Quick start on ANTLR4 in Rust - part3

This is my note in adopting and learning ANTLR4Rust

Series

In the previous article, we implemented a parser with internal state variables. However, if a grammar is huge, it is practically impossible to manage a huge number of state variables. Alternatively, a visitor-like approach can be used.

In an exit method of the root rule in the Listener, we can grab the current context and its children and call custom parser methods:

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impl Listener {
    fn hdr(&self, ctx: &HdrContextAll) -> Row {
        let row_ctx = ctx.row().unwrap();
        self.row(&row_ctx)
    }    fn row(&self, ctx: &RowContextAll) -> Row {
        let mut row = Row::new();
        let field_ctx_list = ctx.field_all();
        for (_i, field_ctx) in field_ctx_list.iter().enumerate() {
            let field = self.field(&field_ctx);
            row.push(field);
        }
        row
    }    fn field(&self, ctx: &FieldContextAll) -> String {
        ctx.get_text()
    }
}
impl CSVListener for Listener {
    fn exit_csvFile(&mut self, ctx: &CsvFileContext) {
        let hdr_ctx = ctx.hdr().unwrap();
        let header = self.hdr(&hdr_ctx);
        self.csv.header = header;
        let row_ctx_list = ctx.row_all();
        for (_i, row_ctx) in row_ctx_list.iter().enumerate() {
            let row = self.row(&row_ctx);
            self.csv.rows.push(row);
        }
    }
}

The minimal working example can be found here.