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Parboiled (Java) 248
Parboiled (Java)
Developer(s) Mathias Doenitz
Initial release November 12, 2009
Development status Active
Written in Java
Operating system Cross-platform
License Apache License 2.0
Website http:/ / www. parboiled. org/
parboiled is an open-source Java library released under an Apache License. It provides support for defining PEG
parsers directly in Java source code.
parboiled is commonly used as an alternative for regular expressions or parser generators (like ANTLR or JavaCC),
especially for smaller and medium-size applications.
Apart from providing the constructs for grammar definition parboiled implements a complete recursive descent
parser with support for abstract syntax tree construction, parse error reporting and parse error recovery.
Example
Since parsing with parboiled does not require a separate lexing phase and there is no special syntax to learn for
grammar definition parboiled makes it comparatively easy to build custom parsers quickly.
Consider this the following classic “calculator” example, with these rules in a simple pseudo notation
Expression ← Term ((‘+’ / ‘-’) Term)*
Term ← Factor (('*' / '/') Factor)*
Factor ← Number / '(' Expression ')'
Number ← [0-9]+
With parboiled this rule description can be translated directly into the following Java code:
import org.parboiled.BaseParser;
public class CalculatorParser extends BaseParser {
public Rule expression() {
}
return sequence(
);
term(),
zeroOrMore(
public Rule term() {
)
sequence(
)
firstOf('+', '-'),
term()