#!/usr/bin/env nomsu -V5.12.12.8
#
    This file contains code that supports manipulating and using collections like lists
    and dictionaries.
    
use "core/metaprogramming.nom"
use "core/control_flow.nom"
use "core/operators.nom"

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

# 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 $ in {x: 1}: add $] == [{key: "x", value: 1}]
    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 (([[1, 2], [3, 4]] flattened) == [1, 2, 3, 4])

externally ($lists flattened) means:
    $flat = []
    for $item in recursive $lists:
        if ($item is a "List"):
            for $ in $item:
                recurse $item on $
        ..else:
            $flat|add $item
    return $flat

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)"

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

test:
    assume ((sorted [3, 1, 2]) == [1, 2, 3])

externally [$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])

externally (unique $items) means:
    $unique = []
    $seen = {}
    for $ in $items:
        unless $seen.$:
            $unique|add $
            $seen.$ = (yes)
    return $unique