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#
This file contains definitions of operators like "+" and "and".
use "core/metaprogramming.nom"
# Indexing
immediately
# NOTE!!! It's critical that there are spaces around %key if it's a string,
otherwise, Lua will get confused and interpret %obj[[[foo]]] as %obj("[foo]")
instead of %obj[ "foo" ].
It's also critical to have parens around %obj, otherwise Lua is too dumb to
realize that {x=1}["x"] is the same as ({x=1})["x"] or that
{x=1}.x is the same as ({x=1}).x
parse [..]
%obj' %key, %obj's %key, %key in %obj, %key'th in %obj, %key of %obj,
%key st in %obj, %key nd in %obj, %key rd in %obj, %key th in %obj,
..as: %obj.%key
# Comparison Operators
immediately
compile [%x < %y] to: Lua value "(\(%x as lua expr) < \(%y as lua expr))"
compile [%x > %y] to: Lua value "(\(%x as lua expr) > \(%y as lua expr))"
compile [%x <= %y] to: Lua value "(\(%x as lua expr) <= \(%y as lua expr))"
compile [%x >= %y] to: Lua value "(\(%x as lua expr) >= \(%y as lua expr))"
# TODO: optimize case of [%x,%y] = [1,2]
compile [%a is %b, %a = %b, %a == %b] to
lua> ".."
local safe = {Text=true, Number=true}
local a_lua, b_lua = \(%a as lua), \(%b as lua)
if safe[\%a.type] or safe[\%b.type] then
return Lua.Value(tree.source, "(", a_lua, " == ", b_lua, ")")
else
return Lua.Value(tree.source, "utils.equivalent(", a_lua, ", ", b_lua, ")")
end
compile [%a isn't %b, %a is not %b, %a not= %b, %a != %b] to
lua> ".."
local safe = {Text=true, Number=true}
local a_lua, b_lua = \(%a as lua), \(%b as lua)
if safe[\%a.type] or safe[\%b.type] then
return Lua.Value(tree.source, "(", a_lua, " ~= ", b_lua, ")")
else
return Lua.Value(tree.source, "(not utils.equivalent(", a_lua, ", ", b_lua, "))")
end
# For strict identity checking, use (%x's id) is (%y's id)
compile [%'s id, id of %] to: Lua value "nomsu.ids[\(% as lua expr)]"
# Variable assignment operator
immediately
compile [%var <- %value] to
lua> "local \%var_lua = \(%var as lua)"
assume %var_lua.is_value or barf "Invalid target for assignment: \%var"
lua> ".."
\%value = \%value:map(function(t)
if Action:is_instance(t) and t.stub == "?" then
return \%var
end
end)
local \%value_lua = \(%value as lua)
assume %value_lua.is_value or barf "Invalid value for assignment: \%value"
lua> ".."
local lua = Lua(tree.source, \%var_lua, ' = ', \%value_lua, ';')
if \%var.type == 'Var' then
lua:add_free_vars({\%var})
end
return lua;
immediately
# Simultaneous mutli-assignments like: x,y,z = 1,x,3;
compile [<- %assignments] to
assume ((%assignments' "type") is "Dict") or barf ".."
Expected a Dict for the assignments part of '<- %' statement, not \%assignments
lua> ".."
local lhs, rhs = Lua(tree.source), Lua(tree.source)
for i, item in ipairs(\%assignments.value) do
local \%target, \%value = item.value[1], item.value[2]
\%value = \%value:map(function(t)
if Action:is_instance(t) and t.stub == "?" then
return \%target
end
end)
local target_lua = \(%target as lua)
if not target_lua.is_value then error("Invalid target for assignment: "..\(%target as text)) end
local value_lua = \(%value as lua)
if not value_lua.is_value then error("Invalid value for assignment: "..\(%value as text)) end
if \%target.type == "Var" then
lhs:add_free_vars({\%target})
end
if i > 1 then
lhs:append(", ")
rhs:append(", ")
end
lhs:append(target_lua)
rhs:append(value_lua)
end
return Lua(tree.source, lhs, " = ", rhs, ";")
immediately
compile [external %var <- %value] to
%var_lua <- (%var as lua)
assume %var_lua.is_value or barf "Invalid target for assignment: \%var"
%value_lua <- (%value as lua)
assume %value_lua.is_value or barf "Invalid value for assignment: \%value"
return: Lua "\%var_lua = \%value_lua;"
compile [with external %externs %body] to
%body_lua <- (%body as lua statements)
lua> "\%body_lua:remove_free_vars(\%externs.value);"
return %body_lua
compile [with %assignments %body] to
%lua <- (%body as lua statements)
lua> ".."
local lhs, rhs = Lua(tree.source), Lua(tree.source)
local vars = {}
for i, item in ipairs(\%assignments.value) do
local \%target, \%value = item.value[1], item.value[2]
if not \%target.type == "Var" then
error("Invalid target for 'with' assignment: "..tostring(\%target))
end
local target_lua = \(%target as lua)
local value_lua = \(%value as lua)
if not value_lua.is_value then
error("Invalid value for assignment: "..tostring(\%value))
end
if \%target.type == "Var" then
lhs:add_free_vars({\%target})
end
if i > 1 then
lhs:append(", ")
rhs:append(", ")
end
lhs:append(target_lua)
rhs:append(value_lua)
vars[i] = \%target
end
\%lua:remove_free_vars(vars)
\%lua:prepend("local ", lhs, " = ", rhs, ";\n")
return
Lua ".."
do
\%lua
end -- 'with' block
immediately
# Math Operators
compile [%x wrapped around %y, %x mod %y] to: Lua value "(\(%x as lua expr) % \(%y as lua expr))"
# 3-part chained comparisons
# (uses a lambda to avoid re-evaluating middle value, while still being an expression)
parse [%x < %y < %z] as: =lua "(function(x,y,z) return x < y and y < z; end)(\%x,\%y,\%z)"
parse [%x <= %y < %z] as: =lua "(function(x,y,z) return x <= y and y < z; end)(\%x,\%y,\%z)"
parse [%x < %y <= %z] as: =lua "(function(x,y,z) return x < y and y <= z; end)(\%x,\%y,\%z)"
parse [%x <= %y <= %z] as: =lua "(function(x,y,z) return x <= y and y <= z; end)(\%x,\%y,\%z)"
parse [%x > %y > %z] as: =lua "(function(x,y,z) return x > y and y > z; end)(\%x,\%y,\%z)"
parse [%x >= %y > %z] as: =lua "(function(x,y,z) return x >= y and y > z; end)(\%x,\%y,\%z)"
parse [%x > %y >= %z] as: =lua "(function(x,y,z) return x > y and y >= z; end)(\%x,\%y,\%z)"
parse [%x >= %y >= %z] as: =lua "(function(x,y,z) return x >= y and y >= z; end)(\%x,\%y,\%z)"
# TODO: optimize for common case where x,y,z are all either variables or number literals
# Boolean Operators
compile [%x and %y] to: Lua value "(\(%x as lua expr) and \(%y as lua expr))"
compile [%x or %y] to: Lua value "(\(%x as lua expr) or \(%y as lua expr))"
# Bitwise Operators
compile [%a OR %b, %a | %b] to: Lua value "bit32.bor(\(%a as lua expr), \(%b as lua expr))"
compile [%a XOR %b] to: Lua value "bit32.bxor(\(%a as lua expr), \(%b as lua expr))"
compile [%a AND %b, %a & %b] to: Lua value "bit32.band(\(%a as lua expr), \(%b as lua expr))"
compile [NOT %, ~ %] to: Lua value "bit32.bnot(\(% as lua expr))"
compile [%x LSHIFT %shift, %x << %shift] to: Lua value "bit32.lshift(\(%x as lua expr), \(%shift as lua expr))"
compile [%x RSHIFT %shift, %x >>> %shift] to: Lua value "bit32.rshift(\(%x as lua expr), \(%shift as lua expr))"
compile [%x ARSHIFT %shift, %x >> %shift] to: Lua value "bit32.arshift(\(%x as lua expr), \(%shift as lua expr))"
# TODO: implement OR, XOR, AND for multiple operands?
# Unary operators
compile [- %] to: Lua value "(- \(% as lua expr))"
compile [not %] to: Lua value "(not \(% as lua expr))"
# Using custom "len()" instead of Lua's "#" operator for compatibility with luajit.
compile [length of %list] to: Lua value "len(\(%list as lua expr))"
# Update operators
immediately
parse [%var + <- %, %var +<- %] as: %var <- (%var + %)
parse [%var - <- %, %var -<- %] as: %var <- (%var - %)
parse [%var * <- %, %var *<- %] as: %var <- (%var * %)
parse [%var / <- %, %var /<- %] as: %var <- (%var / %)
parse [%var ^ <- %, %var ^<- %] as: %var <- (%var ^ %)
parse [%var and <- %] as: %var <- (%var and %)
parse [%var or <- %] as: %var <- (%var or %)
parse [wrap %var around %] as: %var <- (%var wrapped around %)
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