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-------------------------------------------------------------------------------
-- Copyright (c) 2006-2013 Fabien Fleutot and others.
--
-- All rights reserved.
--
-- This program and the accompanying materials are made available
-- under the terms of the Eclipse Public License v1.0 which
-- accompanies this distribution, and is available at
-- http://www.eclipse.org/legal/epl-v10.html
--
-- This program and the accompanying materials are also made available
-- under the terms of the MIT public license which accompanies this
-- distribution, and is available at http://www.lua.org/license.html
--
-- Contributors:
-- Fabien Fleutot - API and implementation
--
-------------------------------------------------------------------------------
--------------------------------------------------------------------------------
--
-- Non-Lua syntax extensions
--
--------------------------------------------------------------------------------
local gg = require 'metalua.grammar.generator'
return function(M)
local _M = gg.future(M)
---------------------------------------------------------------------------
-- Algebraic Datatypes
----------------------------------------------------------------------------
local function adt (lx)
local node = _M.id (lx)
local tagval = node[1]
-- tagkey = `Pair{ `String "key", `String{ -{tagval} } }
local tagkey = { tag="Pair", {tag="String", "tag"}, {tag="String", tagval} }
if lx:peek().tag == "String" or lx:peek().tag == "Number" then
-- TODO support boolean litterals
return { tag="Table", tagkey, lx:next() }
elseif lx:is_keyword (lx:peek(), "{") then
local x = M.table.table (lx)
table.insert (x, 1, tagkey)
return x
else return { tag="Table", tagkey } end
end
M.adt = gg.sequence{ "`", adt, builder = unpack }
M.expr.primary :add(M.adt)
----------------------------------------------------------------------------
-- Anonymous lambda
----------------------------------------------------------------------------
M.lambda_expr = gg.sequence{
"|", _M.func_params_content, "|", _M.expr,
builder = function (x)
local li = x[2].lineinfo
return { tag="Function", x[1],
{ {tag="Return", x[2], lineinfo=li }, lineinfo=li } }
end }
M.expr.primary :add (M.lambda_expr)
--------------------------------------------------------------------------------
-- Allows to write "a `f` b" instead of "f(a, b)". Taken from Haskell.
--------------------------------------------------------------------------------
function M.expr_in_backquotes (lx) return M.expr(lx, 35) end -- 35=limited precedence
M.expr.infix :add{ name = "infix function",
"`", _M.expr_in_backquotes, "`", prec = 35, assoc="left",
builder = function(a, op, b) return {tag="Call", op[1], a, b} end }
--------------------------------------------------------------------------------
-- C-style op+assignments
-- TODO: no protection against side-effects in LHS vars.
--------------------------------------------------------------------------------
local function op_assign(kw, op)
local function rhs(a, b) return { tag="Op", op, a, b } end
local function f(a,b)
if #a ~= #b then gg.parse_error "assymetric operator+assignment" end
local right = { }
local r = { tag="Set", a, right }
for i=1, #a do right[i] = { tag="Op", op, a[i], b[i] } end
return r
end
M.lexer :add (kw)
M.assignments[kw] = f
end
local ops = { add='+='; sub='-='; mul='*='; div='/=' }
for ast_op_name, keyword in pairs(ops) do op_assign(keyword, ast_op_name) end
return M
end
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