228 lines
5.4 KiB
C
228 lines
5.4 KiB
C
#include <assert.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#ifdef ENABLE_READLINE
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#include <stdlib.h>
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#include <readline/readline.h>
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#include <readline/history.h>
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#endif
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#include "expr.h"
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#define ssub(_x, _y) ((_x) >= (_y) ? (_x) - (_y) : 0)
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#define bufprint(_buf, _n, ...) _n += snprintf(_buf + _n, ssub(sizeof(buf), _n), __VA_ARGS__)
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static Expr *e;
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static bool running = true;
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static bool last_status_ok = true;
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#ifdef ENABLE_READLINE
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static bool sigwinch_received = false;
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static size_t completer_idx, completer_len;
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static bool completer_funcs;
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#endif
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static void print_help() {
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fprintf(stderr,
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"Usage:\n"
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" qc \"<expression>\" -- evaluate expression\n"
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" qc -- run in REPL mode\n"
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" qc --help -- show this page\n"
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"Syntax:\n"
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" Numbers: 123.45 or 1.2345e2 or 1.2345E2\n"
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" Precedence | Operations\n"
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" -----------+------------\n"
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" 1 (LtR) | +, -\n"
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" 2 (LtR) | *, /\n"
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" 3 (RtL) | ^\n"
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" Other symbols: (, ), - (prefix)\n");
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char buf[32][128];
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size_t maxw[2];
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maxw[0] = 0;
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fprintf(stderr, "Builtin functions:\n");
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for (size_t i = 0; i < expr_n_builtin_funcs; i++) {
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assert(i < 32);
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size_t n = 0;
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bufprint(buf[i], n, "%s(", expr_builtin_funcs[i].name);
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for (size_t j = 0; j < expr_builtin_funcs[i].n_args; j++) {
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if (j != 0)
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bufprint(buf[i], n, ", ");
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bufprint(buf[i], n, "%s", expr_builtin_funcs[i].arg_names[j]);
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}
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bufprint(buf[i], n, ")");
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if (n > maxw[0])
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maxw[0] = n;
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}
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for (size_t i = 0; i < expr_n_builtin_funcs; i++) {
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fprintf(stderr, " %s%*s - %s\n", buf[i], (int)(maxw[0] - strlen(buf[i])), "", expr_builtin_funcs[i].description);
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}
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maxw[0] = maxw[1] = 0;
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fprintf(stderr, "Builtin variables:\n");
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for (size_t i = 0; i < expr_n_builtin_vars; i++) {
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assert(i < 32);
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size_t n = strlen(expr_builtin_vars[i].name);
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if (n > maxw[0])
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maxw[0] = n;
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n = snprintf(buf[i], 128, "%.*g", 15, expr_builtin_vars[i].val);
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if (n > maxw[1])
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maxw[1] = n;
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}
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for (size_t i = 0; i < expr_n_builtin_vars; i++) {
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fprintf(stderr, " %s%*s = %s%*s - %s\n", expr_builtin_vars[i].name, (int)(maxw[0] - strlen(expr_builtin_vars[i].name)), "", buf[i], (int)(maxw[1] - strlen(buf[i])), "", expr_builtin_vars[i].description);
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}
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}
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static void sig_handler(int signum) {
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running = false;
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fprintf(stderr, "\nExiting\n");
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}
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static bool run(const char *line) {
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if (line == NULL || line[0] == 0)
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return line != NULL;
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if (strcmp(line, "help") == 0) {
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print_help();
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return true;
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}
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double res;
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ExprError err;
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err = expr_set(e, line);
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if (err.err == NULL)
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err = expr_eval(e, &res);
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if (err.err == NULL) {
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printf("%.*g\n", 15, res);
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} else {
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fprintf(stderr, "Error parsing expression:\n");
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fprintf(stderr, "%s\n", line);
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fprintf(stderr, "%*s", (int)err.start, "");
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for (size_t i = err.start; i <= err.end; i++)
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fprintf(stderr, "^");
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fprintf(stderr, "\n%s\n", err.err);
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}
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return err.err == NULL;
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}
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#if ENABLE_READLINE
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static void winch_handler(int signum) {
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sigwinch_received = true;
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}
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static void line_handler(char *line) {
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if (line == NULL) {
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rl_callback_handler_remove();
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running = false;
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} else {
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add_history(line);
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last_status_ok = run(line);
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free(line);
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}
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}
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static char *completer(const char *text, int state) {
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if (!state) {
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completer_idx = 0;
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completer_len = strlen(text);
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completer_funcs = false;
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}
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while (1) {
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if (completer_funcs) {
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if (completer_idx >= expr_n_builtin_funcs) {
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break;
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}
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} else {
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if (completer_idx >= expr_n_builtin_vars) {
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completer_funcs = true;
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completer_idx = 0;
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}
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}
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const char *name;
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if (completer_funcs)
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name = expr_builtin_funcs[completer_idx].name;
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else
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name = expr_builtin_vars[completer_idx].name;
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completer_idx++;
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if (strncmp(name, text, completer_len) == 0) {
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rl_completion_append_character = completer_funcs ? '(' : 0;
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return strdup(name);
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}
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}
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return NULL;
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}
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#endif
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int main(int argc, const char **argv) {
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#ifdef ENABLE_READLINE
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rl_catch_signals = false;
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rl_readline_name = "qc";
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rl_completion_entry_function = completer;
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rl_basic_word_break_characters = "+-*/^() ";
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signal (SIGWINCH, winch_handler);
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#else
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char buf[2048];
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#endif
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struct sigaction action = {0};
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action.sa_handler = sig_handler;
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if (sigaction(SIGINT, &action, NULL) == -1) {
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fprintf(stderr, "Error setting up signal handler: %s\n", strerror(errno));
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return 1;
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}
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e = expr_new();
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if (argc == 1) {
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printf("Running in REPL (read-evaluate-print loop) mode. Type `help` for more information.\n");
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printf("Hit Ctrl+C to exit.\n");
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} else if (argc == 2 && strcmp(argv[1], "-h") != 0 && strcmp(argv[1], "--help") != 0) {
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return !run(argv[1]);
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} else {
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print_help();
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return 1;
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}
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#ifdef ENABLE_READLINE
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rl_callback_handler_install("> ", line_handler);
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fd_set fds;
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#endif
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while (running) {
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#ifdef ENABLE_READLINE
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FD_ZERO(&fds);
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FD_SET(fileno(rl_instream), &fds);
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int r = select(FD_SETSIZE, &fds, NULL, NULL, NULL);
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if (r < 0 && errno != EINTR) {
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rl_callback_handler_remove();
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break;
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}
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if (sigwinch_received) {
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rl_resize_terminal();
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sigwinch_received = false;
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}
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if (r < 0)
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continue;
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if (FD_ISSET(fileno(rl_instream), &fds))
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rl_callback_read_char();
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#else
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printf("> ");
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const char *line = fgets(buf, 2048, stdin);
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if (line == NULL)
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break;
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size_t len = strlen(buf);
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if (len == 0)
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continue;
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buf[len-1] = 0;
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last_status_ok = run(line);
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#endif
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}
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expr_destroy(e);
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return !last_status_ok;
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}
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