computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...

, the abstract syntax of data is its structure described as a

data type In computer science and computer programming, a data type (or simply type) is a collection or grouping of data values, usually specified by a set of possible values, a set of allowed operations on these values, and/or a representation of these ...

(possibly, but not necessarily, an

abstract data type In computer science, an abstract data type (ADT) is a mathematical model for data types, defined by its behavior (semantics) from the point of view of a '' user'' of the data, specifically in terms of possible values, possible operations on data ...

), independent of any particular representation or encoding. This is particularly used in the representation of text in

computer language A computer language is a formal language used to communicate with a computer. Types of computer languages include: * Software construction#Construction languages, Construction language – all forms of communication by which a human can Comput ...

s, which are generally stored in a tree structure as an abstract syntax tree. Abstract syntax, which only consists of the structure of data, is contrasted with concrete syntax, which also includes information about the representation. For example, concrete syntax includes features like parentheses (for grouping) or commas (for lists), which are not included in the abstract syntax, as they are implicit in the structure. Abstract syntaxes are classified as first-order abstract syntax (FOAS), if the structure is abstract but names (identifiers) are still concrete (and thus requires name resolution), and '' higher-order abstract syntax,'' if the names themselves are abstract.

Uses

To be implemented either for computation or communications, a mapping from the abstract syntax to specific machine representations and encodings must be defined; these may be called the " concrete syntax" (in language implementation) or the "transfer syntax" (in communications). A

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

's internal representation of a program will typically be specified by an abstract syntax in terms of categories such as "statement", "expression" and "identifier". This is independent of the source syntax (concrete syntax) of the language being compiled (though it will often be very similar). A

parse tree A parse tree or parsing tree (also known as a derivation tree or concrete syntax tree) is an ordered, rooted tree that represents the syntactic structure of a string according to some context-free grammar. The term ''parse tree'' itself is use ...

is similar to an abstract syntax tree but it will typically also contain features such as parentheses, which are syntactically significant but which are implicit in the structure of the abstract syntax tree.

Algebraic data type In computer programming, especially functional programming and type theory, an algebraic data type (ADT) is a kind of composite data type, i.e., a data type formed by combining other types. Two common classes of algebraic types are product ty ...

s are particularly well-suited to the implementation of abstract syntax.

References

Programming language design Programming language theory Compiler construction Syntax Parsing {{prog-lang-stub

Uses

See also

References