#!/usr/bin/env nomsu -V6.15.13.8
#
    This file contains code that supports manipulating and using collections like lists
    and dictionaries.
    
use "core/metaprogramming"
use "core/control_flow"
use "core/operators"

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

# List functionality:
test:
    $list = [1, 2, 3, 4, 5]
    $visited = {}
    for $i = $x in $list:
        $visited.$i = (yes)
    assume ($visited == {.1, .2, .3, .4, .5})
    $visited = {}
    for $x in $list:
        $visited.$x = (yes)
    assume ($visited == {.1, .2, .3, .4, .5})
    assume (($list, 2 nd to last) == 4)
    assume (($list, first) == 1)
    assume ($list, has 3)
    assume (($list, index of 3) == 3)
    assume ((size of $list) == 5)
    $list, add 6
    assume (($list, last) == 6)
    $list, pop
    assume (($list, last) == 5)
    $list, remove index 1
    assume (($list, first) == 2)
    assume (([1, 2] + [3, 4]) == [1, 2, 3, 4])

# Dict functionality
test:
    $dict = {.x = 1, .y = 2, .z = 3}
    assume (size of $dict) == 3
    assume [: for $k = $v in {.x = 1}: add {.key = $k, .value = $v}] ==
        [{.key = "x", .value = 1}]
    assume ({.x = 1, .y = 1} + {.y = 10, .z = 10}) == {.x = 1, .y = 11, .z = 10}
    assume ({.x = 1, .y = 1} | {.y = 10, .z = 10}) == {.x = 1, .y = 1, .z = 10}
    assume ({.x = 1, .y = 1} & {.y = 10, .z = 10}) == {.y = 1}
    assume ({.x = 1, .y = 1} ~ {.y = 10, .z = 10}) == {.x = 1, .z = 10}

test:
    assume ((entries in {.x = 1}) == [{.key = "x", .value = 1}])

(entries in $dict) parses as [
    : for $k = $v in $dict:
        add {.key = $k, .value = $v}
]

test:
    assume ((keys in {.x = 1}) == ["x"])

[keys in $dict, keys of $dict] all parse as [: for $k = $v in $dict: add $k]
test:
    assume ((values in {.x = 1}) == [1])
[values in $dict, values of $dict] all parse as [: for $k = $v in $dict: add $v]

# Metatable stuff
test:
    $t = {}
    set $t's metatable to {.__tostring = ($ -> "XXX")}
    assume ("\$t" == "XXX")

(set $dict's metatable to $metatable) compiles to
    "setmetatable(\($dict as lua expr), \($metatable as lua expr));"

[$'s metatable, $'metatable] all compile to "getmetatable(\($ as lua expr))"
test:
    assume (({} with fallback $ -> ($ + 1)).10 == 11)

($dict with fallback $key -> $value) compiles to ("
    (function(d)
        local mt = {}
        for k,v in pairs(getmetatable(d) or {}) do mt[k] = v end
        mt.__index = function(self, \($key as lua expr))
            local value = \($value as lua expr)
            self[\($key as lua expr)] = value
            return value
        end
        return setmetatable(d, mt)
    end)(\($dict as lua expr))
")

# Sorting
test:
    $x = [3, 1, 2]
    sort $x
    assume ($x == [1, 2, 3])
    sort $x by $ = (- $)
    assume ($x == [3, 2, 1])
    $keys = {.1 = 999, .2 = 0, .3 = 50}
    sort $x by $ = $keys.$
    assume ($x == [2, 3, 1])
(sort $items) compiles to "table.sort(\($items as lua expr));"
[sort $items by $item = $key_expr, sort $items by $item -> $key_expr]
..all parse as
    do:
        $keys = ({} with fallback $item -> $key_expr)
        lua> "table.sort(\$items, function(x,y) return \$keys[x] < \$keys[y] end)"

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

external:
    test:
        assume ((sorted [3, 1, 2]) == [1, 2, 3])
    
    [$items sorted, sorted $items] all mean:
        $copy = [: for $ in $items: add $]
        sort $copy
        return $copy
    
    [$items sorted by $item = $key, $items sorted by $item -> $key] all parse as
        result of:
            $copy = [: for $ in $items: add $]
            sort $copy by $item = $key
            return $copy
    
    test:
        assume ((unique [1, 2, 1, 3, 2, 3]) == [1, 2, 3])
    
    (unique $items) means:
        $unique = []
        $seen = {}
        for $ in $items:
            unless $seen.$:
                $unique, add $
                $seen.$ = (yes)
        return $unique