A compiler-compiler or compiler generator is a tool that creates a parser, interpreter, or compiler from some form of formal description. The earliest and still most common form of compiler-compiler is a parser generator, whose input is a grammar (usually in BNF) of a programming language, and whose generated output is the source code of a parser.

The ideal compiler compiler takes a description of a programming language and a target instruction set architecture, and automatically generates a usable compiler from them. In practice, the state of the art has yet to reach this degree of sophistication and most compiler generators are not capable of handling semantic or target architecture information.

Variants

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 analysed by the parser. Depending upon the type of parser that should be generated, these routines may construct a parse tree (or AST), or generate executable code directly.

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 1979. 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.

The Production Quality Compiler-Compiler (PQCC) project at Carnegie-Mellon University does not formalize semantics, but does have a semi-formal framework for machine description.

Compiler-compilers exist in many flavors, including bottom-up rewrite machine generators (see JBurg) used to tile syntax trees according to a rewrite grammar for code generation, and attribute grammar parser generators (e.g. ANTLR can be used for simultaneous type checking, constant propagation, and more during the parsing stage).

History

The first compiler-compiler to use that name was written by Tony Brooker in 1960 and was used to create compilers for the Atlas computer at the University of Manchester, including the Atlas Autocode compiler. However it was rather different from modern compiler compilers, and today would probably be described as being somewhere between a highly customisable generic compiler and an extensible-syntax language. The name 'compiler compiler' was far more appropriate for Brooker's system than it is for most modern compiler compilers, which are more accurately described as mere parser generators. It is almost certain that the Compiler Compiler name has entered common use due to Yacc rather than Brooker's work being remembered.

Other examples of parser generators in the yacc vein are ANTLR, Coco/R, CUP, GNU bison, Eli, FSL, META 5, MUG2, Parsley, Pre-cc, SableCC, JavaCC and MixedCC.

See also

• Comparison of parser generators
• Parsing Expression Grammar
• ANTLR
• Flex/Bison
• Lex/Yacc
• Elegant
• PQCC, a compiler-compiler that is more than a parser generator.
• Parser types: LL, LR, SLR, LALR, GLR, Packrat

References

External links

• Brooker Autocodes
• The Catalog of Compiler Construction Tools
• LISA
• Jflex and Cup resources in Italian
• The GENTLE Compiler Construction System

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