support more native-style crow syntax on norns

norns_crow_namespace.lua

--- norns library for crow namespace support
-- enables full syntax support for calling crow functions, and setting crow values
-- does *not* support directly querying values or function responses from crow


--- helper fns for quoting (aka stringifying) lua constructs

quotekey = function(ix)
    -- stringify table keys with [] style
    local fstr = (type(ix)=='number') and '[%g]' or '[%q]'
    return string.format(fstr, ix)
end

quote = function(value)
    -- stringify anything so it can be read as lua code
    if type(value) == 'string' then return string.format('%q',value)
    elseif type(value) ~= 'table' then return tostring(value)
    else -- recur per table element
        local t = {}
        for k,v in pairs(value) do
            table.insert(t, quotekey(k) .. '=' .. quote(v))
        end
        return string.format('{%s}', table.concat(t, ','))
    end
end

quotevarargs = function(...)
    local t = {}
    for _,v in ipairs{...} do
        table.insert(t, quote(v) )
    end
    return table.concat(t, ',')
end


-- metamethods for building up strings of underlying call
-- and calling / setting values on crow
-- note: fn calls & value queries don't return anything
-- specifically means ASL construction won't work
crowSub = {
    __index = function(self, ix)
        -- build up the table access key chain
        self.str = self.str .. quotekey(ix)
        return self
    end,

    __newindex = function(self, ix, val)
        -- set a table value on crow
        self.send(self.str .. quotekey(ix) .. '=' .. val)
    end,

    __call = function(self, ...)
        local qt = quotevarargs(...)
        self.send(self.str .. '(' .. qt .. ')')
        -- TODO future. return a clock object (?) that is invoked when value returns from crow
    end,
}

--- crow table
-- defines fns that relate to crow but run on norns
-- defines ^^response event handlers
-- anything else is forwarded to crow via metamethods
crow = {
    -- set global var on crow
    -- TODO can probably forward directly to crowSub?
    __newindex = function(self, ix, val) crow.send(ix .. '=' .. quote(val)) end,

    -- create a table that will resolve to a crow.send call in crowSub
    __index = function(self, ix) return setmetatable({send=self.send, str=ix}, crowSub) end,
}

setmetatable(crow, crow)

crow.send = function(...) print('crow.send', ...) end
-- crow.send = function(cmd)
--     if norns.crow.dev then
--         _norns.crow_send(norns.crow.dev, cmd)
--     end
-- end



--- TEST code
-- just run this file to see what is sent to crow

-- set global crow var
crow.myvar = 1

-- set table var on crow with string index
crow.tab.key = 2

-- set nested table var on crow with numeric index
crow.tab[3].key = 4

-- call global crow fn no arguments
crow.fn()

-- call global crow fn with arguments
crow.fn(6)

-- call table fn
crow.tab.fn(8,'string',9)

-- call table fn with table argument
crow.tab.fn{1,2,3,'string',3.2,-12389.00}

-- call table fn with k,v pair args
crow.tab.fn{a=1, b=2, c=3}