prscanf.c

Netscape NSPR库源码

static PRStatus
GetFloat(ScanfState *state)
{
    char buf[FMAX + 1], *p;
    int ch;
    PRBool seenDigit = PR_FALSE;

    if (state->width == 0 || state->width > FMAX) {
        state->width = FMAX;
    }
    p = buf;
    GET_IF_WITHIN_WIDTH(state, ch);
    if (WITHIN_WIDTH(state) && (ch == '+' || ch == '-')) {
        *p++ = ch;
        GET_IF_WITHIN_WIDTH(state, ch);
    }
    while (WITHIN_WIDTH(state) && isdigit(ch)) {
        *p++ = ch;
        GET_IF_WITHIN_WIDTH(state, ch);
        seenDigit = PR_TRUE;
    }
    if (WITHIN_WIDTH(state) && ch == DECIMAL_POINT) {
        *p++ = ch;
        GET_IF_WITHIN_WIDTH(state, ch);
        while (WITHIN_WIDTH(state) && isdigit(ch)) {
            *p++ = ch;
            GET_IF_WITHIN_WIDTH(state, ch);
            seenDigit = PR_TRUE;
        }
    }

    /*
     * This is not robust.  For example, "1.2e+" would confuse
     * the code below to read 'e' and '+', only to realize that
     * it should have stopped at "1.2".  But we can't push back
     * more than one character, so there is nothing I can do.
     */

    /* Parse exponent */
    if (WITHIN_WIDTH(state) && (ch == 'e' || ch == 'E') && seenDigit) {
        *p++ = ch;
        GET_IF_WITHIN_WIDTH(state, ch);
        if (WITHIN_WIDTH(state) && (ch == '+' || ch == '-')) {
            *p++ = ch;
            GET_IF_WITHIN_WIDTH(state, ch);
        }
        while (WITHIN_WIDTH(state) && isdigit(ch)) {
            *p++ = ch;
            GET_IF_WITHIN_WIDTH(state, ch);
        }
    }
    if (WITHIN_WIDTH(state)) {
        UNGET(state, ch);
    }
    if (!seenDigit) {
        return PR_FAILURE;
    }
    *p = '\0';
    if (state->assign) {
        PRFloat64 dval = PR_strtod(buf, NULL);

        state->converted = PR_TRUE;
        if (state->sizeSpec == _PR_size_l) {
            *va_arg(state->ap, PRFloat64 *) = dval;
        } else if (state->sizeSpec == _PR_size_L) {
#if defined(OSF1) || defined(IRIX)
            *va_arg(state->ap, double *) = dval;
#else
            *va_arg(state->ap, long double *) = dval;
#endif
        } else {
            *va_arg(state->ap, float *) = (float) dval;
        }
    }
    return PR_SUCCESS;
}

/*
 * Convert, and return the end of the conversion spec.
 * Return NULL on error.
 */

static const char *
Convert(ScanfState *state, const char *fmt)
{
    const char *cPtr;
    int ch;
    char *cArg = NULL;

    state->converted = PR_FALSE;
    cPtr = fmt;
    if (*cPtr != 'c' && *cPtr != 'n' && *cPtr != '[') {
        do {
            ch = GET(state);
        } while (isspace(ch));
        UNGET(state, ch);
    }
    switch (*cPtr) {
        case 'c':
            if (state->assign) {
                cArg = va_arg(state->ap, char *);
            }
            if (state->width == 0) {
                state->width = 1;
            }
            for (; state->width > 0; state->width--) {
                ch = GET(state);
                if (ch == EOF) {
                    return NULL;
                } else if (state->assign) {
                    *cArg++ = ch;
                }
            }
            if (state->assign) {
                state->converted = PR_TRUE;
            }
            break;
        case 'p':
        case 'd': case 'i': case 'o':
        case 'u': case 'x': case 'X':
            if (GetInt(state, *cPtr) == PR_FAILURE) {
                return NULL;
            }
            break;
        case 'e': case 'E': case 'f':
        case 'g': case 'G':
            if (GetFloat(state) == PR_FAILURE) {
                return NULL;
            }
            break;
        case 'n':
            /* do not consume any input */
            if (state->assign) {
                switch (state->sizeSpec) {
                    case _PR_size_none:
                        *va_arg(state->ap, PRIntn *) = state->nChar;
                        break;
                    case _PR_size_h:
                        *va_arg(state->ap, PRInt16 *) = state->nChar;
                        break;
                    case _PR_size_l:
                        *va_arg(state->ap, PRInt32 *) = state->nChar;
                        break;
                    case _PR_size_ll:
                        LL_I2L(*va_arg(state->ap, PRInt64 *), state->nChar);
                        break;
                    default:
                        PR_ASSERT(0);
                }
            }
            break;
        case 's':
            if (state->width == 0) {
                state->width = INT_MAX;
            }
            if (state->assign) {
                cArg = va_arg(state->ap, char *);
            }
            for (; state->width > 0; state->width--) {
                ch = GET(state);
                if ((ch == EOF) || isspace(ch)) {
                    UNGET(state, ch);
                    break;
                }
                if (state->assign) {
                    *cArg++ = ch;
                }
            }
            if (state->assign) {
                *cArg = '\0';
                state->converted = PR_TRUE;
            }
            break;
        case '%':
            ch = GET(state);
            if (ch != '%') {
                UNGET(state, ch);
                return NULL;
            }
            break;
        case '[':
            {
                PRBool complement = PR_FALSE;
                const char *closeBracket;
                size_t n;

                if (*++cPtr == '^') {
                    complement = PR_TRUE;
                    cPtr++;
                }
                closeBracket = strchr(*cPtr == ']' ? cPtr + 1 : cPtr, ']');
                if (closeBracket == NULL) {
                    return NULL;
                }
                n = closeBracket - cPtr;
                if (state->width == 0) {
                    state->width = INT_MAX;
                }
                if (state->assign) {
                    cArg = va_arg(state->ap, char *);
                }
                for (; state->width > 0; state->width--) {
                    ch = GET(state);
                    if ((ch == EOF) 
                            || (!complement && !memchr(cPtr, ch, n))
                            || (complement && memchr(cPtr, ch, n))) {
                        UNGET(state, ch);
                        break;
                    }
                    if (state->assign) {
                        *cArg++ = ch;
                    }
                }
                if (state->assign) {
                    *cArg = '\0';
                    state->converted = PR_TRUE;
                }
                cPtr = closeBracket;
            }
            break;
        default:
            return NULL;
    }
    return cPtr;
}

static PRInt32
DoScanf(ScanfState *state, const char *fmt)
{
    PRInt32 nConverted = 0;
    const char *cPtr;
    int ch;

    state->nChar = 0;
    cPtr = fmt;
    while (1) {
        if (isspace(*cPtr)) {
            /* white space: skip */
            do {
                cPtr++;
            } while (isspace(*cPtr));
            do {
                ch = GET(state);
            } while (isspace(ch));
            UNGET(state, ch);
        } else if (*cPtr == '%') {
            /* format spec: convert */
            cPtr++;
            state->assign = PR_TRUE;
            if (*cPtr == '*') {
                cPtr++;
                state->assign = PR_FALSE;
            }
            for (state->width = 0; isdigit(*cPtr); cPtr++) {
                state->width = state->width * 10 + *cPtr - '0';
            }
            state->sizeSpec = _PR_size_none;
            if (*cPtr == 'h') {
                cPtr++;
                state->sizeSpec = _PR_size_h;
            } else if (*cPtr == 'l') {
                cPtr++;
                if (*cPtr == 'l') {
                    cPtr++;
                    state->sizeSpec = _PR_size_ll;
                } else {
                    state->sizeSpec = _PR_size_l;
                }
            } else if (*cPtr == 'L') {
                cPtr++;
                state->sizeSpec = _PR_size_L;
            }
            cPtr = Convert(state, cPtr);
            if (cPtr == NULL) {
                return (nConverted > 0 ? nConverted : EOF);
            }
            if (state->converted) {
                nConverted++;
            }
            cPtr++;
        } else {
            /* others: must match */
            if (*cPtr == '\0') {
                return nConverted;
            }
            ch = GET(state);
            if (ch != *cPtr) {
                UNGET(state, ch);
                return nConverted;
            }
            cPtr++;
        }
    }
}

static int
StringGetChar(void *stream)
{
    char *cPtr = *((char **) stream);

    if (*cPtr == '\0') {
        return EOF;
    } else {
        *((char **) stream) = cPtr + 1;
        return *cPtr;
    }
}

static void
StringUngetChar(void *stream, int ch)
{
    char *cPtr = *((char **) stream);

    if (ch != EOF) {
        *((char **) stream) = cPtr - 1;
    }
}

PR_IMPLEMENT(PRInt32)
PR_sscanf(const char *buf, const char *fmt, ...)
{
    PRInt32 rv;
    ScanfState state;

    state.get = &StringGetChar;
    state.unget = &StringUngetChar;
    state.stream = (void *) &buf;
    va_start(state.ap, fmt);
    rv = DoScanf(&state, fmt);
    va_end(state.ap);
    return rv;
}