Internal representation of programs in GRASE

A program written in a programming language can be broken down into syntactic components which are related by syntactic rules governing the language. Syntax-directed editors are editors which know and use the syntax of the language while editing a program. While text editors treat programs as text, syntax-directed editors use the underlying syntax of the programming language. A program is stored as an abstract syntax tree that is built by the editor from constructive commands issued by the programmer and the node depth level is the structure level in the program. The elements of the concrete representation of languages, such as keywords, punctuation marks, separators, terminators, etc. are not kept in the tree.