ush-parse.c

一个在LINUX下运行的shell程序

/* ush-parse.c */
/* scanner/parser for ush */

#include "ush.h"
#include "ush-parse.h"

TOKEN gettoken(char *word)
{
    enum
    { NEUTRAL, GTGT, INQUOTE, INWORD }
    state = NEUTRAL;
    int c;
    char *w;

    w = word;

    while ((c = getchar()) != EOF) {
	switch (state) {
	case NEUTRAL:
	    switch (c) {
	    case ';':
		return (T_SEMI);
	    case '&':
		return (T_AMP);
	    case '|':
		return (T_BAR);
	    case '<':
		return (T_LT);
	    case '\n':
		return (T_NL);
	    case ' ':
	    case '\t':
		continue;
	    case '>':
		state = GTGT;
		continue;
	    case '"':
		state = INQUOTE;
		continue;
	    default:
		state = INWORD;
		*w++ = c;
		continue;
	    }
	case GTGT:
	    if (c == '>')
		return (T_GTGT);
	    ungetc(c, stdin);
	    return (T_GT);
	case INQUOTE:
	    switch (c) {
	    case '\\':
		*w++ = getchar();
		continue;
	    case '"':
		*w = '\0';
		return (T_WORD);
	    default:
		*w++ = c;
		continue;
	    }
	case INWORD:
	    switch (c) {
	    case '\\':
	    case '&':
	    case '|':
	    case '<':
	    case '>':
	    case '\n':
	    case ' ':
	    case '\t':
		ungetc(c, stdin);
		*w = '\0';
		return (T_WORD);
	    default:
		*w++ = c;
		continue;
	    }
	}
    
    }
    
    return (T_EOF);
}