Renaming sp_pcontext members and methods; less cryptic and more consistent.

Also added comments, and fixing some coding style (mostly in comments too).
There are no functional changes, so no tests or documentation needed.
(This was originally part of a bugfix, but it was decided to not include this
 in that patch; instead it's done separately.)


sql/sp_head.cc:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.
sql/sp_head.h:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.
sql/sp_pcontext.cc:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.
  Also added comments, and fixing some coding style (mostly in comments too).
sql/sp_pcontext.h:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.
  Also added comments, and fixing some coding style (mostly in comments too).
sql/sp_rcontext.cc:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.
sql/sp_rcontext.h:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.
sql/sql_yacc.yy:
  Renaming sp_pcontext members and methods; less cryptic and more consistent.

1 files changed, 78 insertions, 52 deletions

diff --git a/sql/sp_pcontext.h b/sql/sp_pcontext.h
index 872c7c1d505..e61057537da 100644
--- a/sql/sp_pcontext.h
+++ b/sql/sp_pcontext.h
@@ -29,22 +29,23 @@ typedef enum
   sp_param_inout
 } sp_param_mode_t;
 
-typedef struct sp_pvar
+typedef struct sp_variable
 {
   LEX_STRING name;
   enum enum_field_types type;
   sp_param_mode_t mode;
   
   /*
-    offset -- basically, this is an index of variable in the scope of root
-    parsing context. This means, that all variables in a stored routine
-    have distinct indexes/offsets.
+    offset -- this the index to the variable's value in the runtime frame.
+    This is calculated during parsing and used when creating sp_instr_set
+    instructions and Item_splocal items.
+    I.e. values are set/referred by array indexing in runtime.
   */
   uint offset;
 
   Item *dflt;
   create_field field_def;
-} sp_pvar_t;
+} sp_variable_t;
 
 
 #define SP_LAB_REF   0		// Unresolved reference (for goto)
@@ -76,9 +77,10 @@ typedef struct sp_cond_type
   uint mysqlerr;
 } sp_cond_type_t;
 
-/* Sanity check for SQLSTATEs. Will not check if it's really an existing
- * state (there are just too many), but will check length bad characters.
- */
+/*
+  Sanity check for SQLSTATEs. Will not check if it's really an existing
+  state (there are just too many), but will check length bad characters.
+*/
 extern bool
 sp_cond_check(LEX_STRING *sqlstate);
 
@@ -90,7 +92,17 @@ typedef struct sp_cond
 
 
 /*
-  This seems to be an "SP parsing context" or something.
+  The parse-time context, used to keep track on declared variables/parameters,
+  conditions, handlers, cursors and labels, during parsing.
+  sp_contexts are organized as a tree, with one object for each begin-end
+  block, plus a root-context for the parameters.
+  This is used during parsing for looking up defined names (e.g. declared
+  variables and visible labels), for error checking, and to calculate offsets
+  to be used at runtime. (During execution variable values, active handlers
+  and cursors, etc, are referred to by an index in a stack.)
+  The pcontext tree is also kept during execution and is used for error
+  checking (e.g. correct number of parameters), and in the future, used by
+  the debugger.
 */
 
 class sp_pcontext : public Sql_alloc
@@ -134,50 +146,64 @@ class sp_pcontext : public Sql_alloc
   // Parameters and variables
   //
 
+  /*
+    The maximum number of variables used in this and all child contexts
+    In the root, this gives us the number of slots needed for variables
+    during execution.
+  */
   inline uint
-  total_pvars()
+  max_var_index()
   {
-    return m_total_pvars;
+    return m_max_var_index;
   }
 
+  /*
+    The current number of variables used in the parents (from the root),
+    including this context.
+  */
   inline uint
-  current_pvars()
+  current_var_count()
   {
-    return m_poffset + m_pvar.elements;
+    return m_var_offset + m_vars.elements;
   }
 
+  /* The number of variables in this context alone */
   inline uint
-  context_pvars()
+  context_var_count()
   {
-    return m_pvar.elements;
+    return m_vars.elements;
   }
 
+  /* Map index in this pcontext to runtime offset */
   inline uint
-  pvar_context2index(uint i)
+  var_context2runtime(uint i)
   {
-    return m_poffset + i;
+    return m_var_offset + i;
   }
 
+  /* Set type of variable. 'i' is the offset from the top */
   inline void
   set_type(uint i, enum enum_field_types type)
   {
-    sp_pvar_t *p= find_pvar(i);
+    sp_variable_t *p= find_variable(i);
 
     if (p)
       p->type= type;
   }
 
+  /* Set default value of variable. 'i' is the offset from the top */
   inline void
   set_default(uint i, Item *it)
   {
-    sp_pvar_t *p= find_pvar(i);
+    sp_variable_t *p= find_variable(i);
 
     if (p)
       p->dflt= it;
   }
 
-  sp_pvar_t *
-  push_pvar(LEX_STRING *name, enum enum_field_types type, sp_param_mode_t mode);
+  sp_variable_t *
+  push_variable(LEX_STRING *name, enum enum_field_types type,
+                sp_param_mode_t mode);
 
   /*
     Retrieve definitions of fields from the current context and its
@@ -187,12 +213,12 @@ class sp_pcontext : public Sql_alloc
   retrieve_field_definitions(List<create_field> *field_def_lst);
 
   // Find by name
-  sp_pvar_t *
-  find_pvar(LEX_STRING *name, my_bool scoped=0);
+  sp_variable_t *
+  find_variable(LEX_STRING *name, my_bool scoped=0);
 
-  // Find by offset
-  sp_pvar_t *
-  find_pvar(uint offset);
+  // Find by offset (from the top)
+  sp_variable_t *
+  find_variable(uint offset);
 
   /*
     Set the current scope boundary (for default values).
@@ -280,7 +306,7 @@ class sp_pcontext : public Sql_alloc
   pop_cond(uint num)
   {
     while (num--)
-      pop_dynamic(&m_cond);
+      pop_dynamic(&m_conds);
   }
 
   sp_cond_type_t *
@@ -293,22 +319,22 @@ class sp_pcontext : public Sql_alloc
   inline void
   push_handler(sp_cond_type_t *cond)
   {
-    insert_dynamic(&m_handler, (gptr)&cond);
+    insert_dynamic(&m_handlers, (gptr)&cond);
   }
 
   bool
   find_handler(sp_cond_type *cond);
 
   inline uint
-  max_handlers()
+  max_handler_index()
   {
-    return m_hsubsize + m_handlers;
+    return m_max_handler_index + m_context_handlers;
   }
 
   inline void
   add_handlers(uint n)
   {
-    m_handlers+= n;
+    m_context_handlers+= n;
   }
 
   //
@@ -326,51 +352,51 @@ class sp_pcontext : public Sql_alloc
   find_cursor(uint offset, LEX_STRING *n);
 
   inline uint
-  max_cursors()
+  max_cursor_index()
   {
-    return m_csubsize + m_cursor.elements;
+    return m_max_cursor_index + m_cursors.elements;
   }
 
   inline uint
-  current_cursors()
+  current_cursor_count()
   {
-    return m_coffset + m_cursor.elements;
+    return m_cursor_offset + m_cursors.elements;
   }
 
 protected:
 
   /*
-    m_total_pvars -- number of variables (including all types of arguments)
+    m_max_var_index -- number of variables (including all types of arguments)
     in this context including all children contexts.
     
-    m_total_pvars >= m_pvar.elements.
+    m_max_var_index >= m_vars.elements.
 
-    m_total_pvars of the root parsing context contains number of all
+    m_max_var_index of the root parsing context contains number of all
     variables (including arguments) in all enclosed contexts.
   */
-  uint m_total_pvars;		
+  uint m_max_var_index;		
 
   // The maximum sub context's framesizes
-  uint m_csubsize;
-  uint m_hsubsize;
-  uint m_handlers;		// No. of handlers in this context
+  uint m_max_cursor_index;
+  uint m_max_handler_index;
+  uint m_context_handlers;      // No. of handlers in this context
 
 private:
 
   sp_pcontext *m_parent;	// Parent context
 
   /*
-    m_poffset -- basically, this is an index of the first variable in this
-    parsing context.
+    m_var_offset -- this is an index of the first variable in this
+                    parsing context.
     
-    m_poffset is 0 for root context.
+    m_var_offset is 0 for root context.
 
     Since now each variable is stored in separate place, no reuse is done,
-    so m_poffset is different for all enclosed contexts.
+    so m_var_offset is different for all enclosed contexts.
   */
-  uint m_poffset;
+  uint m_var_offset;
 
-  uint m_coffset;		// Cursor offset for this context
+  uint m_cursor_offset;		// Cursor offset for this context
 
   /*
     Boundary for finding variables in this context. This is the number
@@ -382,11 +408,11 @@ private:
 
   int m_num_case_exprs;
 
-  DYNAMIC_ARRAY m_pvar;		// Parameters/variables
+  DYNAMIC_ARRAY m_vars;		// Parameters/variables
   DYNAMIC_ARRAY m_case_expr_id_lst; /* Stack of CASE expression ids. */
-  DYNAMIC_ARRAY m_cond;		// Conditions
-  DYNAMIC_ARRAY m_cursor;	// Cursors
-  DYNAMIC_ARRAY m_handler;	// Handlers, for checking of duplicates
+  DYNAMIC_ARRAY m_conds;        // Conditions
+  DYNAMIC_ARRAY m_cursors;	// Cursors
+  DYNAMIC_ARRAY m_handlers;	// Handlers, for checking for duplicates
 
   List<sp_label_t> m_label;	// The label list