Lexical Analizer
This commit is contained in:
Roberto Ierusalimschy
462
llex.c
Normal file
462
llex.c
Normal file
@@ -0,0 +1,462 @@
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/*
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** $Id: $
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** Lexical Analizer
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** See Copyright Notice in lua.h
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*/
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#include <ctype.h>
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#include <string.h>
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#include "lglobal.h"
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#include "llex.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lparser.h"
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#include "lstring.h"
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#include "ltokens.h"
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#include "luadebug.h"
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#include "lzio.h"
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static int current; /* look ahead character */
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static ZIO *lex_z;
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int luaX_linenumber;
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int lua_debug=0;
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#define next() (current = zgetc(lex_z))
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static void addReserved (void)
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{
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static struct {
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char *name;
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int token;
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} reserved [] = {
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{"and", AND}, {"do", DO}, {"else", ELSE}, {"elseif", ELSEIF},
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{"end", END}, {"function", FUNCTION}, {"if", IF}, {"local", LOCAL},
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{"nil", NIL}, {"not", NOT}, {"or", OR}, {"repeat", REPEAT},
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{"return", RETURN}, {"then", THEN}, {"until", UNTIL}, {"while", WHILE}
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};
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static int firsttime = 1;
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if (firsttime) {
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int i;
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firsttime = 0;
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for (i=0; i<(sizeof(reserved)/sizeof(reserved[0])); i++) {
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TaggedString *ts = luaS_new(reserved[i].name);
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ts->marked = reserved[i].token; /* reserved word (always > 255) */
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}
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}
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}
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#define MAX_IFS 5
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/* "ifstate" keeps the state of each nested $if the lexical is dealing with. */
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static struct {
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int elsepart; /* true if its in the $else part */
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int condition; /* true if $if condition is true */
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int skip; /* true if part must be skiped */
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} ifstate[MAX_IFS];
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static int iflevel; /* level of nested $if's */
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static struct textbuff {
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char *text;
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int tokensize;
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int buffsize;
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} textbuff;
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static void firstline (void)
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{
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int c = zgetc(lex_z);
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if (c == '#')
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while((c=zgetc(lex_z)) != '\n' && c != EOZ) /* skip first line */;
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zungetc(lex_z);
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}
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void luaX_setinput (ZIO *z)
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{
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addReserved();
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current = '\n';
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luaX_linenumber = 0;
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iflevel = 0;
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ifstate[0].skip = 0;
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ifstate[0].elsepart = 1; /* to avoid a free $else */
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lex_z = z;
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firstline();
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textbuff.buffsize = 20;
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textbuff.text = luaM_buffer(textbuff.buffsize);
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}
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/*
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** =======================================================
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** PRAGMAS
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** =======================================================
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*/
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#define PRAGMASIZE 20
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static void skipspace (void)
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{
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while (current == ' ' || current == '\t') next();
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}
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static int checkcond (char *buff)
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{
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static char *opts[] = {"nil", "1"};
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int i = luaO_findstring(buff, opts);
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if (i >= 0) return i;
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else if (isalpha((unsigned char)buff[0]) || buff[0] == '_')
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return luaG_globaldefined(buff);
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else {
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luaY_syntaxerror("invalid $if condition", buff);
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return 0; /* to avoid warnings */
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}
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}
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static void readname (char *buff)
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{
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int i = 0;
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skipspace();
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while (isalnum(current) || current == '_') {
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if (i >= PRAGMASIZE) {
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buff[PRAGMASIZE] = 0;
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luaY_syntaxerror("pragma too long", buff);
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}
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buff[i++] = current;
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next();
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}
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buff[i] = 0;
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}
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static void inclinenumber (void);
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static void ifskip (void)
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{
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while (ifstate[iflevel].skip) {
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if (current == '\n')
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inclinenumber();
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else if (current == EOZ)
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luaY_syntaxerror("input ends inside a $if", "");
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else next();
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}
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}
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static void inclinenumber (void)
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{
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static char *pragmas [] =
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{"debug", "nodebug", "endinput", "end", "ifnot", "if", "else", NULL};
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next(); /* skip '\n' */
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++luaX_linenumber;
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if (current == '$') { /* is a pragma? */
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char buff[PRAGMASIZE+1];
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int ifnot = 0;
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int skip = ifstate[iflevel].skip;
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next(); /* skip $ */
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readname(buff);
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switch (luaO_findstring(buff, pragmas)) {
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case 0: /* debug */
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if (!skip) lua_debug = 1;
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break;
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case 1: /* nodebug */
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if (!skip) lua_debug = 0;
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break;
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case 2: /* endinput */
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if (!skip) {
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current = EOZ;
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iflevel = 0; /* to allow $endinput inside a $if */
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}
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break;
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case 3: /* end */
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if (iflevel-- == 0)
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luaY_syntaxerror("unmatched $end", "$end");
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break;
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case 4: /* ifnot */
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ifnot = 1;
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/* go through */
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case 5: /* if */
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if (iflevel == MAX_IFS-1)
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luaY_syntaxerror("too many nested `$ifs'", "$if");
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readname(buff);
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iflevel++;
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ifstate[iflevel].elsepart = 0;
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ifstate[iflevel].condition = checkcond(buff) ? !ifnot : ifnot;
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ifstate[iflevel].skip = skip || !ifstate[iflevel].condition;
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break;
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case 6: /* else */
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if (ifstate[iflevel].elsepart)
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luaY_syntaxerror("unmatched $else", "$else");
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ifstate[iflevel].elsepart = 1;
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ifstate[iflevel].skip =
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ifstate[iflevel-1].skip || ifstate[iflevel].condition;
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break;
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default:
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luaY_syntaxerror("invalid pragma", buff);
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}
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skipspace();
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if (current == '\n') /* pragma must end with a '\n' ... */
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inclinenumber();
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else if (current != EOZ) /* or eof */
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luaY_syntaxerror("invalid pragma format", buff);
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ifskip();
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}
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}
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/*
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** =======================================================
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** LEXICAL ANALIZER
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** =======================================================
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*/
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static void save (int c)
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{
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if (textbuff.tokensize >= textbuff.buffsize)
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textbuff.text = luaM_buffer(textbuff.buffsize *= 2);
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textbuff.text[textbuff.tokensize++] = c;
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}
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char *luaX_lasttoken (void)
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{
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save(0);
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return textbuff.text;
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}
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#define save_and_next() (save(current), next())
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static int read_long_string (void)
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{
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int cont = 0;
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while (1) {
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switch (current) {
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case EOZ:
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save(0);
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return WRONGTOKEN;
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case '[':
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save_and_next();
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if (current == '[') {
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cont++;
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save_and_next();
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}
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continue;
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case ']':
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save_and_next();
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if (current == ']') {
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if (cont == 0) goto endloop;
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cont--;
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save_and_next();
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}
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continue;
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case '\n':
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save('\n');
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inclinenumber();
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continue;
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default:
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save_and_next();
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}
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} endloop:
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save_and_next(); /* pass the second ']' */
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textbuff.text[textbuff.tokensize-2] = 0; /* erases ']]' */
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luaY_lval.pTStr = luaS_new(textbuff.text+2);
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textbuff.text[textbuff.tokensize-2] = ']'; /* restores ']]' */
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return STRING;
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}
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int luaY_lex (void)
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{
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static int linelasttoken = 0;
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double a;
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textbuff.tokensize = 0;
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if (lua_debug)
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luaY_codedebugline(linelasttoken);
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linelasttoken = luaX_linenumber;
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while (1) {
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switch (current) {
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case '\n':
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inclinenumber();
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linelasttoken = luaX_linenumber;
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continue;
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case ' ': case '\t': case '\r': /* CR: to avoid problems with DOS */
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next();
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continue;
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case '-':
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save_and_next();
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if (current != '-') return '-';
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do { next(); } while (current != '\n' && current != EOZ);
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textbuff.tokensize = 0;
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continue;
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case '[':
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save_and_next();
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if (current != '[') return '[';
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else {
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save_and_next(); /* pass the second '[' */
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return read_long_string();
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}
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case '=':
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save_and_next();
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if (current != '=') return '=';
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else { save_and_next(); return EQ; }
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case '<':
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save_and_next();
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if (current != '=') return '<';
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else { save_and_next(); return LE; }
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case '>':
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save_and_next();
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if (current != '=') return '>';
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else { save_and_next(); return GE; }
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case '~':
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save_and_next();
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if (current != '=') return '~';
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else { save_and_next(); return NE; }
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case '"':
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case '\'': {
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int del = current;
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save_and_next();
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while (current != del) {
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switch (current) {
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case EOZ:
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case '\n':
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save(0);
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return WRONGTOKEN;
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case '\\':
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next(); /* do not save the '\' */
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switch (current) {
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case 'n': save('\n'); next(); break;
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case 't': save('\t'); next(); break;
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case 'r': save('\r'); next(); break;
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case '\n': save('\n'); inclinenumber(); break;
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default : save_and_next(); break;
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}
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break;
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default:
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save_and_next();
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}
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}
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next(); /* skip delimiter */
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save(0);
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luaY_lval.pTStr = luaS_new(textbuff.text+1);
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textbuff.text[textbuff.tokensize-1] = del; /* restore delimiter */
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return STRING;
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}
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case '.':
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save_and_next();
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if (current == '.')
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{
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save_and_next();
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if (current == '.')
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{
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save_and_next();
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return DOTS; /* ... */
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}
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else return CONC; /* .. */
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}
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else if (!isdigit(current)) return '.';
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/* current is a digit: goes through to number */
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a=0.0;
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goto fraction;
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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a=0.0;
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do {
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a=10.0*a+(current-'0');
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save_and_next();
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} while (isdigit(current));
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if (current == '.') {
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save_and_next();
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if (current == '.') {
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save(0);
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luaY_error(
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"ambiguous syntax (decimal point x string concatenation)");
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}
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}
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fraction:
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{ double da=0.1;
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while (isdigit(current))
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{
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a+=(current-'0')*da;
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da/=10.0;
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save_and_next();
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}
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if (toupper(current) == 'E') {
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int e=0;
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int neg;
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double ea;
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save_and_next();
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neg=(current=='-');
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if (current == '+' || current == '-') save_and_next();
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if (!isdigit(current)) {
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save(0); return WRONGTOKEN; }
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do {
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e=10.0*e+(current-'0');
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save_and_next();
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} while (isdigit(current));
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for (ea=neg?0.1:10.0; e>0; e>>=1)
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{
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if (e & 1) a*=ea;
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ea*=ea;
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}
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}
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luaY_lval.vReal = a;
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return NUMBER;
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}
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case EOZ:
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save(0);
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if (iflevel > 0)
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luaY_error("missing $endif");
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return 0;
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default:
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if (current != '_' && !isalpha(current)) {
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save_and_next();
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return textbuff.text[0];
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}
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else { /* identifier or reserved word */
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TaggedString *ts;
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do {
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save_and_next();
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} while (isalnum(current) || current == '_');
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save(0);
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ts = luaS_new(textbuff.text);
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if (ts->marked > 255)
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return ts->marked; /* reserved word */
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luaY_lval.pTStr = ts;
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return NAME;
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}
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}
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}
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}
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Reference in New Issue
Block a user