alpha p2

core/middleware.lua

@@ -0,0 +1,169 @@
+local M = {}
+
+function M.json_decode(json)
+    if type(json) ~= "string" then
+        return nil, "input must be a string"
+    end
+
+    local pos = 1
+    local len = #json
+
+    local function skip_ws()
+        while pos <= len and json:sub(pos,pos):match("%s") do
+            pos = pos + 1
+        end
+    end
+
+    local function parse_value()
+        skip_ws()
+        local c = json:sub(pos,pos)
+        if c == "{" then return parse_object()
+        elseif c == "[" then return parse_array()
+        elseif c == '"' then return parse_string()
+        elseif c:match("[%d%-]") then return parse_number()
+        elseif json:sub(pos,pos+3) == "true" then pos=pos+4; return true
+        elseif json:sub(pos,pos+4) == "false" then pos=pos+5; return false
+        elseif json:sub(pos,pos+3) == "null" then pos=pos+4; return nil
+        else return nil, "invalid value at position "..pos
+        end
+    end
+
+    function parse_string()
+        pos = pos + 1
+        local start_pos = pos
+        local str = ""
+        while pos <= len do
+            local c = json:sub(pos,pos)
+            if c == '"' then
+                str = str .. json:sub(start_pos,pos-1)
+                pos = pos + 1
+                return str
+            elseif c == "\\" then
+                str = str .. json:sub(start_pos,pos-1)
+                pos = pos + 1
+                local esc = json:sub(pos,pos)
+                local map = {b="\b", f="\f", n="\n", r="\r", t="\t", ['"']='"', ["\\"]="\\", ["/"]="/"}
+                str = str .. (map[esc] or esc)
+                pos = pos + 1
+                start_pos = pos
+            else
+                pos = pos + 1
+            end
+        end
+        return nil, "unterminated string"
+    end
+
+    function parse_number()
+        local start_pos = pos
+        while pos <= len and json:sub(pos,pos):match("[%d%+%-eE%.]") do
+            pos = pos + 1
+        end
+        local n = tonumber(json:sub(start_pos,pos-1))
+        if not n then return nil, "invalid number at position "..start_pos end
+        return n
+    end
+
+    function parse_array()
+        pos = pos + 1
+        local arr = {}
+        skip_ws()
+        if json:sub(pos,pos) == "]" then pos=pos+1; return arr end
+        while true do
+            local val, err = parse_value()
+            if err then return nil, err end
+            table.insert(arr,val)
+            skip_ws()
+            local c = json:sub(pos,pos)
+            if c == "]" then pos=pos+1; break
+            elseif c == "," then pos=pos+1
+            else return nil, "expected ',' or ']' at position "..pos
+            end
+        end
+        return arr
+    end
+
+    function parse_object()
+        pos = pos + 1
+        local obj = {}
+        skip_ws()
+        if json:sub(pos,pos) == "}" then pos=pos+1; return obj end
+        while true do
+            skip_ws()
+            if json:sub(pos,pos) ~= '"' then return nil, "expected string key at "..pos end
+            local key, err = parse_string()
+            if err then return nil, err end
+            skip_ws()
+            if json:sub(pos,pos) ~= ":" then return nil, "expected ':' at "..pos end
+            pos = pos + 1
+            local val, err = parse_value()
+            if err then return nil, err end
+            obj[key] = val
+            skip_ws()
+            local c = json:sub(pos,pos)
+            if c == "}" then pos=pos+1; break
+            elseif c == "," then pos=pos+1
+            else return nil, "expected ',' or '}' at "..pos
+            end
+        end
+        return obj
+    end
+
+    local result, err = parse_value()
+    if err then return nil, err end
+    skip_ws()
+    if pos <= len then return nil, "trailing characters at "..pos end
+    return result
+end
+
+function M.json_encode(value)
+    local t = type(value)
+    if t == "nil" then
+        return "null"
+    elseif t == "boolean" then
+        return tostring(value)
+    elseif t == "number" then
+        return tostring(value)
+    elseif t == "string" then
+        return '"' .. value:gsub('[%z\1-\31\\"]', {
+            ['\\'] = '\\\\',
+            ['"'] = '\\"',
+            ['\b'] = '\\b',
+            ['\f'] = '\\f',
+            ['\n'] = '\\n',
+            ['\r'] = '\\r',
+            ['\t'] = '\\t'
+        }):gsub("[%z\1-\31]", function(c)
+            return string.format("\\u%04x", c:byte())
+        end) .. '"'
+    elseif t == "table" then
+        local is_array = true
+        local max_index = 0
+        for k,v in pairs(value) do
+            if type(k) ~= "number" then
+                is_array = false
+            else
+                if k > max_index then max_index = k end
+            end
+        end
+
+        local items = {}
+        if is_array then
+            for i = 1, max_index do
+                table.insert(items, M.json_encode(value[i]))
+            end
+            return "[" .. table.concat(items,",") .. "]"
+        else
+            for k,v in pairs(value) do
+                if type(k) ~= "string" then
+                    return nil, "object keys must be strings"
+                end
+                table.insert(items, M.json_encode(k) .. ":" .. M.json_encode(v))
+            end
+            return "{" .. table.concat(items,",") .. "}"
+        end
+    else
+        return nil, "unsupported type: " .. t
+    end
+end
+
+return M