"

 COPYRIGHT (c) 1988 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:'

              All Rights Reserved

!ReadStream methodsFor:'reading'!

peek

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

     return nil, if there is no next element.

     - tuned for speed on String/ByteArray/Array-Streams"

%{  /* NOCONTEXT */

    REGISTER int pos;

    unsigned ch;

    OBJ coll;

    OBJ cls;

    extern OBJ ByteArray;

    coll = _INST(collection);

    if (_isNonNilObject(coll)

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

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

            RETURN ( nil );

        }

        if (pos > 0) {

            cls = _qClass(coll);

            if (cls == String) {

                if (pos <= _stringSize(coll)) {

                    ch = _stringVal(coll)[pos-1];

                    RETURN ( _MKCHARACTER(ch) );

                }

            } else if (cls == ByteArray) {

                if (pos <= _byteArraySize(coll)) {

                    ch = _ByteArrayInstPtr(coll)->ba_element[pos-1];

                    RETURN ( _MKSMALLINT(ch) );

                }

            } else if (cls == Array) {

                if (pos <= _arraySize(coll)) {

                    RETURN ( _ArrayInstPtr(coll)->a_element[pos-1]);

                }

            }

        }

    }

%}

.

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

    ^ collection at:position

!

next

    "return the next element; advance read pointer.

     return nil, if there is no next element.

     - tuned for speed on String/ByteArray/Array-Streams"

    |ret|

%{  /* NOCONTEXT */

    REGISTER int pos;

    unsigned ch;

    OBJ coll;

    coll = _INST(collection);

    if (_isNonNilObject(coll)

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        pos = _intVal(_INST(position));

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

            RETURN ( nil );

        }

        if (pos > 0) {

            OBJ cls;

            cls = _qClass(coll);

            if (cls == String) {

                if (pos <= _stringSize(coll)) {

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

                    ch = _stringVal(coll)[pos-1];

                    RETURN ( _MKCHARACTER(ch) );

                }

            } else if (cls == ByteArray) {

                if (pos <= _byteArraySize(coll)) {

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

                    ch = _ByteArrayInstPtr(coll)->ba_element[pos-1];

                    RETURN ( _MKSMALLINT(ch) );

                }

            } else if (cls == Array) {

                if (pos <= _arraySize(coll)) {

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

                    RETURN ( _ArrayInstPtr(coll)->a_element[pos-1]);

                }

            }

        }

    }

%}

.

    (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).

     - tuned for speed on String-Streams for faster scanning"

%{  /* NOCONTEXT */

    OBJ coll;

    coll = _INST(collection);

    if (__isString(coll)

     && _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 <= _stringSize(coll))) {

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

            pos = pos + 1;

            if (pos <= _stringSize(coll)) {

                ch = _stringVal(coll)[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.

     - tuned for speed on String-Streams for faster scanning"

    |value nextOne|

%{

    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);

%}

.

    "fall-back for non-string streams - we have to continue where

     above primitive left off, in case of a large integer ...

     (instead of doing a super nextDecimalInteger)"

    nextOne := self peek.

    [nextOne notNil and:[nextOne isDigitRadix:10]] whileTrue:[

        value = (value * 10) + nextOne digitValue.

        nextOne := self nextPeek

    ].

    ^ value

!

nextWord

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

     return a string containing those characters.

     - tuned for speed on String-Streams for faster scanning"

%{

    /* speedup, if collection is a string */

    int pos, limit, sz;

    int len;

    char buffer[256];

    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.

     - tuned for speed on String-Streams for faster scanning"

%{

    int pos, limit, sz;

    int len;

    char buffer[256];

    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

!

skipThrough:anObject

    "skip all objects up-to and including anObject, return anObject on success,

     nil if end-of-stream is reached before. 

     On success, the next read operation will return the element after anObject.

     - reimplemented for speed on String-Streams for faster scanning"

%{  /* NOCONTEXT */

    OBJ coll;

    coll = _INST(collection);

    if (__isString(coll)

     && __isCharacter(anObject)

     && _isSmallInteger(_INST(position))

     && _isSmallInteger(_INST(readLimit))) {

        REGISTER unsigned char *chars;

        REGISTER int pos, limit;

        unsigned ch;

        int sz;

        pos = _intVal(_INST(position));

        if (pos <= 0) {

            RETURN ( nil );

        }

        limit = _intVal(_INST(readLimit));

        sz = _stringSize(coll);

        if (limit > sz) limit = sz;

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

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

        while (pos < limit) {

            if (*chars == ch) {

                ch = *++chars;

                pos++;

                _INST(position) = _MKSMALLINT(pos);

                RETURN ( anObject );

            }

            chars++;

            pos++;

        }

        RETURN ( nil );

    }

%}

.

    ^ super skipThrough:anObject

!

skipSeparators

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

     Return the peeked character or nil, if the end-of-stream was reached.

     - reimplemented for speed on String-Streams for faster scanning"

%{  /* 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

!

skipSeparatorsExceptCR

    "skip all whitespace except newlines;

     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 != 0x0B)) {

                _INST(position) = _MKSMALLINT(pos);

                RETURN ( _MKCHARACTER(ch) );

            }

            pos++;

        }

        _INST(position) = _MKSMALLINT(pos);

        RETURN ( nil );

    }

%}

.

    ^ super skipSeparatorsExceptCR

!

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'.