/*
** $Id: llex.c,v 2.63.1.2 2013/08/30 15:49:41 roberto Exp $
** Lexical Analyzer
** See Copyright Notice in lua.h
*/

#include <locale.h>
#include <string.h>

#define llex_c
#define LUA_CORE

#include "lua.h"

#include "lctype.h"
#include "ldo.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))

#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>", "<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_SIZET / 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;
	for (i = 0; i < NUM_RESERVED; i++)
	{
		TString *ts = luaS_new(L, luaX_tokens[i]);
		luaS_fix(ts);                     /* reserved words are never collected */
		ts->tsv.extra = cast_byte(i + 1); /* reserved word */
	}
}

const char *luaX_token2str(LexState *ls, int token)
{
	if (token < FIRST_RESERVED)
	{ /* single-byte symbols? */
		lua_assert(token == cast(unsigned char, token));
		return (lisprint(token)) ? luaO_pushfstring(ls->L, LUA_QL("%c"), token) : luaO_pushfstring(ls->L, "char(%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, LUA_QS, 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_NUMBER:
			save(ls, '\0');
			return luaO_pushfstring(ls->L, LUA_QS, luaZ_buffer(ls->buff));
		default:
			return luaX_token2str(ls, token);
	}
}

static l_noret lexerror(LexState *ls, const char *msg, int token)
{
	char buff[LUA_IDSIZE];
	luaO_chunkid(buff, getstr(ls->source), LUA_IDSIZE);
	msg = luaO_pushfstring(ls->L, "%s:%d: %s", buff, ls->linenumber, msg);
	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 function's table so that
** it will not be collected until the end of the function's compilation
** (by that time it should be anchored in function's prototype)
*/
TString *luaX_newstring(LexState *ls, const char *str, size_t l)
{
	lua_State *L = ls->L;
	TValue *o;                             /* entry for `str' */
	TString *ts = luaS_newlstr(L, str, l); /* create new string */
	setsvalue2s(L, L->top++, ts);          /* temporarily anchor it in stack */
	o = luaH_set(L, ls->fs->h, L->top - 1);
	if (ttisnil(o))
	{ /* not in use yet? (see 'addK') */
		/* boolean value does not need GC barrier;
       table has no metatable, so it does not need to invalidate cache */
		setbvalue(o, 1); /* t[string] = true */
		luaC_checkGC(L);
	}
	else
	{                                   /* string already present */
		ts = rawtsvalue(keyfromval(o)); /* re-use value previously stored */
	}
	L->top--; /* 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 >= MAX_INT)
		luaX_syntaxerror(ls, "chunk has too many lines");
}

void luaX_setinput(lua_State *L, LexState *ls, ZIO *z, TString *source,
				   int firstchar)
{
	ls->decpoint = '.';
	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_new(L, LUA_ENV);                   /* create env name */
	luaS_fix(ls->envn);                                /* never collect this name */
	luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER); /* initialize buffer */
}

/*
** =======================================================
** LEXICAL ANALYZER
** =======================================================
*/

static int check_next(LexState *ls, const char *set)
{
	if (ls->current == '\0' || !strchr(set, ls->current))
		return 0;
	save_and_next(ls);
	return 1;
}

/*
** change all characters 'from' in buffer to 'to'
*/
static void buffreplace(LexState *ls, char from, char to)
{
	size_t n = luaZ_bufflen(ls->buff);
	char *p = luaZ_buffer(ls->buff);
	while (n--)
		if (p[n] == from) p[n] = to;
}

#if !defined(getlocaledecpoint)
#define getlocaledecpoint() (localeconv()->decimal_point[0])
#endif

#define buff2d(b, e) luaO_str2d(luaZ_buffer(b), luaZ_bufflen(b) - 1, e)

/*
** in case of format error, try to change decimal point separator to
** the one defined in the current locale and check again
*/
static void trydecpoint(LexState *ls, SemInfo *seminfo)
{
	char old = ls->decpoint;
	ls->decpoint = getlocaledecpoint();
	buffreplace(ls, old, ls->decpoint); /* try new decimal separator */
	if (!buff2d(ls->buff, &seminfo->r))
	{
		/* format error with correct decimal point: no more options */
		buffreplace(ls, ls->decpoint, '.'); /* undo change (for error message) */
		lexerror(ls, "malformed number", TK_NUMBER);
	}
}

/* LUA_NUMBER */
/*
** this function is quite liberal in what it accepts, as 'luaO_str2d'
** will reject ill-formed numerals.
*/
static void read_numeral(LexState *ls, SemInfo *seminfo)
{
	const char *expo = "Ee";
	int first = ls->current;
	lua_assert(lisdigit(ls->current));
	save_and_next(ls);
	if (first == '0' && check_next(ls, "Xx")) /* hexadecimal? */
		expo = "Pp";
	for (;;)
	{
		if (check_next(ls, expo)) /* exponent part? */
			check_next(ls, "+-"); /* optional exponent sign */
		if (lisxdigit(ls->current) || ls->current == '.')
			save_and_next(ls);
		else
			break;
	}
	save(ls, '\0');
	buffreplace(ls, '.', ls->decpoint); /* follow locale for decimal point */
	if (!buff2d(ls->buff, &seminfo->r)) /* format error? */
		trydecpoint(ls, seminfo);       /* try to update decimal point separator */
}

/*
** skip a sequence '[=*[' or ']=*]' and return its number of '='s or
** -1 if sequence is malformed
*/
static int skip_sep(LexState *ls)
{
	int 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 : (-count) - 1;
}

static void read_long_string(LexState *ls, SemInfo *seminfo, int sep)
{
	save_and_next(ls);     /* skip 2nd `[' */
	if (currIsNewline(ls)) /* string starts with a newline? */
		inclinenumber(ls); /* skip it */
	for (;;)
	{
		switch (ls->current)
		{
			case EOZ:
				lexerror(ls, (seminfo) ? "unfinished long string" : "unfinished long comment", 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) + (2 + sep),
									 luaZ_bufflen(ls->buff) - 2 * (2 + sep));
}

static void escerror(LexState *ls, int *c, int n, const char *msg)
{
	int i;
	luaZ_resetbuffer(ls->buff); /* prepare error message */
	save(ls, '\\');
	for (i = 0; i < n && c[i] != EOZ; i++)
		save(ls, c[i]);
	lexerror(ls, msg, TK_STRING);
}

static int readhexaesc(LexState *ls)
{
	int c[3], i; /* keep input for error message */
	int r = 0;   /* result accumulator */
	c[0] = 'x';  /* for error message */
	for (i = 1; i < 3; i++)
	{ /* read two hexadecimal digits */
		c[i] = next(ls);
		if (!lisxdigit(c[i]))
			escerror(ls, c, i + 1, "hexadecimal digit expected");
		r = (r << 4) + luaO_hexavalue(c[i]);
	}
	return r;
}

static int readdecesc(LexState *ls)
{
	int c[3], i;
	int r = 0; /* result accumulator */
	for (i = 0; i < 3 && lisdigit(ls->current); i++)
	{ /* read up to 3 digits */
		c[i] = ls->current;
		r = 10 * r + c[i] - '0';
		next(ls);
	}
	if (r > UCHAR_MAX)
		escerror(ls, c, i, "decimal escape too large");
	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 */
				next(ls); /* do not save the `\' */
				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 '\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 */
						next(ls); /* skip the 'z' */
						while (lisspace(ls->current))
						{
							if (currIsNewline(ls))
								inclinenumber(ls);
							else
								next(ls);
						}
						goto no_save;
					}
					default:
					{
						if (!lisdigit(ls->current))
							escerror(ls, &ls->current, 1, "invalid escape sequence");
						/* digital escape \ddd */
						c = readdecesc(ls);
						goto only_save;
					}
				}
			read_save:
				next(ls); /* read next character */
			only_save:
				save(ls, c); /* save 'c' */
			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? */
					int sep = skip_sep(ls);
					luaZ_resetbuffer(ls->buff); /* `skip_sep' may dirty the buffer */
					if (sep >= 0)
					{
						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 '[' */
				int sep = skip_sep(ls);
				if (sep >= 0)
				{
					read_long_string(ls, seminfo, sep);
					return TK_STRING;
				}
				else if (sep == -1)
					return '[';
				else
					lexerror(ls, "invalid long string delimiter", 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 ':':
			{
				next(ls);
				if (ls->current != ':')
					return ':';
				else
				{
					next(ls);
					return TK_DBCOLON;
				}
			}
			case '"':
			case '\'':
			{ /* short literal strings */
				read_string(ls, ls->current, seminfo);
				return TK_STRING;
			}
			case '.':
			{ /* '.', '..', '...', or number */
				save_and_next(ls);
				if (check_next(ls, "."))
				{
					if (check_next(ls, "."))
						return TK_DOTS; /* '...' */
					else
						return TK_CONCAT; /* '..' */
				}
				else if (!lisdigit(ls->current))
					return '.';
				/* else go through */
			}
			case '0':
			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
			{
				read_numeral(ls, seminfo);
				return TK_NUMBER;
			}
			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->tsv.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;
}
