added helper function for code equations in primcorec

--- a/src/HOL/BNF/BNF_FP_Base.thy	Thu Sep 19 01:15:26 2013 +0200
+++ b/src/HOL/BNF/BNF_FP_Base.thy	Thu Sep 19 02:30:45 2013 +0200
@@ -172,6 +172,15 @@
    (if b then f y else if b' then x' else f y')"
   by simp
 
+lemma if_then_else_True_False:
+  "(if p then False else r) \<longleftrightarrow> \<not> p \<and> r"
+  "(if p then True else r) \<longleftrightarrow> p \<or> r"
+  "(if p then q else False) \<longleftrightarrow> p \<and> q"
+  "(if p then q else True) \<longleftrightarrow> \<not> p \<or> q"
+by simp_all
+
+lemmas bool_if_simps = bool_simps(7,8,15-17,19,21-24,29-32) if_then_else_True_False
+
 ML_file "Tools/bnf_fp_util.ML"
 ML_file "Tools/bnf_fp_def_sugar_tactics.ML"
 ML_file "Tools/bnf_fp_def_sugar.ML"

--- a/src/HOL/BNF/Tools/bnf_fp_rec_sugar_util.ML	Thu Sep 19 01:15:26 2013 +0200
+++ b/src/HOL/BNF/Tools/bnf_fp_rec_sugar_util.ML	Thu Sep 19 02:30:45 2013 +0200
@@ -59,6 +59,7 @@
     (typ -> typ -> term -> term) -> typ list -> typ -> term -> term
   val expand_corec_code_rhs: Proof.context -> (term -> bool) -> typ list -> term -> term
   val massage_corec_code_rhs: Proof.context -> (term -> term list -> term) -> typ -> term -> term
+  val simplify_bool_ifs: theory -> term -> term list
   val rec_specs_of: binding list -> typ list -> typ list -> (term -> int list) ->
     ((term * term list list) list) list -> local_theory ->
     (bool * rec_spec list * typ list * thm * thm list) * local_theory
@@ -297,6 +298,15 @@
 fun massage_corec_code_rhs ctxt massage_ctr =
   massage_let_and_if ctxt (K false) (uncurry massage_ctr o Term.strip_comb);
 
+fun add_conjuncts (Const (@{const_name conj}, _) $ t $ t') = add_conjuncts t o add_conjuncts t'
+  | add_conjuncts t = cons t;
+
+fun conjuncts t = add_conjuncts t [];
+
+fun simplify_bool_ifs thy =
+  Raw_Simplifier.rewrite_term thy @{thms bool_if_simps[THEN eq_reflection]} []
+  #> conjuncts #> (fn [@{term True}] => [] | ts => ts);
+
 fun indexed xs h = let val h' = h + length xs in (h upto h' - 1, h') end;
 fun indexedd xss = fold_map indexed xss;
 fun indexeddd xsss = fold_map indexedd xsss;