Leo (text editor)

Leo is an open-source text editor/outliner that features clones (virtual copies of outline nodes) as a central tool of organization, navigation, customization and scripting.

Languages

Leo can manipulate text or code in any human or computer programming language (e.g., Python, C, C++, Java), as Leo is a language-independent or "adaptable LPE" (

Leo's foremost functionality, in addition to text editing, is that of an outliner, with a "vast range of convenience features for structuring and managing outlines" both by drag-and-drop via GUI and by keyboard commands.^[2] Leo's outline pane shows a tree of data nodes. Nodes contain headlines, body text, and other information. Headlines naturally serve as descriptions of the body text. For example, @file nodes are nodes whose headline starts with @file. Leo trees are in fact directed acyclic graphs; nodes may have more than one parent. Leo calls such nodes clones. Clones appear in several places in the outline pane. Views are simply nodes whose children contain clones. A single outline may contain arbitrarily many views of the nodes contained therein.

External files

@file nodes represent external files, files on the computer's file system other than the outline file. When saving an outline Leo automatically writes all changed @file trees back to the external files. Comments, called sentinel lines, in external files represent the outline structure. When Leo reads an outline, these comments allow Leo to recreate @file trees using only the data in the external file. @auto nodes and @clean nodes represent external files without using sentinel comments. When reading @auto nodes, Leo uses the program structure of the external file to create the @auto tree. When reading @clean nodes, Leo uses the structure of the outline to create the @clean tree.

Scripting

Leo's outline or hierarchical structure is distinct from the web of interleaved program and documentation "chunks" associated with classic