In computer science, an abstract syntax tree (AST), or just syntax tree, is a tree representation of the abstract syntactic structure of source code written in a programming language. Each node of the tree denotes a construct occurring in the source code. The syntax is 'abstract' in the sense that it does not represent every detail that appears in the real syntax. For instance, grouping parentheses are implicit in the tree structure, and a syntactic construct such as an if-condition-then expression may be denoted by a single node with two branches.
This makes abstract syntax trees different from concrete syntax trees, traditionally called parse trees, which are often built by a parser as part of the source code translation and compiling process. Once built, additional information is added to the AST by subsequent processing, e.g., contextual analysis.
Abstract syntax trees are also used in program analysis and program transformation systems.
Famous quotes containing the words abstract and/or tree:
“One of the fundamental reasons why so many doctors become cynical and disillusioned is precisely because, when the abstract idealism has worn thin, they are uncertain about the value of the actual lives of the patients they are treating. This is not because they are callous or personally inhuman: it is because they live in and accept a society which is incapable of knowing what a human life is worth.”
—John Berger (b. 1926)
“Every man is a potential genius until he does something.”
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