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添加一些语法解析器注释

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This commit is contained in:
andy
2024-10-27 20:42:48 +08:00
parent 70233276c6
commit 87b76b4caa
8 changed files with 35 additions and 20 deletions
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4
src/lapi.c
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@@ -56,16 +56,20 @@ const char lua_ident[] =
/*
** Convert an acceptable index to a pointer to its respective value.
** Non-valid indices return the special nil value 'G(L)->nilvalue'.
将可接受的索引转换为指向其相应值的指针。无效索引返回特殊的nil值“G（L）->nilvalue”。
*/
static TValue *index2value (lua_State *L, int idx) {
// ci 是当前函数 的上下文 每个函数有自己的栈
CallInfo *ci = L->ci;
if (idx > 0) {
// idx 大于0是函数调用？
StkId o = ci->func.p + idx;
api_check(L, idx <= ci->top.p - (ci->func.p + 1), "unacceptable index");
if (o >= L->top.p) return &G(L)->nilvalue;
else return s2v(o);
}
else if (!ispseudo(idx)) { /* negative index */
// idx小于等于0是栈顶向下的距离
api_check(L, idx != 0 && -idx <= L->top.p - (ci->func.p + 1),
"invalid index");
return s2v(L->top.p + idx);

1
src/lapi.h
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@@ -13,6 +13,7 @@
/* Increments 'L->top.p', checking for stack overflows */
// 栈增 check一下是否已满
#define api_incr_top(L) {L->top.p++; \
api_check(L, L->top.p <= L->ci->top.p, \
"stack overflow");}

6
src/ldo.c
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@@ -311,7 +311,7 @@ void luaD_shrinkstack (lua_State *L) {
luaE_shrinkCI(L); /* shrink CI list */
}
// 栈自增
void luaD_inctop (lua_State *L) {
luaD_checkstack(L, 1);
L->top.p++;
@@ -968,7 +968,7 @@ int luaD_pcall (lua_State *L, Pfunc func, void *u,
** Execute a protected parser.
*/
struct SParser { /* data to 'f_parser' */
ZIO *z;
ZIO *z; // 输入流
Mbuffer buff; /* dynamic structure used by the scanner */
Dyndata dyd; /* dynamic structures used by the parser */
const char *mode;
@@ -1001,7 +1001,7 @@ static void f_parser (lua_State *L, void *ud) {
luaF_initupvals(L, cl);
}
// L 解析器状态，z 输入流
int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
const char *mode) {
struct SParser p;

4
src/lobject.h
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@@ -690,7 +690,7 @@ typedef struct Proto {
{ TValue *io = (obj); LClosure *x_ = (x); \
val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_VLCL)); \
checkliveness(L,io); }
// 保存闭包到栈
#define setclLvalue2s(L,o,cl) setclLvalue(L,s2v(o),cl)
#define setfvalue(obj,x) \
@@ -766,7 +766,7 @@ typedef union Closure {
{ TValue *io = (obj); Table *x_ = (x); \
val_(io).gc = obj2gco(x_); settt_(io, ctb(LUA_VTABLE)); \
checkliveness(L,io); }
// 把表保存到 栈中
#define sethvalue2s(L,o,h) sethvalue(L,s2v(o),h)

32
src/lparser.c
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@@ -61,6 +61,7 @@ typedef struct BlockCnt {
/*
** prototypes for recursive non-terminal functions
递归非终结函数的原型
*/
static void statement (LexState *ls);
static void expr (LexState *ls, expdesc *v);
@@ -119,7 +120,7 @@ static void checknext (LexState *ls, int c) {
luaX_next(ls);
}
// 如果c为null 则输出错误
#define check_condition(ls,c,msg) { if (!(c)) luaX_syntaxerror(ls, msg); }
@@ -127,6 +128,7 @@ static void checknext (LexState *ls, int c) {
** Check that next token is 'what' and skip it. In case of error,
** raise an error that the expected 'what' should match a 'who'
** in line 'where' (if that is not the current line).
如果下一个 token 是what 则读取下一个 token ，否则产生一个错误
*/
static void check_match (LexState *ls, int what, int who, int where) {
if (l_unlikely(!testnext(ls, what))) {
@@ -140,7 +142,7 @@ static void check_match (LexState *ls, int what, int who, int where) {
}
}
// 如果下一个token是名称 则解析下一个token
static TString *str_checkname (LexState *ls) {
TString *ts;
check(ls, TK_NAME);
@@ -785,6 +787,7 @@ static void close_func (LexState *ls) {
** check whether current token is in the follow set of a block.
** 'until' closes syntactical blocks, but do not close scope,
** so it is handled in separate.
检查当前 token 是否在块的后续集合中。'直到'关闭语法块，但不关闭作用域，因此它是单独处理的
*/
static int block_follow (LexState *ls, int withuntil) {
switch (ls->t.token) {
@@ -796,7 +799,7 @@ static int block_follow (LexState *ls, int withuntil) {
}
}
// 主要是这个函数解析脚本
static void statlist (LexState *ls) {
/* statlist -> { stat [';'] } */
while (!block_follow(ls, 1)) {
@@ -987,7 +990,7 @@ static void parlist (LexState *ls) {
luaK_reserveregs(fs, fs->nactvar); /* reserve registers for parameters */
}
// 函数的 参数部分, 用 () 包括的部分
static void body (LexState *ls, expdesc *e, int ismethod, int line) {
/* body -> '(' parlist ')' block END */
FuncState new_fs;
@@ -1192,7 +1195,7 @@ static void simpleexp (LexState *ls, expdesc *v) {
luaX_next(ls);
}
// 匹配单目运算符
static UnOpr getunopr (int op) {
switch (op) {
case TK_NOT: return OPR_NOT;
@@ -1203,7 +1206,7 @@ static UnOpr getunopr (int op) {
}
}
// 匹配双目运算符
static BinOpr getbinopr (int op) {
switch (op) {
case '+': return OPR_ADD;
@@ -1257,19 +1260,23 @@ static const struct {
/*
** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
** where 'binop' is any binary operator with a priority higher than 'limit'
读取子表达式 limit 用于限制表达式优先级
*/
static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
BinOpr op;
UnOpr uop;
enterlevel(ls);
// 如果是单目运算符
uop = getunopr(ls->t.token);
if (uop != OPR_NOUNOPR) { /* prefix (unary) operator? */
int line = ls->linenumber;
luaX_next(ls); /* skip operator */
subexpr(ls, v, UNARY_PRIORITY);
luaK_prefix(ls->fs, uop, v, line);
} else {
// 如果是单目运算符 则执行表达式
simpleexp(ls, v);
}
else simpleexp(ls, v);
/* expand while operators have priorities higher than 'limit' */
op = getbinopr(ls->t.token);
while (op != OPR_NOBINOPR && priority[op].left > limit) {
@@ -1287,7 +1294,7 @@ static BinOpr subexpr (LexState *ls, expdesc *v, int limit) {
return op; /* return first untreated operator */
}
// 读取表达式
static void expr (LexState *ls, expdesc *v) {
subexpr(ls, v, 0);
}
@@ -1635,7 +1642,7 @@ static void forstat (LexState *ls, int line) {
leaveblock(fs); /* loop scope ('break' jumps to this point) */
}
// 解析 if 或 elseif 到 then 之间的语句块
static void test_then_block (LexState *ls, int *escapelist) {
/* test_then_block -> [IF | ELSEIF] cond THEN block */
BlockCnt bl;
@@ -1672,7 +1679,7 @@ static void test_then_block (LexState *ls, int *escapelist) {
luaK_patchtohere(fs, jf);
}
// if 语句块
static void ifstat (LexState *ls, int line) {
/* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
FuncState *fs = ls->fs;
@@ -1842,12 +1849,13 @@ static void retstat (LexState *ls) {
testnext(ls, ';'); /* skip optional semicolon */
}
// 解析token
static void statement (LexState *ls) {
int line = ls->linenumber; /* may be needed for error messages */
enterlevel(ls);
switch (ls->t.token) {
case ';': { /* stat -> ';' (empty statement) */
// 分号什么也不做 直接解析下一个 token
luaX_next(ls); /* skip ';' */
break;
}
@@ -1948,6 +1956,7 @@ LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
setclLvalue2s(L, L->top.p, cl); /* anchor it (to avoid being collected) */
luaD_inctop(L);
lexstate.h = luaH_new(L); /* create table for scanner */
// 把这个表保存到栈顶？
sethvalue2s(L, L->top.p, lexstate.h); /* anchor it */
luaD_inctop(L);
funcstate.f = cl->p = luaF_newproto(L);
@@ -1958,6 +1967,7 @@ LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
lexstate.dyd = dyd;
dyd->actvar.n = dyd->gt.n = dyd->label.n = 0;
luaX_setinput(L, &lexstate, z, funcstate.f->source, firstchar);
// 把这个输入流当作一个函数来调用
mainfunc(&lexstate, &funcstate);
lua_assert(!funcstate.prev && funcstate.nups == 1 && !lexstate.fs);
/* all scopes should be correctly finished */

2
src/lparser.h
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@@ -81,7 +81,7 @@ typedef enum {
// 已编号的变量
#define vkisindexed(k) (VINDEXED <= (k) && (k) <= VINDEXSTR)
// 定义表达式数据结构
typedef struct expdesc {
expkind k;
union {

2
src/lzio.c
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@@ -35,7 +35,7 @@ int luaZ_fill (ZIO *z) {
return cast_uchar(*(z->p++));
}
// 初始化输入流
void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
z->L = L;
z->reader = reader;

4
src/lzio.h
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@@ -14,7 +14,7 @@
#define EOZ (-1) /* end of stream */
// 输入流
typedef struct Zio ZIO;
// 获取下一个字符
@@ -52,7 +52,7 @@ LUAI_FUNC size_t luaZ_read (ZIO* z, void *b, size_t n); /* read next n bytes */
/* --------- Private Part ------------------ */
// 输入流
struct Zio {
size_t n; /* bytes still unread */
const char *p; /* current position in buffer */