Comments

llex.c

@@ -254,9 +254,10 @@ static int read_numeral (LexState *ls, SemInfo *seminfo) {
 
 
 /*
-** reads a sequence '[=*[' or ']=*]', leaving the last bracket.
-** If sequence is well formed, return its number of '='s + 2; otherwise,
-** return 1 if there is no '='s or 0 otherwise (an unfinished '[==...').
+** read a sequence '[=*[' or ']=*]', leaving the last bracket. If
+** sequence is well formed, return its number of '='s + 2; otherwise,
+** return 1 if it is a single bracket (no '='s and no 2nd bracket);
+** otherwise (an unfinished '[==...') return 0.
 */
 static size_t skip_sep (LexState *ls) {
   size_t count = 0;
@@ -481,34 +482,34 @@ static int llex (LexState *ls, SemInfo *seminfo) {
       }
       case '=': {
         next(ls);
-        if (check_next1(ls, '=')) return TK_EQ;
+        if (check_next1(ls, '=')) return TK_EQ;  /* '==' */
         else return '=';
       }
       case '<': {
         next(ls);
-        if (check_next1(ls, '=')) return TK_LE;
-        else if (check_next1(ls, '<')) return TK_SHL;
+        if (check_next1(ls, '=')) return TK_LE;  /* '<=' */
+        else if (check_next1(ls, '<')) return TK_SHL;  /* '<<' */
         else return '<';
       }
       case '>': {
         next(ls);
-        if (check_next1(ls, '=')) return TK_GE;
-        else if (check_next1(ls, '>')) return TK_SHR;
+        if (check_next1(ls, '=')) return TK_GE;  /* '>=' */
+        else if (check_next1(ls, '>')) return TK_SHR;  /* '>>' */
         else return '>';
       }
       case '/': {
         next(ls);
-        if (check_next1(ls, '/')) return TK_IDIV;
+        if (check_next1(ls, '/')) return TK_IDIV;  /* '//' */
         else return '/';
       }
       case '~': {
         next(ls);
-        if (check_next1(ls, '=')) return TK_NE;
+        if (check_next1(ls, '=')) return TK_NE;  /* '~=' */
         else return '~';
       }
       case ':': {
         next(ls);
-        if (check_next1(ls, ':')) return TK_DBCOLON;
+        if (check_next1(ls, ':')) return TK_DBCOLON;  /* '::' */
         else return ':';
       }
       case '"': case '\'': {  /* short literal strings */
@@ -547,7 +548,7 @@ static int llex (LexState *ls, SemInfo *seminfo) {
             return TK_NAME;
           }
         }
-        else {  /* single-char tokens (+ - / ...) */
+        else {  /* single-char tokens ('+', '*', '%', '{', '}', ...) */
           int c = ls->current;
           next(ls);
           return c;

lparser.c

@@ -945,7 +945,7 @@ static void setvararg (FuncState *fs, int nparams) {
 
 
 static void parlist (LexState *ls) {
-  /* parlist -> [ param { ',' param } ] */
+  /* parlist -> [ {NAME ','} (NAME | '...') ] */
   FuncState *fs = ls->fs;
   Proto *f = fs->f;
   int nparams = 0;
@@ -953,12 +953,12 @@ static void parlist (LexState *ls) {
   if (ls->t.token != ')') {  /* is 'parlist' not empty? */
     do {
       switch (ls->t.token) {
-        case TK_NAME: {  /* param -> NAME */
+        case TK_NAME: {
           new_localvar(ls, str_checkname(ls));
           nparams++;
           break;
         }
-        case TK_DOTS: {  /* param -> '...' */
+        case TK_DOTS: {
           luaX_next(ls);
           isvararg = 1;
           break;
@@ -1752,7 +1752,7 @@ static void checktoclose (LexState *ls, int level) {
 
 
 static void localstat (LexState *ls) {
-  /* stat -> LOCAL ATTRIB NAME {',' ATTRIB NAME} ['=' explist] */
+  /* stat -> LOCAL NAME ATTRIB { ',' NAME ATTRIB } ['=' explist] */
   FuncState *fs = ls->fs;
   int toclose = -1;  /* index of to-be-closed variable (if any) */
   Vardesc *var;  /* last variable */

ltable.c

@@ -166,17 +166,24 @@ static Node *mainpositionTV (const Table *t, const TValue *key) {
 
 
 /*
-** Check whether key 'k1' is equal to the key in node 'n2'.
-** This equality is raw, so there are no metamethods. Floats
-** with integer values have been normalized, so integers cannot
-** be equal to floats. It is assumed that 'eqshrstr' is simply
-** pointer equality, so that short strings are handled in the
-** default case.
+** Check whether key 'k1' is equal to the key in node 'n2'. This
+** equality is raw, so there are no metamethods. Floats with integer
+** values have been normalized, so integers cannot be equal to
+** floats. It is assumed that 'eqshrstr' is simply pointer equality, so
+** that short strings are handled in the default case.
 ** A true 'deadok' means to accept dead keys as equal to their original
-** values, which can only happen if the original key was collectable.
-** All dead values are compared in the default case, by pointer
-** identity.  (Note that dead long strings are also compared by
-** identity).
+** values. All dead keys are compared in the default case, by pointer
+** identity. (Only collectable objects can produce dead keys.) Note that
+** dead long strings are also compared by identity.
+** Once a key is dead, its corresponding value may be collected, and
+** then another value can be created with the same address. If this
+** other value is given to 'next', 'equalkey' will signal a false
+** positive. In a regular traversal, this situation should never happen,
+** as all keys given to 'next' came from the table itself, and therefore
+** could not have been collected. Outside a regular traversal, we
+** have garbage in, garbage out. What is relevant is that this false
+** positive does not break anything.  (In particular, 'next' will return
+** some other valid item on the table or nil.)
 */
 static int equalkey (const TValue *k1, const Node *n2, int deadok) {
   if ((rawtt(k1) != keytt(n2)) &&  /* not the same variants? */