nomsu/lib/object.nom

#!/usr/bin/env nomsu -V4.8.10
#
    This file contains the implementation of an Object-Oriented programming system.

%globals.METAMETHOD_MAP = {..}
    "as text":"__tostring", "clean up":"__gc", "+ 1":"__add", "- 1":"__sub"
    "* 1":"__mul", "/ 1":"__div", "-":"__unm", "// 1":"__idiv", "mod 1":"__mod"
    "^ 1":"__pow", "& 1":"__band", "| 1":"__bor", "~ 1":"__bxor", "~":"__bnot"
    "<< 1":"__bshl", ">> 1":"__bshr", "== 1":"__eq", "< 1":"__lt", "<= 1":"__le"
    "set 1 = 2":"__newindex", size:"__len", iterate:"__ipairs", "iterate all":"__pairs"

test:
    object (Dog):
        (Dog).genus = "Canus"
        my action [set up]: %me.barks or= 0
        my action [bark, woof]:
            %barks = ("Bark!" for % in 1 to %me.barks)
            return (%barks::joined with " ")
        
        my action [get pissed off]: %me.barks += 1
    
    %d = (Dog {barks:2})
    assume (type of %d) == "Dog"
    assume (%d is a "Dog")
    assume %d.barks == 2
    assume ((%d::bark) == "Bark! Bark!")
    assume ((%d::woof) == "Bark! Bark!")
    %d::get pissed off
    assume (%d.barks == 3)
    assume ((%d::bark) == "Bark! Bark! Bark!")
    assume (%d.genus == "Canus")
    assume ("\(%d.class)" == "Dog")
    assume (%d.genus == "Canus")
    assume (%d.barks == 3)
    %d2 = (Dog {})
    assume (%d2.barks == 0) or barf "Default initializer failed"
    with {%d:Dog {barks:1}}:
        assume ((%d::bark) == "Bark!")
    object (Corgi) extends (Dog):
        my action [sploot] "splooted"
        my action [bark, woof]:
            %barks = ("Yip!" for % in 1 to %me.barks)
            return (%barks::joined with " ")
    
    %corg = (Corgi {})
    assume (%corg.barks == 0)
    with {%d:Corgi {barks:1}}:
        assume ((%d::sploot) == "splooted") or barf "subclass method failed"
        assume ((%d::bark) == "Yip!") or barf "inheritance failed"
        assume ((%d::woof) == "Yip!")
    
    with {%d:Dog {barks:2}}:
        assume ((%d::bark) == "Bark! Bark!")
(my action %actions %body) compiles to:
    lua> "\
        ..local fn_name = \%actions[1].stub:as_lua_id()
        local \%args = table.map(\%actions[1]:get_args(), function(a) return tostring(nomsu:compile(a)) end)
        table.insert(\%args, 1, \(\%me as lua id))
        local lua = LuaCode(tree.source, "class.", fn_name, " = ", \(..)
            what (%args -> %body) compiles to
        ..)
        for i=2,#\%actions do
            local alias = \%actions[i]
            local alias_name = alias.stub:as_lua_id()
            local \%alias_args = table.map(alias:get_args(), function(a) return tostring(nomsu:compile(a)) end)
            table.insert(\%alias_args, 1, \(\%me as lua id))
            lua:append("\\nclass.", alias_name, " = ")
            if utils.equivalent(\%args, \%alias_args) then
                lua:append("class.", fn_name)
            else
                lua:append("function(")
                lua:concat_append(\%alias_args, ", ")
                lua:append(")\\n    return class.", fn_name, "(")
                lua:concat_append(\%args, ", ")
                lua:append(")\\nend")
            end
        end
        return lua"

(object %classname extends %parent %class_body) compiles to:
    unless (%classname.type == "Action"):
        compile error at %classname "Expected this to be an action, not a \(%classname.type)"
    for % in %classname:
        unless (% is text):
            compile error at % "Class names should not have arguments."
    
    return (..)
        Lua "\
            ..do
                local class = {name=\(quote %classname.stub)}
                class.__type = class.name
                setmetatable(class, {
                    __index=\(%parent as lua expr),
                    __tostring=function(cls) return cls.name end,
                    __call=function(cls, inst)
                        inst = setmetatable(inst or {}, cls)
                        if inst.set_up then inst:set_up() end
                        return inst
                    end,
                })
                nomsu.environment[(class.name.." 1"):as_lua_id()] = class
                nomsu.environment[class.name:as_lua_id()] = function() return class end
                class.__index = class
                class.class = class
                class.__tostring = function(inst)
                    return inst.name..getmetatable(_Dict{}).__tostring(inst)
                end
                \(%class_body as lua statements)
                for stub,metamethod in pairs(globals.METAMETHOD_MAP) do
                    class[metamethod] = class[stub:as_lua_id()]
                end
            end"

(object %classname %class_body) parses as (..)
    object %classname extends (nil) %class_body