/*

** $Id: llex.c $

** Lexical Analyzer

** See Copyright Notice in lua.h

*/

#define llex_c

#define LUA_CORE

#include "lprefix.h"

#include <locale.h>

#include <string.h>

#include "lua.h"

#include "lctype.h"

#include "ldebug.h"

#include "ldo.h"

#include "lgc.h"

#include "llex.h"

#include "lobject.h"

#include "lparser.h"

#include "lstate.h"

#include "lstring.h"

#include "ltable.h"

#include "lzio.h"

#define next(ls) (ls->current = zgetc(ls->z))

/* minimum size for string buffer */

#if !defined(LUA_MINBUFFER)

#define LUA_MINBUFFER 32

#endif

#define currIsNewline(ls) (ls->current == '\n' || ls->current == '\r')

/* ORDER RESERVED */

static const char *const luaX_tokens [] = {

"and", "break", "do", "else", "elseif",

"end", "false", "for", "function", "goto", "if",

"in", "local", "nil", "not", "or", "repeat",

"return", "then", "true", "until", "while",

"//", "..", "...", "==", ">=", "<=", "~=",

"<<", ">>", "::", "<eof>",

"<number>", "<integer>", "<name>", "<string>"

};

#define save_and_next(ls) (save(ls, ls->current), next(ls))

static l_noret lexerror (LexState *ls, const char *msg, int token);

static void save (LexState *ls, int c) {

Mbuffer *b = ls->buff;

if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {

size_t newsize;

if (luaZ_sizebuffer(b) >= MAX_SIZE/2)

lexerror(ls, "lexical element too long", 0);

newsize = luaZ_sizebuffer(b) * 2;

luaZ_resizebuffer(ls->L, b, newsize);

}

b->buffer[luaZ_bufflen(b)++] = cast_char(c);

}

void luaX_init (lua_State *L) {

int i;

TString *e = luaS_newliteral(L, LUA_ENV); /* create env name */

luaC_fix(L, obj2gco(e)); /* never collect this name */

for (i=0; i<NUM_RESERVED; i++) {

TString *ts = luaS_new(L, luaX_tokens[i]);

luaC_fix(L, obj2gco(ts)); /* reserved words are never collected */

ts->extra = cast_byte(i+1); /* reserved word */

}

}

const char *luaX_token2str (LexState *ls, int token) {

if (token < FIRST_RESERVED) { /* single-byte symbols? */

if (lisprint(token))

return luaO_pushfstring(ls->L, "'%c'", token);

else /* control character */

return luaO_pushfstring(ls->L, "'<\\%d>'", token);

}

else {

const char *s = luaX_tokens[token - FIRST_RESERVED];

if (token < TK_EOS) /* fixed format (symbols and reserved words)? */

return luaO_pushfstring(ls->L, "'%s'", s);

else /* names, strings, and numerals */

return s;

}

}

static const char *txtToken (LexState *ls, int token) {

switch (token) {

case TK_NAME: case TK_STRING:

case TK_FLT: case TK_INT:

save(ls, '\0');

return luaO_pushfstring(ls->L, "'%s'", luaZ_buffer(ls->buff));

default:

return luaX_token2str(ls, token);

}

}

static l_noret lexerror (LexState *ls, const char *msg, int token) {

msg = luaG_addinfo(ls->L, msg, ls->source, ls->linenumber);

if (token)

luaO_pushfstring(ls->L, "%s near %s", msg, txtToken(ls, token));

luaD_throw(ls->L, LUA_ERRSYNTAX);

}

l_noret luaX_syntaxerror (LexState *ls, const char *msg) {

lexerror(ls, msg, ls->t.token);

}

/*

** Creates a new string and anchors it in scanner's table so that it

** will not be collected until the end of the compilation; by that time

** it should be anchored somewhere. It also internalizes long strings,

** ensuring there is only one copy of each unique string. The table

** here is used as a set: the string enters as the key, while its value

** is irrelevant. We use the string itself as the value only because it

** is a TValue readily available. Later, the code generation can change

** this value.

*/

TString *luaX_newstring (LexState *ls, const char *str, size_t l) {

lua_State *L = ls->L;

TString *ts = luaS_newlstr(L, str, l); /* create new string */

TString *oldts = luaH_getstrkey(ls->h, ts);

if (oldts != NULL) /* string already present? */

return oldts; /* use it */

else { /* create a new entry */

TValue *stv = s2v(L->top.p++); /* reserve stack space for string */

setsvalue(L, stv, ts); /* temporarily anchor the string */

luaH_set(L, ls->h, stv, stv); /* t[string] = string */

/* table is not a metatable, so it does not need to invalidate cache */

luaC_checkGC(L);

L->top.p--; /* remove string from stack */

}

return ts;

}

/*

** increment line number and skips newline sequence (any of

** \n, \r, \n\r, or \r\n)

*/

static void inclinenumber (LexState *ls) {

int old = ls->current;

lua_assert(currIsNewline(ls));

next(ls); /* skip '\n' or '\r' */

if (currIsNewline(ls) && ls->current != old)

next(ls); /* skip '\n\r' or '\r\n' */

if (++ls->linenumber >= INT_MAX)

lexerror(ls, "chunk has too many lines", 0);

}

void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,

int firstchar) {

ls->t.token = 0;

ls->L = L;

ls->current = firstchar;

ls->lookahead.token = TK_EOS; /* no look-ahead token */

ls->z = z;

ls->fs = NULL;

ls->linenumber = 1;

ls->lastline = 1;

ls->source = source;

ls->envn = luaS_newliteral(L, LUA_ENV); /* get env name */

luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER); /* initialize buffer */

}

/*

** =======================================================

** LEXICAL ANALYZER

** =======================================================

*/

static int check_next1 (LexState *ls, int c) {

if (ls->current == c) {

next(ls);

return 1;

}

else return 0;

}

/*

** Check whether current char is in set 'set' (with two chars) and

** saves it

*/

static int check_next2 (LexState *ls, const char *set) {

lua_assert(set[2] == '\0');

if (ls->current == set[0] || ls->current == set[1]) {

save_and_next(ls);

return 1;

}

else return 0;

}

/* LUA_NUMBER */

/*

** This function is quite liberal in what it accepts, as 'luaO_str2num'

** will reject ill-formed numerals. Roughly, it accepts the following

** pattern:

**

** %d(%x|%.|([Ee][+-]?))* | 0[Xx](%x|%.|([Pp][+-]?))*

**

** The only tricky part is to accept [+-] only after a valid exponent

** mark, to avoid reading '3-4' or '0xe+1' as a single number.

**

** The caller might have already read an initial dot.

*/

static int read_numeral (LexState *ls, SemInfo *seminfo) {

TValue obj;

const char *expo = "Ee";

int first = ls->current;

lua_assert(lisdigit(ls->current));

save_and_next(ls);

if (first == '0' && check_next2(ls, "xX")) /* hexadecimal? */

expo = "Pp";

for (;;) {

if (check_next2(ls, expo)) /* exponent mark? */

check_next2(ls, "-+"); /* optional exponent sign */

else if (lisxdigit(ls->current) || ls->current == '.') /* '%x|%.' */

save_and_next(ls);

else break;

}

if (lislalpha(ls->current)) /* is numeral touching a letter? */

save_and_next(ls); /* force an error */

save(ls, '\0');

if (luaO_str2num(luaZ_buffer(ls->buff), &obj) == 0) /* format error? */

lexerror(ls, "malformed number", TK_FLT);

if (ttisinteger(&obj)) {

seminfo->i = ivalue(&obj);

return TK_INT;

}

else {

lua_assert(ttisfloat(&obj));

seminfo->r = fltvalue(&obj);

return TK_FLT;

}

}

/*

** 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;

int s = ls->current;

lua_assert(s == '[' || s == ']');

save_and_next(ls);

while (ls->current == '=') {

save_and_next(ls);

count++;

}

return (ls->current == s) ? count + 2

: (count == 0) ? 1

: 0;

}

static void read_long_string (LexState *ls, SemInfo *seminfo, size_t sep) {

int line = ls->linenumber; /* initial line (for error message) */

save_and_next(ls); /* skip 2nd '[' */

if (currIsNewline(ls)) /* string starts with a newline? */

inclinenumber(ls); /* skip it */

for (;;) {

switch (ls->current) {

case EOZ: { /* error */

const char *what = (seminfo ? "string" : "comment");

const char *msg = luaO_pushfstring(ls->L,

"unfinished long %s (starting at line %d)", what, line);

lexerror(ls, msg, TK_EOS);

break; /* to avoid warnings */

}

case ']': {

if (skip_sep(ls) == sep) {

save_and_next(ls); /* skip 2nd ']' */

goto endloop;

}

break;

}

case '\n': case '\r': {

save(ls, '\n');

inclinenumber(ls);

if (!seminfo) luaZ_resetbuffer(ls->buff); /* avoid wasting space */

break;

}

default: {

if (seminfo) save_and_next(ls);

else next(ls);

}

}

} endloop:

if (seminfo)

seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + sep,

luaZ_bufflen(ls->buff) - 2 * sep);

}

static void esccheck (LexState *ls, int c, const char *msg) {

if (!c) {

if (ls->current != EOZ)

save_and_next(ls); /* add current to buffer for error message */

lexerror(ls, msg, TK_STRING);

}

}

static int gethexa (LexState *ls) {

save_and_next(ls);

esccheck (ls, lisxdigit(ls->current), "hexadecimal digit expected");

return luaO_hexavalue(ls->current);

}

static int readhexaesc (LexState *ls) {

int r = gethexa(ls);

r = (r << 4) + gethexa(ls);

luaZ_buffremove(ls->buff, 2); /* remove saved chars from buffer */

return r;

}

static unsigned long readutf8esc (LexState *ls) {

unsigned long r;

int i = 4; /* chars to be removed: '\', 'u', '{', and first digit */

save_and_next(ls); /* skip 'u' */

esccheck(ls, ls->current == '{', "missing '{'");

r = cast_ulong(gethexa(ls)); /* must have at least one digit */

while (cast_void(save_and_next(ls)), lisxdigit(ls->current)) {

i++;

esccheck(ls, r <= (0x7FFFFFFFu >> 4), "UTF-8 value too large");

r = (r << 4) + luaO_hexavalue(ls->current);

}

esccheck(ls, ls->current == '}', "missing '}'");

next(ls); /* skip '}' */

luaZ_buffremove(ls->buff, i); /* remove saved chars from buffer */

return r;

}

static void utf8esc (LexState *ls) {

char buff[UTF8BUFFSZ];

int n = luaO_utf8esc(buff, readutf8esc(ls));

for (; n > 0; n--) /* add 'buff' to string */

save(ls, buff[UTF8BUFFSZ - n]);

}

static int readdecesc (LexState *ls) {

int i;

int r = 0; /* result accumulator */

for (i = 0; i < 3 && lisdigit(ls->current); i++) { /* read up to 3 digits */

r = 10*r + ls->current - '0';

save_and_next(ls);

}

esccheck(ls, r <= UCHAR_MAX, "decimal escape too large");

luaZ_buffremove(ls->buff, i); /* remove read digits from buffer */

return r;

}

static void read_string (LexState *ls, int del, SemInfo *seminfo) {

save_and_next(ls); /* keep delimiter (for error messages) */

while (ls->current != del) {

switch (ls->current) {

case EOZ:

lexerror(ls, "unfinished string", TK_EOS);

break; /* to avoid warnings */

case '\n':

case '\r':

lexerror(ls, "unfinished string", TK_STRING);

break; /* to avoid warnings */

case '\\': { /* escape sequences */

int c; /* final character to be saved */

save_and_next(ls); /* keep '\\' for error messages */

switch (ls->current) {

case 'a': c = '\a'; goto read_save;

case 'b': c = '\b'; goto read_save;

case 'f': c = '\f'; goto read_save;

case 'n': c = '\n'; goto read_save;

case 'r': c = '\r'; goto read_save;

case 't': c = '\t'; goto read_save;

case 'v': c = '\v'; goto read_save;

case 'x': c = readhexaesc(ls); goto read_save;

case 'u': utf8esc(ls); goto no_save;

case '\n': case '\r':

inclinenumber(ls); c = '\n'; goto only_save;

case '\\': case '\"': case '\'':

c = ls->current; goto read_save;

case EOZ: goto no_save; /* will raise an error next loop */

case 'z': { /* zap following span of spaces */

luaZ_buffremove(ls->buff, 1); /* remove '\\' */

next(ls); /* skip the 'z' */

while (lisspace(ls->current)) {

if (currIsNewline(ls)) inclinenumber(ls);

else next(ls);

}

goto no_save;

}

default: {

esccheck(ls, lisdigit(ls->current), "invalid escape sequence");

c = readdecesc(ls); /* digital escape '\ddd' */

goto only_save;

}

}

read_save:

next(ls);

/* go through */

only_save:

luaZ_buffremove(ls->buff, 1); /* remove '\\' */

save(ls, c);

/* go through */

no_save: break;

}

default:

save_and_next(ls);

}

}

save_and_next(ls); /* skip delimiter */

seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1,

luaZ_bufflen(ls->buff) - 2);

}

static int llex (LexState *ls, SemInfo *seminfo) {

luaZ_resetbuffer(ls->buff);

for (;;) {

switch (ls->current) {

case '\n': case '\r': { /* line breaks */

inclinenumber(ls);

break;

}

case ' ': case '\f': case '\t': case '\v': { /* spaces */

next(ls);

break;

}

case '-': { /* '-' or '--' (comment) */

next(ls);

if (ls->current != '-') return '-';

/* else is a comment */

next(ls);

if (ls->current == '[') { /* long comment? */

size_t sep = skip_sep(ls);

luaZ_resetbuffer(ls->buff); /* 'skip_sep' may dirty the buffer */

if (sep >= 2) {

read_long_string(ls, NULL, sep); /* skip long comment */

luaZ_resetbuffer(ls->buff); /* previous call may dirty the buff. */

break;

}

}

/* else short comment */

while (!currIsNewline(ls) && ls->current != EOZ)

next(ls); /* skip until end of line (or end of file) */

break;

}

case '[': { /* long string or simply '[' */

size_t sep = skip_sep(ls);

if (sep >= 2) {

read_long_string(ls, seminfo, sep);

return TK_STRING;

}

else if (sep == 0) /* '[=...' missing second bracket? */

lexerror(ls, "invalid long string delimiter", TK_STRING);

return '[';

}

case '=': {

next(ls);

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; /* '<<' */

else return '<';

}

case '>': {

next(ls);

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; /* '//' */

else return '/';

}

case '~': {

next(ls);

if (check_next1(ls, '=')) return TK_NE; /* '~=' */

else return '~';

}

case ':': {

next(ls);

if (check_next1(ls, ':')) return TK_DBCOLON; /* '::' */

else return ':';

}

case '"': case '\'': { /* short literal strings */

read_string(ls, ls->current, seminfo);

return TK_STRING;

}

case '.': { /* '.', '..', '...', or number */

save_and_next(ls);

if (check_next1(ls, '.')) {

if (check_next1(ls, '.'))

return TK_DOTS; /* '...' */

else return TK_CONCAT; /* '..' */

}

else if (!lisdigit(ls->current)) return '.';

else return read_numeral(ls, seminfo);

}

case '0': case '1': case '2': case '3': case '4':

case '5': case '6': case '7': case '8': case '9': {

return read_numeral(ls, seminfo);

}

case EOZ: {

return TK_EOS;

}

default: {

if (lislalpha(ls->current)) { /* identifier or reserved word? */

TString *ts;

do {

save_and_next(ls);

} while (lislalnum(ls->current));

ts = luaX_newstring(ls, luaZ_buffer(ls->buff),

luaZ_bufflen(ls->buff));

seminfo->ts = ts;

if (isreserved(ts)) /* reserved word? */

return ts->extra - 1 + FIRST_RESERVED;

else {

return TK_NAME;

}

}

else { /* single-char tokens ('+', '*', '%', '{', '}', ...) */

int c = ls->current;

next(ls);

return c;

}

}

}

}

}

void luaX_next (LexState *ls) {

ls->lastline = ls->linenumber;

if (ls->lookahead.token != TK_EOS) { /* is there a look-ahead token? */

ls->t = ls->lookahead; /* use this one */

ls->lookahead.token = TK_EOS; /* and discharge it */

}

else

ls->t.token = llex(ls, &ls->t.seminfo); /* read next token */

}

int luaX_lookahead (LexState *ls) {

lua_assert(ls->lookahead.token == TK_EOS);

ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);

return ls->lookahead.token;

}