IOClassesImpl.mesa
Copyright Ó 1985, 1986, 1988, 1990, 1991 by Xerox Corporation. All rights reserved.
MBrown on January 13, 1984 1:32 pm
Russ Atkinson (RRA) May 10, 1985 4:24:56 pm PDT
Eduardo Pelegri-Llopart December 5, 1988 2:29:20 pm PST
Willie-sue, April 6, 1990 5:12 pm PDT
DIRECTORY
IO USING [Backup, CharsAvail, Close, CreateStream, CreateStreamProcs, EndOf, EndOfStream, EraseChar, Flush, GetBlock, GetChar, PeekChar, PutBlock, PutChar, Reset, SP, STREAM, StreamProcs, UnsafeBlock, UnsafeGetBlock, UnsafePutBlock],
IOClasses USING [],
IOUtils USING [closedStreamProcs],
RefText USING [ObtainScratch, ReleaseScratch];
IOClassesImpl:
CEDAR
PROGRAM
IMPORTS IO, IOUtils, RefText
EXPORTS IOClasses
SHARES IO --for representation of StreamProcs
= BEGIN
STREAM: TYPE = IO.STREAM;
StreamProcs: TYPE = IO.StreamProcs;
UnsafeBlock: TYPE = IO.UnsafeBlock;
Comment-filtered Input Stream
FilterCommentsStreamData: TYPE = REF FilterCommentsStreamRecord;
FilterCommentsStreamRecord:
TYPE =
RECORD [
inStringLiteral: BOOL ¬ FALSE,
inCharLiteral: BOOL ¬ FALSE,
inExtendedChar: BOOL ¬ FALSE
];
FilterCommentsStreamProcs:
REF
IO.StreamProcs =
IO.CreateStreamProcs[
variety: $input, class: $CommentFilter,
getChar: FilterCommentsStreamGetChar
];
CreateCommentFilterStream:
PUBLIC
PROC [input:
STREAM]
RETURNS [
STREAM] = {
RETURN[
IO.CreateStream[
streamProcs: FilterCommentsStreamProcs, backingStream: input,
streamData: NEW[FilterCommentsStreamRecord ¬ []]]];
};
FilterCommentsStreamGetChar:
PROC [self:
STREAM]
RETURNS [char:
CHAR] = {
data: FilterCommentsStreamData = NARROW[self.streamData];
char ¬ self.backingStream.GetChar[];
May raise IO.EndOfStream.
SELECT
TRUE
FROM
data.inExtendedChar => {
data.inExtendedChar ¬ FALSE; -- not really, but rest of extended char can't contain '"
};
data.inCharLiteral => {
data.inCharLiteral ¬ FALSE;
IF char = '\\ THEN data.inExtendedChar ¬ TRUE;
};
data.inStringLiteral => {
SELECT char
FROM
'\\ => data.inExtendedChar ¬ TRUE;
'\" => data.inStringLiteral ¬ FALSE; -- not really, but if following char is '" it will look like a new string literal, which is ok
ENDCASE;
};
ENDCASE =>
SELECT char
FROM
'\" => data.inStringLiteral ¬ TRUE;
'\' => data.inCharLiteral ¬ TRUE;
'<, '\253 => {
nest: INT ¬ 1;
IF char = '<
THEN {
IF self.backingStream.EndOf[] THEN GO TO notComment;
IF self.backingStream.PeekChar[] # '< THEN GO TO notComment;
char ¬ self.backingStream.GetChar[];
};
DO
char ¬ self.backingStream.GetChar[];
SELECT char
FROM
'< =>
IF self.backingStream.PeekChar[] = '<
THEN {
char ¬ self.backingStream.GetChar[];
nest ¬ nest + 1;
};
'> =>
IF self.backingStream.PeekChar[] = '>
THEN {
char ¬ self.backingStream.GetChar[];
nest ¬ nest - 1;
IF nest <= 0 THEN GO TO endComment;
};
'\253 => nest ¬ nest + 1;
'\273 => {nest ¬ nest - 1; IF nest <= 0 THEN GO TO endComment};
ENDCASE;
ENDLOOP;
EXITS
notComment => {};
endComment => {char ¬ IO.SP};
};
'- =>
IF
NOT self.backingStream.EndOf[]
AND self.backingStream.PeekChar[] = '-
THEN {
Skip over the comment. Return ending CR, LF, or SP if ends without CR, or raise IO.EndOfStream if comment ends with end of input.
[] ¬ self.backingStream.GetChar[];
DO
SELECT (char ¬ self.backingStream.GetChar[])
FROM
'\l, '\r => EXIT;
'- =>
IF self.backingStream.GetChar[] = '-
THEN {
char ¬ IO.SP; EXIT };
ENDCASE;
ENDLOOP;
}
ENDCASE;
};
Concatenated Input Stream
CatInputStreamData: TYPE = REF CatInputStreamRecord;
CatInputStreamRecord:
TYPE =
RECORD [
input1, input2: STREAM,
state: CatInputStreamState];
CatInputStreamState: TYPE = { initial, swapped, closed };
CatInputStreamProcs:
REF
IO.StreamProcs = IO.CreateStreamProcs[
variety: $input, class: $Concatenated,
getChar: CatInputStreamGetChar,
getBlock: CatInputStreamGetBlock,
unsafeGetBlock: CatInputStreamUnsafeGetBlock,
charsAvail: CatInputStreamCharsAvail,
backup: CatInputStreamBackup,
endOf: CatInputStreamEndOf,
reset: CatInputStreamReset,
close: CatInputStreamClose
];
CreateCatInputStream:
PUBLIC
PROC [input1, input2:
STREAM]
RETURNS [
STREAM] = {
RETURN[IO.CreateStream[streamProcs: CatInputStreamProcs, streamData: NEW[CatInputStreamRecord ¬ [input1: input1, input2: input2, state: $initial]]]];
};
CatInputStreamGetChar:
PROC [self:
STREAM]
RETURNS [
CHAR] = {
data: CatInputStreamData = NARROW[self.streamData];
{
ENABLE IO.EndOfStream => IF data.state = $initial THEN GOTO nextStream;
RETURN[data.input1.GetChar[]];
EXITS nextStream => {
SwapStreams[data];
RETURN[data.input1.GetChar[]];
}
}
};
SwapStreams:
PROC [data: CatInputStreamData] = {
we preserve the information for debugging purposes
temp: STREAM ¬ data.input1;
IF data.state # $initial THEN ERROR;
data.input1 ¬ data.input2;
data.input2 ¬ temp;
data.state ¬ $swapped;
};
CatInputStreamGetBlock:
PROC [self:
STREAM, block:
REF
TEXT, startIndex:
NAT, count:
NAT]
RETURNS [nBytesRead:
NAT] = {
data: CatInputStreamData = NARROW[self.streamData];
nBytesRead ¬ data.input1.GetBlock[block, startIndex, count];
IF nBytesRead > 0 OR data.state = $swapped THEN RETURN [nBytesRead];
SwapStreams[data];
RETURN[data.input1.GetBlock[block, startIndex, count]];
};
CatInputStreamUnsafeGetBlock:
PROC [self:
STREAM, block: UnsafeBlock]
RETURNS [nBytesRead:
INT] =
TRUSTED {
data: CatInputStreamData = NARROW[self.streamData];
nBytesRead ¬ data.input1.UnsafeGetBlock[block];
IF nBytesRead > 0 OR data.state = $swapped THEN RETURN [nBytesRead];
SwapStreams[data];
RETURN[data.input1.UnsafeGetBlock[block]];
};
CatInputStreamEndOf:
PROC [self:
STREAM]
RETURNS [
BOOL] = {
data: CatInputStreamData = NARROW[self.streamData];
IF NOT data.input1.EndOf[] THEN RETURN [FALSE];
IF data.state = $swapped THEN RETURN [TRUE];
SwapStreams[data];
RETURN [data.input1.EndOf[]];
};
CatInputStreamCharsAvail:
PROC [self:
STREAM, wait:
BOOL]
RETURNS [
INT] = {
data: CatInputStreamData = NARROW[self.streamData];
RETURN[data.input1.CharsAvail[wait]];
};
CatInputStreamBackup:
PROC [self:
STREAM, char:
CHAR] = {
data: CatInputStreamData = NARROW[self.streamData];
data.input1.Backup[char];
};
CatInputStreamReset:
PROC [self:
STREAM] = {
data: CatInputStreamData = NARROW[self.streamData];
data.input1.Reset[];
data.input2.Reset[];
};
CatInputStreamClose:
PROC [self:
STREAM, abort:
BOOL] = {
data: CatInputStreamData = NARROW[self.streamData];
data.input1.Close[];
data.input2.Close[];
data.state ¬ $closed;
self.streamProcs ¬ IOUtils.closedStreamProcs;
};
Dribble Output Stream
DribbleStreamData: TYPE = REF DribbleStreamRecord;
DribbleStreamRecord: TYPE = RECORD [outputStream: STREAM];
DribbleStreamProcs:
REF StreamProcs ¬
IO.CreateStreamProcs[
variety: $output, class: $Dribble,
putChar: DribbleStreamPutChar,
putBlock: DribbleStreamPutBlock,
unsafePutBlock: DribbleStreamUnsafePutBlock,
flush: DribbleStreamFlush,
eraseChar: DribbleStreamEraseChar,
reset: DribbleStreamReset,
close: DribbleStreamClose
];
CreateDribbleOutputStream:
PUBLIC
PROC [output1, output2:
STREAM]
RETURNS [
STREAM] = {
RETURN[
IO.CreateStream[
streamProcs: DribbleStreamProcs,
streamData: NEW[DribbleStreamRecord ¬ [outputStream: output2]],
backingStream: output1]];
};
DribbleStreamPutChar:
PROC [self:
STREAM, char:
CHAR] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.PutChar[char];
data.outputStream.PutChar[char];
};
DribbleStreamPutBlock:
PROC [self:
STREAM, block:
REF
READONLY
TEXT, startIndex:
NAT, count:
NAT] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.PutBlock[block, startIndex, count];
data.outputStream.PutBlock[block, startIndex, count];
};
DribbleStreamUnsafePutBlock:
PROC [self:
STREAM, block: IO.UnsafeBlock] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.UnsafePutBlock[block];
data.outputStream.UnsafePutBlock[block];
};
DribbleStreamFlush:
PROC [self:
STREAM] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.Flush[];
data.outputStream.Flush[];
};
DribbleStreamEraseChar:
PROC [self:
STREAM, char:
CHAR] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.EraseChar[char];
data.outputStream.EraseChar[char];
};
DribbleStreamReset:
PROC [self:
STREAM] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.Reset[];
data.outputStream.Reset[];
};
DribbleStreamClose:
PROC [self:
STREAM, abort:
BOOL] = {
data: DribbleStreamData = NARROW[self.streamData];
self.backingStream.Close[abort];
data.outputStream.Close[abort];
};