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lua/llex.c

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/*
** $Id: llex.c,v 1.115 2002/10/22 16:45:52 roberto Exp roberto $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/
#include <ctype.h>
#include <string.h>
#include "lua.h"
#include "ldo.h"
#include "llex.h"
#include "lobject.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "lzio.h"
#define next(LS) (LS->current = zgetc(LS->z))
/* ORDER RESERVED */
static const char *const token2string [] = {
"and", "break", "do", "else", "elseif",
"end", "false", "for", "function", "if",
"in", "local", "nil", "not", "or", "repeat",
"return", "then", "true", "until", "while", "*name",
"..", "...", "==", ">=", "<=", "~=",
"*number", "*string", "<eof>"
};
void luaX_init (lua_State *L) {
int i;
for (i=0; i<NUM_RESERVED; i++) {
TString *ts = luaS_new(L, token2string[i]);
luaS_fix(ts); /* reserved words are never collected */
lua_assert(strlen(token2string[i])+1 <= TOKEN_LEN);
ts->tsv.reserved = cast(lu_byte, i+1); /* reserved word */
}
}
#define MAXSRC 80
void luaX_checklimit (LexState *ls, int val, int limit, const char *msg) {
if (val > limit) {
msg = luaO_pushfstring(ls->L, "too many %s (limit=%d)", msg, limit);
luaX_syntaxerror(ls, msg);
}
}
static void luaX_error (LexState *ls, const char *s, const char *token) {
lua_State *L = ls->L;
char buff[MAXSRC];
luaO_chunkid(buff, getstr(ls->source), MAXSRC);
luaO_pushfstring(L, "%s:%d: %s near `%s'", buff, ls->linenumber, s, token);
luaD_throw(L, LUA_ERRSYNTAX);
}
void luaX_syntaxerror (LexState *ls, const char *msg) {
const char *lasttoken;
switch (ls->t.token) {
case TK_NAME:
lasttoken = getstr(ls->t.seminfo.ts);
break;
case TK_STRING:
case TK_NUMBER:
lasttoken = luaZ_buffer(ls->buff);
break;
default:
lasttoken = luaX_token2str(ls, ls->t.token);
break;
}
luaX_error(ls, msg, lasttoken);
}
const char *luaX_token2str (LexState *ls, int token) {
if (token < FIRST_RESERVED) {
lua_assert(token == (char)token);
return luaO_pushfstring(ls->L, "%c", token);
}
else
return token2string[token-FIRST_RESERVED];
}
static void luaX_lexerror (LexState *ls, const char *s, int token) {
if (token == TK_EOS)
luaX_error(ls, s, luaX_token2str(ls, token));
else
luaX_error(ls, s, luaZ_buffer(ls->buff));
}
static void inclinenumber (LexState *LS) {
next(LS); /* skip `\n' */
++LS->linenumber;
luaX_checklimit(LS, LS->linenumber, MAX_INT, "lines in a chunk");
}
void luaX_setinput (lua_State *L, LexState *LS, ZIO *z, TString *source) {
LS->L = L;
LS->lookahead.token = TK_EOS; /* no look-ahead token */
LS->z = z;
LS->fs = NULL;
LS->linenumber = 1;
LS->lastline = 1;
LS->source = source;
next(LS); /* read first char */
if (LS->current == '#') {
do { /* skip first line */
next(LS);
} while (LS->current != '\n' && LS->current != EOZ);
}
}
/*
** =======================================================
** LEXICAL ANALYZER
** =======================================================
*/
/* use buffer to store names, literal strings and numbers */
/* extra space to allocate when growing buffer */
#define EXTRABUFF 32
/* maximum number of chars that can be read without checking buffer size */
#define MAXNOCHECK 5
#define checkbuffer(LS, len) \
if (((len)+MAXNOCHECK)*sizeof(char) > luaZ_sizebuffer((LS)->buff)) \
luaZ_openspace((LS)->L, (LS)->buff, (len)+EXTRABUFF)
#define save(LS, c, l) \
(luaZ_buffer((LS)->buff)[l++] = cast(char, c))
#define save_and_next(LS, l) (save(LS, LS->current, l), next(LS))
static size_t readname (LexState *LS) {
size_t l = 0;
checkbuffer(LS, l);
do {
checkbuffer(LS, l);
save_and_next(LS, l);
} while (isalnum(LS->current) || LS->current == '_');
save(LS, '\0', l);
return l-1;
}
/* LUA_NUMBER */
static void read_numeral (LexState *LS, int comma, SemInfo *seminfo) {
size_t l = 0;
checkbuffer(LS, l);
if (comma) save(LS, '.', l);
while (isdigit(LS->current)) {
checkbuffer(LS, l);
save_and_next(LS, l);
}
if (LS->current == '.') {
save_and_next(LS, l);
if (LS->current == '.') {
save_and_next(LS, l);
save(LS, '\0', l);
luaX_lexerror(LS,
"ambiguous syntax (decimal point x string concatenation)",
TK_NUMBER);
}
}
while (isdigit(LS->current)) {
checkbuffer(LS, l);
save_and_next(LS, l);
}
if (LS->current == 'e' || LS->current == 'E') {
save_and_next(LS, l); /* read `E' */
if (LS->current == '+' || LS->current == '-')
save_and_next(LS, l); /* optional exponent sign */
while (isdigit(LS->current)) {
checkbuffer(LS, l);
save_and_next(LS, l);
}
}
save(LS, '\0', l);
if (!luaO_str2d(luaZ_buffer(LS->buff), &seminfo->r))
luaX_lexerror(LS, "malformed number", TK_NUMBER);
}
static void read_long_string (LexState *LS, SemInfo *seminfo) {
int cont = 0;
size_t l = 0;
checkbuffer(LS, l);
save(LS, '[', l); /* save first `[' */
save_and_next(LS, l); /* pass the second `[' */
if (LS->current == '\n') /* string starts with a newline? */
inclinenumber(LS); /* skip it */
for (;;) {
checkbuffer(LS, l);
switch (LS->current) {
case EOZ:
save(LS, '\0', l);
luaX_lexerror(LS, (seminfo) ? "unfinished long string" :
"unfinished long comment", TK_EOS);
break; /* to avoid warnings */
case '[':
save_and_next(LS, l);
if (LS->current == '[') {
cont++;
save_and_next(LS, l);
}
continue;
case ']':
save_and_next(LS, l);
if (LS->current == ']') {
if (cont == 0) goto endloop;
cont--;
save_and_next(LS, l);
}
continue;
case '\n':
save(LS, '\n', l);
inclinenumber(LS);
if (!seminfo) l = 0; /* reset buffer to avoid wasting space */
continue;
default:
save_and_next(LS, l);
}
} endloop:
save_and_next(LS, l); /* skip the second `]' */
save(LS, '\0', l);
if (seminfo)
seminfo->ts = luaS_newlstr(LS->L, luaZ_buffer(LS->buff) + 2, l - 5);
}
static void read_string (LexState *LS, int del, SemInfo *seminfo) {
size_t l = 0;
checkbuffer(LS, l);
save_and_next(LS, l);
while (LS->current != del) {
checkbuffer(LS, l);
switch (LS->current) {
case EOZ:
save(LS, '\0', l);
luaX_lexerror(LS, "unfinished string", TK_EOS);
break; /* to avoid warnings */
case '\n':
save(LS, '\0', l);
luaX_lexerror(LS, "unfinished string", TK_STRING);
break; /* to avoid warnings */
case '\\':
next(LS); /* do not save the `\' */
switch (LS->current) {
case 'a': save(LS, '\a', l); next(LS); break;
case 'b': save(LS, '\b', l); next(LS); break;
case 'f': save(LS, '\f', l); next(LS); break;
case 'n': save(LS, '\n', l); next(LS); break;
case 'r': save(LS, '\r', l); next(LS); break;
case 't': save(LS, '\t', l); next(LS); break;
case 'v': save(LS, '\v', l); next(LS); break;
case '\n': save(LS, '\n', l); inclinenumber(LS); break;
case EOZ: break; /* will raise an error next loop */
default: {
if (!isdigit(LS->current))
save_and_next(LS, l); /* handles \\, \", \', and \? */
else { /* \xxx */
int c = 0;
int i = 0;
do {
c = 10*c + (LS->current-'0');
next(LS);
} while (++i<3 && isdigit(LS->current));
if (c > UCHAR_MAX) {
save(LS, '\0', l);
luaX_lexerror(LS, "escape sequence too large", TK_STRING);
}
save(LS, c, l);
}
}
}
break;
default:
save_and_next(LS, l);
}
}
save_and_next(LS, l); /* skip delimiter */
save(LS, '\0', l);
seminfo->ts = luaS_newlstr(LS->L, luaZ_buffer(LS->buff) + 1, l - 3);
}
int luaX_lex (LexState *LS, SemInfo *seminfo) {
for (;;) {
switch (LS->current) {
case '\n': {
inclinenumber(LS);
continue;
}
case '-': {
next(LS);
if (LS->current != '-') return '-';
/* else is a comment */
next(LS);
if (LS->current == '[' && (next(LS), LS->current == '['))
read_long_string(LS, NULL); /* long comment */
else /* short comment */
while (LS->current != '\n' && LS->current != EOZ)
next(LS);
continue;
}
case '[': {
next(LS);
if (LS->current != '[') return '[';
else {
read_long_string(LS, seminfo);
return TK_STRING;
}
}
case '=': {
next(LS);
if (LS->current != '=') return '=';
else { next(LS); return TK_EQ; }
}
case '<': {
next(LS);
if (LS->current != '=') return '<';
else { next(LS); return TK_LE; }
}
case '>': {
next(LS);
if (LS->current != '=') return '>';
else { next(LS); return TK_GE; }
}
case '~': {
next(LS);
if (LS->current != '=') return '~';
else { next(LS); return TK_NE; }
}
case '"':
case '\'': {
read_string(LS, LS->current, seminfo);
return TK_STRING;
}
case '.': {
next(LS);
if (LS->current == '.') {
next(LS);
if (LS->current == '.') {
next(LS);
return TK_DOTS; /* ... */
}
else return TK_CONCAT; /* .. */
}
else if (!isdigit(LS->current)) return '.';
else {
read_numeral(LS, 1, seminfo);
return TK_NUMBER;
}
}
case EOZ: {
return TK_EOS;
}
default: {
if (isspace(LS->current)) {
next(LS);
continue;
}
else if (isdigit(LS->current)) {
read_numeral(LS, 0, seminfo);
return TK_NUMBER;
}
else if (isalpha(LS->current) || LS->current == '_') {
/* identifier or reserved word */
size_t l = readname(LS);
TString *ts = luaS_newlstr(LS->L, luaZ_buffer(LS->buff), l);
if (ts->tsv.reserved > 0) /* reserved word? */
return ts->tsv.reserved - 1 + FIRST_RESERVED;
seminfo->ts = ts;
return TK_NAME;
}
else {
int c = LS->current;
if (iscntrl(c))
luaX_error(LS, "invalid control char",
luaO_pushfstring(LS->L, "char(%d)", c));
next(LS);
return c; /* single-char tokens (+ - / ...) */
}
}
}
}
}
#undef next
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