From 58d3dda33f46348b3df51af8b3c04115d340e2b6 Mon Sep 17 00:00:00 2001
From: "pem@mysql.com" <>
Date: Tue, 17 Dec 2002 10:01:52 +0100
Subject: [PATCH] Added parsing of CASE (both generic and "simple").

---
 sql/sp_head.cc     |  1 +
 sql/sp_head.h      |  2 ++
 sql/sp_pcontext.cc | 14 --------
 sql/sp_pcontext.h  |  5 +--
 sql/sql_yacc.yy    | 84 +++++++++++++++++++++++++++++++++++++++++-----
 5 files changed, 80 insertions(+), 26 deletions(-)

diff --git a/sql/sp_head.cc b/sql/sp_head.cc
index 226701bafe4..c61256e5edb 100644
--- a/sql/sp_head.cc
+++ b/sql/sp_head.cc
@@ -84,6 +84,7 @@ eval_func_item(THD *thd, Item *it, enum enum_field_types type)
 }
 
 sp_head::sp_head(LEX_STRING *name, LEX *lex)
+  : m_simple_case(FALSE)
 {
   const char *dstr = (const char*)lex->buf;
 
diff --git a/sql/sp_head.h b/sql/sp_head.h
index 097eb6718e6..f6d06b61f43 100644
--- a/sql/sp_head.h
+++ b/sql/sp_head.h
@@ -35,6 +35,8 @@ class sp_head : public Sql_alloc
 
 public:
 
+  my_bool m_simple_case;	// TRUE if parsing simple case, FALSE otherwise
+
   static void *operator new(size_t size)
   {
     return (void*) sql_alloc((uint) size);
diff --git a/sql/sp_pcontext.cc b/sql/sp_pcontext.cc
index 96296e54184..407151c3e38 100644
--- a/sql/sp_pcontext.cc
+++ b/sql/sp_pcontext.cc
@@ -106,20 +106,6 @@ sp_pcontext::push_label(char *name, uint ip)
   return lab;
 }
 
-sp_label_t *
-sp_pcontext::push_gen_label(uint ip)
-{
-  sp_label_t *lab= NULL;
-  char *s= my_malloc(10, MYF(MY_WME)); // 10=...
-
-  if (s)
-  {
-    sprintf(s, ".%08x", m_genlab++); // ...9+1
-    lab= push_label(s, ip);
-  }
-  return lab;
-}
-
 sp_label_t *
 sp_pcontext::find_label(char *name)
 {
diff --git a/sql/sp_pcontext.h b/sql/sp_pcontext.h
index 2eb59172365..6ab38e77017 100644
--- a/sql/sp_pcontext.h
+++ b/sql/sp_pcontext.h
@@ -99,7 +99,7 @@ class sp_pcontext : public Sql_alloc
   inline void
   pop(uint num = 1)
   {
-    if (num >= m_i)
+    if (num < m_i)
       m_i -= num;
   }
 
@@ -119,9 +119,6 @@ class sp_pcontext : public Sql_alloc
   sp_label_t *
   push_label(char *name, uint ip);
 
-  sp_label_t *
-  push_gen_label(uint ip);
-
   sp_label_t *
   find_label(char *name);
 
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 3d562dcfdbe..dff59520149 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -1030,7 +1030,6 @@ sp_decl_idents:
 	  }
 	;
 
-/* Dummy for the spset thing. Will go away when the SET problem is fixed. */
 sp_proc_stmt:
 	  {
 	    Lex->sphead->reset_lex(YYTHD);
@@ -1045,13 +1044,39 @@ sp_proc_stmt:
 	    lex->sphead->restore_lex(YYTHD);
           }
 	| IF sp_if END IF {}
-/*	| sp_case */
+	| CASE_SYM WHEN_SYM
+	  {
+	    Lex->sphead->m_simple_case= FALSE;
+	  }
+	  sp_case END CASE_SYM {}
+	| CASE_SYM expr WHEN_SYM
+	  {
+	    /* We "fake" this by using an anonymous variable which we
+	       set to the expression. Note that all WHENs are evaluate
+	       at the same frame level, so we then know that it's the
+	       top-most variable in the frame. */
+	    LEX *lex= Lex;
+	    uint offset= lex->spcont->current_framesize();
+	    sp_instr_set *i = new sp_instr_set(lex->sphead->instructions(),
+	                                       offset, $2, MYSQL_TYPE_STRING);
+	    LEX_STRING dummy;
+
+	    dummy.str= (char *)"";
+	    dummy.length= 0;
+	    lex->spcont->push(&dummy, MYSQL_TYPE_STRING, sp_param_in);
+	    lex->sphead->add_instr(i);
+	    lex->sphead->m_simple_case= TRUE;
+	  }
+	  sp_case END CASE_SYM
+	  {
+	    Lex->spcont->pop();
+	  }
 	| sp_labeled_control
 	  {}
 	| { /* Unlabeled controls get a secret label. */
 	    LEX *lex= Lex;
 
-	    lex->spcont->push_gen_label(lex->sphead->instructions());
+	    lex->spcont->push_label((char *)"", lex->sphead->instructions());
 	  }
 	  sp_unlabeled_control
 	  {
@@ -1127,7 +1152,7 @@ sp_if:
 	    uint ip= sp->instructions();
 	    sp_instr_jump_if_not *i = new sp_instr_jump_if_not(ip, $1);
 
-	    sp->push_backpatch(i, ctx->push_gen_label(0));  /* Forward only */
+	    sp->push_backpatch(i, ctx->push_label((char *)"", 0));
             sp->add_instr(i);
 	  }
 	  sp_proc_stmts
@@ -1139,15 +1164,13 @@ sp_if:
 
 	    sp->add_instr(i);
 	    sp->backpatch(ctx->pop_label());
-	    sp->push_backpatch(i, ctx->push_gen_label(0));  /* Forward only */
+	    sp->push_backpatch(i, ctx->push_label((char *)"", 0));
 	  }
 	  sp_elseifs
 	  {
 	    LEX *lex= Lex;
-	    sp_head *sp= lex->sphead;
-	    sp_pcontext *ctx= lex->spcont;
 
-	    sp->backpatch(ctx->pop_label());
+	    lex->sphead->backpatch(lex->spcont->pop_label());
 	  }
 	;
 
@@ -1157,6 +1180,51 @@ sp_elseifs:
 	| ELSE sp_proc_stmts
 	;
 
+sp_case:
+	  expr THEN_SYM
+	  {
+	    sp_head *sp= Lex->sphead;
+	    sp_pcontext *ctx= Lex->spcont;
+	    uint ip= sp->instructions();
+	    sp_instr_jump_if_not *i;
+
+	    if (! sp->m_simple_case)
+	      i= new sp_instr_jump_if_not(ip, $1);
+	    else
+	    { /* Simple case: <caseval> = <whenval> */
+	      Item *var= (Item*) new Item_splocal(ctx->current_framesize()-1);
+	      Item *expr= Item_bool_func2::eq_creator(var, $1);
+
+	      i= new sp_instr_jump_if_not(ip, expr);
+	    }
+	    sp->push_backpatch(i, ctx->push_label((char *)"", 0));
+            sp->add_instr(i);
+	  }
+	  sp_proc_stmts
+	  {
+	    sp_head *sp= Lex->sphead;
+	    sp_pcontext *ctx= Lex->spcont;
+	    uint ip= sp->instructions();
+	    sp_instr_jump *i = new sp_instr_jump(ip);
+
+	    sp->add_instr(i);
+	    sp->backpatch(ctx->pop_label());
+	    sp->push_backpatch(i, ctx->push_label((char *)"", 0));
+	  }
+	  sp_whens
+	  {
+	    LEX *lex= Lex;
+
+	    lex->sphead->backpatch(lex->spcont->pop_label());
+	  }
+	;
+
+sp_whens:
+	  /* Empty */
+	| WHEN_SYM sp_case
+	| ELSE sp_proc_stmts
+	;
+
 sp_labeled_control:
 	  IDENT ':'
 	  {