T2FileOps: CEDAR DEFINITIONS = BEGINclassBit: CARDINAL = 1;				-- non-default class nameformatBit: CARDINAL = 2;			-- non-default format namecommentBit: CARDINAL = 4;		-- comment property set truerunsBit: CARDINAL = 8;				-- text node has looks runspropsBit: CARDINAL = 16;			-- text node has propertiesOp: TYPE = CHAR;ENDOFFILE: Op = 0C;NOCHILD: Op = ENDOFFILE+1;BRANCHCONTENTSPECS: Op = NOCHILD+1;CHILDSPECS: Op = BRANCHCONTENTSPECS+1;ITEMCONTENTSPECS: Op = CHILDSPECS+1;STARTC: Op = ITEMCONTENTSPECS+1;ENDC: Op = STARTC+1;STARTBR: Op = ENDC+1;ENDITEMS: Op = STARTBR+1;NODATA: Op = ENDITEMS+1;CLASSDATA: Op = NODATA+1;ENDPROPS: Op = CLASSDATA+1;PROPERTY: Op = ENDPROPS+1;APPLICATION: Op = PROPERTY+1;FORMAL: Op = APPLICATION+1;numLooks: CARDINAL = 48; -- reserve extra 16 bits for future use such as OS character setNOLOOKS: Op = FORMAL+1;addLooksFirst: Op = NOLOOKS+1;addLooksLast: Op = addLooksFirst+numLooks-1;lastLooksFirst: Op = addLooksLast+1;lastLooksLast: Op = lastLooksFirst+numLooks-1;branch: Op = lastLooksLast+1;lastBranch: Op = branch+commentBit*2-1;text: Op = lastBranch+1;lastText: Op = text+propsBit*2-1;list: Op = lastText+1;lastList: Op = list+commentBit*2-1;box: Op = lastList+1;lastBox: Op = box+commentBit*2-1;basic: Op = lastBox+1;lastBasic: Op = basic+commentBit*2-1;IntBytes: TYPE = MACHINE DEPENDENT RECORD [first (0:9..15): [0..127] _ 0, -- first byte written on filesecond (0:2..8): [0..127] _ 0, -- second byte writtenthirdBottom (0:0..1): [0..3] _ 0, -- bottom bits of third byte writtenthirdTop (1:11..15): [0..31] _ 0, -- top bits of third byte writtenfourth (1:4..10): [0..127] _ 0, -- fourth byte writtenunused (1:0..3): [0..15] _ 0 -- these are always 0];LengthByte: TYPE = MACHINE DEPENDENT RECORD [unused (0:0..7): [0..255] _ 0,others (0:8..8): BOOLEAN _ FALSE, -- tells if other bytes are presentdata (0:9..15): [0..127] _ 0];ThirdByte: TYPE = MACHINE DEPENDENT RECORD [unused (0:0..7): [0..255] _ 0,others (0:8..8): BOOLEAN _ FALSE,dataTop (0:9..13): [0..31] _ 0, -- top 5 bits of datadataBottom (0:14..15): [0..3] _ 0 -- bottom 2 bits of data];controlTrailerId: CHAR = 232C;DataPaddedFlag: CHAR = 205C;DataUnpaddedFlag: CHAR = 250C;versionNumber: CHAR = 2C;isBranchFlagBit: CARDINAL = 1;END.  ®  T2FileOps.MesaLast Edited by: Paxton, August 19, 1983 11:20 amFile representation for Tioga2File representationfile = text control properties trailertext = characters of text nodes separated by CR's and padded with 0 at end if necessary control = control information for parsing the file; starts with 0 to indicate end of plain text part of fileproperties = {key value} -- both keys and values stored as ropestrailer = -- 14 bytes at end of file1 byte controlTrailerId, 1 byte (DataPaddedFlag | DataUnpaddedFlag), 1 byte version number, 1 byte of flags, 2 bytes for length of properties, 4 bytes for length of text, 4 bytes for length of fileBranch nodebranch =OP [if OP.class then className] [if OP.format then formatName] {prop}(BRANCHCONTENTSPECS contentsSpecs | {item}) -- the contents of the branch(NOCHILD -- branch has no children -- |CHILDSPECS childSpecs -- class op will create children from the specs -- |STARTC {child} ENDC -- the children will be parsed left to right when parse the parent -- |ENDITEMS {child} ENDC {ctrlLen dataLen} numChildren -- can create unparsed children --)The OP also includes a comment bit.The ctrlLen dataLen pairs are in reverse order for the children.  Thus when read from end, get info for first child first.Need opcode after items since branches don't have a special starting code, and therefore we wouldn't be able to tell the end of the items from the beginning of the children if the first child didn't have comment or properties.The STARTC&ENDC version is called "whole tree mode" and is used for branches inside list or box nodes and for branches nested more than 2 levels deep in the document tree.  In this mode, the child branches are parsed at the same time the parent is parsed, so there is no need for control and data lengths.  If the parent is stored in whole tree mode, the children must all be stored that way also.  No child can begin with ENDC, so the parsing of the children can simply go on until it encounters an ENDC.We put an ENDC after the children even in the case where we give the lengths and number of children info so that we can be sure to be able to parse a branch even if we don't know the length of the control information ahead of time.Basic, Box, or List nodebasic, box, or list = OP [if OP.class then className] [if OP.format then formatName] {prop}(STARTBR {branch} | ITEMCONTENTSPECS contentsSpecs | {item | basic}) (NODATA | CLASSDATA data)The OP includes bits saying whether or not there is a class name and a format name.The OP also includes a bit saying whether or not this is a comment node.If there is no class name, the class defaults to "Basic", "Box", or "List" respectively.If there is no format name, the format defaults to "Default".There are no contents for a basic node.If the contents are branches, they are represented using whole tree mode as defined above.  Notice that the contents are either all branches or all non-branches.No branch, item, or basic can begin with NODATA or CLASSDATA, so the parsing of the contents can go on until it encounters one of these ops.Text nodetext = OP [if OP.class then className] [if OP.format then formatName][if OP.runs then runs] [if OP.comment then text] [if OP.props then {prop} ENDPROPS]The OP has bits for presence of class name, format name, runs, and properties. There is also a comment bit saying whether or not this is a comment node.  If it is, the text appears in the control info.Miscellaneousitem = text | box | listprop = PROPERTY propertyName propertyValueSpecs | APPLICATION | FORMALruns = numberOfRuns {run}run = (lookSeq | NOLOOKS) runLengthlookSeq = {addLooks} lastLooksaddlooks = BYTE [addLooksFirst..addLooksLast]lastLooks = BYTE [lastLooksFirst..lastLooksLast]General definitionsGeneral opsLooks related opsBranch nodesText nodesList nodesBox nodesBasic nodesLengthslengths are given in as few bytes as possible according to following schemefirst bit of each byte tells if other bytes follow (up to 4 bytes max)concat other 7 bits of bytes with leading 0's to form lengththus can represent lengths up to 2**28-1 if use 4 byteslengths of 127 or less fit in 1 bytelengths in [128..4095] fit in 2 bytesTrailer infoTrailer flags Êe  –"cedar" style˜ Jšœ™Jšœ0™0head2™head3™Ibodyšœ&™&MšœX™XM™lMšœÏc'™@šœ
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