<\body> > The program has been written in C++. You need and the utility in order to compile . Currently, the source (in the directory) of the implementation has been divided into the following parts: <\itemize> A set of basic and generic data structures in the directory. Standard resources for , such as fonts, languages, encodings and dictionaries, in the directory. A documented graphical toolkit in the directory (although the documentation is a bit outdated). The extension language for in the directory. The typesetting part of the editor in the directory . The editor in the directory . The server in the directory . All parts use the data structures from . The graphical toolkit depends on for the fonts. The extension language is independent from and . The typesetting part depends on all other parts except from . The main editor and the server use all previous parts. The data are contained in the directory which corresponds to the distribution without the source code. Roughly speaking, we have the following kind of data: <\itemize> Font data in (encodings, files, etc.). Language data in (hyphenation patterns, dictionaries, etc.). Document styles in . Initialization and other programs in . The directory contains some miscellaneous data like the edit icon (). represents all texts by trees (for a fixed text, the corresponding tree is called the ). The nodes of such a tree are labeled by standard which are listed in and . The labels of the leaves of the tree are strings, which are either invisible (such as lengths or macro definitions), or visible (the real text). The meaning of the text and the way it is typeset essentially depend on the current environment. The environment mainly consists of a relative hash table of type string,tree\>, i.e. a mapping from the environment variables to their tree values. The current language and the current font are examples of system environment variables; new variables can be defined by the user. All text strings in consist of sequences of either specific or universal symbols. A specific symbol is a character, different from , '> and '>. Its meaning may depend on the particular font which is being used. A universal symbol is a string starting with '>, followed by an arbitrary sequence of characters different from , '> and '>, and ending with '>. The meaning of universal characters does not depend on the particular font which is used, but different fonts may render them in a different way. The language of the text is capable performing a further semantic analysis of a text phrase. At least, it is capable of splitting a phrase up into (which are smaller phrases) and inform the typesetter about the desired spaces between words and hyphenation information. In the future, additional semantics may be added into languages. For instance, spell checkers might be implemented for natural languages and parsers for mathematical formulas or programming languages. Roughly speaking, the typesetter of takes a tree on input and produces a box, while accessing and modifying the typesetting environment. The class is multifunctional. Its principal method is used for displaying the box on a post-script device (either the screen or a printer). But it also contains a lot of typesetting information, such as logical and ink bounding boxes, the positions of scripts, etc. Another functionality of boxes is to convert between physical cursors (positions on the screen) and logical cursors (paths in the edit tree). Actually, boxes are also organized into a tree, which often simplifies the conversion. However, because of macro expansions and line and page breaking, the conversion routines may become quite intricate. Notice also that, besides a horizontal and vertical position, the physical cursor also contains an infinitesimal horizontal position. Roughly speaking, this infinitesimal coordinate is used to give certain boxes (such as color changes) an extra infinitesimal width. In you find different routines for modifying the edit tree. Modifications go in several steps: <\enumerate> A certain input event triggers an action, such as , which intends to modify the edit tree. All modifications which or its subroutines will make to the edit tree eventually break down to seven elementary modification routines, namely , , , , , and . Before performing the required modification, the elementary modification routine first notifies all views of the same text of the modification. On notification, each view updates several things, such as the cursor position. It also notifies the modification to the typesetter of the text, since the typesetter maintains a list of already typeset paragraphs. When all views have been notified of the modification, we really perform it. Each user action like a keystroke or a mouse click is responsible for inserting between sequences of elementary modifications. When undoing a modification, the editor will move to the previous undo point. <\initial> <\collection> <\references> <\collection> |?>> > |?>> > > > > > |?>> <\auxiliary> <\collection> <\associate|toc> |math font series||1Introduction> |math font series||2Intern representation of texts> 2.1Text 2.2The language |math font series||3Typesetting texts> |math font series||4Making modifications in texts>