From fc80ace6e4b27386ff961fe900556bf44c606e46 Mon Sep 17 00:00:00 2001
From: Geza Lore <gezalore@gmail.com>
Date: Sat, 16 Oct 2021 19:18:06 +0100
Subject: [PATCH] Reduce size of astgen generated implementation boilerplate.

Rely on C++ templates instead for simplicity. No functional change.
---
 src/V3Ast.h | 24 +++++++++++++++---------
 src/astgen  | 49 ++++++++++---------------------------------------
 2 files changed, 25 insertions(+), 48 deletions(-)

diff --git a/src/V3Ast.h b/src/V3Ast.h
index 56e93bb4d..9d7abd681 100644
--- a/src/V3Ast.h
+++ b/src/V3Ast.h
@@ -1838,16 +1838,22 @@ protected:
 private:
     void iterateListBackwards(AstNVisitor& v);
 
-    // CONVERSION
+    // For internal use only.
+    template <typename T> inline static bool privateTypeTest(const AstNode* nodep);
+
 public:
-    // These for use by VN_IS macro only
-    template <class T> static bool privateIs(const AstNode* nodep);
-
-    // These for use by VN_CAST macro only
-    template <class T> static T* privateCast(AstNode* nodep);
-
-    // These for use by VN_CAST_CONST macro only
-    template <class T> static const T* privateConstCast(const AstNode* nodep);
+    // For use via the VN_IS macro only
+    template <typename T> inline static bool privateIs(const AstNode* nodep) {
+        return nodep && privateTypeTest<T>(nodep);
+    }
+    // For use via the VN_CAST macro only
+    template <typename T> inline static T* privateCast(AstNode* nodep) {
+        return privateIs<T>(nodep) ? reinterpret_cast<T*>(nodep) : nullptr;
+    }
+    // For use via the VN_CAST_CONST macro only
+    template <typename T> inline static const T* privateConstCast(const AstNode* nodep) {
+        return privateIs<T>(nodep) ? reinterpret_cast<const T*>(nodep) : nullptr;
+    }
 };
 
 // Specialisations of privateIs/privateCast
diff --git a/src/astgen b/src/astgen
index a2cf43088..6328e4adc 100755
--- a/src/astgen
+++ b/src/astgen
@@ -516,52 +516,23 @@ def write_visitor(filename):
 def write_impl(filename):
     with open_file(filename) as fh:
         fh.write("\n")
-        fh.write("    // These for use by VN_IS only\n")
+        fh.write("// For internal use. They assume argument is not nullptr.\n")
         for typen in sorted(Classes.keys()):
-            fh.write("template<> inline bool AstNode::privateIs<Ast" + typen +
-                     ">(const AstNode* nodep) { ")
+            fh.write("template<> inline bool AstNode::privateTypeTest<Ast" +
+                     typen + ">(const AstNode* nodep) { ")
             if typen == "Node":
-                fh.write("return nodep != NULL; ")
+                fh.write("return true; ")
             else:
-                fh.write("return nodep && ")
+                fh.write("return ")
                 if re.search(r'^Node', typen):
                     fh.write(
-                        "(static_cast<int>(nodep->type()) >= static_cast<int>(AstType::first"
-                        + typen + ")) && ")
+                        "static_cast<int>(nodep->type()) >= static_cast<int>(AstType::first"
+                        + typen + ") && ")
                     fh.write(
-                        "(static_cast<int>(nodep->type()) <= static_cast<int>(AstType::last"
-                        + typen + ")); ")
+                        "static_cast<int>(nodep->type()) <= static_cast<int>(AstType::last"
+                        + typen + "); ")
                 else:
-                    fh.write(
-                        "(static_cast<int>(nodep->type()) == static_cast<int>(AstType::at"
-                        + typen + ")); ")
-            fh.write("}\n")
-
-        fh.write("    // These for use by VN_CAST macro only\n")
-        for typen in sorted(Classes.keys()):
-            fh.write("template<> inline Ast" + typen +
-                     "* AstNode::privateCast<Ast" + typen +
-                     ">(AstNode* nodep) { ")
-            if typen == "Node":
-                fh.write("return nodep; ")
-            else:
-                fh.write("return AstNode::privateIs<Ast" + typen +
-                         ">(nodep) ? ")
-                fh.write("reinterpret_cast<Ast" + typen + "*>(nodep) : NULL; ")
-            fh.write("}\n")
-
-        fh.write("    // These for use by VN_CAST_CONST macro only\n")
-        for typen in sorted(Classes.keys()):
-            fh.write("template<> inline const Ast" + typen +
-                     "* AstNode::privateConstCast<Ast" + typen +
-                     ">(const AstNode* nodep) { ")
-            if typen == "Node":
-                fh.write("return nodep; ")
-            else:
-                fh.write("return AstNode::privateIs<Ast" + typen +
-                         ">(nodep) ? ")
-                fh.write("reinterpret_cast<const Ast" + typen +
-                         "*>(nodep) : NULL; ")
+                    fh.write("nodep->type() == AstType::at" + typen + "; ")
             fh.write("}\n")