Move anselme code into its own directory

anselme/parser/expression/secondary/infix/infix_or_suffix.lua

@@ -0,0 +1,32 @@
+-- same as infix, but skip if no valid expression after the operator instead of erroring
+-- useful for operators that are both valid as infix and as suffix
+
+local infix = require("anselme.parser.expression.secondary.infix.infix")
+local escape = require("anselme.common").escape
+local expression_to_ast = require("anselme.parser.expression.to_ast")
+
+return infix {
+	-- returns exp, rem if expression found
+	-- returns nil if no expression found
+	search = function(self, source, str, limit_pattern, current_priority, operating_on_primary)
+		if not self:match(str, current_priority, operating_on_primary) then
+			return nil
+		end
+		return self:maybe_parse(source, str, limit_pattern, current_priority, operating_on_primary)
+	end,
+
+	parse = function() error("no guaranteed parse for this operator") end,
+
+	-- return AST, rem
+	-- return nil
+	maybe_parse = function(self, source, str, limit_pattern, current_priority, primary)
+		local start_source = source:clone()
+		local escaped = escape(self.operator)
+
+		local sright = source:consume(str:match("^("..escaped..")(.*)$"))
+		local s, right, rem = pcall(expression_to_ast, source, sright, limit_pattern, self.priority)
+		if not s then return nil end
+
+		return self:build_ast(primary, right):set_source(start_source), rem
+	end,
+}