From d9c2d065698641837bc75ded236b23d5aaa36fd4 Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Thu, 10 Sep 2020 20:55:10 +0800
Subject: *table string comment

---
 src/lua51/lstring.c | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

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

diff --git a/src/lua51/lstring.c b/src/lua51/lstring.c
index 73d34c4..cadbb4b 100644
--- a/src/lua51/lstring.c
+++ b/src/lua51/lstring.c
@@ -25,19 +25,19 @@ void luaS_resize (lua_State *L, int newsize) {
   GCObject **newhash;
   stringtable *tb;
   int i;
-  if (G(L)->gcstate == GCSsweepstring)//如果GC在回收字符串阶段，不要rehash
+  if (G(L)->gcstate == GCSsweepstring)//如果GC在回收字符串阶段，不要rehash，等GC完了再搞
     return;  /* cannot resize during GC traverse */
   newhash = luaM_newvector(L, newsize, GCObject *); //建立一个新的散列桶，并清空
   tb = &G(L)->strt;//旧的散列桶
   for (i=0; i<newsize; i++) newhash[i] = NULL;
-  //遍历就的散列桶，并填入新的散列桶
+  //遍历旧的散列桶，并填入新的散列桶
 	/* rehash */
   for (i=0; i<tb->size; i++) {
-    GCObject *p = tb->hash[i];
+    GCObject *p = tb->hash[i]; // 某个桶
     while (p) {  /* for each node in the list */
       GCObject *next = p->gch.next;  /* save next */
-      unsigned int h = gco2ts(p)->hash;
-			//新的散列值
+      unsigned int h = gco2ts(p)->hash; //c 保存hash值
+			//新的散列值，并加入桶中
       int h1 = lmod(h, newsize);  /* new position */
       lua_assert(cast_int(h%newsize) == lmod(h, newsize));
       p->gch.next = newhash[h1];//c 接在同一个hash的最前面  /* chain it */
@@ -45,37 +45,42 @@ void luaS_resize (lua_State *L, int newsize) {
       p = next;
     }
   }
+	// 释放旧散列桶
   luaM_freearray(L, tb->hash, tb->size, TString *);
   tb->size = newsize;
-  tb->hash = newhash;
+  tb->hash = newhash; // 设置新散列桶
 }
 
 
-//c 新建字符串
+//c 新建字符串并加入散列桶
 static TString *newlstr (lua_State *L, const char *str, size_t l,
                                        unsigned int h) {
   TString *ts;
   stringtable *tb;
   if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
     luaM_toobig(L);
+	//c 同时申请了TString和字符串内存，字符串内容会紧跟在TString结构后边
   ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));
   ts->tsv.len = l;
   ts->tsv.hash = h;
   ts->tsv.marked = luaC_white(G(L));
   ts->tsv.tt = LUA_TSTRING;
   ts->tsv.reserved = 0;
-  memcpy(ts+1, str, l*sizeof(char));
+
+  memcpy(ts+1, str, l*sizeof(char)); //c 复制字符串内容
   ((char *)(ts+1))[l] = '\0';  /* ending 0 */
-  tb = &G(L)->strt;
-	// 计算hash值
-  h = lmod(h, tb->size);
+
+  tb = &G(L)->strt; //c 散列桶
+
+  h = lmod(h, tb->size);	//c 计算hash值并将这个字符串加入桶
   ts->tsv.next = tb->hash[h];  /* chain new entry */
   tb->hash[h] = obj2gco(ts);
   tb->nuse++;
-	//c 给字符串通扩容，如果字符串数量大于桶容量
-	//c 给桶扩容为2倍
+
+	//c 如果字符串数量大于桶容量，给字符串通扩容，给桶扩容为2倍
   if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
     luaS_resize(L, tb->size*2);  /* too crowded */
+
   return ts;
 }
 
@@ -89,11 +94,14 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
 	//c 如果字符串非常长，不要逐位计算散列值，每step步取一个字符计算即可
   for (l1=l; l1>=step; l1-=step)  /* compute hash */
     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
+	//c 遍历这个hash对应的散列桶
   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
        o != NULL;
        o = o->gch.next) {
     TString *ts = rawgco2ts(o);
-    if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {//c 如果散列值相同，用memcmp快速对比
+		//c 如果长度相同，用memcmp快速对比
+    if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
+			//c 这个字符串已经存在，直接返回这个引用
 			//c 如果字符串被标记了回收(gch.marked)，重新标记它不要回收
       /* string may be dead */
       if (isdead(G(L), o)) changewhite(o);
-- 
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