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use pest_consume::{match_nodes, Error, Parser};
#[derive(Debug)]
enum CSVField<'a> {
Number(f64),
String(&'a str),
}
type CSVRecord<'a> = Vec<CSVField<'a>>;
type CSVFile<'a> = Vec<CSVRecord<'a>>;
type Result<T> = std::result::Result<T, Error<Rule>>;
type Node<'i> = pest_consume::Node<'i, Rule, ()>;
#[derive(Parser)]
#[grammar = "../examples/csv/csv.pest"]
struct CSVParser;
#[pest_consume::parser]
impl CSVParser {
fn EOI(_input: Node) -> Result<()> {
Ok(())
}
fn number(input: Node) -> Result<f64> {
input
.as_str()
.parse::<f64>()
// `input.error` links the error to the location in the input file where it occurred.
.map_err(|e| input.error(e.to_string()))
}
fn string(input: Node) -> Result<&str> {
Ok(input.as_str())
}
fn field(input: Node) -> Result<CSVField> {
Ok(match_nodes!(input.children();
[number(n)] => CSVField::Number(n),
[string(s)] => CSVField::String(s),
))
}
fn record(input: Node) -> Result<CSVRecord> {
Ok(match_nodes!(input.children();
[field(fields)..] => fields.collect(),
))
}
fn file(input: Node) -> Result<CSVFile> {
Ok(match_nodes!(input.children();
[record(records).., EOI(_)] => records.collect(),
))
}
}
fn parse_csv(input_str: &str) -> Result<CSVFile> {
let inputs = CSVParser::parse(Rule::file, input_str)?;
Ok(match_nodes!(<CSVParser>; inputs;
[file(e)] => e,
))
}
fn main() {
let successful_parse = parse_csv("-273.15, ' a string '\n\n42, 0");
println!("success: {:?}", successful_parse.unwrap());
let unsuccessful_parse = parse_csv("0, 273.15.12");
println!("failure: {}", unsuccessful_parse.unwrap_err());
}
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