Major restructuring, switched over to use the new declarative parser.

Some rules in the bulk test file no longer parse, but all rules in the
demonstration rule-sets do.

src/mw_parser/utils.clj

@@ -0,0 +1,39 @@
+(ns mw-parser.utils)
+
+
+(defn rule?
+  "Return true if the argument appears to be a parsed rule tree, else false."
+  [maybe-rule]
+  (and (coll? maybe-rule) (= (first maybe-rule) :RULE)))
+
+
+(defn TODO
+  "Marker to indicate I'm not yet finished!"
+  [message]
+  message)
+
+
+(defn suitable-fragment?
+  "Return `true` if `tree-fragment` appears to be a tree fragment of the expected `type`."
+  [tree-fragment type]
+  (and (coll? tree-fragment)
+       (= (first tree-fragment) type)))
+
+
+(defn assert-type
+  "If `tree-fragment` is not a tree fragment of the expected `type`, throw an exception."
+  [tree-fragment type]
+  (assert (suitable-fragment? tree-fragment type)
+          (throw (Exception. (format "Expected a %s fragment" type)))))
+
+
+(defn search-tree
+  "Return the first element of this tree which has this tag in a depth-first, left-to-right search"
+  [tree tag]
+  (cond
+    (= (first tree) tag) tree
+    :else (first
+            (remove nil?
+                    (map
+                      #(search-tree % tag)
+                      (rest tree))))))