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:
“If the world would only build temples to Machinery in the abstract then everything would be perfect. The painter and sculptor would have plenty to do, and could, in complete peace and suitably honoured, pursue their trade without further trouble.”
—Wyndham Lewis (1882–1957)
“If you believe in the soul, do not clutch at sensual sweetness before it is ripe on the slow tree of cause and effect.”
—Ralph Waldo Emerson (1803–1882)