formspecconvert.lua

local function formspec_escape(text)
    text = string.gsub(text,"\\","\\\\")
    text = string.gsub(text,"%]","\\]")
    text = string.gsub(text,"%[","\\[")
    text = string.gsub(text,";","\\;")
    text = string.gsub(text,",","\\,")
	return text
end

local function assert_fields(tbl, names, i)
    for _, name in ipairs(names) do
        local found = false
        for fieldname, _ in ipairs(tbl) do
            if fieldname == name then
                found = true
            end
        end
        if not found then
            error("Element " .. i .. " has no '" .. name .. "' field")
        end
    end
end

local function assert_type(tbl, eln, ex, i)
    if type(tbl[eln]) ~= ex then
        error("The '" .. eln .. "' field of Element " .. i .. " is of type '" .. type(tbl[eln])
            .. "', expected was '" .. ex .. "'")
    end
end

local function boolstr(b)
    if b == true then
        return "true"
    else
        return "false"
    end
end

local conv_tbl = {
    -- Type     additional Check Func  args        arg types              template
     {"invsize", true,                {"w", "h"}, {"number", "number"}, "size[{w},{h}]"},
     {"size", true, {"w", "h"}, {"number", "number"}, "size[{w},{h}]"},
     {"list", function(t) return t.startingitemindex == nil end, 
        {"inventorylocation", "listname", "x", "y", "w", "h"},
        {"string", "string", "number", "number", "number", "number"},
        "list[{inventorylocation};{listname};{x},{y};{w},{h}]"},
    {"list", function(t) return t.startingitemindex ~= nil end, 
        {"inventorylocation", "listname", "x", "y", "w", "h", "startingitemindex"},
        {"string", "string", "number", "number", "number", "number", "number"},
        "list[{inventorylocation};{listname};{x},{y};{w},{h};{startingitemindex}]"},
    {"image", true, {"x", "y", "w", "h", "texturename"},
        {"number", "number", "number", "number", "string"},
        "image[{x},{y};{w},{h};{texturename}]"},
    {"item_image", true, {"x", "y", "w", "h", "itemname"},
        {"number", "number", "number", "number", "string"},
        "item_image[{x},{y};{w},{h};{itemname}]"},
    {"background", true, {"x", "y", "w", "h", "texturename"},
        {"number", "number", "number", "number", "string"},
        "background[{x},{y};{w},{h};{texturename}]"},
    {"pwdfield", true, {"x", "y", "w", "h", "name", "label"},
        {"number", "number", "number", "number", "string", "string"},
        "pwdfield[{x},{y};{w},{h};{name};{label}]"},
    {"field", function(t) return t.x ~= nil end,
        {"x", "y", "w", "h", "name", "label", "default"},
        {"number", "number", "number", "number", "string", "string", "string"},
        "field[{x},{y};{w},{h};{name};{label};{default}]"},
    {"field", function(t) return t.x == nil end,
        {"name", "label", "default"},
        {"string", "string", "string"},
        "field[{name};{label};{default}]"},
    {"textarea", true, {"x", "y", "w", "h", "name", "label", "default"},
        {"number", "number", "number", "number", "string", "string", "string"},
        "textarea[{x},{y};{w},{h};{name};{label};{default}]"},
    {"label", true, {"x", "y", "label"}, {"number", "number", "string"},
        "label[{x},{y};{label}]"},
    {"vertlabel", true, {"x", "y", "label"}, {"number", "number", "string"},
        "vertlabel[{x},{y};{label}]"},
    {"button", true, {"x", "y", "w", "h", "name", "label"},
        {"number", "number", "number", "number", "string", "string"},
        "button[{x},{y};{w},{h};{name};{label}]"},
    {"image_button", function(t, i)
            if t.noclip == nil and (t.drawborder ~= nil or t.pressed ~= nil) then
                error("Element " .. i .. " does have 'drawborder' or 'pressed' field but not 'noclip'")
            end
            if t.drawborder == nil and t.pressed ~= nil then
                error("Element " .. i .. " does have 'pressed' field but not 'drawborder'")
            end
            return t.noclip == nil and t.drawborder == nil and t.pressed == nil
        end,
        {"x", "y", "w", "h", "texturename", "name", "label"},
        {"number", "number", "number", "number", "string", "string", "string"},
        "image_button[{x},{y};{w},{h};{texturename};{name};{label}]"},
    {"image_button", function(t)
            return t.noclip ~= nil and t.drawborder == nil and t.pressed == nil
        end,
        {"x", "y", "w", "h", "texturename", "name", "label", "noclip"},
        {"number", "number", "number", "number", "string",
            "string", "string", "boolean"},
        "image_button[{x},{y};{w},{h};{texturename};{name};{label};{noclip};true]"},
    {"image_button", function(t)
            return t.noclip ~= nil and t.drawborder ~= nil and t.pressed == nil
        end,
        {"x", "y", "w", "h", "texturename", "name", "label", "noclip", "drawborder"},
        {"number", "number", "number", "number", "string",
            "string", "string", "boolean", "boolean"},
        "image_button[{x},{y};{w},{h};{texturename};{name};{label};{noclip};{drawborder}]"},
    {"image_button", function(t)
            return t.noclip ~= nil and t.drawborder ~= nil and t.pressed ~= nil
        end,
        {"x", "y", "w", "h", "texturename", "name", "label", "noclip", "drawborder", "pressed"},
        {"number", "number", "number", "number", "string",
            "string", "string", "boolean", "boolean", "string"},
        "image_button[{x},{y};{w},{h};{texturename};{name};{label};{noclip};{drawborder};{pressed}]"},
    {"item_image_button", true,
        {"x", "y", "w", "h", "itemname", "name", "label"},
        {"number", "number", "number", "number", "string", "string", "string"},
        "item_image_button[{x},{y};{w},{h};{itemname};{name};{label}]"},
    {"button_exit", true, {"x", "y", "w", "h", "name", "label"},
        {"number", "number", "number", "number", "string", "string"},
        "button_exit[{x},{y};{w},{h};{name};{label}]"},
    {"image_button_exit", true,
        {"x", "y", "w", "h", "texturename", "name", "label"},
        {"number", "number", "number", "number", "string", "string", "string"},
        "image_button_exit[{x},{y};{w},{h};{texturename};{name};{label}]"},
    {"textlist", function(t) return t.tranparent == nil end,
        {"x", "y", "w", "h", "name", "list"},
        {"number", "number", "number", "number", "string", {"table", colors=true}},
        "textlist[{x},{y};{w},{h};{name};{list}]"},
    {"textlist", function(t) return t.tranparent ~= nil end,
        {"x", "y", "w", "h", "name", "list", "transparent"},
        {"number", "number", "number", "number", "string", {"table", colors=true}, "boolean"},
        "textlist[{x},{y};{w},{h};{name};{list};{transparent}]"},
    {"tabheader", true, {"x", "y", "name", "captions",
            "current_tab", "transparent", "drawborder"},
        {"number", "number", "string", "table", "number",
            "boolean", "boolean"},
        "tabheader[{x},{y};{name};{captions};{current_tab};{transparent};{drawborder}]"},
    {"box", true, {"x", "y", "w", "h", "color"},
        {"number", "number", "number", "number", {"string", color=true}},
        "box[{x},{y};{w},{h};{color}]"},
    {"dropdown", true, {"x", "y", "w", "name", "items", "index"},
        {"number", "number", "number", "string", "table", "number"},
        "dropdown[{x},{y};{w};{name};{items};{index}]"},
    {"checkbox", function(t) return t.selected == nil end,
        {"x", "y", "name", "label"},
        {"number", "number", "string", "string"},
        "checkbox[{x},{y};{name};{label}]"},
    {"checkbox", function(t) return t.selected ~= nil end,
        {"x", "y", "name", "label", "selected"},
        {"number", "number", "string", "string", "boolean"},
        "checkbox[{x},{y};{name};{label};{selected}]"},
}

function formspectable2formspecstring(tbl)
    local outstring = ""
    if type(tbl) ~= "table" then
        error("Expected 'table' for first argument, got '" .. type(tbl) .. "'")
    end
    for i, el in ipairs(tbl) do
        if type(el) ~= "table" then
            error("Element " .. i .. " is not of type 'table', but '" .. type(el) .. "'")
        end
        local t = tbl[1]
        if t == nil then
            error("Element " .. i .. " has no type field")
        end
        local processed = false
        for _, conv in conv_tbl do
            if t == conv[1] then
                if type(conv[2]) == "boolean" and conv[2] == true then 
                    conv[2] = function(t) return true end
                end
                if conv[2](tbl, i) then
                    processed = true
                    assert_fields(tbl, conv[3], i)
                    for j, ftype in conv[4] do
                        if type(ftype) == "table" then
                            ftype = ftype[1]
                        end
                        assert_type(tbl, conv[3][j], ftype, i)
                    end
                    local out = conv[5]
                    for j, fname in conv[3] do
                        if type(tbl[fname]) == "string" then
                            if type(conv[4][j]) == "table" and conv[4][j].color then
                                _col = tbl[fname]
                                if #_col ~= 6 then
                                    error("Argument " .. j .. " of Element " .. i .. " is " .. #_col .." characters long, expected was 6")
                                end
                                for l in 1, #_col do
                                    _cc = string.byte(_col, l)
                                    if (_cc >= 48 and _cc <= 57) or (_cc >= 65 and _cc <= 70) or (_cc >= 97 and _cc <= 102) then
                                        --Character valid
                                    else
                                        error("Character " .. l .. " of Argument " .. j .. " of Element " .. i .. " is " .. string.char(_cc) .. ", expected was one of 0123456789ABCDEFabcdef")
                                    end
                                end
                            end
                            out = out:gsub("{" .. fname .. "}", formspec_escape(tbl[fname]))
                        elseif type(tbl[fname]) == "number" then
                            out = out:gsub("{" .. fname .. "}", tbl[fname])
                        elseif type(tbl[fname]) == "boolean" then
                            out = out:gsub("{" .. fname .. "}", boolstr(tbl[fname]))
                        elseif type(tbl[fname]) == "table" then
                            local out2 = ""
                            for k, tv in ipairs(tbl[fname]) do
                                if type(tv) == "string" then
                                    if type(conv[4][j]) == "table" and conv[4][j].colors and tv:sub(1,1) == "#" then
                                        tv = "#" .. tv
                                    end
                                    out2 = out2 .. formspec_escape(tv)
                                elseif type(tv) == "number" then
                                    out2 = out2 .. tv
                                elseif type(tv) == "boolean" then
                                    out2 = out2 .. boolstr(tv)
                                elseif type(tv) == "table" and type(conv[4][j]) == "table" and conv[4][j].colors then
                                    _col = tv.color
                                    _txt = tv.text
                                    if _col == nil then
                                        error("Element " .. i .. ", Argument " .. j .. " has no 'color' field")
                                    elseif _txt == nil then
                                        error("Element " .. i .. ", Argument " .. j .. " has no 'text' field")
                                    end
                                    if type(_col) ~= "string" then
                                        error("The 'color' field of Element " .. i .. ", Argument " .. j .. " is of type '" .. type(_col) .. "', expected was 'string'")
                                    elseif type(_txt) ~= "string"  then
                                        error("The 'text' field of Element " .. i .. ", Argument " .. j .. " is of type '" .. type(_col) .. "', expected was 'string'")
                                    end
                                    if #_col ~= 6 then
                                        error("The 'color' field of Element " .. i .. ", Argument " .. j .. " is " .. #_col .." characters long, expected was 6")
                                    end
                                    for l in 1, #_col do
                                        _cc = string.byte(_col, l)
                                        if (_cc >= 48 and _cc <= 57) or (_cc >= 65 and _cc <= 70) or (_cc >= 97 and _cc <= 102) then
                                            --Character valid
                                        else
                                            error("Character " .. l .. " of the 'color' field of Element " .. i .. ", Argument " .. j .. " is " .. string.char(_cc) .. ", expected was one of 0123456789ABCDEFabcdef")
                                        end
                                    end
                                    out2 = out2 .. "#" .. _col .. formspec_escape(tv)
                                else
                                    error("Cannot serialize " .. type(tv) .. " in table Element " .. i .. ", Argument " .. j)
                                end
                                if not k == #tbl[fname] then
                                    out2 = out2 .. ","
                                end
                            end
                            out = out:gsub("{" .. fname .. "}", out2)
                        end
                    end
                    outstring = outstring .. out
                end
            end
        end
        if not processed then
            error("Element " .. i .. " has unknown type '" .. t .. "'")
        end
    end
    return outstring
end