From 3ee68d906e87052ff5e11a3ef50ea184baaeb28e Mon Sep 17 00:00:00 2001
From: tyfkda <tyfkda@gmail.com>
Date: Sat, 14 Oct 2023 08:52:49 +0900
Subject: [PATCH] Expand macro argument non destructive

---
 src/cpp/macro.c  | 25 +++++++++++++++++++++----
 tests/cpptest.sh |  2 ++
 tool/pp.js       | 18 ++++++++++++++++--
 3 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/src/cpp/macro.c b/src/cpp/macro.c
index 2fc67392d..1cb18c5d5 100644
--- a/src/cpp/macro.c
+++ b/src/cpp/macro.c
@@ -1,6 +1,7 @@
 #include "../config.h"
 #include "macro.h"
 
+#include <alloca.h>
 #include <assert.h>
 #include <limits.h>  // INT_MAX
 #include <stdlib.h>  // malloc
@@ -192,6 +193,15 @@ static Vector *subst(Macro *macro, Table *param_table, Vector *args, HideSet *hs
   if (body == NULL)
     return os;
 
+  Vector **expanded_args = NULL;
+  if (args != NULL && args->len > 0) {
+    expanded_args = alloca(sizeof(*expanded_args) * args->len);
+    if (expanded_args == NULL)
+      error("alloca failed");
+    for (int i = 0; i < args->len; ++i)
+      expanded_args[i] = NULL;
+  }
+
   for (int i = 0; i < body->len; ++i) {
     const Token *tok = body->data[i];
 
@@ -261,10 +271,17 @@ static Vector *subst(Macro *macro, Table *param_table, Vector *args, HideSet *hs
         intptr_t j;
         if (table_try_get(param_table, tok->ident, (void*)&j)) {
           assert(j < args->len);
-          Vector *arg = args->data[j];
-          macro_expand(arg);
-          for (int k = 0; k < arg->len; ++k) {
-            const Token *t = arg->data[k];
+          Vector *expanded = expanded_args[j];
+          if (expanded == NULL) {
+            Vector *arg = args->data[j];
+            expanded = new_vector();
+            for (int i = 0; i < arg->len; ++i)
+              vec_push(expanded, arg->data[i]);
+            macro_expand(expanded);
+            expanded_args[j] = expanded;
+          }
+          for (int k = 0; k < expanded->len; ++k) {
+            const Token *t = expanded->data[k];
             vec_push(os, t);
           }
           continue;
diff --git a/tests/cpptest.sh b/tests/cpptest.sh
index 63b3b3eee..ae9ff0c79 100755
--- a/tests/cpptest.sh
+++ b/tests/cpptest.sh
@@ -144,6 +144,8 @@ test_macro() {
 
   try '#if in macro arguments' '{bar}' "#define FOO(x)  {x}\nFOO(\n#if 1\nbar\n#else\nqux\n#endif\n)"
 
+  try 'expand and stringify' 'a(m_z, "M(z)")' "#define MinM(x) a(x, # x)\n#define M(x) m_ ## x\nMinM(M(z))"
+
   try ', ## empty' 'foo(fmt)'          "#define FOO(fmt, ...)  foo(fmt, ## __VA_ARGS__)\nFOO(fmt)"
   try ', ## some'  'foo(fmt,1, 2, 3)'  "#define FOO(fmt, ...)  foo(fmt, ## __VA_ARGS__)\nFOO(fmt, 1, 2, 3)"
 
diff --git a/tool/pp.js b/tool/pp.js
index 76bf977e5..dc2f13446 100755
--- a/tool/pp.js
+++ b/tool/pp.js
@@ -125,6 +125,7 @@ class MacroExpander {
   }
 
   subst(is, fp, ap, hs) {
+    const expandedAp = ap.map(_ => null)
     const os = []
     for (let i = 0; i < is.length; ++i) {
       const tt = is[i]
@@ -175,7 +176,11 @@ class MacroExpander {
 
         const j = fp.indexOf(tt.t)
         if (j >= 0) {
-          os.push(...this.expand(ap[j]))
+          let expanded = expandedAp[j]
+          if (expanded == null) {
+            expanded = expandedAp[j] = this.expand([...ap[j]])
+          }
+          os.push(...expanded)
           continue
         }
       }
@@ -212,7 +217,8 @@ class MacroExpander {
   }
 
   stringize(x) {
-    const s = `"${x}"`  // TODO: Escape
+    const actual = x.map((t) => t.t.toString()).join('')
+    const s = `"${actual}"`  // TODO: Escape
     return new Token(TK_OTHER, s)
   }
 
@@ -415,6 +421,14 @@ function main() {
         'STR': new Macro(['x'], '# x'),
       })
 
+  pptest(
+      'a(m_z, "M(z)")',
+      'MinM(M(z))',
+      {
+        'MinM': new Macro(['x'], 'a(x, # x)'),
+        'M': new Macro(['x'], 'm_ ## x'),
+      })
+
   process.exit(errorCount === 0 ? 0 : 1)
 }