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no more assignment expressions (they don't fit in Lua...)

v5-2
Roberto Ierusalimschy 26 years ago
parent
0870a2d1d8
commit
2679461637
4 changed files with 20 additions and 83 deletions
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  1. 8
      lopcodes.h
  2. 51
      lparser.c
  3. 32
      lvm.c
  4. 12
      manual.tex

8
lopcodes.h
View File

@ -1,5 +1,5 @@
/*
** $Id: lopcodes.h,v 1.30 1999/03/04 21:15:50 roberto Exp roberto $
** $Id: lopcodes.h,v 1.31 1999/03/05 21:16:07 roberto Exp roberto $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/
@ -26,7 +26,6 @@ TAILCALL,/* b c v_c...v_1 f (return) f(v1,...,v_c) */
PUSHNIL,/* b - nil_0...nil_b */
POP,/* b a_b...a_1 - */
POPDUP,/* b v a_b...a_1 v */
PUSHNUMBERW,/* w - (float)w */
PUSHNUMBER,/* b - (float)b */
@ -56,18 +55,13 @@ CREATEARRAYW,/* w - newarray(size = w) */
CREATEARRAY,/* b - newarray(size = b) */
SETLOCAL,/* b x - LOC[b]=x */
SETLOCALDUP,/* b x x LOC[b]=x */
SETGLOBALW,/* w x - VAR[CNST[w]]=x */
SETGLOBAL,/* b x - VAR[CNST[b]]=x */
SETGLOBALDUPW,/*w x x VAR[CNST[w]]=x */
SETGLOBALDUP,/* b x x VAR[CNST[b]]=x */
SETTABLEPOP,/* - v i t - t[i]=v */
SETTABLEPOPDUP,/* - v i t v t[i]=v */
SETTABLE,/* b v a_b...a_1 i t a_b...a_1 i t t[i]=v */
SETTABLEDUP,/* b v a_b...a_1 i t v a_b...a_1 i t t[i]=v */
SETLISTW,/* w c v_c...v_1 t t t[i+w*FPF]=v_i */
SETLIST,/* b c v_c...v_1 t t t[i+b*FPF]=v_i */

51
lparser.c
View File

@ -1,5 +1,5 @@
/*
** $Id: lparser.c,v 1.26 1999/03/04 21:17:26 roberto Exp roberto $
** $Id: lparser.c,v 1.27 1999/03/05 21:16:07 roberto Exp roberto $
** LL(1) Parser and code generator for Lua
** See Copyright Notice in lua.h
*/
@ -99,7 +99,7 @@ typedef struct FuncState {
/*
** prototypes for non-terminal functions
*/
static int assignment (LexState *ls, vardesc *v, int nvars, OpCode *codes);
static int assignment (LexState *ls, vardesc *v, int nvars);
static int cond (LexState *ls);
static int funcname (LexState *ls, vardesc *v);
static int funcparams (LexState *ls, int slf);
@ -114,7 +114,6 @@ static void chunk (LexState *ls);
static void constructor (LexState *ls);
static void decinit (LexState *ls, listdesc *d);
static void exp0 (LexState *ls, vardesc *v);
static void Gexp (LexState *ls, vardesc *v);
static void exp1 (LexState *ls);
static void exp2 (LexState *ls, vardesc *v);
static void explist (LexState *ls, listdesc *e);
@ -467,22 +466,16 @@ static void lua_pushvar (LexState *ls, vardesc *var) {
}
/* to be used by "storevar" and assignment */
static OpCode set_pop[] = {SETLOCAL, SETGLOBAL, SETTABLEPOP, SETTABLE};
static OpCode set_dup[] = {SETLOCALDUP, SETGLOBALDUP, SETTABLEPOPDUP,
SETTABLEDUP};
static void storevar (LexState *ls, vardesc *var, OpCode *codes) {
static void storevar (LexState *ls, vardesc *var) {
switch (var->k) {
case VLOCAL:
code_oparg(ls, codes[0], var->info, -1);
code_oparg(ls, SETLOCAL, var->info, -1);
break;
case VGLOBAL:
code_oparg(ls, codes[1], var->info, -1);
code_oparg(ls, SETGLOBAL, var->info, -1);
break;
case VINDEXED:
code_opcode(ls, codes[2], -3);
code_opcode(ls, SETTABLEPOP, -3);
break;
default:
LUA_INTERNALERROR("invalid var kind to store");
@ -739,7 +732,7 @@ static int stat (LexState *ls) {
next(ls);
needself = funcname(ls, &v);
body(ls, needself, line);
storevar(ls, &v, set_pop);
storevar(ls, &v);
return 1;
}
@ -765,7 +758,7 @@ static int stat (LexState *ls) {
close_exp(ls, v.info, 0);
}
else { /* stat -> ['%'] NAME assignment */
int left = assignment(ls, &v, 1, set_pop);
int left = assignment(ls, &v, 1);
adjuststack(ls, left); /* remove eventual 'garbage' left on stack */
}
return 1;
@ -948,19 +941,6 @@ static void exp0 (LexState *ls, vardesc *v) {
}
static void Gexp (LexState *ls, vardesc *v) {
/* Gexp -> exp0 | assignment */
exp0(ls, v);
if (v->k != VEXP && (ls->token == '=' || ls->token == ',')) {
int left = assignment(ls, v, 1, set_dup);
deltastack(ls, 1); /* DUP operations push an extra value */
if (left > 0)
code_oparg(ls, POPDUP, left, -left);
v->k = VEXP; v->info = 0; /* this expression is closed now */
}
}
static void push (LexState *ls, stack_op *s, int op) {
if (s->top >= MAXOPS)
luaX_error(ls, "expression too complex");
@ -1015,9 +995,9 @@ static void simpleexp (LexState *ls, vardesc *v, stack_op *s) {
ifpart(ls, 1, ls->linenumber);
break;
case '(': /* simpleexp -> '(' Gexp ')' */
case '(': /* simpleexp -> '(' exp0 ')' */
next(ls);
Gexp(ls, v);
exp0(ls, v);
check(ls, ')');
return;
@ -1239,7 +1219,7 @@ static void decinit (LexState *ls, listdesc *d) {
}
static int assignment (LexState *ls, vardesc *v, int nvars, OpCode *codes) {
static int assignment (LexState *ls, vardesc *v, int nvars) {
int left = 0;
unloaddot(ls, v);
if (ls->token == ',') { /* assignment -> ',' NAME assignment */
@ -1248,7 +1228,7 @@ static int assignment (LexState *ls, vardesc *v, int nvars, OpCode *codes) {
var_or_func(ls, &nv);
if (nv.k == VEXP)
luaX_error(ls, "syntax error");
left = assignment(ls, &nv, nvars+1, set_pop);
left = assignment(ls, &nv, nvars+1);
}
else { /* assignment -> '=' explist1 */
listdesc d;
@ -1258,15 +1238,16 @@ static int assignment (LexState *ls, vardesc *v, int nvars, OpCode *codes) {
}
if (v->k != VINDEXED || left+(nvars-1) == 0) {
/* global/local var or indexed var without values in between */
storevar(ls, v, codes);
storevar(ls, v);
}
else { /* indexed var with values in between*/
code_oparg(ls, codes[3], left+(nvars-1), -1);
left += 2; /* table/index are not popped, because they aren't on top */
code_oparg(ls, SETTABLE, left+(nvars-1), -1);
left += 2; /* table&index are not popped, because they aren't on top */
}
return left;
}
static void constructor (LexState *ls) {
/* constructor -> '{' part [';' part] '}' */
int line = ls->linenumber;

32
lvm.c
View File

@ -1,5 +1,5 @@
/*
** $Id: lvm.c,v 1.52 1999/03/04 21:15:50 roberto Exp roberto $
** $Id: lvm.c,v 1.53 1999/03/05 21:16:07 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
@ -356,11 +356,6 @@ StkId luaV_execute (Closure *cl, TProtoFunc *tf, StkId base) {
S->top -= aux;
break;
case POPDUP: aux = *pc++;
*(S->top-aux-1) = *(S->top-1);
S->top -= aux;
break;
case PUSHNUMBERW: aux += highbyte(*pc++);
case PUSHNUMBER: aux += *pc++;
ttype(S->top) = LUA_T_NUMBER;
@ -424,45 +419,20 @@ StkId luaV_execute (Closure *cl, TProtoFunc *tf, StkId base) {
*((S->stack+base) + aux) = *(--S->top);
break;
case SETLOCALDUP: aux = *pc++;
*((S->stack+base) + aux) = *(S->top-1);
break;
case SETGLOBALW: aux += highbyte(*pc++);
case SETGLOBAL: aux += *pc++;
luaV_setglobal(tsvalue(&consts[aux]));
break;
case SETGLOBALDUPW: aux += highbyte(*pc++);
case SETGLOBALDUP: aux += *pc++;
*S->top = *(S->top-1);
S->top++;
luaV_setglobal(tsvalue(&consts[aux]));
break;
case SETTABLEPOP:
luaV_settable(S->top-3);
S->top -= 2; /* pop table and index */
break;
case SETTABLEPOPDUP: {
TObject temp = *(S->top-1);
luaV_settable(S->top-3);
S->top--; /* pop index (temp goes into "table" position) */
*(S->top-1) = temp;
break;
}
case SETTABLE:
luaV_settable(S->top-3-(*pc++));
break;
case SETTABLEDUP:
*S->top = *(S->top-1);
S->top++;
luaV_settable(S->top-(3+1)-(*pc++));
break;
case SETLISTW: aux += highbyte(*pc++);
case SETLIST: aux += *pc++; {
int n = *(pc++);

12
manual.tex
View File

@ -1,4 +1,4 @@
% $Id: manual.tex,v 1.24 1999/02/25 19:13:56 roberto Exp roberto $
% $Id: manual.tex,v 1.25 1999/03/04 21:23:39 roberto Exp roberto $
\documentclass[11pt]{article}
\usepackage{fullpage,bnf}
@ -41,7 +41,7 @@ Waldemar Celes
\tecgraf\ --- Computer Science Department --- PUC-Rio
}
%\date{\small \verb$Date: 1999/02/25 19:13:56 $}
%\date{\small \verb$Date: 1999/03/04 21:23:39 $}
\maketitle
@ -697,14 +697,6 @@ according to its condition.
Its final value is the value of the chosen expression.
An absent else-part is equivalent to \verb|else nil|.
\subsubsection{Assignment Expressions}
\begin{Produc}
\produc{exp}{\ter{(} varlist1 \ter{=} explist1 \ter{)}}
\end{Produc}%
An \Index{assignment expression} executes a multiple assignment,
and results in the final value of its first right hand expression
(that is, the value assigned to the first variable in the variable list).
\subsubsection{Table Constructors} \label{tableconstructor}
Table \Index{constructors} are expressions that create tables;
every time a constructor is evaluated, a new table is created.

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