Added arithmetic actions to right hand side. Made 'is' and 'are' synonyms.

src/mw_parser/core.clj

@@ -1,8 +1,15 @@
 ;; A very simple parser which parses production rules of the following forms:
 ;;
 ;; "if altitude is less than 100 and state is forest then state should be climax and deer should be 3"
-;; "if altitude is 100 and fertility is 25 then state should be heath"
+;; "if altitude is 100 or fertility is 25 then state should be heath and fertility should be 24.3"
 ;; "if altitude is 100 or fertility is 25 then state should be heath"
+;; "if deer is more than 2 and wolves is 0 and fertility is more than 20 then deer should be deer + 2"
+;; "if deer is more than 1 and wolves is more than 1 then deer should be deer - wolves"
+;;
+;; It should also but does not yet parse rules of the form
+;; "if 6 neighbours have state is water then state should be fishery"
+;; "if state is forest or state is climax and some neighbours have state is fire then 3 in 5 chance that state should be fire"
+;; "if state is pasture and more than 3 neighbours have state is scrub then state should be scrub"
 ;;
 ;; it generates rules in the form expected by mw-engine.core
 
@@ -14,29 +21,31 @@
 (declare parse-not-condition)
 (declare parse-simple-condition)
 
-(defn parse-less-condition [[property is less than value & rest]]
-  (cond (and (= is "is") (= less "less") (= than "than"))
-        [(list '< (list 'get-int 'cell (keyword property)) value)
-         rest]))
+(defn parse-less-condition
+  "Parse '[property] is less than [value]."
+  [[property is less than value & rest]]
+  (cond (and (member? is '("is" "are")) (= less "less") (= than "than"))
+        [(list '< (list 'get-int 'cell (keyword property)) (read-string value)) rest]))
 
-(defn parse-more-condition [[property is more than value & rest]]
-  (cond (and (= is "is") (= more "more") (= than "than"))
-        [(list '> (list 'get-int 'cell (keyword property)) value)
-         :remainder rest]))
+(defn parse-more-condition
+  "Parse '[property] is more than [value]."
+  [[property is more than value & rest]]
+  (cond (and (member? is '("is" "are")) (= more "more") (= than "than"))
+        [(list '> (list 'get-int 'cell (keyword property)) (read-string value)) rest]))
 
 (defn parse-is-condition
   "Parse clauses of the form 'x is y', but not 'x is more than y' or 'x is less than y'.
    It is necessary to disambiguate whether value is a numeric or keyword."
   [[property is value & rest]]
-  (cond (and (= is "is")
+  (cond (and (member? is '("is" "are"))
              (not (member? value '("more" "less" "exactly" "not"))))
         [(cond
-          (re-matches #"^[0-9]*$" value)(list '= (list 'get-int 'cell (keyword property)) (. Integer parseInt value))
+          (re-matches #"^[0-9.]*$" value)(list '= (list 'get-int 'cell (keyword property)) (read-string value))
           true (list '= (list (keyword property) 'cell) (keyword value)))
          rest]))
 
 (defn parse-not-condition [[property is not & rest]]
-  (cond (and (= is "is") (= not "not"))
+  (cond (and (member? is '("is" "are")) (= not "not"))
         (let [partial (parse-simple-condition (cons property (cons is rest)))]
           (cond partial
                 (let [[condition remainder] partial]
@@ -47,7 +56,6 @@
   [tokens]
   (or (parse-is-condition tokens)
       (parse-not-condition tokens)
-      (parse-exactly-condition tokens)
       (parse-less-condition tokens)
       (parse-more-condition tokens)))
 
@@ -88,11 +96,24 @@
    (= (first tokens) "if")
    (parse-conditions (rest tokens))))
 
-(defn parse-simple-action [previous [property should be value & rest]]
+(defn parse-arithmetic-action [previous [prop1 should be prop2 operator value & rest]]
+  (if (and (= should "should")
+           (= be "be")
+           (member? operator '("+" "-" "*" "/")))
+    [(list 'merge (or previous 'cell)
+           {(keyword prop1) (list (symbol operator) (list 'get-int 'cell (keyword prop2))
+                                  (cond
+                                     (re-matches #"^[0-9.]*$" value) (read-string value)
+                                     true (list 'get-int 'cell (keyword value))))}) rest]))
+
+(defn parse-set-action [previous [property should be value & rest]]
   (if (and (= should "should") (= be "be"))
     [(list 'merge (or previous 'cell)
-           {(keyword property) (cond (re-matches #"^[0-9]*$" value) (. Integer parseInt value) true (keyword value))}) rest])
-  )
+           {(keyword property) (cond (re-matches #"^[0-9.]*$" value) (read-string value) true (keyword value))}) rest]))
+
+(defn parse-simple-action [previous tokens]
+    (or (parse-arithmetic-action previous tokens)
+        (parse-set-action previous tokens)))
 
 (defn parse-actions
   "Parse actions from tokens."