add another algo

algtour.lua

@@ -0,0 +1,113 @@
+local nested_tables = {}
+
+-- strings might contain characters that are part of the table syntax.
+-- We need to mask them, otherwise they might break our parser
+-- based on https://www.lua.org/pil/20.4.html
+local function code(s)
+    -- mask all escaped characters
+    return s:gsub("\\(.)", function (c)
+        return string.format("\\%03d", string.byte(c))
+    end):gsub("([\"'])(.-)%1", function (_, match) -- detect all strings
+        return "'" .. match:gsub("([,;{}%[%]=])", function (c)
+            return string.format("\\%03d", string.byte(c))
+        end) .. "'"
+    end)
+end
+
+local function decode(s)
+    return s:gsub("\\(%d%d%d)", function (d)
+        return string.char(d)
+    end)
+end
+
+
+local function parse_value(str)
+    if str == "nil" then
+        return true, nil
+    elseif str == "true" then
+        return true, true
+    elseif str == "false" then
+        return true, false
+    elseif str:find("^([\"']).-%1$") then
+        return true, decode(str:sub(2, -2))
+    elseif tonumber(str) then
+        return true, tonumber(str)
+    elseif nested_tables[str] then
+        return true, nested_tables[str]
+    end
+    return false, string.format("unable to parse '%s'", str)
+end
+
+local function parse_key(str)
+    if str:find("^%[.*%]$") then
+        -- if in brackets, we can threat it like a value
+        local success, key = parse_value(str:sub(2, -2))
+        if not success then
+            return false, key
+        end
+        if key == nil then 
+            return false, "nil cannot be a key"
+        end
+        return true, key
+    end
+    -- make sure the key is a valid identifier
+    if str:find("^[%a_][%a%d_]*$") then
+        return true, str
+    end
+    return false, string.format("'%s' is not a valid key", str)
+end
+
+local function parse_flat_table(str)
+    if str:find("{%s*}") then return true, {} end
+    str = str:gsub("^{(.-)[,;]?%s*}$", "%1,")
+    local next_index = 1
+
+    local res = {}
+    for pair in str:gmatch("(.-)[,;]") do
+        local key, value, success
+        if pair:find("=") then
+            key, value = pair:match("^(.-)=(.*)$")
+            key = key:gsub("^%s*(.-)%s*$", "%1")
+            success, key = parse_key(key)
+            if not success then return false, key end
+        else
+            while res[next_index] ~= nil do
+                next_index = next_index + 1
+            end
+            key = next_index
+            next_index = next_index + 1
+            value = pair
+        end
+        value = value:gsub("^%s*(.-)%s*$", "%1")
+        success, value = parse_value(value)
+        if not success then return false, value end
+
+        res[key] = value
+    end
+
+    return true, res
+end
+
+local function stringToTable(str)
+    str = code(str)
+
+    nested_tables = {}
+    local success = true
+    local tbl
+
+    local replacements = 0
+    local table_count = 0
+    repeat
+        str, replacements = str:gsub("({[^{}]*})", function (match)
+            table_count = table_count + 1
+            success, tbl = parse_flat_table(match)
+            nested_tables["\\t" .. tostring(table_count)] = tbl
+            return "\\t" .. tostring(table_count)
+        end)
+    until replacements == 0 or success == false
+    return success and (nested_tables[str] or "not a table") or tbl
+end
+
+function test_string_to_table.s2ttour(str)
+    return stringToTable(str)
+end

init.lua

@@ -5,6 +5,7 @@ test_string_to_table.modpath = minetest.get_modpath("test_string_to_table") .. D
 dofile(test_string_to_table.modpath .. "alg1.lua")
 dofile(test_string_to_table.modpath .. "alg2.lua")
 dofile(test_string_to_table.modpath .. "alg3.lua")
+dofile(test_string_to_table.modpath .. "algtour.lua")
 
 local tests = {
     '{1, 2, 3}',
@@ -26,6 +27,7 @@ local function test(alg)
     for _, case in ipairs(tests) do
         local ret = {case, test_string_to_table[alg](case)}
         table.insert(outcome, ret)
+        minetest.log(dump(ret))
     end
     local t2 = minetest.get_us_time()
     minetest.log("action",alg .. " = " .. (t2-t1))
@@ -33,4 +35,5 @@ end
 
 -- test("s2t1")
 -- test("s2t2")
-test("s2t3")
+-- test("s2t3")
+test("s2ttour")