Having gotten the basic REPL working, I needed to begin building the parsing stuff. For that, I decided on porting my idiotically simple recursive-descent parser library to Rust because that seemed like a thing I might do, and I’m nothing if not me.<\/p>\n\n\n\n\n\n\n\n
The original Elision <\/em>parser used ANTLR<\/a>. (I would link to this, but I think it predates the history of Elision in Github, which starts with the handover to ORNL.) The ANTLR-based parser worked well for a while but the files soon became numerous and very large and bootstrap parsing was taking too long.<\/p>\n\n\n\n Logan Lamb and I each built a parser (a friendly competition fueled by lack of communication) to replace the ANTLR parser. Logan used a recursive descent parser library (I think it was the Parboiled parser, seen here<\/a>), and I… wrote a tiny class in Scala<\/a> that used a two-buffer approach (it would fill one buffer while the other was parsed) and allowed for rapid parsing of left-linear grammars (as seen here<\/a>).<\/p>\n\n\n\n