mirror of https://github.com/lua/lua
new `read' option `*u' (read-until) + simpler implementation for `read'
This commit is contained in:
Roberto Ierusalimschy
parent
777061e441
commit
9559c111a3
174
liolib.c
174
liolib.c
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@ -1,5 +1,5 @@
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/*
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** $Id: liolib.c,v 1.114 2001/06/07 13:46:29 roberto Exp roberto $
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** $Id: liolib.c,v 1.115 2001/06/08 16:48:32 roberto Exp roberto $
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** Standard I/O (and system) library
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** See Copyright Notice in lua.h
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*/
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@ -205,6 +205,62 @@ static int io_appendto (lua_State *L) {
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*/
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#ifndef LUA_MAXUNTIL
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#define LUA_MAXUNTIL 100
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#endif
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/*
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** Knuth-Morris-Pratt algorithm for string searching
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** (based on `Algorithms in MODULA-3', Robert Sedgewick;
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** Addison-Wesley, 1993.)
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*/
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static void prep_read_until (int next[], const l_char *p, int pl) {
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int i = 0;
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int j = -1;
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next[0] = -1;
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while (i < pl) {
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if (j == -1 || p[i] == p[j]) {
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i++; j++; next[i] = j;
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}
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else j = next[j];
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}
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}
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static int read_until (lua_State *L, FILE *f, const l_char *p, int pl) {
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l_charint c;
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int j;
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int next[LUA_MAXUNTIL+1];
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luaL_Buffer b;
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luaL_buffinit(L, &b);
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prep_read_until(next, p, pl);
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j = 0;
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while ((c = fgetc(f)) != EOF) {
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NoRead:
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if (c == p[j]) {
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j++; /* go to next char in pattern */
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if (j == pl) { /* complete match? */
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luaL_pushresult(&b); /* close buffer */
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return 1; /* always success */
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}
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}
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else if (j == 0)
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luaL_putchar(&b, c);
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else { /* match fail */
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luaL_addlstring(&b, p, j - next[j]); /* put failed part on result */
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j = next[j]; /* backtrack pattern index */
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goto NoRead; /* repeat without reading next char */
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}
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}
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/* end of file without a match */
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luaL_addlstring(&b, p, j); /* put failed part on result */
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luaL_pushresult(&b); /* close buffer */
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return (lua_strlen(L, -1) > 0);
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}
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static int read_number (lua_State *L, FILE *f) {
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double d;
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if (fscanf(f, l_s("%lf"), &d) == 1) {
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@ -215,105 +271,48 @@ static int read_number (lua_State *L, FILE *f) {
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}
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static int read_word (lua_State *L, FILE *f) {
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l_charint c;
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luaL_Buffer b;
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luaL_buffinit(L, &b);
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do { c = fgetc(f); } while (isspace(c)); /* skip spaces */
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while (c != EOF && !isspace(c)) {
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luaL_putchar(&b, c);
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c = fgetc(f);
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}
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static int test_eof (lua_State *L, FILE *f) {
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l_charint c = fgetc(f);
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ungetc(c, f);
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luaL_pushresult(&b); /* close buffer */
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return (lua_strlen(L, -1) > 0);
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}
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static int read_line (lua_State *L, FILE *f) {
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int n = 0;
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luaL_Buffer b;
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luaL_buffinit(L, &b);
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for (;;) {
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l_char *p = luaL_prepbuffer(&b);
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if (!fgets(p, LUAL_BUFFERSIZE, f)) /* read fails? */
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break;
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n = strlen(p);
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if (p[n-1] != l_c('\n'))
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luaL_addsize(&b, n);
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else {
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luaL_addsize(&b, n-1); /* do not add the `\n' */
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break;
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}
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}
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luaL_pushresult(&b); /* close buffer */
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return (n > 0); /* read something? */
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}
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static void read_file (lua_State *L, FILE *f) {
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size_t len = 0;
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size_t size = LUAL_BUFFERSIZE;
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size_t oldsize = 0;
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l_char *buffer = NULL;
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for (;;) {
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l_char *newbuffer = (l_char *)l_realloc(buffer, oldsize, size);
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if (newbuffer == NULL) {
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l_free(buffer, oldsize);
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lua_error(L, l_s("not enough memory to read a file"));
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}
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buffer = newbuffer;
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len += fread(buffer+len, sizeof(l_char), size-len, f);
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if (len < size) break; /* did not read all it could */
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oldsize = size;
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size *= 2;
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}
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lua_pushlstring(L, buffer, len);
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l_free(buffer, size);
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lua_pushlstring(L, NULL, 0);
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return (c != EOF);
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}
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static int read_chars (lua_State *L, FILE *f, size_t n) {
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if (n == 0) { /* test eof? */
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l_charint c = fgetc(f);
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ungetc(c, f);
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lua_pushlstring(L, NULL, 0);
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return (c != EOF);
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}
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else {
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l_char *buffer;
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size_t n1;
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l_char statbuff[LUAL_BUFFERSIZE];
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if (n <= LUAL_BUFFERSIZE)
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buffer = statbuff;
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else {
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buffer = (l_char *)l_malloc(n);
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if (buffer == NULL)
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lua_error(L, l_s("not enough memory to read a file"));
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}
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n1 = fread(buffer, sizeof(l_char), n, f);
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lua_pushlstring(L, buffer, n1);
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if (buffer != statbuff) l_free(buffer, n);
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return (n1 > 0 || n == 0);
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}
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size_t rlen;
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luaL_Buffer b;
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luaL_buffinit(L, &b);
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rlen = LUAL_BUFFERSIZE;
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do {
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l_char *p = luaL_prepbuffer(&b);
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if (rlen > n) rlen = n;
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rlen = fread(p, sizeof(l_char), rlen, f);
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luaL_addsize(&b, rlen);
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n -= rlen;
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} while (n > 0 && rlen > 0); /* until end of count or eof */
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luaL_pushresult(&b); /* close buffer */
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return (n == 0 || lua_strlen(L, -1) > 0);
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}
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static int io_read (lua_State *L) {
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FILE *f = getopthandle(L, INFILE);
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int nargs = lua_gettop(L)-1;
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int nargs = lua_gettop(L) - 1;
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int success;
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int n;
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if (nargs == 0) { /* no arguments? */
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success = read_line(L, f);
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success = read_until(L, f, l_s("\n"), 1); /* read until \n (a line) */
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n = 2; /* will return n-1 results */
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}
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else { /* ensure stack space for all results and for auxlib's buffer */
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luaL_checkstack(L, nargs+LUA_MINSTACK, l_s("too many arguments"));
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success = 1;
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for (n = 1; n<=nargs && success; n++) {
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if (lua_type(L, n) == LUA_TNUMBER)
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success = read_chars(L, f, (size_t)lua_tonumber(L, n));
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if (lua_type(L, n) == LUA_TNUMBER) {
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size_t l = (size_t)lua_tonumber(L, n);
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success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
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}
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else {
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const l_char *p = lua_tostring(L, n);
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if (!p || p[0] != l_c('*'))
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@ -323,15 +322,22 @@ static int io_read (lua_State *L) {
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success = read_number(L, f);
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break;
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case l_c('l'): /* line */
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success = read_line(L, f);
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success = read_until(L, f, l_s("\n"), 1); /* read until \n */
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break;
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case l_c('a'): /* file */
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read_file(L, f);
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read_chars(L, f, ~((size_t)0)); /* read MAX_SIZE_T chars */
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success = 1; /* always success */
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break;
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case l_c('w'): /* word */
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success = read_word(L, f);
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lua_error(L, "option `*w' is deprecated");
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break;
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case l_c('u'): { /* read until */
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size_t pl = lua_strlen(L, n) - 2;
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luaL_arg_check(L, 0 < pl && pl <= LUA_MAXUNTIL, n,
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l_s("invalid read-until length"));
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success = read_until(L, f, p+2, (int)pl);
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break;
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}
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default:
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luaL_argerror(L, n, l_s("invalid format"));
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success = 0; /* to avoid warnings */
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