First try

Project-02-03-04/cfg_build.py

@@ -0,0 +1,134 @@
+from cfg.CFG_Node import (
+    CFG_Node,
+    CFG_CALL,
+    CFG_RETURN,
+    CFG_DIAMOND,
+)
+
+import compiler
+import syntax
+
+
+# -------------------------------------------------
+# Expressions — NO CFG NODES
+# -------------------------------------------------
+
+class CONST(compiler.CONST):
+    def cfa(self, pred, end):
+        return pred
+
+
+class ID(compiler.ID):
+    def cfa(self, pred, end):
+        return pred
+
+
+class AOP(compiler.AOP):
+    def cfa(self, pred, end):
+        return pred
+
+
+class COMP(compiler.COMP):
+    def cfa(self, pred, end):
+        return pred
+
+
+class EQOP(compiler.EQOP):
+    def cfa(self, pred, end):
+        return pred
+
+
+class LOP(compiler.LOP):
+    def cfa(self, pred, end):
+        return pred
+
+
+# -------------------------------------------------
+# Statements
+# -------------------------------------------------
+
+class ASSIGN(compiler.ASSIGN):
+    def cfa(self, pred, end):
+        n = CFG_Node(self)
+        pred.add_child(n)
+        return n
+
+
+class SEQ(compiler.SEQ):
+    def cfa(self, pred, end):
+        mid = self.exp1.cfa(pred, end)
+        if mid is None:
+            return None
+        return self.exp2.cfa(mid, end)
+
+
+class IF(compiler.IF):
+    def cfa(self, pred, end):
+        cond = CFG_DIAMOND(self)
+        pred.add_child(cond)
+
+        join = CFG_Node()
+
+        then_end = self.exp1.cfa(cond, end)
+        else_end = self.exp2.cfa(cond, end)
+
+        if then_end is not None:
+            then_end.add_child(join)
+        if else_end is not None:
+            else_end.add_child(join)
+
+        return join
+
+
+class WHILE(compiler.WHILE):
+    def cfa(self, pred, end):
+        cond = CFG_DIAMOND(self)
+        pred.add_child(cond)
+
+        body_end = self.body.cfa(cond, end)
+        if body_end is not None:
+            body_end.add_child(cond)
+
+        after = CFG_Node()
+        cond.add_child(after)
+
+        return after
+
+
+# -------------------------------------------------
+# Functions / calls
+# -------------------------------------------------
+
+class CALL(compiler.CALL):
+    def cfa(self, pred, end):
+        n = CFG_CALL(self)
+        pred.add_child(n)
+        return n
+
+
+class DECL(compiler.DECL):
+    def cfa(self, pred, end):
+        entry = CFG_Node(self)
+        pred.add_child(entry)
+        return self.body.cfa(entry, end)
+
+
+class LET(compiler.LET):
+    def cfa(self, pred, end):
+        current = pred
+
+        decls = self.decl if isinstance(self.decl, list) else [self.decl]
+        for d in decls:
+            current = d.cfa(current, end)
+            if current is None:
+                return None
+
+        return self.body.cfa(current, end)
+
+
+class RETURN(syntax.EXPRESSION):
+    def cfa(self, pred, end):
+        n = CFG_RETURN(self)
+        pred.add_child(n)
+        n.add_child(end)   # direct jump to global END
+        return None        # no fallthrough