Parser generator

In computer science, a compiler-compiler or compiler generator is a programming tool that creates a parser, interpreter, or compiler from some form of formal description of a language and machine. The input may be a text file containing the grammar written in BNF or EBNF that defines the syntax of a programming language, and whose generated output is some source code of the parser for the programming language, although other definitions exist.

Usually, the resulting source code will have to be extended upon before a complete compiler emerge.

A typical parser generator associates executable code with each of the rules of the grammar that should be executed when these rules are applied by the parser. These pieces of code are sometimes referred to as semantic action routines since they define the semantics of the syntactic structure that is analyzed by the parser. Depending upon the type of parser that should be generated, these routines may construct a parse tree (or abstract syntax tree), or generate executable code directly.

One of the earliest (1964), surprisingly powerful, versions of compiler-compilers is META II, which accepted grammars and code generation rules, and is able to compile itself and other languages.

Some experimental compiler-compilers take as input a formal description of programming language semantics, typically using denotational semantics. This approach is often called 'semantics-based compiling', and was pioneered by Peter Mosses' Semantic Implementation System (SIS) in 1978. However, both the generated compiler and the code it produced were inefficient in time and space. No production compilers are currently built in this way, but research continues.

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