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authorRoberto Ierusalimschy <roberto@inf.puc-rio.br>2019-10-22 14:08:22 -0300
committerRoberto Ierusalimschy <roberto@inf.puc-rio.br>2019-10-22 14:08:22 -0300
commite592f94a643de0bf8d62f6c6128fe752c673f5ac (patch)
tree50a4c591601eb5aaf53014c1c3039a8e2523ca45 /lobject.h
parent6e1aec7a677a9891f2f8ca57e039d9984fdc69bc (diff)
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Details (mostly comments)
Diffstat (limited to 'lobject.h')
-rw-r--r--lobject.h31
1 files changed, 23 insertions, 8 deletions
diff --git a/lobject.h b/lobject.h
index a22148c0..0c38affe 100644
--- a/lobject.h
+++ b/lobject.h
@@ -17,11 +17,12 @@
17 17
18 18
19/* 19/*
20** Extra tags for non-values 20** Extra tags for collectable non-values
21*/ 21*/
22#define LUA_TUPVAL LUA_NUMTAGS /* upvalues */ 22#define LUA_TUPVAL LUA_NUMTAGS /* upvalues */
23#define LUA_TPROTO (LUA_NUMTAGS+1) /* function prototypes */ 23#define LUA_TPROTO (LUA_NUMTAGS+1) /* function prototypes */
24 24
25
25/* 26/*
26** number of all possible tags (including LUA_TNONE) 27** number of all possible tags (including LUA_TNONE)
27*/ 28*/
@@ -30,7 +31,7 @@
30 31
31/* 32/*
32** tags for Tagged Values have the following use of bits: 33** tags for Tagged Values have the following use of bits:
33** bits 0-3: actual tag (a LUA_T* value) 34** bits 0-3: actual tag (a LUA_T* constant)
34** bits 4-5: variant bits 35** bits 4-5: variant bits
35** bit 6: whether value is collectable 36** bit 6: whether value is collectable
36*/ 37*/
@@ -86,24 +87,35 @@ typedef struct TValue {
86 87
87 88
88/* Macros for internal tests */ 89/* Macros for internal tests */
90
91/* collectable object has the same tag as the original value */
89#define righttt(obj) (ttypetag(obj) == gcvalue(obj)->tt) 92#define righttt(obj) (ttypetag(obj) == gcvalue(obj)->tt)
90 93
94/*
95** Any value being manipulated by the program either is non
96** collectable, or the collectable object has the right tag
97** and it is not dead.
98*/
91#define checkliveness(L,obj) \ 99#define checkliveness(L,obj) \
92 ((void)L, lua_longassert(!iscollectable(obj) || \ 100 ((void)L, lua_longassert(!iscollectable(obj) || \
93 (righttt(obj) && (L == NULL || !isdead(G(L),gcvalue(obj)))))) 101 (righttt(obj) && (L == NULL || !isdead(G(L),gcvalue(obj))))))
94 102
95 103
96/* Macros to set values */ 104/* Macros to set values */
105
106/* set a value's tag */
97#define settt_(o,t) ((o)->tt_=(t)) 107#define settt_(o,t) ((o)->tt_=(t))
98 108
99 109
110/* main macro to copy values (from 'obj1' to 'obj2') */
100#define setobj(L,obj1,obj2) \ 111#define setobj(L,obj1,obj2) \
101 { TValue *io1=(obj1); const TValue *io2=(obj2); \ 112 { TValue *io1=(obj1); const TValue *io2=(obj2); \
102 io1->value_ = io2->value_; io1->tt_ = io2->tt_; \ 113 io1->value_ = io2->value_; settt_(io1, io2->tt_); \
103 checkliveness(L,io1); lua_assert(!isreallyempty(io1)); } 114 checkliveness(L,io1); lua_assert(!isnonstrictnil(io1)); }
104 115
105/* 116/*
106** different types of assignments, according to destination 117** Different types of assignments, according to source and destination.
118** (They are mostly equal now, but may be different in the future.)
107*/ 119*/
108 120
109/* from stack to stack */ 121/* from stack to stack */
@@ -118,13 +130,16 @@ typedef struct TValue {
118#define setobj2t setobj 130#define setobj2t setobj
119 131
120 132
121 133/*
134** Entries in the Lua stack
135*/
122typedef union StackValue { 136typedef union StackValue {
123 TValue val; 137 TValue val;
124} StackValue; 138} StackValue;
125 139
126 140
127typedef StackValue *StkId; /* index to stack elements */ 141/* index to stack elements */
142typedef StackValue *StkId;
128 143
129/* convert a 'StackValue' to a 'TValue' */ 144/* convert a 'StackValue' to a 'TValue' */
130#define s2v(o) (&(o)->val) 145#define s2v(o) (&(o)->val)
@@ -166,7 +181,7 @@ typedef StackValue *StkId; /* index to stack elements */
166/* 181/*
167** macro to detect non-standard nils (used only in assertions) 182** macro to detect non-standard nils (used only in assertions)
168*/ 183*/
169#define isreallyempty(v) (ttisnil(v) && !ttisstrictnil(v)) 184#define isnonstrictnil(v) (ttisnil(v) && !ttisstrictnil(v))
170 185
171 186
172/* 187/*