From 78f9635111ec647719bb1b1622b1cb6f47ef1be1 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Mon, 26 Jul 2010 12:53:23 -0300
Subject: several new comments
---
lobject.h | 70 +++++++++++++++++++++++++++++++++++++++------------------------
1 file changed, 43 insertions(+), 27 deletions(-)
(limited to 'lobject.h')
diff --git a/lobject.h b/lobject.h
index 54d77960..a23cc560 100644
--- a/lobject.h
+++ b/lobject.h
@@ -1,5 +1,5 @@
/*
-** $Id: lobject.h,v 2.40 2010/05/07 18:44:46 roberto Exp roberto $
+** $Id: lobject.h,v 2.41 2010/06/04 13:25:10 roberto Exp roberto $
** Type definitions for Lua objects
** See Copyright Notice in lua.h
*/
@@ -56,17 +56,18 @@ typedef struct GCheader {
** Union of all Lua values
*/
typedef union {
- GCObject *gc;
- void *p;
- lua_Number n;
- int b;
- lua_CFunction f;
+ GCObject *gc; /* collectable objects */
+ void *p; /* light userdata */
+ lua_Number n; /* numbers */
+ int b; /* booleans */
+ lua_CFunction f; /* light C functions */
} Value;
/*
-** Tagged Values
+** Tagged Values. This is the basic representation of values in Lua,
+** an actual value plus a tag with its type.
*/
#define TValuefields Value value_; int tt_
@@ -76,7 +77,7 @@ typedef struct lua_TValue {
} TValue;
-/* macro defining a nil value to be used in definitions */
+/* macro defining a nil value */
#define NILCONSTANT {NULL}, LUA_TNIL
@@ -125,6 +126,8 @@ typedef struct lua_TValue {
#define iscollectable(o) (ttype(o) >= LUA_TSTRING)
+
+/* Macros for internal tests */
#define righttt(obj) (ttype(obj) == gcvalue(obj)->gch.tt)
#define checkconsistency(obj) lua_assert(!iscollectable(obj) || righttt(obj))
@@ -191,7 +194,7 @@ typedef struct lua_TValue {
/*
-** different types of sets, according to destination
+** different types of assignments, according to destination
*/
/* from stack to (same) stack */
@@ -215,7 +218,7 @@ typedef TValue *StkId; /* index to stack elements */
/*
-** String headers for string table
+** Header for string value; string bytes follow the end of this structure
*/
typedef union TString {
L_Umaxalign dummy; /* ensures maximum alignment for strings */
@@ -228,11 +231,16 @@ typedef union TString {
} TString;
+/* get the actual string (array of bytes) from a TString */
#define getstr(ts) cast(const char *, (ts) + 1)
-#define svalue(o) getstr(rawtsvalue(o))
+/* get the actual string (array of bytes) from a Lua value */
+#define svalue(o) getstr(rawtsvalue(o))
+/*
+** Header for userdata; memory area follows the end of this structure
+*/
typedef union Udata {
L_Umaxalign dummy; /* ensures maximum alignment for `local' udata */
struct {
@@ -246,15 +254,26 @@ typedef union Udata {
/*
-** Upvalues from a function prototype
+** Description of an upvalue for function prototypes
*/
typedef struct Upvaldesc {
TString *name; /* upvalue name (for debug information) */
- lu_byte instack;
+ lu_byte instack; /* whether it is in stack */
lu_byte idx; /* index of upvalue (in stack or in outer function's list) */
} Upvaldesc;
+/*
+** Description of a local variable for function prototypes
+** (used for debug information)
+*/
+typedef struct LocVar {
+ TString *varname;
+ int startpc; /* first point where variable is active */
+ int endpc; /* first point where variable is dead */
+} LocVar;
+
+
/*
** Function Prototypes
*/
@@ -264,7 +283,7 @@ typedef struct Proto {
Instruction *code;
struct Proto **p; /* functions defined inside the function */
int *lineinfo; /* map from opcodes to source lines */
- struct LocVar *locvars; /* information about local variables */
+ LocVar *locvars; /* information about local variables */
Upvaldesc *upvalues; /* upvalue information */
union Closure *cache; /* last created closure with this prototype */
TString *source;
@@ -277,24 +296,16 @@ typedef struct Proto {
int linedefined;
int lastlinedefined;
GCObject *gclist;
- lu_byte numparams;
+ lu_byte numparams; /* number of fixed parameters */
lu_byte is_vararg;
- lu_byte maxstacksize;
+ lu_byte maxstacksize; /* maximum stack used by this function */
} Proto;
-typedef struct LocVar {
- TString *varname;
- int startpc; /* first point where variable is active */
- int endpc; /* first point where variable is dead */
-} LocVar;
-
-
/*
-** Upvalues
+** Lua Upvalues
*/
-
typedef struct UpVal {
CommonHeader;
TValue *v; /* points to stack or to its own value */
@@ -318,14 +329,14 @@ typedef struct UpVal {
typedef struct CClosure {
ClosureHeader;
lua_CFunction f;
- TValue upvalue[1];
+ TValue upvalue[1]; /* list of upvalues */
} CClosure;
typedef struct LClosure {
ClosureHeader;
struct Proto *p;
- UpVal *upvals[1];
+ UpVal *upvals[1]; /* list of upvalues */
} LClosure;
@@ -339,6 +350,7 @@ typedef union Closure {
#define getproto(o) (clvalue(o)->l.p)
+
/*
** Tables
*/
@@ -383,8 +395,12 @@ typedef struct Table {
#define sizenode(t) (twoto((t)->lsizenode))
+/*
+** (address of) a fixed nil value
+*/
#define luaO_nilobject (&luaO_nilobject_)
+
LUAI_DDEC const TValue luaO_nilobject_;
LUAI_FUNC int luaO_int2fb (unsigned int x);
--
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