Mono optimizations (start with string concat and space eating)

1 files changed, 72 insertions, 0 deletions

diff --git a/src/mono_opt.sml b/src/mono_opt.sml
new file mode 100644
index 00000000..2f98a9c7
--- /dev/null
+++ b/src/mono_opt.sml
@@ -0,0 +1,72 @@
+(* Copyright (c) 2008, Adam Chlipala
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * - The names of contributors may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *)
+
+structure MonoOpt :> MONO_OPT = struct
+
+open Mono
+structure U = MonoUtil
+
+fun typ t = t
+fun decl d = d
+
+fun exp e =
+    case e of
+        EPrim (Prim.String s) =>
+        let
+            val (_, chs) =
+                CharVector.foldl (fn (ch, (lastSpace, chs)) =>
+                                     let
+                                         val isSpace = Char.isSpace ch
+                                     in
+                                         if isSpace andalso lastSpace then
+                                             (true, chs)
+                                         else
+                                             (isSpace, ch :: chs)
+                                     end)
+                                 (false, []) s
+        in
+            EPrim (Prim.String (String.implode (rev chs)))
+        end
+                                       
+        
+      | EStrcat ((EPrim (Prim.String s1), loc), (EPrim (Prim.String s2), _)) =>
+        let
+            val s =
+                if size s1 > 0 andalso size s2 > 0
+                   andalso Char.isSpace (String.sub (s1, size s1 - 1))
+                   andalso Char.isSpace (String.sub (s2, 0)) then
+                    s1 ^ String.extract (s2, 1, NONE)
+                else
+                    s1 ^ s2
+        in
+            EPrim (Prim.String s)
+        end
+      | _ => e
+
+val optimize = U.File.map {typ = typ, exp = exp, decl = decl}
+
+end