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use crate::ast::*;
pub fn parse(arg: &str) -> Value {
let token = arg.trim();
parse_number(token)
.or(parse_bool(token))
.or(parse_symbol(token))
.unwrap()
}
fn parse_symbol(token: &str) -> Result<Value, String> {
Ok(Value::Sym(token.to_string()))
}
fn parse_bool(token: &str) -> Result<Value, String> {
token
.parse::<bool>()
.map(Value::Bool)
.map_err(|e| e.to_string())
}
fn parse_number(token: &str) -> Result<Value, String> {
token
.parse::<i32>()
.map(Value::Num)
.map_err(|e| e.to_string())
}
#[cfg(test)]
mod tests {
use super::parse;
use super::Value::*;
use proptest::prelude::*;
proptest! {
#[test]
fn parse_integer_as_number(i in -1000i32..1000) {
let result = parse(&i.to_string());
assert_eq!(Num(i), result);
}
}
#[test]
fn parse_truth_values_as_booleans() {
assert_eq!(Bool(true), parse("true"));
assert_eq!(Bool(false), parse("false"));
}
#[test]
fn parse_identifiers_values_as_symbols() {
assert_eq!(Sym("foo".to_string()), parse("foo"));
}
#[test]
fn ignores_whitespace() {
assert_eq!(Sym("foo".to_string()), parse(" foo \n\r"));
assert_eq!(Num(-42), parse("\n-42"));
}
}
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