From PEG to a practical parser

This is a tool to transcribe Parsing Expression Grammar into a parser written in Java.

Parsing Expression Grammar (PEG) is a new way to specify recursive-descent parsers with limited backtracking. The use of backtracking lifts the LL(1) restriction usually imposed by top-down parsers. In addition, PEG can define parsers with integrated lexing.

Unlike some existing parser generators for PEG, the tool does not produce a complex and storage-hungry “packrat parser”, but a collection of transparent recursive procedures. It is named “Mouse” to set it apart from pack rats.

An integral feature of “Mouse” is the mechanism for specifying semantics (also in Java). This makes “Mouse” a convenient tool if one needs an ad-hoc language processor. Being written in Java, the processor is operating-system independent.

Included in the package is PEG Explorer, an interactive tool to investigate the effect of limited backtracking.

Included are also PEGs for Java and C.

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