Beginnings of tree simplification

src/squirrel_parse/parser.clj

@@ -212,26 +212,6 @@
 
 (def grammar (join "\n" (flatten (list basic-rules datatype-rules keyword-rules))))
 
-
-(defn ignorable?
-  "True if `x` is something which just clutters up the parse tree."
-  [x]
-  (and
-    (coll? x)(contains? #{:SPACE :OPT-SPACE :COMMENT :OPT-KW-DATA} (first x))))
-
-
-(defn remove-recursive
-  "Return a collection like this `collection` from which items which are matched
-  by this `predicate` have been removed at all levels."
-  [predicate collection]
-  (map
-    #(if
-       (coll? %)
-       (remove-recursive predicate %)
-       %)
-    (remove predicate collection)))
-
-
 (def parse
   "Parse the argument, assumed to be a string in the correct syntax, and return a parse tree."
   (insta/parser grammar))

src/squirrel_parse/simplify.clj

@@ -0,0 +1,70 @@
+(ns ^{:doc "A parser for SQL: simplify/normalise a parse tree."
+      :author "Simon Brooke"}
+  squirrel-parse.simplify
+  (:require [clojure.string :refer [join split trim triml upper-case]]))
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; squirrel-parse.simplify: simplify/normalise a parse tree.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2018 Simon Brooke
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+
+(defn ignorable?
+  "True if `x` is something which just clutters up the parse tree."
+  [x]
+  (and
+    (coll? x)(contains? #{:SPACE :OPT-SPACE :COMMENT :OPT-KW-DATA} (first x))))
+
+
+(defn remove-recursive
+  "Return a collection like this `collection` from which items which are matched
+  by this `predicate` have been removed at all levels."
+  [predicate collection]
+  (map
+    #(if
+       (coll? %)
+       (remove-recursive predicate %)
+       %)
+    (remove predicate collection)))
+
+(defn flatten-statements
+  [parse-tree]
+  (if
+    (and (coll? parse-tree) (not (empty? parse-tree)))
+    (if
+      (= (first parse-tree) :STATEMENTS)
+      (cond
+        (>= (count parse-tree) 3)
+        (cons (nth parse-tree 1) (flatten-statements (nth parse-tree 2)))
+        (>= (count parse-tree) 2)
+        (list (nth parse-tree 1))
+        true
+        ())
+      parse-tree)
+    parse-tree))
+
+
+(defn simplify [parse-tree]
+  (flatten-statements
+    (remove-recursive ignorable? parse-tree)))
+
+