nomsu/core/collections.nom

#..
    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/dict functions:

# Indexing
immediately:
    compile [..]
        %index st to last in %list, %index nd to last in %list, %index rd to last in %list
        %index th to last in %list
    ..to: Lua value "utils.nth_to_last(\(%list as lua expr), \(%index as lua expr))"

immediately:
    parse [first in %list, first %list] as: 1 st in %list
    parse [last in %list, last %list] as: 1 st to last in %list

# Membership testing
immediately:
    action [%item is in %list, %list contains %item, %list has %item]
        for %key = %value in %list
            if (%key is %item): return (yes)
        return (no)

    action [..]
        %item isn't in %list, %item is not in %list
        %list doesn't contain %item, %list does not contain %item
        %list doesn't have %item, %list does not have %item
    ..:
        for %key = %value in %list
            if (%key is %item): return (no)
        return (yes)

immediately:
    # Note: it's important to have the space after "[" to prevent confusion if %index is a string
    compile [%list has key %index, %list has index %index] to
        Lua value ".."
            ((\(%list as lua expr))[ \(%index as lua expr)] ~= nil)

    # Note: it's important to have the space after "[" to prevent confusion if %index is a string
    compile [..]
        %list doesn't have key %index, %list does not have key %index
        %list doesn't have index %index, %list does not have index %index
    ..to: Lua value "((\(%list as lua expr))[ \(%index as lua expr)] == nil)"

    compile [number of keys in %list] to:
        Lua value "utils.size(\(%list as lua expr))"

    compile [append %item to %list, add %item to %list, to %list add %item, to %list append %item] to:
        Lua "table.insert(\(%list as lua expr), \(%item as lua expr))"

    compile [pop from %list, remove last from %list] to:
        Lua "table.remove(\(%list as lua expr))"

    compile [remove index %index from %list] to:
        Lua "table.remove(\(%list as lua expr), \(%index as lua expr))"

# List Comprehension
immediately:
    compile [%expression for %item in %iterable] to:
        assume (%item.type is "Var") or barf ".."
            List comprehension has the wrong type for the loop variable. Expected Var, but got: \(%item.type)
        return
            Lua value ".."
                (function()
                    local comprehension = {};
                    for i,\(%item as lua expr) in ipairs(\(%iterable as lua expr)) do
                        comprehension[i] = \(%expression as lua expr);
                    end
                    return comprehension;
                end)()
    parse [%expression for all %iterable] as: %expression for % in %iterable

    compile [..]
        %expression for %index from %start to %stop via %step
        %expression for %index from %start to %stop by %step
    ..to:
        assume (%index.type is "Var") or barf ".."
            List comprehension has the wrong type for the loop variable. Expected Var, but got: \(%index.type)
        return
            Lua value ".."
                (function()
                    local comprehension = {};
                    for \(%index as lua expr)=\(%start as lua expr),\(%stop as lua expr),\(%step as lua expr) do
                        comprehension[#comprehension+1] = \(%expression as lua expr);
                    end
                    return comprehension;
                end)()
    parse [%expression for all ] as: %expression for % in %iterable
    parse [%expression for %var from %start to %stop] as: %expression for %var from %start to %stop via 1
    parse [..]
        %expression for all %start to %stop by %step
        %expression for all %start to %stop via %step
    ..as: %expression for % from %start to %stop via %step
    parse [%expression for all %start to %stop] as: %expression for all %start to %stop via 1

    compile [%expression for %key = %value in %iterable] to:
        assume (%key.type is "Var") or barf ".."
            List comprehension has the wrong type for the key loop variable. Expected Var, but got: \(%key.type)
        assume (%value.type is "Var") or barf ".."
            List comprehension has the wrong type for the value loop variable. Expected Var, but got: \(%value.type)
        return
            Lua value ".."
                (function()
                    local comprehension = {};
                    for \(%key as lua expr), \(%value as lua expr) in pairs(\(%iterable as lua expr)) do
                        table.insert(comprehension, \(%expression as lua expr));
                    end
                    return comprehension;
                end)()

# Dict comprehensions
immediately:
    compile [%key = %value for %item in %iterable] to:
        assume (%item.type is "Var") or barf ".."
            Dict comprehension has the wrong type for the loop variable. Expected Var, but got: \(%item.type)
        # Note: it's important to have the space after "[" to prevent confusion if %key is a string
        return
            Lua value ".."
                (function()
                    local comprehension = {};
                    for i,\(%item as lua expr) in ipairs(\(%iterable as lua expr)) do
                        comprehension[ \(%key as lua expr)] = \(%value as lua expr)
                    end
                    return comprehension;
                end)()
    parse [%key = %value for all %iterable] as: %key = %value for % in %iterable

    compile [%key = %value for %src_key = %src_value in %iterable] to:
        assume (%src_key.type is "Var") or barf ".."
            Dict comprehension has the wrong type for the key loop variable. Expected Var, but got: \(%src_key.type)
        assume (%src_value.type is "Var") or barf ".."
            Dict comprehension has the wrong type for the value loop variable. Expected Var, but got: \(%src_value.type)
        # Note: it's important to have the space after "[" to prevent confusion if %key is a string
        return
            Lua value ".."
                (function()
                    local comprehension = {};
                    for \(%src_key as lua expr), \(%src_value as lua expr) in pairs(\(%iterable as lua expr)) do
                        comprehension[ \(%key as lua expr)] = \(%value as lua expr);
                    end
                    return comprehension;
                end)()

immediately:
    action [%lists flattened]:
        %flat <- []
        for %list in %lists:
            for %item in %list:
                add %item to %flat
        return %flat

    parse [entries in %dict] as: {key:%k, value:%v} for %k = %v in %dict
    parse [keys in %dict] as: %k for %k = %v in %dict
    parse [values in %dict] as: %v for %k = %v in %dict

# Sorting:
immediately:
    compile [sort %items] to: Lua "table.sort(\(%items as lua expr));"
    compile [sort %items by %key_expr] to
        Lua ".."
            utils.sort(\(%items as lua expr), function(_)
                return \(%key_expr as lua expr);
            end);

immediately:
    action [%items sorted, sorted %items]:
        %copy <- (% for all %items)
        sort %copy
        return %copy
    action [%items sorted by %key]:
        %copy <- (% for all %items)
        sort %copy by %key
        return %copy

    action [unique %items]:
        %unique <- []
        %seen <- {}
        for all %items:
            unless: % in %seen
                add % to %unique
                (% in %seen) <- (yes)
        return %unique

immediately:
    # Metatable stuff
    compile [set %dict's metatable to %metatable] to
        Lua "setmetatable(\(%dict as lua expr), \(%metatable as lua expr));"

    compile [new counter] to: Lua value "setmetatable({}, {__index=function() return 0; end})"

    compile [new default dict] to
        Lua value ".."
            setmetatable({}, {__index=function(self, key)
                t = {};
                self[key] = t;
                return t;
            end})

# TODO: maybe make a generator/coroutine?