From 4c3f2deb53045f91efd9a758b6208e0dda85d8d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=8D=8Ddiohabara=E5=8D=8D?= <diohabara@gmail.com>
Date: Wed, 26 Jul 2023 09:15:36 -0500
Subject: [PATCH] feat: add ternary operator(?)

---
 ccc.h      |  1 +
 codegen.c  | 12 ++++++++++++
 parse.c    | 20 ++++++++++++++++++--
 tests      |  3 +++
 tokenize.c |  2 +-
 type.c     |  3 +++
 6 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/ccc.h b/ccc.h
index c1c480d..3bb3df9 100644
--- a/ccc.h
+++ b/ccc.h
@@ -122,6 +122,7 @@ typedef enum {
   ND_SHR,        // >>
   ND_A_SHL,      // <<=
   ND_A_SHR,      // >>=
+  ND_TERNARY,    // ? :
 } NodeKind;
 // AST node type
 typedef struct Node Node;
diff --git a/codegen.c b/codegen.c
index c30bb98..7c53aac 100644
--- a/codegen.c
+++ b/codegen.c
@@ -391,6 +391,18 @@ void gen(Node *node) {
       store(node->ty);
       inc(node);
       return;
+    case ND_TERNARY:
+      int seq = labelseq++;
+      gen(node->cond);
+      printf("  pop rax\n");
+      printf("  cmp rax, 0\n");
+      printf("  je .Lelse%d\n", seq);
+      gen(node->then);
+      printf("  jmp .Lend%d\n", seq);
+      printf(".Lelse%d:\n", seq);
+      gen(node->els);
+      printf(".Lend%d:\n", seq);
+      return;
     case ND_A_ADD:
     case ND_A_SUB:
     case ND_A_MUL:
diff --git a/parse.c b/parse.c
index a9dab99..8615360 100644
--- a/parse.c
+++ b/parse.c
@@ -161,6 +161,7 @@ bool is_typename();
 Node *stmt();
 Node *expr();
 Node *assign();
+Node *conditional();
 Node *bitand();
 Node * bitor ();
 Node *bitxor();
@@ -820,10 +821,10 @@ Node *expr() {
   }
   return node;
 }
-// assign = logor (assign-op assign)?
+// assign = conditional (assign-op assign)?
 // assign-op = "=" | "+=" | "-=" | "*=" | "/=" | "%=" | "<<=" | ">>="
 Node *assign() {
-  Node *node = logor();
+  Node *node = conditional();
   Token *tok;
   if (tok = consume("=")) {
     node = new_binary(ND_ASSIGN, node, assign(), tok);
@@ -852,6 +853,21 @@ Node *assign() {
   return node;
 }
 
+// conditional = logor ("?" expr ":" condtional)?
+Node *conditional() {
+  Node *node = logor();
+  Token *tok = consume("?");
+  while (!tok) {
+    return node;
+  }
+  Node *ternary = new_node(ND_TERNARY, tok);
+  ternary->cond = node;
+  ternary->then = expr();
+  expect(":");
+  ternary->els = conditional();
+  return ternary;
+}
+
 // logor = logand ("||" logand)*
 Node *logor() {
   Node *node = logand();
diff --git a/tests b/tests
index 049261d..83c7218 100644
--- a/tests
+++ b/tests
@@ -825,6 +825,9 @@ int main() {
   assert(-1, ({ int i=-1; i; }), "int i=-1; i;");
   assert(-1, ({ int i=-1; i>>=1; i; }), "int i=1; i>>1;");
 
+  assert(2, 0?1:2, "0?1:2");
+  assert(1, 1?1:2, "0?1:2");
+
   printf("OK\n");
   return 0;
 }
diff --git a/tokenize.c b/tokenize.c
index 862dab0..688c912 100644
--- a/tokenize.c
+++ b/tokenize.c
@@ -285,7 +285,7 @@ Token *tokenize() {
       continue;
     }
     // Single-letter punctuator
-    if (strchr("+-*/()<>;={},&[].,!~|^:", *p)) {
+    if (strchr("+-*/()<>;={},&[].,!~|^:?", *p)) {
       cur = new_token(TK_RESERVED, cur, p++, 1);
       continue;
     }
diff --git a/type.c b/type.c
index a2ad22e..ef75572 100644
--- a/type.c
+++ b/type.c
@@ -165,6 +165,9 @@ void visit(Node* node) {
     case ND_BITNOT:
       node->ty = node->lhs->ty;
       return;
+    case ND_TERNARY:
+      node->ty = node->then->ty;
+      return;
     case ND_COMMA:
       node->ty = node->lhs->ty;
       return;