change to C interpreters, introducing tail

Author: jsiek

interp_Cfun.py

@@ -32,13 +32,13 @@ def interp_exp(self, e, env):
       case _:
         return super().interp_exp(e, env)
 
-  def interp_stmt(self, s, env, cont):
+  def interp_tail(self, s, env):
     match s:
       case TailCall(func, args):
         return self.interp_exp(Call(func, args), env)
       case _:
-        return super().interp_stmt(s, env, cont)
-    
+        return super().interp_tail(s, env)
+      
   def interp(self, p):
     match p:
       case CProgramDefs(defs):

interp_Cif.py

@@ -4,19 +4,32 @@
 
 class InterpCif(InterpLif):
 
-  def interp_stmt(self, s, env, cont):
-    match s:
-      case Return(value):
-        return self.interp_exp(value, env)
-      case Goto(label):
-        return self.interp_stmts(self.blocks[label], env)
-      case _:
-        return super().interp_stmt(s, env, cont)
-    
   def interp(self, p):
     match p:
       case CProgram(blocks):
         env = {}
         self.blocks = blocks
         self.interp_stmts(blocks[label_name('start')], env)
-    
+
+  def interp_stmts(self, ss, env):
+    match ss:
+      case [t]:
+        return self.interp_tail(t, env)
+      case [s, *ss]:
+        self.interp_stmt(s, env, [])
+        return self.interp_stmts(ss, env)
+
+  def interp_tail(self, s, env):
+    match s:
+      case Return(value):
+        return self.interp_exp(value, env)
+      case Goto(label):
+        return self.interp_stmts(self.blocks[label], env)
+      case If(test, [Goto(thn)], [Goto(els)]):
+        match self.interp_exp(test, env):
+          case True:
+            return self.interp_stmts(self.blocks[thn], env)
+          case False:
+            return self.interp_stmts(self.blocks[els], env)
+      case _:
+        return super().interp_tail(s, env)

interp_Lfun.py

@@ -56,7 +56,6 @@ def interp(self, p):
       case Module(ss):
         env = {}
         self.interp_stmts(ss, env)
-        #trace('interp global env: ' + repr(env))
         if 'main' in env.keys():
             self.apply_fun(env['main'], [], None)
       case _:

interp_Lint.py

@@ -67,10 +67,11 @@ def interp_stmt(self, s, env, cont):
         raise Exception('error in interp_stmt, unexpected ' + repr(s))
 
   def interp_stmts(self, ss, env):
-    if len(ss) == 0:
-      return None
-    else:
-      return self.interp_stmt(ss[0], env, ss[1:])
+    match ss:
+      case []:
+        return 0
+      case [s, *ss]:
+        return self.interp_stmt(s, env, ss)
 
   def interp(self, p):
     match p: