% language=uk \environment luametatex-style \startcomponent luametatex-enhancements \startchapter[reference=enhancements,title={Basic \TEX\ enhancements}] \startsection[title={Introduction}] \startsubsection[title={Primitive behaviour}] From day one, \LUATEX\ has offered extra features compared to the superset of \PDFTEX, which includes \ETEX, and \ALEPH. This has not been limited to the possibility to execute \LUA\ code via \prm {directlua}, but \LUATEX\ also adds functionality via new \TEX|-|side primitives or extensions to existing ones. The same is true for \LUAMETATEX. Some primitives have \type {luatex} in their name and there will be no \type {luametatex} variants. This is because we consider \LUAMETATEX\ to be \LUATEX 2\high{+}. Contrary to the \LUATEX\ engine \LUAMETATEX\ enables all its primitives. You can clone (a selection of) primitives with a different prefix, like: \starttyping \directlua { tex.enableprimitives('normal',tex.extraprimitives()) } \stoptyping The \type {extraprimitives} function returns the whole list or a subset, specified by one or more keywords \type {core}, \type {tex}, \type {etex} or \type {luatex}. \footnote {At some point this function might be changed to return the whole list always}. But be aware that the curly braces may not have the proper \prm {catcode} assigned to them at this early time (giving a \quote {Missing number} error), so it may be needed to put these assignments before the above line: \starttyping \catcode `\{=1 \catcode `\}=2 \stoptyping More fine|-|grained primitives control is possible and you can look up the details in \in {section} [luaprimitives]. There are only three kinds of primitives: \type {tex}, \type {etex} and \type {luatex} but a future version might drop this and no longer make that distinction as it no longer serves a purpose. \stopsubsection \startsubsection[title={Experiments}] There are a few extensions to the engine regarding the macro machinery. Some are already well tested but others are (still) experimental. Although they are likely to stay, their exact behaviour might evolve. Because \LUAMETATEX\ is also used for experiments, this is not a problem. We can always decide to also add some of what is discussed here to \LUATEX, but it will happen with a delay. There are all kinds of small improvements that might find their way into stock \LUATEX: a few more helpers, some cleanup of code, etc. We'll see. In any case, if you play with these before they are declared stable, unexpected side effects are what you have to accept. \stopsubsection \startsubsection[title={Version information}] \startsubsubsection[title={\lpr {luatexbanner}, \lpr {luatexversion} and \lpr {luatexrevision}}] \topicindex{version} \topicindex{banner} There are three primitives to test the version of \LUATEX\ (and \LUAMETATEX): \unexpanded\def\VersionHack#1% otherwise different luatex and luajittex runs {\ctxlua{% local banner = "\luatexbanner" local banner = string.match(banner,"(.+)\letterpercent(") or banner context(string.gsub(banner ,"jit",""))% }} \starttabulate[|l|l|pl|] \DB primitive \BC value \BC explanation \NC \NR \TB \NC \lpr {luatexbanner} \NC \VersionHack{\luatexbanner} \NC the banner reported on the command line \NC \NR \NC \lpr {luatexversion} \NC \the\luatexversion \NC a combination of major and minor number \NC \NR \NC \lpr {luatexrevision} \NC \the\luatexrevision \NC the revision number \NC \NR \LL \stoptabulate A version is defined as follows: \startitemize \startitem The major version is the integer result of \lpr {luatexversion} divided by 100. The primitive is an \quote {internal variable}, so you may need to prefix its use with \prm {the} or \prm {number} depending on the context. \stopitem \startitem The minor version is a number running from 0 upto 99. \stopitem \startitem The revision is reported by \lpr {luatexrevision}. Contrary to other engines in \LUAMETATEX\ is also a number so one needs to prefix it with \prm {the} or \prm {number}. \footnote {In the past it always was good to prefix the revision with \prm {number} anyway, just to play safe, although there have for instance been times that \PDFTEX\ had funny revision indicators that at some point ended up as letters due to the internal conversions.} \stopitem \startitem The full version number consists of the major version (\type {X}), minor version (\type {YY}) and revision (\type {ZZ}), separated by dots, so \type {X.YY.ZZ}. \stopitem \stopitemize \stopsubsubsection The \LUAMETATEX\ version number starts at~2 in order to prevent a clash with \LUATEX, and the version commands are the same. This is a way to indicate that these projects are related. \startsubsubsection[title={\lpr {formatname}}] \topicindex{format} The \lpr {formatname} syntax is identical to \prm {jobname}. In \INITEX, the expansion is empty. Otherwise, the expansion is the value that \prm {jobname} had during the \INITEX\ run that dumped the currently loaded format. You can use this token list to provide your own version info. \stopsubsubsection \stopsubsection \stopsection \startsection[title={\UNICODE\ text support}] \startsubsection[title={Extended ranges}] \topicindex{\UNICODE} Text input and output is now considered to be \UNICODE\ text, so input characters can use the full range of \UNICODE\ ($2^{20}+2^{16}-1 = \hbox{0x10FFFF}$). Later chapters will talk of characters and glyphs. Although these are not interchangeable, they are closely related. During typesetting, a character is always converted to a suitable graphic representation of that character in a specific font. However, while processing a list of to|-|be|-|typeset nodes, its contents may still be seen as a character. Inside the engine there is no clear separation between the two concepts. Because the subtype of a glyph node can be changed in \LUA\ it is up to the user. Subtypes larger than 255 indicate that font processing has happened. A few primitives are affected by this, all in a similar fashion: each of them has to accommodate for a larger range of acceptable numbers. For instance, \prm {char} now accepts values between~0 and $1{,}114{,}111$. This should not be a problem for well|-|behaved input files, but it could create incompatibilities for input that would have generated an error when processed by older \TEX|-|based engines. The affected commands with an altered initial (left of the equal sign) or secondary (right of the equal sign) value are: \prm {char}, \prm {lccode}, \prm {uccode}, \lpr {hjcode}, \prm {catcode}, \prm {sfcode}, \lpr {efcode}, \lpr {lpcode}, \lpr {rpcode}, \prm {chardef}. As far as the core engine is concerned, all input and output to text files is \UTF-8 encoded. Input files can be pre|-|processed using the \type {reader} callback. This will be explained in \in {section} [iocallback]. Normalization of the \UNICODE\ input is on purpose not built|-|in and can be handled by a macro package during callback processing. We have made some practical choices and the user has to live with those. Output in byte|-|sized chunks can be achieved by using characters just outside of the valid \UNICODE\ range, starting at the value $1{,}114{,}112$ (0x110000). When the time comes to print a character $c>=1{,}114{,}112$, \LUATEX\ will actually print the single byte corresponding to $c$ minus 1{,}114{,}112. Contrary to other \TEX\ engines, the output to the terminal is as|-|is so there is no escaping with \type {^^}. We operate in a \UTF\ universe. \stopsubsection \startsubsection[title={\lpr {Uchar}}] \topicindex{\UNICODE} The expandable command \lpr {Uchar} reads a number between~0 and $1{,}114{,}111$ and expands to the associated \UNICODE\ character. \stopsubsection \startsubsection[title={Extended tables}] All traditional \TEX\ and \ETEX\ registers can be 16-bit numbers. The affected commands are: \startfourcolumns \startlines \prm {count} \prm {dimen} \prm {skip} \prm {muskip} \prm {marks} \prm {toks} \prm {countdef} \prm {dimendef} \prm {skipdef} \prm {muskipdef} \prm {toksdef} \prm {insert} \prm {box} \prm {unhbox} \prm {unvbox} \prm {copy} \prm {unhcopy} \prm {unvcopy} \prm {wd} \prm {ht} \prm {dp} \prm {setbox} \prm {vsplit} \stoplines \stopfourcolumns Fonts are loaded via \LUA\ and a minimal amount of information is kept at the \TEX\ end. Sharing resources is up to the loaders. The engine doesn't really care about what a character (or glyph) number represents (a \UNICODE\ or index) as it only is interested in dimensions. \stopsubsection \stopsection \startsection[title={Attributes}] \startsubsection[title={Nodes}] \topicindex {nodes} When \TEX\ reads input it will interpret the stream according to the properties of the characters. Some signal a macro name and trigger expansion, others open and close groups, trigger math mode, etc. What's left over becomes the typeset text. Internally we get a linked list of nodes. Characters become \nod {glyph} nodes that have for instance a \type {font} and \type {char} property and \typ {\kern 10pt} becomes a \nod {kern} node with a \type {width} property. Spaces are alien to \TEX\ as they are turned into \nod {glue} nodes. So, a simple paragraph is mostly a mix of sequences of \nod {glyph} nodes (words) and \nod {glue} nodes (spaces). A node can have a subtype so that it can be recognized as for instance a space related glue. The sequences of characters at some point are extended with \nod {disc} nodes that relate to hyphenation. After that font logic can be applied and we get a list where some characters can be replaced, for instance multiple characters can become one ligature, and font kerns can be injected. This is driven by the font properties. Boxes (like \prm {hbox} and \prm {vbox}) become \nod {hlist} or \nod {vlist} nodes with \type {width}, \type {height}, \type {depth} and \type {shift} properties and a pointer \type {list} to its actual content. Boxes can be constructed explicitly or can be the result of subprocesses. For instance, when lines are broken into paragraphs, the lines are a linked list of \nod {hlist} nodes, possibly with glue and penalties in between. Internally nodes have a number. This number is actually an index in the memory used to store nodes. So, to summarize: all that you enter as content eventually becomes a node, often as part of a (nested) list structure. They have a relative small memory footprint and carry only the minimal amount of information needed. In traditional \TEX\ a character node only held the font and slot number, in \LUATEX\ we also store some language related information, the expansion factor, etc. Now that we have access to these nodes from \LUA\ it makes sense to be able to carry more information with a node and this is where attributes kick in. \stopsubsection \startsubsection[title={Attribute registers}] \topicindex {attributes} Attributes are a completely new concept in \LUATEX. Syntactically, they behave a lot like counters: attributes obey \TEX's nesting stack and can be used after \prm {the} etc.\ just like the normal \prm {count} registers. \startsyntax \attribute <16-bit number> <32-bit number>!crlf \attributedef <16-bit number> \stopsyntax Conceptually, an attribute is either \quote {set} or \quote {unset}. Unset attributes have a special negative value to indicate that they are unset, that value is the lowest legal value: \type {-"7FFFFFFF} in hexadecimal, a.k.a. $-2147483647$ in decimal. It follows that the value \type {-"7FFFFFFF} cannot be used as a legal attribute value, but you {\it can\/} assign \type {-"7FFFFFFF} to \quote {unset} an attribute. All attributes start out in this \quote {unset} state in \INITEX. Attributes can be used as extra counter values, but their usefulness comes mostly from the fact that the numbers and values of all \quote {set} attributes are attached to all nodes created in their scope. These can then be queried from any \LUA\ code that deals with node processing. Further information about how to use attributes for node list processing from \LUA\ is given in~\in {chapter}[nodes]. Attributes are stored in a sorted (sparse) linked list that are shared when possible. This permits efficient testing and updating. You can define many thousands of attributes but normally such a large number makes no sense and is also not that efficient because each node carries a (possibly shared) link to a list of currently set attributes. But they are a convenient extension and one of the first extensions we implemented in \LUATEX. In \LUAMETATEX\ we try to minimize the memory footprint and creation of these attribute lists more aggressive sharing them. This feature is still somewhat experimental. \stopsubsection \startsubsection[title={Box attributes}] \topicindex {attributes} \topicindex {boxes} Nodes typically receive the list of attributes that is in effect when they are created. This moment can be quite asynchronous. For example: in paragraph building, the individual line boxes are created after the \prm {par} command has been processed, so they will receive the list of attributes that is in effect then, not the attributes that were in effect in, say, the first or third line of the paragraph. Similar situations happen in \LUATEX\ regularly. A few of the more obvious problematic cases are dealt with: the attributes for nodes that are created during hyphenation, kerning and ligaturing borrow their attributes from their surrounding glyphs, and it is possible to influence box attributes directly. When you assemble a box in a register, the attributes of the nodes contained in the box are unchanged when such a box is placed, unboxed, or copied. In this respect attributes act the same as characters that have been converted to references to glyphs in fonts. For instance, when you use attributes to implement color support, each node carries information about its eventual color. In that case, unless you implement mechanisms that deal with it, applying a color to already boxed material will have no effect. Keep in mind that this incompatibility is mostly due to the fact that separate specials and literals are a more unnatural approach to colors than attributes. It is possible to fine-tune the list of attributes that are applied to a \type {hbox}, \type {vbox} or \type {vtop} by the use of the keyword \type {attr}. The \type {attr} keyword(s) should come before a \type {to} or \type {spread}, if that is also specified. An example is: \startbuffer[tex] \attribute997=123 \attribute998=456 \setbox0=\hbox {Hello} \setbox2=\hbox attr 999 = 789 attr 998 = -"7FFFFFFF{Hello} \stopbuffer \startbuffer[lua] for b=0,2,2 do for a=997, 999 do tex.sprint("box ", b, " : attr ",a," : ",tostring(tex.box[b] [a])) tex.sprint("\\quad\\quad") tex.sprint("list ",b, " : attr ",a," : ",tostring(tex.box[b].list[a])) tex.sprint("\\par") end end \stopbuffer \typebuffer[tex] Box 0 now has attributes 997 and 998 set while box 2 has attributes 997 and 999 set while the nodes inside that box will all have attributes 997 and 998 set. Assigning the maximum negative value causes an attribute to be ignored. To give you an idea of what this means at the \LUA\ end, take the following code: \typebuffer[lua] Later we will see that you can access properties of a node. The boxes here are so called \nod {hlist} nodes that have a field \type {list} that points to the content. Because the attributes are a list themselves you can access them by indexing the node (here we do that with \type {[a]}). Running this snippet gives: \start \getbuffer[tex] \startpacked \tt \ctxluabuffer[lua] \stoppacked \stop Because some values are not set we need to apply the \type {tostring} function here so that we get the word \type {nil}. \stopsubsection \stopsection \startsection[title={\LUA\ related primitives}] \startsubsection[title={\prm {directlua}}] In order to merge \LUA\ code with \TEX\ input, a few new primitives are needed. The primitive \prm {directlua} is used to execute \LUA\ code immediately. The syntax is \startsyntax \directlua \stopsyntax The \syntax {} is expanded fully, and then fed into the \LUA\ interpreter. After reading and expansion has been applied to the \syntax {}, the resulting token list is converted to a string as if it was displayed using \type {\the\toks}. On the \LUA\ side, each \prm {directlua} block is treated as a separate chunk. In such a chunk you can use the \type {local} directive to keep your variables from interfering with those used by the macro package. The conversion to and from a token list means that you normally can not use \LUA\ line comments (starting with \type {--}) within the argument. As there typically will be only one \quote {line} the first line comment will run on until the end of the input. You will either need to use \TEX|-|style line comments (starting with \%), or change the \TEX\ category codes locally. Another possibility is to say: \starttyping \begingroup \endlinechar=10 \directlua ... \endgroup \stoptyping Then \LUA\ line comments can be used, since \TEX\ does not replace line endings with spaces. Of course such an approach depends on the macro package that you use. The \prm {directlua} command is expandable. Since it passes \LUA\ code to the \LUA\ interpreter its expansion from the \TEX\ viewpoint is usually empty. However, there are some \LUA\ functions that produce material to be read by \TEX, the so called print functions. The most simple use of these is \type {tex.print( s)}. The characters of the string \type {s} will be placed on the \TEX\ input buffer, that is, \quote {before \TEX's eyes} to be read by \TEX\ immediately. For example: \startbuffer \count10=20 a\directlua{tex.print(tex.count[10]+5)}b \stopbuffer \typebuffer expands to \getbuffer Here is another example: \startbuffer $\pi = \directlua{tex.print(math.pi)}$ \stopbuffer \typebuffer will result in \getbuffer Note that the expansion of \prm {directlua} is a sequence of characters, not of tokens, contrary to all \TEX\ commands. So formally speaking its expansion is null, but it places material on a pseudo-file to be immediately read by \TEX, as \ETEX's \prm {scantokens}. For a description of print functions look at \in {section} [sec:luaprint]. Because the \syntax {} is a chunk, the normal \LUA\ error handling is triggered if there is a problem in the included code. The \LUA\ error messages should be clear enough, but the contextual information is still pretty bad. Often, you will only see the line number of the right brace at the end of the code. While on the subject of errors: some of the things you can do inside \LUA\ code can break up \LUAMETATEX\ pretty bad. If you are not careful while working with the node list interface, you may even end up with assertion errors from within the \TEX\ portion of the executable. \stopsubsection \startsubsection[title={\lpr {luaescapestring}}] \topicindex {escaping} This primitive converts a \TEX\ token sequence so that it can be safely used as the contents of a \LUA\ string: embedded backslashes, double and single quotes, and newlines and carriage returns are escaped. This is done by prepending an extra token consisting of a backslash with category code~12, and for the line endings, converting them to \type {n} and \type {r} respectively. The token sequence is fully expanded. \startsyntax \luaescapestring \stopsyntax Most often, this command is not actually the best way to deal with the differences between \TEX\ and \LUA. In very short bits of \LUA\ code it is often not needed, and for longer stretches of \LUA\ code it is easier to keep the code in a separate file and load it using \LUA's \type {dofile}: \starttyping \directlua { dofile("mysetups.lua") } \stoptyping \stopsubsection \startsubsection[title={\lpr {luafunction}, \lpr {luafunctioncall} and \lpr {luadef}}] The \prm {directlua} commands involves tokenization of its argument (after picking up an optional name or number specification). The tokenlist is then converted into a string and given to \LUA\ to turn into a function that is called. The overhead is rather small but when you have millions of calls it can have some impact. For this reason there is a variant call available: \lpr {luafunction}. This command is used as follows: \starttyping \directlua { local t = lua.get_functions_table() t[1] = function() tex.print("!") end t[2] = function() tex.print("?") end } \luafunction1 \luafunction2 \stoptyping Of course the functions can also be defined in a separate file. There is no limit on the number of functions apart from normal \LUA\ limitations. Of course there is the limitation of no arguments but that would involve parsing and thereby give no gain. The function, when called in fact gets one argument, being the index, so in the following example the number \type {8} gets typeset. \starttyping \directlua { local t = lua.get_functions_table() t[8] = function(slot) tex.print(slot) end } \stoptyping The \lpr {luafunctioncall} primitive does the same but is unexpandable, for instance in an \prm {edef}. In addition \LUATEX\ provides a definer: \starttyping \luadef\MyFunctionA 1 \global\luadef\MyFunctionB 2 \protected\global\luadef\MyFunctionC 3 \stoptyping You should really use these commands with care. Some references get stored in tokens and assume that the function is available when that token expands. On the other hand, as we have tested this functionality in relative complex situations normal usage should not give problems. \stopsubsection \startsubsection[title={\lpr {luabytecode} and \lpr {luabytecodecall}}] Analogue to the function callers discussed in the previous section we have byte code callers. Again the call variant is unexpandable. \starttyping \directlua { lua.bytecode[9998] = function(s) tex.sprint(s*token.scan_int()) end lua.bytecode[5555] = function(s) tex.sprint(s*token.scan_dimen()) end } \stoptyping This works with: \starttyping \luabytecode 9998 5 \luabytecode 5555 5sp \luabytecodecall9998 5 \luabytecodecall5555 5sp \stoptyping The variable \type {s} in the code is the number of the byte code register that can be used for diagnostic purposes. The advantage of bytecode registers over function calls is that they are stored in the format (but without upvalues). \stopsubsection \stopsection \startsection[title={Catcode tables}] \startsubsection[title={Catcodes}] \topicindex {catcodes} Catcode tables are a new feature that allows you to switch to a predefined catcode regime in a single statement. You can have lots of different tables, but if you need a dozen you might wonder what you're doing. This subsystem is backward compatible: if you never use the following commands, your document will not notice any difference in behaviour compared to traditional \TEX. The contents of each catcode table is independent from any other catcode table, and its contents is stored and retrieved from the format file. \stopsubsection \startsubsection[title={\lpr {catcodetable}}] \startsyntax \catcodetable <15-bit number> \stopsyntax The primitive \lpr {catcodetable} switches to a different catcode table. Such a table has to be previously created using one of the two primitives below, or it has to be zero. Table zero is initialized by \INITEX. \stopsubsection \startsubsection[title={\lpr {initcatcodetable}}] \startsyntax \initcatcodetable <15-bit number> \stopsyntax The primitive \lpr {initcatcodetable} creates a new table with catcodes identical to those defined by \INITEX. The new catcode table is allocated globally: it will not go away after the current group has ended. If the supplied number is identical to the currently active table, an error is raised. The initial values are: \starttabulate[|c|c|l|l|] \DB catcode \BC character \BC equivalent \BC category \NC \NR \TB \NC 0 \NC \tttf \letterbackslash \NC \NC \type {escape} \NC \NR \NC 5 \NC \tttf \letterhat\letterhat M \NC return \NC \type {car_ret} \NC \NR \NC 9 \NC \tttf \letterhat\letterhat @ \NC null \NC \type {ignore} \NC \NR \NC 10 \NC \tttf \NC space \NC \type {spacer} \NC \NR \NC 11 \NC {\tttf a} \endash\ {\tttf z} \NC \NC \type {letter} \NC \NR \NC 11 \NC {\tttf A} \endash\ {\tttf Z} \NC \NC \type {letter} \NC \NR \NC 12 \NC everything else \NC \NC \type {other} \NC \NR \NC 14 \NC \tttf \letterpercent \NC \NC \type {comment} \NC \NR \NC 15 \NC \tttf \letterhat\letterhat ? \NC delete \NC \type {invalid_char} \NC \NR \LL \stoptabulate \stopsubsection \startsubsection[title={\lpr {savecatcodetable}}] \startsyntax \savecatcodetable <15-bit number> \stopsyntax \lpr {savecatcodetable} copies the current set of catcodes to a new table with the requested number. The definitions in this new table are all treated as if they were made in the outermost level. The new table is allocated globally: it will not go away after the current group has ended. If the supplied number is the currently active table, an error is raised. \stopsubsection \stopsection \startsection[title={Tokens, commands and strings}] \startsubsection[title={\lpr {scantextokens}}] \topicindex {tokens+scanning} The syntax of \lpr {scantextokens} is identical to \prm {scantokens}. This primitive is a slightly adapted version of \ETEX's \prm {scantokens}. The differences are: \startitemize \startitem The last (and usually only) line does not have a \prm {endlinechar} appended. \stopitem \startitem \lpr {scantextokens} never raises an EOF error, and it does not execute \prm {everyeof} tokens. \stopitem \startitem There are no \quote {\unknown\ while end of file \unknown} error tests executed. This allows the expansion to end on a different grouping level or while a conditional is still incomplete. \stopitem \stopitemize \stopsubsection \startsubsection[title={\lpr {toksapp}, \lpr {tokspre}, \lpr {etoksapp}, \lpr {etokspre}, \lpr {gtoksapp}, \lpr {gtokspre}, \lpr {xtoksapp}, \lpr {xtokspre}}] Instead of: \starttyping \toks0\expandafter{\the\toks0 foo} \stoptyping you can use: \starttyping \etoksapp0{foo} \stoptyping The \type {pre} variants prepend instead of append, and the \type {e} variants expand the passed general text. The \type {g} and \type {x} variants are global. \stopsubsection \startsubsection[title={\prm {csstring}, \lpr {begincsname} and \lpr {lastnamedcs}}] These are somewhat special. The \prm {csstring} primitive is like \prm {string} but it omits the leading escape character. This can be somewhat more efficient than stripping it afterwards. The \lpr {begincsname} primitive is like \prm {csname} but doesn't create a relaxed equivalent when there is no such name. It is equivalent to \starttyping \ifcsname foo\endcsname \csname foo\endcsname \fi \stoptyping The advantage is that it saves a lookup (don't expect much speedup) but more important is that it avoids using the \prm {if} test. The \lpr {lastnamedcs} is one that should be used with care. The above example could be written as: \starttyping \ifcsname foo\endcsname \lastnamedcs \fi \stoptyping This is slightly more efficient than constructing the string twice (deep down in \LUATEX\ this also involves some \UTF8 juggling), but probably more relevant is that it saves a few tokens and can make code a bit more readable. \stopsubsection \startsubsection[title={\lpr {clearmarks}}] \topicindex {marks} This primitive complements the \ETEX\ mark primitives and clears a mark class completely, resetting all three connected mark texts to empty. It is an immediate command. \startsyntax \clearmarks <16-bit number> \stopsyntax \stopsubsection \startsubsection[title={\lpr {alignmark} and \lpr {aligntab}}] The primitive \lpr {alignmark} duplicates the functionality of \type {#} inside alignment preambles, while \lpr {aligntab} duplicates the functionality of \type {&}. \stopsubsection \startsubsection[title={\lpr {letcharcode}}] This primitive can be used to assign a meaning to an active character, as in: \starttyping \def\foo{bar} \letcharcode123=\foo \stoptyping This can be a bit nicer than using the uppercase tricks (using the property of \prm {uppercase} that it treats active characters special). \stopsubsection \startsubsection[title={\lpr {glet}}] This primitive is similar to: \starttyping \protected\def\glet{\global\let} \stoptyping but faster (only measurable with millions of calls) and probably more convenient (after all we also have \type {\gdef}). \stopsubsection \startsubsection[title={\lpr {expanded}, \lpr {immediateassignment} and \lpr {immediateassigned}}] \topicindex {expansion} The \lpr {expanded} primitive takes a token list and expands its content which can come in handy: it avoids a tricky mix of \prm {expandafter} and \prm {noexpand}. You can compare it with what happens inside the body of an \prm {edef}. But this kind of expansion still doesn't expand some primitive operations. \startbuffer \newcount\NumberOfCalls \def\TestMe{\advance\NumberOfCalls1 } \edef\Tested{\TestMe foo:\the\NumberOfCalls} \edef\Tested{\TestMe foo:\the\NumberOfCalls} \edef\Tested{\TestMe foo:\the\NumberOfCalls} \meaning\Tested \stopbuffer \typebuffer The result is a macro that has the not expanded code in its body: \getbuffer Instead we can define \tex {TestMe} in a way that expands the assignment immediately. You need of course to be aware of preventing look ahead interference by using a space or \tex {relax} (often an expression works better as it doesn't leave an \tex {relax}). \startbuffer \def\TestMe{\immediateassignment\advance\NumberOfCalls1 } \edef\Tested{\TestMe foo:\the\NumberOfCalls} \edef\Tested{\TestMe foo:\the\NumberOfCalls} \edef\Tested{\TestMe foo:\the\NumberOfCalls} \meaning\Tested \stopbuffer \typebuffer This time the counter gets updates and we don't see interference in the resulting \tex {Tested} macro: \getbuffer Here is a somewhat silly example of expanded comparison: \startbuffer \def\expandeddoifelse#1#2#3#4% {\immediateassignment\edef\tempa{#1}% \immediateassignment\edef\tempb{#2}% \ifx\tempa\tempb \immediateassignment\def\next{#3}% \else \immediateassignment\def\next{#4}% \fi \next} \edef\Tested {(\expandeddoifelse{abc}{def}{yes}{nop}/% \expandeddoifelse{abc}{abc}{yes}{nop})} \meaning\Tested \stopbuffer \typebuffer It gives: \getbuffer A variant is: \starttyping \def\expandeddoifelse#1#2#3#4% {\immediateassigned{ \edef\tempa{#1}% \edef\tempb{#2}% }% \ifx\tempa\tempb \immediateassignment\def\next{#3}% \else \immediateassignment\def\next{#4}% \fi \next} \stoptyping The possible error messages are the same as using assignments in preambles of alignments and after the \prm {accent} command. The supported assignments are the so called prefixed commands (except box assignments). \stopsubsection \startsubsection[title={\lpr {ignorepars}}] This primitive is like \prm {ignorespaces} but also skips paragraph ending commands (normally \prm {par} and empty lines). \stopsubsection \startsubsection[title={\lpr {futureexpand}, \lpr {futureexpandis}, \lpr {futureexpandisap}}] These commands are used as: \starttyping \futureexpand\sometoken\whenfound\whennotfound \stoptyping When there is no match and a space was gobbled a space will be put back. The \type {is} variant doesn't do that while the \type {isap} even skips \type {\pars}, These characters stand for \quote {ignorespaces} and \quote {ignorespacesandpars}. \stopsubsection \startsubsection[title={\lpr {aftergrouped}}] There is a new experimental feature that can inject multiple tokens to after the group ends. An example demonstrate its use: \startbuffer { \aftergroup A \aftergroup B \aftergroup C test 1 : } { \aftergrouped{What comes next 1} \aftergrouped{What comes next 2} \aftergrouped{What comes next 3} test 2 : } { \aftergroup A \aftergrouped{What comes next 1} \aftergroup B \aftergrouped{What comes next 2} \aftergroup C \aftergrouped{What comes next 3} test 3 : } { \aftergrouped{What comes next 1} \aftergroup A \aftergrouped{What comes next 2} \aftergroup B \aftergrouped{What comes next 3} \aftergroup C test 4 : } \stopbuffer \typebuffer This gives: \startpacked\getbuffer\stoppacked \stopsubsection \stopsection \startsection[title=Conditions] \startsubsection[title={\lpr{ifabsnum} and \lpr {ifabsdim}}] There are two tests that we took from \PDFTEX: \startbuffer \ifabsnum -10 = 10 the same number \fi \ifabsdim -10pt = 10pt the same dimension \fi \stopbuffer \typebuffer This gives \blank {\tt \getbuffer} \blank \stopsubsection \startsubsection[title={\lpr{ifcmpnum}, \lpr {ifcmpdim}, \lpr {ifnumval}, \lpr {ifdimval}, \lpr {ifchknum} and \lpr {ifchkdim}}] \topicindex {conditions+numbers} \topicindex {conditions+dimensions} \topicindex {numbers} \topicindex {dimensions} New are the ones that compare two numbers or dimensions: \startbuffer \ifcmpnum 5 8 less \or equal \else more \fi \ifcmpnum 5 5 less \or equal \else more \fi \ifcmpnum 8 5 less \or equal \else more \fi \stopbuffer \typebuffer \blank {\tt \getbuffer} \blank and \startbuffer \ifcmpdim 5pt 8pt less \or equal \else more \fi \ifcmpdim 5pt 5pt less \or equal \else more \fi \ifcmpdim 8pt 5pt less \or equal \else more \fi \stopbuffer \typebuffer \blank {\tt \getbuffer} \blank There are also some number and dimension tests. All four expose the \type {\else} branch when there is an error, but two also report if the number is less, equal or more than zero. \startbuffer \ifnumval -123 \or < \or = \or > \or ! \else ? \fi \ifnumval 0 \or < \or = \or > \or ! \else ? \fi \ifnumval 123 \or < \or = \or > \or ! \else ? \fi \ifnumval abc \or < \or = \or > \or ! \else ? \fi \ifdimval -123pt \or < \or = \or > \or ! \else ? \fi \ifdimval 0pt \or < \or = \or > \or ! \else ? \fi \ifdimval 123pt \or < \or = \or > \or ! \else ? \fi \ifdimval abcpt \or < \or = \or > \or ! \else ? \fi \stopbuffer \typebuffer \blank {\tt \getbuffer} \blank \startbuffer \ifchknum -123 \or okay \else bad \fi \ifchknum 0 \or okay \else bad \fi \ifchknum 123 \or okay \else bad \fi \ifchknum abc \or okay \else bad \fi \ifchkdim -123pt \or okay \else bad \fi \ifchkdim 0pt \or okay \else bad \fi \ifchkdim 123pt \or okay \else bad \fi \ifchkdim abcpt \or okay \else bad \fi \stopbuffer \typebuffer \blank {\tt \getbuffer} \blank \stopsubsection \startsubsection[title={\lpr {iftok} and \lpr {ifcstok}}] \topicindex {conditions+tokens} \topicindex {tokens} Comparing tokens and macros can be done with \type {\ifx}. Two extra test are provided in \LUAMETATEX: \startbuffer \def\ABC{abc} \def\DEF{def} \def\PQR{abc} \newtoks\XYZ \XYZ {abc} \iftok{abc}{def}\relax (same) \else [different] \fi \iftok{abc}{abc}\relax [same] \else (different) \fi \iftok\XYZ {abc}\relax [same] \else (different) \fi \ifcstok\ABC \DEF\relax (same) \else [different] \fi \ifcstok\ABC \PQR\relax [same] \else (different) \fi \ifcstok{abc}\ABC\relax [same] \else (different) \fi \stopbuffer \typebuffer \startpacked[blank] {\tt\nospacing\getbuffer} \stoppacked You can check if a macro is is defined as protected with \type {\ifprotected} while frozen macros can be tested with \type {\iffrozen}. A provisional \type {\ifusercmd} tests will check if a command is defined at the user level (and this one might evolve). \stopsubsection \startsubsection[title={\lpr {ifcondition}}] \topicindex {conditions} This is a somewhat special one. When you write macros conditions need to be properly balanced in order to let \TEX's fast branch skipping work well. This new primitive is basically a no||op flagged as a condition so that the scanner can recognize it as an if|-|test. However, when a real test takes place the work is done by what follows, in the next example \tex {something}. \starttyping \unexpanded\def\something#1#2% {\edef\tempa{#1}% \edef\tempb{#2} \ifx\tempa\tempb} \ifcondition\something{a}{b}% \ifcondition\something{a}{a}% true 1 \else false 1 \fi \else \ifcondition\something{a}{a}% true 2 \else false 2 \fi \fi \stoptyping If you are familiar with \METAPOST, this is a bit like \type {vardef} where the macro has a return value. Here the return value is a test. Experiments with something \type {\ifdef} actually worked ok but were rejected because in the end it gave no advantage so this generic one has to do. The \type {\ifcondition} test is basically is a no|-|op except when branches are skipped. However, when a test is expected, the scanner gobbles it and the next test result is used. Here is an other example: \startbuffer \def\mytest#1% {\ifabsdim#1>0pt\else \expandafter \unless \fi \iftrue} \ifcondition\mytest{10pt}\relax non-zero \else zero \fi \ifcondition\mytest {0pt}\relax non-zero \else zero \fi \stopbuffer \typebuffer \blank {\tt \getbuffer} \blank The last expansion in a macro like \type {\mytest} has to be a condition and here we use \type {\unless} to negate the result. \stopsubsection \startsubsection[title={\lpr {orelse}}] Sometimes you have successive tests that, when laid out in the source lead to deep trees. The \type {\ifcase} test is an exception. Experiments with \type {\ifcasex} worked out fine but eventually were rejected because we have many tests so it would add a lot. As \LUAMETATEX\ permitted more experiments, eventually an alternative was cooked up, one that has some restrictions but is relative lightweight. It goes like this: \starttyping \ifnum\count0<10 less \orelse\ifnum\count0=10 equal \else more \fi \stoptyping The \type {\orelse} has to be followed by one of the if test commands, except \type {\ifcondition}, and there can be an \type {\unless} in front of such a command. These restrictions make it possible to stay in the current condition (read: at the same level). If you need something more complex, using \type {\orelse} is probably unwise anyway. In case you wonder about performance, there is a little more checking needed when skipping branches but that can be neglected. There is some gain due to staying at the same level but that is only measurable when you runs tens of millions of complex tests and in that case it is very likely to drown in the real action. It's a convenience mechanism, in the sense that it can make your code look a bit easier to follow. There is a nice side effect of this mechanism. When you define: \starttyping \def\quitcondition{\orelse\iffalse} \stoptyping you can do this: \starttyping \ifnum\count0<10 less \orelse\ifnum\count0=10 equal \quitcondition indeed \else more \fi \stoptyping Of course it is only useful at the right level, so you might end up with cases like \starttyping \ifnum\count0<10 less \orelse\ifnum\count0=10 equal \ifnum\count2=30 \expandafter\quitcondition \fi indeed \else more \fi \stoptyping \stopsubsection \startsubsection[title={\lpr {ifprotected}, \lpr {frozen}, \lpr {iffrozen} and \lpr {ifusercmd}}] These checkers deal with control sequences. You can check if a command is a protected one, that is, defined with the \type {\protected} prefix. A command is frozen when it has been defined with the \type {\frozen} prefix. Beware: only macros can be frozen. A user command is a command that is not part of the predefined set of commands. This is an experimental command. \stopsubsection \stopsection \startsection[title={Boxes, rules and leaders}] \startsubsection[title={\lpr {outputbox}}] \topicindex {output} This integer parameter allows you to alter the number of the box that will be used to store the page sent to the output routine. Its default value is 255, and the acceptable range is from 0 to 65535. \startsyntax \outputbox = 12345 \stopsyntax \stopsubsection \startsubsection[title={\prm {vpack}, \prm {hpack} and \prm {tpack}}] These three primitives are like \prm {vbox}, \prm {hbox} and \prm {vtop} but don't apply the related callbacks. \stopsubsection \startsubsection[title={\prm {vsplit}}] \topicindex {splitting} The \prm {vsplit} primitive has to be followed by a specification of the required height. As alternative for the \type {to} keyword you can use \type {upto} to get a split of the given size but result has the natural dimensions then. \stopsubsection \startsubsection[title={Images and reused box objects},reference=sec:imagedandforms] In original \TEX\ image support is dealt with via specials. It's not a native feature of the engine. All that \TEX\ cares about is dimensions, so in practice that meant: using a box with known dimensions that wraps a special that instructs the backend to include an image. The wrapping is needed because a special itself is a whatsit and as such has no dimensions. In \PDFTEX\ a special whatsit for images was introduced and that one {\em has} dimensions. As a consequence, in several places where the engine deals with the dimensions of nodes, it now has to check the details of whatsits. By inheriting code from \PDFTEX, the \LUATEX\ engine also had that property. However, at some point this approach was abandoned and a more natural trick was used: images (and box resources) became a special kind of rules, and as rules already have dimensions, the code could be simplified. When direction nodes and localpar nodes also became first class nodes, whatsits again became just that: nodes representing whatever you want, but without dimensions, and therefore they could again be ignored when dimensions mattered. And, because images were disguised as rules, as mentioned, their dimensions automatically were taken into account. This seperation between front and backend cleaned up the code base already quite a bit. In \LUAMETATEX\ we still have the image specific subtypes for rules, but the engine never looks at subtypes of rules. That was up to the backend. This means that image support is not present in \LUAMETATEX. When an image specification was parsed the special properties, like the filename, or additional attributes, were stored in the backend and all that \LUATEX\ does is registering a reference to an image's specification in the rule node. But, having no backend means nothing is stored, which in turn would make the image inclusion primitives kind of weird. Therefore you need to realize that contrary to \LUATEX, {\em in \LUAMETATEX\ support for images and box reuse is not built in}! However, we can assume that an implementation uses rules in a similar fashion as \LUATEX\ does. So, you can still consider images and box reuse to be core concepts. Here we just mention the primitives that \LUATEX\ provides. They are not available in the engine but can of course be implemented in \LUA. \starttabulate[|l|p|] \DB command \BC explanation \NC \NR \TB \NC \lpr {saveboxresource} \NC save the box as an object to be included later \NC \NR \NC \lpr {saveimageresource} \NC save the image as an object to be included later \NC \NR \NC \lpr {useboxresource} \NC include the saved box object here (by index) \NC \NR \NC \lpr {useimageresource} \NC include the saved image object here (by index) \NC \NR \NC \lpr {lastsavedboxresourceindex} \NC the index of the last saved box object \NC \NR \NC \lpr {lastsavedimageresourceindex} \NC the index of the last saved image object \NC \NR \NC \lpr {lastsavedimageresourcepages} \NC the number of pages in the last saved image object \NC \NR \LL \stoptabulate An implementation probably should accept the usual optional dimension parameters for \type {\use...resource} in the same format as for rules. With images, these dimensions are then used instead of the ones given to \lpr {useimageresource} but the original dimensions are not overwritten, so that a \lpr {useimageresource} without dimensions still provides the image with dimensions defined by \lpr {saveimageresource}. These optional parameters are not implemented for \lpr {saveboxresource}. \starttyping \useimageresource width 20mm height 10mm depth 5mm \lastsavedimageresourceindex \useboxresource width 20mm height 10mm depth 5mm \lastsavedboxresourceindex \stoptyping Examples or optional entries are \type {attr} and \type {resources} that accept a token list, and the \type {type} key. When set to non|-|zero the \type {/Type} entry is omitted. A value of 1 or 3 still writes a \type {/BBox}, while 2 or 3 will write a \type {/Matrix}. But, as said: this is entirely up to the backend. Generic macro packages (like \type {tikz}) can use these assumed primitives so one can best provide them. It is probably, for historic reasons, the only more or less standardized image inclusion interface one can expect to work in all macro packages. \stopsubsection \startsubsection[title={\lpr {hpack}, \lpr {vpack} and \lpr {tpack}}] These three primitives are the equivalents of \type {\hbox}, \type {\vbox} and \type {\vtop} but they don't trigger the packaging related callbacks. Of course one never know if content needs a treatment so using them should be done with care. \stopsubsection \startsubsection[title={\lpr {nohrule} and \lpr {novrule}}] \topicindex {rules} Because introducing a new keyword can cause incompatibilities, two new primitives were introduced: \lpr {nohrule} and \lpr {novrule}. These can be used to reserve space. This is often more efficient than creating an empty box with fake dimensions. \stopsubsection \startsubsection[title={\lpr {gleaders}},reference=sec:gleaders] \topicindex {leaders} This type of leaders is anchored to the origin of the box to be shipped out. So they are like normal \prm {leaders} in that they align nicely, except that the alignment is based on the {\it largest\/} enclosing box instead of the {\it smallest\/}. The \type {g} stresses this global nature. \stopsubsection \stopsection \startsection[title={Languages}] \startsubsection[title={\lpr {hyphenationmin}}] \topicindex {languages} \topicindex {hyphenation} This primitive can be used to set the minimal word length, so setting it to a value of~$5$ means that only words of 6 characters and more will be hyphenated, of course within the constraints of the \prm {lefthyphenmin} and \prm {righthyphenmin} values (as stored in the glyph node). This primitive accepts a number and stores the value with the language. \stopsubsection \startsubsection[title={\prm {boundary}, \prm {noboundary}, \prm {protrusionboundary} and \prm {wordboundary}}] The \prm {noboundary} command is used to inject a whatsit node but now injects a normal node with type \nod {boundary} and subtype~0. In addition you can say: \starttyping x\boundary 123\relax y \stoptyping This has the same effect but the subtype is now~1 and the value~123 is stored. The traditional ligature builder still sees this as a cancel boundary directive but at the \LUA\ end you can implement different behaviour. The added benefit of passing this value is a side effect of the generalization. The subtypes~2 and~3 are used to control protrusion and word boundaries in hyphenation and have related primitives. \stopsubsection \stopsection \startsection[title={Control and debugging}] \startsubsection[title={Tracing}] \topicindex {tracing} If \prm {tracingonline} is larger than~2, the node list display will also print the node number of the nodes. \stopsubsection \startsubsection[title={\lpr {lastnodetype}, \lpr {lastnodesubtype}, \lpr {currentiftype} and \lpr {internalcodesmode}.}] The \ETEX\ command \type {\lastnodetype} is limited to some nodes. When the parameter \type {\internalcodesmode} is set to a non|-|zero value the normal (internally used) numbers are reported. The same is true for \type {\currentiftype}, as we have more conditionals and also use a different order. The \type {\lastnodesubtype} is a bonus. \stopsubsection \stopsection \startsection[title={Files}] \startsubsection[title={File syntax}] \topicindex {files+names} \LUAMETATEX\ will accept a braced argument as a file name: \starttyping \input {plain} \openin 0 {plain} \stoptyping This allows for embedded spaces, without the need for double quotes. Macro expansion takes place inside the argument. The \lpr {tracingfonts} primitive that has been inherited from \PDFTEX\ has been adapted to support variants in reporting the font. The reason for this extension is that a csname not always makes sense. The zero case is the default. \starttabulate[|l|l|] \DB value \BC reported \NC \NR \TB \NC \type{0} \NC \type{\foo xyz} \NC \NR \NC \type{1} \NC \type{\foo (bar)} \NC \NR \NC \type{2} \NC \type{ xyz} \NC \NR \NC \type{3} \NC \type{ xyz} \NC \NR \NC \type{4} \NC \type{} \NC \NR \NC \type{5} \NC \type{} \NC \NR \NC \type{6} \NC \type{ xyz} \NC \NR \LL \stoptabulate \stopsubsection \startsubsection[title={Writing to file}] \topicindex {files+writing} You can now open upto 127 files with \prm {openout}. When no file is open writes will go to the console and log. The \type {write} related primitives have to be implemented as part of a backend! As a consequence a system command is no longer possible but one can use \type {os.execute} to do the same. \stopsubsection \stopsection \startsection[title={Math}] \topicindex {math} We will cover math extensions in its own chapter because not only the font subsystem and spacing model have been enhanced (thereby introducing many new primitives) but also because some more control has been added to existing functionality. Much of this relates to the different approaches of traditional \TEX\ fonts and \OPENTYPE\ math. \stopsection \startsection[title={Fonts}] \topicindex {fonts} Like math, we will cover fonts extensions in its own chapter. Here we stick to mentioning that loading fonts is different in \LUAMETATEX. As in \LUATEX\ we have the extra primitives \type {\fontid} and \type {\setfontid}, \type {\noligs} and \type {\nokerns}, and \type {\nospaces}. The other new primitives in \LUATEX\ have been dropped. \stopsection \startsection[title=Directions] \topicindex {\OMEGA} \topicindex {\ALEPH} \topicindex {directions} \startsubsection[title={Two directions}] The directional model in \LUAMETATEX\ is a simplified version the the model used in \LUATEX. In fact, not much is happening at all: we only register a change in direction. \stopsubsection \startsubsection[title={How it works}] The approach is that we try to make node lists balanced but also try to avoid some side effects. What happens is quite intuitive if we forget about spaces (turned into glue) but even there what happens makes sense if you look at it in detail. However that logic makes in|-|group switching kind of useless when no properly nested grouping is used: switching from right to left several times nested, results in spacing ending up after each other due to nested mirroring. Of course a sane macro package will manage this for the user but here we are discussing the low level injection of directional information. This is what happens: \starttyping \textdirection 1 nur {\textdirection 0 run \textdirection 1 NUR} nur \stoptyping This becomes stepwise: \startnarrower \starttyping injected: [push 1]nur {[push 0]run [push 1]NUR} nur balanced: [push 1]nur {[push 0]run [pop 0][push 1]NUR[pop 1]} nur[pop 0] result : run {RUNrun } run \stoptyping \stopnarrower And this: \starttyping \textdirection 1 nur {nur \textdirection 0 run \textdirection 1 NUR} nur \stoptyping becomes: \startnarrower \starttyping injected: [+TRT]nur {nur [+TLT]run [+TRT]NUR} nur balanced: [+TRT]nur {nur [+TLT]run [-TLT][+TRT]NUR[-TRT]} nur[-TRT] result : run {run RUNrun } run \stoptyping \stopnarrower Now, in the following examples watch where we put the braces: \startbuffer \textdirection 1 nur {{\textdirection 0 run} {\textdirection 1 NUR}} nur \stopbuffer \typebuffer This becomes: \startnarrower \getbuffer \stopnarrower Compare this to: \startbuffer \textdirection 1 nur {{\textdirection 0 run }{\textdirection 1 NUR}} nur \stopbuffer \typebuffer Which renders as: \startnarrower \getbuffer \stopnarrower So how do we deal with the next? \startbuffer \def\ltr{\textdirection 0\relax} \def\rtl{\textdirection 1\relax} run {\rtl nur {\ltr run \rtl NUR \ltr run \rtl NUR} nur} run {\ltr run {\rtl nur \ltr RUN \rtl nur \ltr RUN} run} \stopbuffer \typebuffer It gets typeset as: \startnarrower \startlines \getbuffer \stoplines \stopnarrower We could define the two helpers to look back, pick up a skip, remove it and inject it after the dir node. But that way we loose the subtype information that for some applications can be handy to be kept as|-|is. This is why we now have a variant of \lpr {textdirection} which injects the balanced node before the skip. Instead of the previous definition we can use: \startbuffer[def] \def\ltr{\linedirection 0\relax} \def\rtl{\linedirection 1\relax} \stopbuffer \typebuffer[def] and this time: \startbuffer[txt] run {\rtl nur {\ltr run \rtl NUR \ltr run \rtl NUR} nur} run {\ltr run {\rtl nur \ltr RUN \rtl nur \ltr RUN} run} \stopbuffer \typebuffer[txt] comes out as a properly spaced: \startnarrower \startlines \getbuffer[def,txt] \stoplines \stopnarrower Anything more complex that this, like combination of skips and penalties, or kerns, should be handled in the input or macro package because there is no way we can predict the expected behaviour. In fact, the \lpr {linedir} is just a convenience extra which could also have been implemented using node list parsing. \stopsubsection \startsubsection[title={Controlling glue with \lpr {breakafterdirmode}}] Glue after a dir node is ignored in the linebreak decision but you can bypass that by setting \lpr {breakafterdirmode} to~\type {1}. The following table shows the difference. Watch your spaces. \def\ShowSome#1{% \BC \type{#1} \NC \breakafterdirmode\zerocount\hsize\zeropoint#1 \NC \NC \breakafterdirmode\plusone\hsize\zeropoint#1 \NC \NC \NR } \starttabulate[|l|Tp(1pt)|w(5em)|Tp(1pt)|w(5em)|] \DB \BC \type{0} \NC \BC \type{1} \NC \NC \NR \TB \ShowSome{pre {\textdirection 0 xxx} post} \ShowSome{pre {\textdirection 0 xxx }post} \ShowSome{pre{ \textdirection 0 xxx} post} \ShowSome{pre{ \textdirection 0 xxx }post} \ShowSome{pre { \textdirection 0 xxx } post} \ShowSome{pre {\textdirection 0\relax\space xxx} post} \LL \stoptabulate \stopsubsection \startsubsection[title={Controling parshapes with \lpr {shapemode}}] Another adaptation to the \ALEPH\ directional model is control over shapes driven by \prm {hangindent} and \prm {parshape}. This is controlled by a new parameter \lpr {shapemode}: \starttabulate[|c|l|l|] \DB value \BC \prm {hangindent} \BC \prm {parshape} \NC \NR \TB \BC \type{0} \NC normal \NC normal \NC \NR \BC \type{1} \NC mirrored \NC normal \NC \NR \BC \type{2} \NC normal \NC mirrored \NC \NR \BC \type{3} \NC mirrored \NC mirrored \NC \NR \LL \stoptabulate The value is reset to zero (like \prm {hangindent} and \prm {parshape}) after the paragraph is done with. You can use negative values to prevent this. In \in {figure} [fig:shapemode] a few examples are given. \startplacefigure[reference=fig:shapemode,title={The effect of \type {shapemode}.}] \startcombination[2*3] {\ruledvbox \bgroup \setuptolerance[verytolerant] \hsize .45\textwidth \switchtobodyfont[6pt] \pardirection 0 \textdirection 0 \hangindent 40pt \hangafter -3 \leftskip10pt \input tufte \par \egroup} {TLT: hangindent} {\ruledvbox \bgroup \setuptolerance[verytolerant] \hsize .45\textwidth \switchtobodyfont[6pt] \pardirection 0 \textdirection 0 \parshape 4 0pt .8\hsize 10pt .8\hsize 20pt .8\hsize 0pt \hsize \input tufte \par \egroup} {TLT: parshape} {\ruledvbox \bgroup \setuptolerance[verytolerant] \hsize .45\textwidth \switchtobodyfont[6pt] \pardirection 1 \textdirection 1 \hangindent 40pt \hangafter -3 \leftskip10pt \input tufte \par \egroup} {TRT: hangindent mode 0} {\ruledvbox \bgroup \setuptolerance[verytolerant] \hsize .45\textwidth \switchtobodyfont[6pt] \pardirection 1 \textdirection 1 \parshape 4 0pt .8\hsize 10pt .8\hsize 20pt .8\hsize 0pt \hsize \input tufte \par \egroup} {TRT: parshape mode 0} {\ruledvbox \bgroup \setuptolerance[verytolerant] \hsize .45\textwidth \switchtobodyfont[6pt] \shapemode=3 \pardirection 1 \textdirection 1 \hangindent 40pt \hangafter -3 \leftskip10pt \input tufte \par \egroup} {TRT: hangindent mode 1 & 3} {\ruledvbox \bgroup \setuptolerance[verytolerant] \hsize .45\textwidth \switchtobodyfont[6pt] \shapemode=3 \pardirection 1 \textdirection 1 \parshape 4 0pt .8\hsize 10pt .8\hsize 20pt .8\hsize 0pt \hsize \input tufte \par \egroup} {TRT: parshape mode 2 & 3} \stopcombination \stopplacefigure We have \type {\pardirection}, \type {\textdirection}, \type {\mathdirection} and \type {\linedirection} that is like \type {\textdirection} but with some additional (inline) glue checking. \stopsubsection \startsubsection[title=Orientations] As mentioned, the difference with \LUATEX\ is that we only have numeric directions and that there are only two: left|-|to|-|right (\type {0}) and right|-|to|-|left (\type {1}). The direction of a box is set with \type {direction}. In addition to that boxes can now have an \type {orientation} keyword followed by optional \type {xoffset} and|/|or \type {yoffset} keywords. The offsets don't have consequences for the dimensions. The alternatives \type {xmove} and \type {ymove} on the contrary are reflected in the dimensions. Just play with them. The offsets and moves only are accepted when there is also an orientation, so no time is wasted on testing for these rarely used keywords. There are related primitives \type {\box...} that set these properties. As these are experimental it will not be explained here (yet). They are covered in the descriptions of the development of \LUAMETATEX: articles and|/|or documents in the \CONTEXT\ distribution. For now it is enough to know that the orientation can be up, down, left or right (rotated) and that it has some anchoring variants. Combined with the offsets this permits macro writers to provide solutions for top|-|down and bottom|-|up writing directions, something that is rather macro package specific and used for scripts that need manipulations anyway. The \quote {old} vertical directions were never okay and therefore not used. There are a couple of properties in boxes that you can set and query but that only really take effect when the backend supports them. When usage on \CONTEXT\ shows that is't okay, they will become official, so we just mention them: \type {\boxdirection}, \type {\boxattr}, \type {\boxorientation}, \type {\boxxoffset}, \type {\boxyoffset}, \type {\boxxmove}, \type {\boxymove} and \type {\boxtotal}. \stopsubsection \stopsection \startsection[title=Expressions] The \type {*expr} parsers now accept \type {:} as operator for integer division (the \type {/} operators does rounding. This can be used for division compatible with \type {\divide}. I'm still wondering if adding a couple of bit operators makes sense (for integers). \stopsection \startsection[title=Nodes] The \ETEX\ primitive \type {\lastnodetype} is not honest in reporting the internal numbers as it uses its own values. But you can set \type {\internalcodesmode} to a non|-|zero value to get the real id's instead. In addition there is \type {\lastnodesubtype}. Another last one is \type {\lastnamedcs} which holds the last match but this one should be used with care because one never knows if in the meantime something else \quote {last} has been seen. \stopsection \stopchapter \stopcomponent