1 files changed, 127 insertions, 0 deletions
diff --git a/script/vm/function.lua b/script/vm/function.lua
new file mode 100644
index 00000000..69900141
--- /dev/null
+++ b/script/vm/function.lua
@@ -0,0 +1,127 @@
+---@class vm
+local vm = require 'vm.vm'
+
+---@param func parser.object
+---@return integer min
+---@return integer max
+function vm.countParamsOfFunction(func)
+    local min = 0
+    local max = 0
+    if func.type == 'function'
+    or func.type == 'doc.type.function' then
+        if func.args then
+            max = #func.args
+            min = max
+            for i = #func.args, 1, -1 do
+                local arg = func.args[i]
+                if arg.type == '...'
+                or (arg.name and arg.name[1] =='...') then
+                    max = math.huge
+                elseif not vm.compileNode(arg):isNullable() then
+                    min = i
+                    break
+                end
+            end
+        end
+    end
+    return min, max
+end
+
+---@param func parser.object
+---@return integer min
+---@return integer max
+function vm.countReturnsOfFunction(func)
+    if func.type == 'function' then
+        if not func.returns then
+            return 0, 0
+        end
+        local min, max
+        for _, ret in ipairs(func.returns) do
+            local rmin, rmax = vm.countList(ret)
+            if not min or rmin < min then
+                min = rmin
+            end
+            if not max or rmax > max then
+                max = rmax
+            end
+        end
+        return min, max
+    end
+    if func.type == 'doc.type.function' then
+        return vm.countList(func.returns)
+    end
+    return 0, 0
+end
+
+---@param func parser.object
+---@return integer min
+---@return integer max
+function vm.countReturnsOfCall(func, args)
+    local funcs = vm.getMatchedFunctions(func, args)
+    local min
+    local max
+    for _, f in ipairs(funcs) do
+        local rmin, rmax = vm.countReturnsOfFunction(f)
+        if not min or rmin < min then
+            min = rmin
+        end
+        if not max or rmax > max then
+            max = rmax
+        end
+    end
+    return min or 0, max or 0
+end
+
+---@param list parser.object[]?
+---@return integer min
+---@return integer max
+function vm.countList(list)
+    if not list then
+        return 0, 0
+    end
+    local lastArg = list[#list]
+    if not lastArg then
+        return 0, 0
+    end
+    if lastArg.type == '...' then
+        return #list - 1, math.huge
+    end
+    if lastArg.type == 'call' then
+        local rmin, rmax = vm.countReturnsOfCall(lastArg.node, lastArg.args)
+        return #list - 1 + rmin, #list - 1 + rmax
+    end
+    return #list, #list
+end
+
+---@param func parser.object
+---@param args parser.object[]?
+---@return parser.object[]
+function vm.getMatchedFunctions(func, args)
+    local funcs = {}
+    local node = vm.compileNode(func)
+    for n in node:eachObject() do
+        if n.type == 'function'
+        or n.type == 'doc.type.function' then
+            funcs[#funcs+1] = n
+        end
+    end
+    if #funcs <= 1 then
+        return funcs
+    end
+
+    local amin, amax = vm.countList(args)
+
+    local matched = {}
+    for _, n in ipairs(funcs) do
+        local min, max = vm.countParamsOfFunction(n)
+        if amin >= min and amax <= max then
+            matched[#matched+1] = n
+        end
+    end
+
+    if #matched == 0 then
+        return funcs
+    else
+        return matched
+    end
+end