Search results
Results From The WOW.Com Content Network
In computational learning theory, induction of regular languages refers to the task of learning a formal description (e.g. grammar) of a regular language from a given set of example strings. Although E. Mark Gold has shown that not every regular language can be learned this way (see language identification in the limit ), approaches have been ...
String functions are used in computer programming languages to manipulate a string or query information about a string (some do both).. Most programming languages that have a string datatype will have some string functions although there may be other low-level ways within each language to handle strings directly.
A block is a grouping of code that is treated collectively. Many block syntaxes can consist of any number of items (statements, expressions or other units of code) – including one or zero.
The phrase grammar of most programming languages can be specified using a Type-2 grammar, i.e., they are context-free grammars, [8] though the overall syntax is context-sensitive (due to variable declarations and nested scopes), hence Type-1. However, there are exceptions, and for some languages the phrase grammar is Type-0 (Turing-complete).
When a string grammar is used to define a computer language, some string-grammar parsing tools and compiler-generator tools can be used to more easily create a compiler software system for that particular computer language. Because other grammars can be more difficult to use for parsing text written in a specific computer language, using a ...
It is decidable whether a given grammar is a regular grammar, [f] as well as whether it is an LL grammar for a given k≥0. [26]: 233 If k is not given, the latter problem is undecidable. [26]: 252 Given a context-free grammar, it is not decidable whether its language is regular, [27] nor whether it is an LL(k) language for a given k.
An abstract syntax tree (AST) is a data structure used in computer science to represent the structure of a program or code snippet. It is a tree representation of the abstract syntactic structure of text (often source code) written in a formal language.
For instance, the lexical grammar for many programming languages specifies that a string literal starts with a " character and continues until a matching " is found (escaping makes this more complicated), that an identifier is an alphanumeric sequence (letters and digits, usually also allowing underscores, and disallowing initial digits), and ...