#!/usr/bin/env nomsu -V6.15.13.8
#
    A library for simple object oriented programming.

use "core/metaprogramming"
use "core/operators"
use "core/control_flow"
use "core/collections"
use "core/errors"

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

test:
    an (Empty) is a thing
    a (Buffer) is a thing:
        $its.is_a_buffer = (yes)
        ($its, set up) means:
            $its.bits or= []
        ($it, as text) means ($it.bits, joined)
        [($its, add $bit), ($its, append $bit)] all mean: $its.bits, add $bit
    assume (Buffer).is_a_buffer
    $b = (a Buffer)
    assume (type of $b) == "Buffer"
    assume $b.is_a_buffer
    assume "\$b" == ""
    assume ($b, as text) == ""
    $b = (a Buffer with {.bits = ["x"]})
    $b, 
        add "y"
        append "z"
    assume "\$b" == "xyz"
    assume $b == (a Buffer with {.bits = ["x", "y", "z"]})
    assume $b != (a Buffer with {.bits = []})
    a (Comma Buffer) is a (Buffer):
        ($it, as text) means ($it.bits, joined with ",")
        ($its, number of commas) means ((#$its.bits) - 1)
    $csv = (a Comma Buffer)
    assume $csv.is_a_buffer
    assume "\$csv" == ""
    $csv, add "x"
    $csv, add "y"
    assume "\$csv" == "x,y"
    assume ($csv, number of commas) == 1
    a (Vec) is a thing with {.x, .y}:
        ($its, + $other) means (Vec {.x = ($its.x + $other.x), .y = ($its.y + $other.y)})
    
    assume ((Vec {.x = 1, .y = 2}) + (Vec {.x = 10, .y = 10})) ==
        Vec {.x = 11, .y = 12}
    
    assume
        ((Vec {.x = 1, .y = 2}) + (Vec {.x = 10, .y = 10})) != (Vec {.x = 0, .y = 0})

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

$($ as text like a dict) = ({}'s metatable).__tostring
external:
    [
        a $parent class named $classname with $members $(initialize $)
        an $parent class named $classname with $members $(initialize $)
    ] all mean:
        $class = {.__type = $classname}
        $class.__index = $class
        $class.class = $class
        $class.__tostring = ($ -> "\($.__type) \($ as text like a dict)")
        $class.__eq = ({}'s metatable).__eq
        $class.__len = ({}'s metatable).__len
        if $members:
            $class.__members = $members
            $class.__newindex =
                for ($its $key = $value):
                    if $members.$key:
                        rawset $its $key $value
                    ..else:
                        fail "Cannot set \$key, it's not one of the allowed member fields."
        
        set $class's metatable to {
            .__index = $parent, .__tostring = ($class -> $class.__type)
            .__call =
                for ($class with $initial_values):
                    if ($initial_values == (nil)): return $class
                    set $initial_values's metatable to $class
                    if $initial_values.set_up:
                        $initial_values, set up
                    return $initial_values
        }
        
        if $(initialize $):
            initialize $class
            for $stub = $metamethod in $METAMETHOD_MAP:
                if $class.($stub, as lua id):
                    $class.$metamethod = $class.($stub, as lua id)
        
        return $class
    
    [
        a $classname is a $parent with $members $class_body
        an $classname is a $parent with $members $class_body
        a $classname is an $parent with $members $class_body
        an $classname is an $parent with $members $class_body
    ] all compile to:
        $class_id = ($classname.stub, as lua id)
        $lua =
            Lua ("
                \$class_id = a_1_class_named_2_with(\($parent as lua), \(quote $classname.stub), \
                ..\($members as lua)\(
                    (
                        Lua ("
                            , function(\$class_id)
                                local it, its = \$class_id, \$class_id;
                                \($class_body as lua)
                            end
                        ")
                    ) if $class_body else ""
                ))
                a_\$class_id = function(initial_values) return \$class_id(initial_values or {}) end
                an_\$class_id, a_\($class_id)_with, an_\($class_id)_with = a_\$class_id, a_\$class_id, a_\$class_id
            ")
        $lua, add free vars [$class_id, "a_\$class_id", "an_\$class_id"]
        return $lua
    
    [
        a $classname is a thing with $members $class_body
        an $classname is a thing with $members $class_body
        a $classname is an thing with $members $class_body
        an $classname is an thing with $members $class_body
    ] all parse as (a $classname is a (nil) with $members $class_body)
    
    [a $classname is a thing $class_body, an $classname is a thing $class_body]
    ..all parse as (a $classname is a (nil) with (nil) $class_body)
    
    [
        a $classname is a $parent $class_body, an $classname is a $parent $class_body
        a $classname is an $parent $class_body, an $classname is an $parent $class_body
    ] all parse as (a $classname is a $parent with (nil) $class_body)