Views and Elision

Views and Elision

Buffers are presented in textual views, where each view is associated with a distinct collection of prettyprinting rules. Views may differ radically from one another. For example, one view may present an object as source code and another view may present the object only error messages about the code.

The collection of specific views supported by Ada-ASSURED is described in Defined Views. The default view is called BASEVIEW.

Each window is associated with a particular view. Command change-view changes the view associated with a given window or creates a new window associated with a particular view.

Prettyprinting of objects in windows is determined not only by the view, but also by the prettyprinting width. Text may exceed the prettyprinting width, but will do so only if the prettyprinting rules provide no effective method for breaking excessively long lines. If editor parameter word wrap is on, the prettyprinting width is defined to be the window width; if word wrap is off, the prettyprinting width is defined to be editor parameter absolute right margin.

An object saved to a file in structure or attributed format is saved in its entirety regardless of view; such a file can always be re-read into the editor that wrote it. In contrast, if an object is saved to a file in text format, the text saved is the prettyprinting of the object in some particular view; if that view is incomplete, it may be impossible to recreate the object by re-reading and parsing the file. Special prettyprinting rules associated with writing files in text format are described in Files.

Within a given view of an object, each phrase has two prettyprinting rules termed its ``principal scheme'' and the ``alternate scheme''. If the alternate scheme is chosen for a given phrase, the phrase is displayed according to its alternate schemes in every view. Because the alternate scheme is mostly used for eliding substructures, it is also known as ``elision''.

The exact distinction between the principal and alternate prettyprinting schemes is described on a per-view basis in the section titled Defined Views. However, the alternate scheme is typically used for displaying a phrase in an abbreviated format (e.g., ...); by toggling between the principal and alternate schemes, one controls elision of phrases.

An object saved to a file in structure or attributed format preserves the settings of prettyprinting schemes; on re-reading such a file, the schemes are restored. In contrast, if an object is saved to a file in text format, the text saved is the textual display of the object according to the settings of prettyprinting schemes; if that text is incomplete (e.g., ...), it may be impossible to recreate the object by re-reading and parsing the file. Special prettyprinting rules associated with writing files in text format are described in Files.

Commands for views and elision are: