1 files changed, 66 insertions, 2 deletions

diff --git a/src/fold.cff b/src/fold.cff
index acfd613..2e7cae3 100644
--- a/src/fold.cff
+++ b/src/fold.cff
@@ -106,8 +106,8 @@ fn fbinary(ex *Expr) void {
    if ty->is(:Bool) {
       ty = typeof2(l.ty, r.ty);
    }
-   numcast(l, ty);
-   numcast(r, ty);
+   if isnumtype(l.ty) { numcast(l, ty); }
+   if isnumtype(r.ty) { numcast(r, ty); }
 
    if op == '/' and ty->is(:Int) and ri.i == 0 { // div/0
       return;
@@ -124,12 +124,35 @@ fn fbinary(ex *Expr) void {
    case op == '/'  and ty->is(:Int); ei.i = li.i / ri.i;
    case op == '/'  and ty->is(:Flo); *ef  = *lf   / *rf;
    case op == '%'  and ty == ty_u64; ei.u = li.u % ri.u;
+   case op == '%'  and ty->is(:Int); ei.i = li.i % ri.i;
    case op == '&'  and ty->is(:Int); ei.i = li.i & ri.i;
    case op == '|'  and ty->is(:Int); ei.i = li.i | ri.i;
    case op == '^'  and ty->is(:Int); ei.i = li.i ^ ri.i;
    case op == '<<' and ty->is(:Int); ei.i = li.i << ri.i;
    case op == '>>' and ty->is(:Int) and !ty.u.Int.sgn; ei.u = li.u >> ri.u;
    case op == '>>' and ty->is(:Int); ei.i = li.i >> ri.i;
+   case op == '==' and ty->is(:Flo); *eb = *lf  == *rf;
+   case op == '==' and ty->is(:Int); *eb = li.i == ri.i;
+   case op == '!=' and ty->is(:Flo); *eb = *lf  != *rf;
+   case op == '!=' and ty->is(:Int); *eb = li.i != ri.i;
+   case op ==  '<' and ty->is(:Flo); *eb = *lf  <  *rf;
+   case op ==  '<' and ty == ty_u64; *eb = li.u <  ri.u;
+   case op ==  '<' and ty->is(:Int); *eb = li.i <  ri.i;
+   case op ==  '>' and ty->is(:Flo); *eb = *lf  >  *rf;
+   case op ==  '>' and ty == ty_u64; *eb = li.u >  ri.u;
+   case op ==  '>' and ty->is(:Int); *eb = li.i >  ri.i;
+   case op == '<=' and ty->is(:Flo); *eb = *lf  <= *rf;
+   case op == '<=' and ty == ty_u64; *eb = li.u <= ri.u;
+   case op == '<=' and ty->is(:Int); *eb = li.i <= ri.i;
+   case op == '>=' and ty->is(:Flo); *eb = *lf  >= *rf;
+   case op == '>=' and ty == ty_u64; *eb = li.u >= ri.u;
+   case op == '>=' and ty->is(:Int); *eb = li.i >= ri.i;
+   
+   case op == '+' and l.u.#tag == :StrLit and r.u.IntLit.u <= l.u.StrLit.#len;
+      assert(r.u.#tag == :IntLit, "str + ?");
+      ex.u = :StrLit(l.u.StrLit[r.u.IntLit.u::l.u.StrLit.#len]);
+      return;
+
    case else return;
    }
 
@@ -140,6 +163,38 @@ fn fbinary(ex *Expr) void {
    }
 }
 
+fn fcond(ex *Expr) void {
+   let test = ex.u.Cond.test,
+       t = ex.u.Cond.t,
+       f = ex.u.Cond.f;
+   let fo0 = fold(test);
+   if !fo0 {
+      return;
+   }
+   let ty = ex.ty;
+   *ex = test.u.BoolLit ? (do fold(t); *t;) : (do fold(f); *f;);
+   ex.ty = ty;
+}
+
+fn findex(ex *Expr) void {
+   let l = ex.u.Index.lhs,
+       r = ex.u.Index.rhs;
+   let fl = fold(l), fr = fold(r);
+   if !fl or !fr {
+      return;
+   }
+
+   if l.u.#tag == :StrLit {
+      if r.u.IntLit.u > l.u.StrLit.#len {
+         return;
+      }
+      ex.u = :IntLit{l.u.StrLit[r.u.IntLit.u]};
+   } else {
+      assert(#f,"bad");
+   }
+
+}
+
 extern fn fold(ex *Expr) bool {
    switch ex.u.#tag {
    case :IntLit, :FloLit, :BoolLit;
@@ -155,6 +210,12 @@ extern fn fold(ex *Expr) bool {
    case :BinOp;
       fbinary(ex);
 
+   case :Cond;
+      fcond(ex);
+
+   case :Index;
+      findex(ex);
+
    case else;
       return #f;
    }
@@ -164,6 +225,9 @@ extern fn fold(ex *Expr) bool {
       numcast(ex, ex.ty);
       return #t;
 
+   case :StrLit, :NullLit, :EnumIni;
+      return #t;
+
    case else;
       return #f;
    }