Move anselme code into its own directory

anselme/ast/Quote.lua

@@ -0,0 +1,41 @@
+-- prevent an expression from being immediately evaluated, and instead only evaluate it when the node is explicitely called
+-- it can be used to evaluate the expression on demand, as if the quote call AST was simply replaced by the unevaluated associated expression AST.
+-- kinda like a function, but no parameters, no closure and no new scope
+-- keep in mind that this thus bypass any scoping rule, closure, etc.
+--
+-- used for infix operators where the evaluation of the right term depends of the left one (lazy boolean operators, conditionals, etc.)
+
+local ast = require("anselme.ast")
+
+local Quote
+Quote = ast.abstract.Node {
+	type = "quote",
+
+	expression = nil,
+
+	init = function(self, expression)
+		self.expression = expression
+		self.format_priority = expression.format_priority
+	end,
+
+	_format = function(self, ...)
+		return self.expression:format(...) -- Quote is generated transparently by operators
+	end,
+
+	traverse = function(self, fn, ...)
+		fn(self.expression, ...)
+	end,
+
+	dispatch = function(self, state, args)
+		if args.arity == 0 then
+			return self, args
+		else
+			return nil, "Quote! does not accept arguments"
+		end
+	end,
+	call_dispatched = function(self, state, args)
+		return self.expression:eval(state)
+	end
+}
+
+return Quote