This project contains many examples of using Lex and Yacc style tools to build parsers. I named this project after Lex and Yacc in honor of the classic UNIX tools. I do include an example project using the Flex and Bison programs, but most of the examples here are for the Java platform. I use various parsing libraries to build simple example calculators.
Parsing input is a valuable skill to know, ranging from writing grammars to walking syntax trees. Knowing the types of parsing capabilities will help one select an appropriate library.
This project contains several modules that demonstrates parsing a simple language using different libraries. The grammar is simple. The input should be a list of simple assignments statements (e.g. "a = 2 * 3;"). The list can also reference previously assigned variables (e.g. "b = a * a;")
This project uses the classic Lex and Yacc tools to build a C program that reads
its input from stdin and prints out the resulting variables.
https://www.gnu.org/software/bison/
http://web.mit.edu/gnu/doc/html/flex_1.html
ANTLR2, an LL parser, is one of the oldest Java parsing libraries out there, and while no longer maintained, it is still oddly used in many places. So despite being old, I decided to show an example.
ANTLR4, an adaptive LL parser, supports direct forms of left recursion grammars (but not indirect grammars). This gives one plenty of flexibility to write easy to understand grammars.
CookCC is an LALR parser. It is written in Java and has an interesting feature of allowing one to write the grammar as annotations to be processed by an annotation processing tool (APT).
https://coconut2015.github.io/cookcc/index.html
JParsec is a combinator parser, basically a Java implementation of the Haskell Parsec project.
https://github.com/jparsec/jparsec/wiki/Tutorial
JFlex is just a lexical analyzer, based on deterministic finite automata (DFA). It can execute actions when certain rules are matched. JFlex does not support context free grammars. I show an example of tokenizing a properties file.
What can I do to support better error handling?