Merge branch 'master' of ssh://git.eclipse.org/gitroot/koneki/org.eclipse.koneki...

[metalua.git] / metalua / compiler / parser / ext.lua

diff --git a/metalua/compiler/parser/ext.lua b/metalua/compiler/parser/ext.lua
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+++ b/metalua/compiler/parser/ext.lua
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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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