From 63cb4fbbb961da133c68865845eaf22d9b876700 Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Sun, 27 Sep 2020 20:31:53 +0800
Subject: *misc

---
 src/lua51/lparser.c | 59 +++++++++++++++++++++++++++++++++++------------------
 1 file changed, 39 insertions(+), 20 deletions(-)

(limited to 'src/lua51/lparser.c')

diff --git a/src/lua51/lparser.c b/src/lua51/lparser.c
index 7da34e7..d868981 100644
--- a/src/lua51/lparser.c
+++ b/src/lua51/lparser.c
@@ -140,6 +140,7 @@ static void checkname(LexState *ls, expdesc *e) {
 }
 
 
+//c 注册一个局部变量，并返回对应的编号ID
 static int registerlocalvar (LexState *ls, TString *varname) {
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
@@ -157,13 +158,15 @@ static int registerlocalvar (LexState *ls, TString *varname) {
   new_localvar(ls, luaX_newstring(ls, "" v, (sizeof(v)/sizeof(char))-1), n)
 
 
+//c  new_localvar()  adjustlocalvars()  removevars() 用来管理局部变量
+
+//c 对于 local a,b,c = 1, 2,3 这样的语句，生成等号坐标对应的变量
 static void new_localvar (LexState *ls, TString *name, int n) {
   FuncState *fs = ls->fs;
-  luaY_checklimit(fs, fs->nactvar+n+1, LUAI_MAXVARS, "local variables");
-  fs->actvar[fs->nactvar+n] = cast(unsigned short, registerlocalvar(ls, name));
+  luaY_checklimit(fs, fs->nactvar+n+1, LUAI_MAXVARS, "local variables");//最多支持200个局部变量
+  fs->actvar[fs->nactvar+n] = cast(unsigned short, registerlocalvar(ls, name)); // 
 }
 
-
 static void adjustlocalvars (LexState *ls, int nvars) {
   FuncState *fs = ls->fs;
   fs->nactvar = cast_byte(fs->nactvar + nvars);
@@ -172,7 +175,6 @@ static void adjustlocalvars (LexState *ls, int nvars) {
   }
 }
 
-
 static void removevars (LexState *ls, int tolevel) {
   FuncState *fs = ls->fs;
   while (fs->nactvar > tolevel)
@@ -380,22 +382,32 @@ static void close_func (LexState *ls) {
 }
 
 
-//c! 编译生成字节码，分析阶段的唯一入口，返回proto指针
+//c!! 编译器入口
+//c! 词法分析>语法分析并生成字节码
+//c 编译生成字节码，分析阶段的唯一入口，返回proto指针
 Proto *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff, const char *name) {
+	//c 词法分析、语法分析和代码生成过程中的数据都在这里
   struct LexState lexstate;
-  struct FuncState funcstate; // 分析过程中的临时数据
+  struct FuncState funcstate;
+
   lexstate.buff = buff;
   luaX_setinput(L, &lexstate, z, luaS_new(L, name));
   open_func(&lexstate, &funcstate);
   funcstate.f->is_vararg = VARARG_ISVARARG;  /* main func. is always vararg */
-  luaX_next(&lexstate);  /* read first token */
-  chunk(&lexstate);
+
+	// lua通过一次遍历就从源代码生成了字节码，为了加快编译
+  luaX_next(&lexstate);  /* read first token */ 
+  chunk(&lexstate); 
+
+	// 代码生成结束进行一些收尾工作
   check(&lexstate, TK_EOS);
   close_func(&lexstate);
+
   lua_assert(funcstate.prev == NULL);
   lua_assert(funcstate.f->nups == 0);
   lua_assert(lexstate.fs == NULL);
-  return funcstate.f; //c 最终生成的字节码
+
+  return funcstate.f; //c 最终生成的函数原型
 }
 
 
@@ -431,12 +443,12 @@ static void yindex (LexState *ls, expdesc *v) {
 ** =======================================================================
 */
 
-
+// 存放表消息
 struct ConsControl {
-  expdesc v;  /* last list item read */
-  expdesc *t;  /* table descriptor */
-  int nh;  /* total number of `record' elements */
-  int na;  /* total number of array elements */
+  expdesc v;  /* last list item read */ //表在构造过程中最后一个表达式的信息
+  expdesc *t;  /* table descriptor */ //表构造表达式的信息
+  int nh;  /* total number of `record' elements */ // 初始化表时，散列部分数据数量
+  int na;  /* total number of array elements */ // 初始化表时，数组部分数据数量
   int tostore;  /* number of array elements pending to be stored */
 };
 
@@ -500,12 +512,15 @@ static void constructor (LexState *ls, expdesc *t) {
   /* constructor -> ?? */
   FuncState *fs = ls->fs;
   int line = ls->linenumber;
-  int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0);
+  int pc = luaK_codeABC(fs, OP_NEWTABLE, 0, 0, 0); // 这条指令会被重定向，A参数会被设为寄存器上某个值
+
   struct ConsControl cc;
   cc.na = cc.nh = cc.tostore = 0;
   cc.t = t;
+
   init_exp(t, VRELOCABLE, pc);
   init_exp(&cc.v, VVOID, 0);  /* no value (yet) */
+
   luaK_exp2nextreg(ls->fs, t);  /* fix it at stack top (for gc) */
   checknext(ls, '{');
   do {
@@ -594,12 +609,13 @@ static void body (LexState *ls, expdesc *e, int needself, int line) {
 }
 
 
+//c 表达式
 static int explist1 (LexState *ls, expdesc *v) {
   /* explist1 -> expr { `,' expr } */
   int n = 1;  /* at least one expression */
-  expr(ls, v);
+  expr(ls, v); // 先生成lparser.h > expdesc结构
   while (testnext(ls, ',')) {
-    luaK_exp2nextreg(ls->fs, v);
+    luaK_exp2nextreg(ls->fs, v); // 根据expdesc结构内容生成对应的字节码
     expr(ls, v);
     n++;
   }
@@ -725,6 +741,7 @@ static void primaryexp (LexState *ls, expdesc *v) {
 }
 
 
+//构造表达式
 static void simpleexp (LexState *ls, expdesc *v) {
   /* simpleexp -> NUMBER | STRING | NIL | true | false | ... |
                   constructor | FUNCTION body | primaryexp */
@@ -1177,6 +1194,7 @@ static void localfunc (LexState *ls) {
 }
 
 
+//c 定义局部变量语句
 static void localstat (LexState *ls) {
   /* stat -> LOCAL NAME {`,' NAME} [`=' explist1] */
   int nvars = 0;
@@ -1191,8 +1209,8 @@ static void localstat (LexState *ls) {
     e.k = VVOID;
     nexps = 0;
   }
-  adjust_assign(ls, nvars, nexps, &e);
-  adjustlocalvars(ls, nvars);
+  adjust_assign(ls, nvars, nexps, &e); // 根据等号左右两边的个数调整，如果右边少于左边，则多余的置为nil
+  adjustlocalvars(ls, nvars); //根据变量数量调整FuncState结构中的nactvar，并调整startpc
 }
 
 
@@ -1268,7 +1286,7 @@ static void retstat (LexState *ls) {
   luaK_ret(fs, first, nret);
 }
 
-
+//c 语法分析，直接生成字节码
 static int statement (LexState *ls) {
   int line = ls->linenumber;  /* may be needed for error messages */
   switch (ls->t.token) {
@@ -1332,6 +1350,7 @@ static void chunk (LexState *ls) {
     testnext(ls, ';');
     lua_assert(ls->fs->f->maxstacksize >= ls->fs->freereg &&
                ls->fs->freereg >= ls->fs->nactvar);
+		// 更新寄存器的位置，给本地变量留位置
     ls->fs->freereg = ls->fs->nactvar;  /* free registers */
   }
   leavelevel(ls);
-- 
cgit v1.1-26-g67d0