89 lines
3.4 KiB
Lua
89 lines
3.4 KiB
Lua
--------------------------------------------------------------------------------
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--
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-- Non-Lua syntax extensions
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--
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--------------------------------------------------------------------------------
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module ("mlp", package.seeall)
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--------------------------------------------------------------------------------
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-- Alebraic Datatypes
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--------------------------------------------------------------------------------
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local function adt (lx)
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local tagval = id (lx) [1]
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local tagkey = {tag="Pair", {tag="String", "tag"}, {tag="String", tagval} }
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if lx:peek().tag == "String" or lx:peek().tag == "Number" then
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return { tag="Table", tagkey, lx:next() }
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elseif lx:is_keyword (lx:peek(), "{") then
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local x = table (lx)
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_G.table.insert (x, 1, tagkey)
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return x
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else return { tag="Table", tagkey } end
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end
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expr:add{ "`", adt, builder = fget(1) }
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--------------------------------------------------------------------------------
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-- Anonymous lambda
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--------------------------------------------------------------------------------
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local lambda_expr = gg.sequence{
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"|", func_params_content, "|", expr,
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builder= function (x)
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local li = x[2].lineinfo
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return { tag="Function", x[1],
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{ {tag="Return", x[2], lineinfo=li }, lineinfo=li } }
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end }
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-- In an earlier version, lambda_expr took an expr_list rather than an expr
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-- after the 2nd bar. However, it happened to be much more of a burden than an
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-- help, So finally I disabled it. If you want to return several results,
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-- use the long syntax.
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--------------------------------------------------------------------------------
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-- local lambda_expr = gg.sequence{
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-- "|", func_params_content, "|", expr_list,
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-- builder= function (x)
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-- return {tag="Function", x[1], { {tag="Return", unpack(x[2]) } } } end }
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expr:add (lambda_expr)
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--------------------------------------------------------------------------------
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-- Allows to write "a `f` b" instead of "f(a, b)". Taken from Haskell.
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-- This is not part of Lua 5.1 syntax, so it's added to the expression
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-- afterwards, so that it's easier to disable.
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--------------------------------------------------------------------------------
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local function expr_in_backquotes (lx) return expr(lx, 35) end
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expr.infix:add{ name = "infix function",
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"`", expr_in_backquotes, "`", prec = 35, assoc="left",
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builder = function(a, op, b) return {tag="Call", op[1], a, b} end }
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--------------------------------------------------------------------------------
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-- table.override assignment
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--------------------------------------------------------------------------------
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mlp.lexer:add "<-"
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stat.assignments["<-"] = function (a, b)
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assert( #a==1 and #b==1, "No multi-args for '<-'")
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return { tag="Call", { tag="Index", { tag="Id", "table" },
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{ tag="String", "override" } },
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a[1], b[1]}
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end
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--------------------------------------------------------------------------------
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-- C-style op+assignments
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--------------------------------------------------------------------------------
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local function op_assign(kw, op)
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local function rhs(a, b)
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return { tag="Op", op, a, b }
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end
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local function f(a,b)
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return { tag="Set", a, _G.table.imap(rhs, a, b) }
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end
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mlp.lexer:add (kw)
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mlp.stat.assignments[kw] = f
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end
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_G.table.iforeach (op_assign,
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{"+=", "-=", "*=", "/="},
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{"add", "sub", "mul", "div"}) |