extern crate lemon_tree; use lemon_tree::{lem_fn, LemonTree}; type Expr = f64; type Exprs = Vec; #[lem_fn("NUM(value)")] pub fn expr_1(value: f64) -> Expr {value} #[lem_fn("MINUS Expr(a)")] pub fn expr_2(a: Expr) -> Expr {-a} #[lem_fn("PLUS Expr(a)")] pub fn expr_3(a: Expr) -> Expr {a} #[lem_fn("Expr(a) PLUS Expr(b)")] pub fn expr_4(a: Expr, b: Expr) -> Expr {a + b} #[lem_fn("Expr(a) MINUS Expr(b)")] pub fn expr_5(a: Expr, b: Expr) -> Expr {a - b} #[lem_fn("Expr(a) TIMES Expr(b)")] pub fn expr_6(a: Expr, b: Expr) -> Expr {a * b} #[lem_fn("Expr(a) DIVIDE Expr(b)")] pub fn expr_7(a: Expr, b: Expr) -> Expr {a / b} #[lem_fn("PAR_OPEN Expr(0) PAR_CLOSE")] pub fn expr_8(a: Expr) -> Expr {a} #[lem_fn("Expr(item)")] pub fn exprs_1(item: Expr) -> Exprs {vec![item]} #[lem_fn("Exprs(items) SEMICOLON Expr(item)")] pub fn exprs_2(mut items: Exprs, item: Expr) -> Exprs {items.push(item); items} #[derive(LemonTree)] #[lem_opt(token_type="f64", left="PLUS MINUS", left="DIVIDE TIMES", trace=">>")] #[lem("Exprs(exprs) [SEMICOLON]")] pub struct Program { exprs: Exprs, } fn parse(parser: &mut ::Parser, mut input: &str) -> Exprs { loop { input = input.trim_start(); match input.bytes().next() { Some(c) => match c { b'+' => parser.add_token(::Token::PLUS, 0.0).unwrap(), b'-' => parser.add_token(::Token::MINUS, 0.0).unwrap(), b'*' => parser.add_token(::Token::TIMES, 0.0).unwrap(), b'/' => parser.add_token(::Token::DIVIDE, 0.0).unwrap(), b'(' => parser.add_token(::Token::PAR_OPEN, 0.0).unwrap(), b')' => parser.add_token(::Token::PAR_CLOSE, 0.0).unwrap(), b';' => parser.add_token(::Token::SEMICOLON, 0.0).unwrap(), b'0' ..= b'9' | b'.' => { let pos = input.bytes().position(|c| !c.is_ascii_digit() && c!=b'.').unwrap_or(input.len()); let value = input[.. pos].parse().unwrap(); parser.add_token(::Token::NUM, value).unwrap(); input = &input[pos-1 ..]; } _ => panic!("Invalid token") } None => { return parser.end().unwrap().exprs; } } input = &input[1 ..]; } } #[test] fn calc_1() { let mut parser = Program::get_parser(()); assert_eq!(parse(&mut parser, "2 + 2 * 2; (2+2) * 2"), vec![6.0, 8.0]); assert_eq!(parse(&mut parser, "2 * 2 + 2; (2*2) + 2"), vec![6.0, 6.0]); assert_eq!(parse(&mut parser, "-1*30"), vec![-30.0]); assert_eq!(parse(&mut parser, "0--1;"), vec![1.0]); assert_eq!(parse(&mut parser, "(((0)))"), vec![0.0]); assert_eq!(parse(&mut parser, "0.123 + 10"), vec![10.123]); assert_eq!(parse(&mut parser, "0.123 / (1.0-1.0)"), vec![f64::INFINITY]); }