Editing Compiler-compiler (section)

===Metacompilers===
{{blockquote|Metacompilers reduce the task of writing compilers by automating the aspects that are the same regardless of the object language. This makes possible the design of [[domain-specific language]]s which are appropriate to the specification of a particular problem. A metacompiler reduces the cost of producing [[Translator (computing)|translator]]s for such [[domain-specific language|domain-specific]] object languages to a point where it becomes economically feasible to include in the solution of a problem a [[domain-specific language]] design.<ref name="CWIC" />}}

As a metacompiler's [[metalanguage]] will usually be a powerful string and symbol processing language, they often have strong applications for general-purpose applications, including generating a wide range of other software engineering and analysis tools.<ref name="CWIC" /><ref name="bayfront" />

Besides being useful for [[domain-specific language]] development, a metacompiler is a prime example of a domain-specific language, designed for the domain of compiler writing.

A metacompiler is a [[Metaprogramming|metaprogram]] ''usually written in its own metalanguage'' or an existing computer programming language. The process of a metacompiler, written in its own metalanguage, compiling itself is equivalent to [[History of compiler construction#Self-hosting compilers|self-hosting compiler]]. Most common compilers written today are self-hosting compilers. Self-hosting is a powerful tool, of many metacompilers, allowing the easy extension of their own metaprogramming metalanguage. The feature that separates a metacompiler apart from other compiler compilers is that it takes as input a specialized [[metaprogramming]] language that describes all aspects of the compiler's operation. A metaprogram produced by a metacompiler is as complete a program as a [[Computer program|program]] written in [[C++]], [[BASIC]] or any other general [[programming language]]. The metaprogramming [[metalanguage]] is a powerful attribute allowing easier development of computer programming languages and other computer tools. Command line processors, text string transforming and analysis are easily coded using metaprogramming metalanguages of metacompilers.

A full featured development package includes a [[Linker (computing)|linker]] and a [[Run time (program lifecycle phase)|run time]] support [[Library (computing)|library]]. Usually, a machine-oriented [[system programming language]], such as [[C (programming language)|C]] or C++, is needed to write the support library. A library consisting of support functions needed for the compiling process usually completes the full metacompiler package.

====The meaning of metacompiler====
In computer science, the prefix ''[[Meta (prefix)#Epistemology|meta]]'' is commonly used to mean ''about (its own category)''. For example, [[metadata]] are data that describe other data. A language that is used to describe other languages is a [[metalanguage]]. Meta may also mean [[Meta (prefix)|''on a higher level of abstraction'']]. A [[metalanguage]] operates on a higher level of abstraction in order to describe properties of a language. [[Backus–Naur form]] (BNF) is a formal [[metalanguage]] originally used to define [[ALGOL 60]]. BNF is a weak [[metalanguage]], for it describes only the [[syntax]] and says nothing about the [[semantics]] or meaning. Metaprogramming is the writing of [[computer program]]s with the ability to treat [[Computer program|program]]s as their data. A metacompiler takes as input a [[metaprogramming|metaprogram]] written in a [[metalanguage|specialized metalanguages]] (a higher level abstraction) specifically designed for the purpose of metaprogramming.<ref name="CWIC" /><ref name="TMETA" /> The output is an executable object program.

An analogy can be drawn: That as a ''C++'' compiler takes as input a ''C++'' programming language program, a ''meta''compiler takes as input a [[metaprogramming|''meta''programming]] [[metalanguage]] program.