Move anselme code into its own directory

anselme/ast/Definition.lua

@@ -0,0 +1,63 @@
+local ast = require("anselme.ast")
+local Nil, Overloadable
+
+local operator_priority = require("anselme.common").operator_priority
+
+local Definition = ast.abstract.Node {
+	type = "definition",
+
+	symbol = nil,
+	expression = nil,
+	format_priority = operator_priority["_=_"],
+
+	init = function(self, symbol, expression)
+		self.symbol = symbol
+		self.expression = expression
+	end,
+
+	_format = function(self, ...)
+		return self.symbol:format(...).." = "..self.expression:format_right(...)
+	end,
+
+	traverse = function(self, fn, ...)
+		fn(self.symbol, ...)
+		fn(self.expression, ...)
+	end,
+
+	_eval = function(self, state)
+		if self.symbol.exported and state.scope:defined_in_current(self.symbol) then
+			return Nil:new() -- export vars: can reuse existing defining
+		end
+
+		local symbol = self.symbol:eval(state)
+		if symbol.alias then
+			state.scope:define_alias(symbol, self.expression)
+		else
+			local val = self.expression:eval(state)
+
+			if Overloadable:issub(val) then
+				state.scope:define_overloadable(symbol, val)
+			else
+				state.scope:define(symbol, val)
+			end
+		end
+
+		return Nil:new()
+	end,
+
+	_prepare = function(self, state)
+		local symbol, val = self.symbol, self.expression
+		symbol:prepare(state)
+		val:prepare(state)
+
+		-- predefine exported variables
+		if symbol.exported then
+			self:eval(state)
+		end
+	end
+}
+
+package.loaded[...] = Definition
+Nil, Overloadable = ast.Nil, ast.abstract.Overloadable
+
+return Definition