"

 COPYRIGHT (c) 1988-93 by Claus Gittinger

              All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

PositionableStream subclass:#ReadStream

       instanceVariableNames:''

       classVariableNames:''

       poolDictionaries:''

       category:'Streams'

!

ReadStream comment:'

COPYRIGHT (c) 1988-93 by Claus Gittinger

              All Rights Reserved

ReadStream defines protocol for reading streamwise over collections. Code here

is specially tuned for streaming over strings.

%W% %E%

'!

!ReadStream methodsFor:'access-reading'!

peek

    "return the next element; do NOT advance read pointer.

%{  /* NOCONTEXT */

    REGISTER int pos;

    unsigned ch;

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

        if (pos > _intVal(_INST(readLimit))) {

            RETURN ( nil );

        }

        }

    }

%}

.

    (position > readLimit) ifTrue:[^ nil].

    ^ collection at:position

!

next

    "return the next element; advance read pointer.

    |ret|

%{  /* NOCONTEXT */

    REGISTER int pos;

    unsigned ch;

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

        if (pos > _intVal(_INST(readLimit))) {

            RETURN ( nil );

        }

        }

    }

%}

.

    (position > readLimit) ifTrue:[^ nil].

    ret := collection at:position.

    position := position + 1.

    ^ ret

!

nextPeek

    "advance read pointer return the peek element.

     this is equivalent to (self next; peek).

%{  /* NOCONTEXT */

    if (_isString(_INST(collection))

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        REGISTER int pos;

        unsigned ch;

        pos = _intVal(_INST(position));

        if (pos > _intVal(_INST(readLimit))) {

            RETURN ( nil );

        }

        if ((pos > 0)

         && (pos < _qSize(_INST(collection)) - OHDR_SIZE)) {

            _INST(position) = _MKSMALLINT(pos + 1);

            pos = pos + 1;

            if (pos < _qSize(_INST(collection)) - OHDR_SIZE) {

                ch = _stringVal(_INST(collection))[pos-1];

                RETURN ( _MKCHARACTER(ch) );

            }

            RETURN ( nil );

        }

    }

%}

.

    (position > readLimit) ifTrue:[^ nil].

    position := position + 1.

    (position > readLimit) ifTrue:[^ nil].

    ^ collection at:position

!

nextDecimalInteger

    "read the next integer in radix 10. dont skip whitespace.

    |value|

%{

    int pos, limit, sz;

    register unsigned char *cp;

    register unsigned ch;

    int val = 0;

    if (_isString(_INST(collection))

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

        limit = _intVal(_INST(readLimit));

        sz = _qSize(_INST(collection)) - OHDR_SIZE;

        if (sz < limit)

            limit = sz; 

        cp = _stringVal(_INST(collection)) + pos - 1;

        for (;;) {

            if (pos > limit) break;

            ch = *cp;

            if ((ch < '0') || (ch > '9')) break;

            val = val * 10 + (ch - '0');

            pos++;

            if (val > (_MAX_INT / 10)) goto oops;

            cp++;

        }

        _INST(position) = _MKSMALLINT(pos);

        return _MKSMALLINT(val);

    }

oops:

    value = _MKSMALLINT(val);

%}

.

    [self peek notNil and:[self peek isDigitRadix:10]] whileTrue:[

        value = (value * 10) + self peek digitValue.

        self next

    ].

    ^ value

!

nextWord

    "read the next word (i.e. up to non letter-or-digit).

     return a string containing those characters.

%{

    /* speedup, if collection is a string */

    int pos, limit, sz;

    int len;

    char buffer[1024];

    register unsigned char *cp;

    register unsigned ch;

    if (_isString(_INST(collection))

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

        limit = _intVal(_INST(readLimit));

        sz = _qSize(_INST(collection)) - OHDR_SIZE;

        if (sz < limit)

            limit = sz; 

        cp = _stringVal(_INST(collection)) + pos - 1;

        for (;;) {

            if (pos > limit) break;

            ch = *cp;

            if (ch > ' ') break;

            if ((ch != ' ') && (ch != '\t') && (ch != '\r')

             && (ch != '\n') && (ch != 0x0b)) break;

            cp++;

            pos++;

        }

        len = 0;

        for (;;) {

            if (pos > limit) break;

            ch = *cp & 0xFF;

            if (! (((ch >= 'a') && (ch <= 'z')) ||

                   ((ch >= 'A') && (ch <= 'Z')) ||

                   ((ch >= '0') && (ch <= '9'))))

                break;

            buffer[len++] = ch;

            if (len >= (sizeof(buffer)-1)) {

                /* emergency */

                break;

            }

            pos++;

            cp++;

        }

        _INST(position) = _MKSMALLINT(pos);

        buffer[len] = '\0';

        RETURN ( (len != 0) ? _MKSTRING(buffer COMMA_CON) : nil );

    }

%}

.

    ^ super nextWord

!

nextSymbol

    "read the next selector-symbol (i.e. up to non letter-or-digit).

     return a string containing those characters.

%{

    int pos, limit, sz;

    int len;

    char buffer[1024];

    register unsigned char *cp;

    register unsigned ch;

    if (_isString(_INST(collection))

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

        limit = _intVal(_INST(readLimit));

        sz = _qSize(_INST(collection)) - OHDR_SIZE;

        if (sz < limit)

            limit = sz; 

        cp = _stringVal(_INST(collection)) + pos - 1;

        len = 0;

        for (;;) {

            if (pos > limit) break;

            ch = *cp;

            if (! (((ch >= 'a') && (ch <= 'z')) ||

                   ((ch >= 'A') && (ch <= 'Z')) ||

                   ((ch >= '0') && (ch <= '9')) ||

                   (ch == ':')))

                break;

            buffer[len++] = ch;

            if (len >= (sizeof(buffer)-1)) {

                /* emergency */

                break;

            }

            pos++;

            cp++;

        }

        _INST(position) = _MKSMALLINT(pos);

        buffer[len] = '\0';

        RETURN ( (len != 0) ? _MKSTRING(buffer COMMA_CON) : nil );

    }

%}

.

    ^ super nextSymbol

!

%{  /* NOCONTEXT */

    if (_isString(_INST(collection))

     && _isCharacter(anObject)

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        REGISTER unsigned char *chars;

        REGISTER int pos, limit;

        pos = _intVal(_INST(position));

        if (pos <= 0) {

            RETURN ( nil );

        }

        limit = _intVal(_INST(readLimit));

        if (limit > (_qSize(_INST(collection)) - OHDR_SIZE))

            limit = _qSize(_INST(collection)) - OHDR_SIZE;

        chars = (unsigned char *)(_stringVal(_INST(collection)) + pos - 1);

        ch = _intVal(_characterVal(anObject)) & 0xFF;

        while (pos < limit) {

            if (*chars == ch) {

                ch = *++chars;

                pos++;

                _INST(position) = _MKSMALLINT(pos);

            }

            chars++;

            pos++;

        }

        RETURN ( nil );

    }

%}

.

!

skipSeparators

    "skip all whitespace; next will return next non-white-space element.

%{  /* NOCONTEXT */

    if (_isString(_INST(collection))

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        REGISTER unsigned char *chars;

        REGISTER unsigned ch;

        REGISTER int pos;

        int limit;

        pos = _intVal(_INST(position));

        if (pos <= 0) {

            RETURN ( nil );

        }

        limit = _intVal(_INST(readLimit));

        if (limit > (_qSize(_INST(collection)) - OHDR_SIZE))

            limit = _qSize(_INST(collection)) - OHDR_SIZE;

        chars = (unsigned char *)(_stringVal(_INST(collection)) + pos - 1);

        while (pos <= limit) {

            ch = *chars++;

            if ((ch != ' ') && (ch != '\t') && (ch != '\r')

             && (ch != '\n') && (ch != 0x0B)) {

                _INST(position) = _MKSMALLINT(pos);

                RETURN ( _MKCHARACTER(ch) );

            }

            pos++;

        }

        _INST(position) = _MKSMALLINT(pos);

        RETURN ( nil );

    }

%}

.

    ^ super skipSeparators

!

skipToAll:aCollection

    "skip for the sequence given by the argument, aCollection;

     return nil if not found, self otherwise. On a successful match, next read

     will return elements of aCollection."

    |oldPos buffer l first idx|

    oldPos := self position.

    l := aCollection size.

    first := aCollection at:1.

    [self atEnd] whileFalse:[

        buffer := self next:l.

        buffer = aCollection ifTrue:[

            self position:(self position - l).

            ^ self

        ].

        idx := buffer indexOf:first startingAt:2.

        idx == 0 ifFalse:[

            self position:(self position - l + idx - 1)

        ]

    ].

    self position:oldPos.

    ^ nil

    "|s|

     s := ReadStream on:'12345678901234567890'.

     s skipToAll:'901'.

     s next:4"

! !

!ReadStream methodsFor:'access-writing'!

nextPut:anElement

    ^ self error:'ReadStreams cannot write'

! !