ '>'?
+            /   .
+]]
+
 grammar 'Exp' [[
 Exp         <-  (UnUnit BinUnit*)
             ->  Binary
@@ -332,9 +339,12 @@ Single      <-  !FUNCTION Name
 Suffix      <-  SuffixWithoutCall
             /   ({} PL SuffixCall DirtyPR {})
             ->  Call
-SuffixCall  <-  Sp ({} {| (COMMA / Exp->NoNil)+ |} {})
+SuffixCall  <-  Sp ({} {| (COMMA / CallArg)+ |} {})
             ->  PackExpList
             /   %nil
+CallArg     <-  Sp (Name {} {'?'? ':'} Sps DocType)
+            ->  CallArgSnip
+            /   Exp->NoNil
 SuffixWithoutCall
             <-  (DOT (Name / MissField))
             ->  GetField
diff --git a/test/signature/init.lua b/test/signature/init.lua
index 931a8d73..40fb33dc 100644
--- a/test/signature/init.lua
+++ b/test/signature/init.lua
@@ -242,3 +242,48 @@ function f(x: table<number, string>, y: any, z: any)
 ]],
     arg = {12, 35},
 }
+
+
+TEST [[
+local function x(a, b)
+end
+
+x(  aaaa  $, 2)
+]]
+{
+    label = "function x(a: any, b: any)",
+    arg = {12, 17},
+}
+
+TEST [[
+local function x(a, b)
+end
+
+x($   aaaa  , 2)
+]]
+{
+    label = "function x(a: any, b: any)",
+    arg = {12, 17},
+}
+
+TEST [[
+local function x(a, b)
+end
+
+x(aaaa  ,$    2)
+]]
+{
+    label = "function x(a: any, b: any)",
+    arg = {20, 25},
+}
+
+TEST [[
+local function x(a, b)
+end
+
+x(aaaa  ,    2     $)
+]]
+{
+    label = "function x(a: any, b: any)",
+    arg = {20, 25},
+}