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implement unary + and -, add useful functions to Token

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This commit is contained in:
Lukáš Hozda 2017-10-28 16:08:24 +02:00
parent 7f4fbd940a
commit 679f0de6b6
2 changed files with 143 additions and 13 deletions
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15
src/engine.rs
View File

@ -7,7 +7,7 @@ use std::fmt;
use parser::{lex, parse, Expr, Stmt, FnDef};
use fn_register::FnRegister;
use std::ops::{Add, Sub, Mul, Div};
use std::ops::{Add, Sub, Mul, Div, Neg};
use std::cmp::{Ord, Eq};
#[derive(Debug)]
@ -1317,6 +1317,14 @@ impl Engine {
)
}
macro_rules! reg_un {
($engine:expr, $x:expr, $op:expr, $( $y:ty ),*) => (
$(
$engine.register_fn($x, ($op as fn(x: $y)->$y));
)*
)
}
macro_rules! reg_cmp {
($engine:expr, $x:expr, $op:expr, $( $y:ty ),*) => (
$(
@ -1329,6 +1337,7 @@ impl Engine {
fn sub<T: Sub>(x: T, y: T) -> <T as Sub>::Output { x - y }
fn mul<T: Mul>(x: T, y: T) -> <T as Mul>::Output { x * y }
fn div<T: Div>(x: T, y: T) -> <T as Div>::Output { x / y }
fn neg<T: Neg>(x: T) -> <T as Neg>::Output { -x }
fn lt<T: Ord>(x: T, y: T) -> bool { x < y }
fn lte<T: Ord>(x: T, y: T) -> bool { x <= y }
fn gt<T: Ord>(x: T, y: T) -> bool { x > y }
@ -1337,6 +1346,7 @@ impl Engine {
fn ne<T: Eq>(x: T, y: T) -> bool { x != y }
fn and(x: bool, y: bool) -> bool { x && y }
fn or(x: bool, y: bool) -> bool { x || y }
fn not(x: bool) -> bool { !x }
fn concat(x: String, y: String) -> String { x + &y }
reg_op!(engine, "+", add, i32, i64, u32, u64, f32, f64);
@ -1354,6 +1364,9 @@ impl Engine {
reg_op!(engine, "||", or, bool);
reg_op!(engine, "&&", and, bool);
reg_un!(engine, "-", neg, i32, i64, f32, f64);
reg_un!(engine, "!", not, bool);
engine.register_fn("+", concat);
// engine.register_fn("[]", idx);

141
src/parser.rs
View File

@ -4,12 +4,13 @@ use std::iter::Peekable;
use std::str::Chars;
use std::char;
#[derive(Debug)]
#[derive(Debug, Clone)]
pub enum LexError {
UnexpectedChar,
MalformedEscapeSequence,
MalformedNumber,
MalformedChar,
Nothing
}
impl Error for LexError {
@ -19,6 +20,7 @@ impl Error for LexError {
LexError::MalformedEscapeSequence => "Unexpected values in escape sequence",
LexError::MalformedNumber => "Unexpected characters in number",
LexError::MalformedChar => "Char constant not a single character",
LexError::Nothing => "This error is for internal use only"
}
}
@ -111,7 +113,7 @@ pub enum Expr {
False,
}
#[derive(Debug)]
#[derive(Debug, Clone)]
pub enum Token {
IntConst(i64),
Identifier(String),
@ -124,7 +126,9 @@ pub enum Token {
LSquare,
RSquare,
Plus,
UnaryPlus,
Minus,
UnaryMinus,
Multiply,
Divide,
Semicolon,
@ -155,7 +159,91 @@ pub enum Token {
LexErr(LexError),
}
impl Token {
// if another operator is after these, it's probably an unary operator
// not sure about fn's name
pub fn is_next_unary(&self) -> bool {
use self::Token::*;
match *self {
LCurly | // (+expr) - is unary
// RCurly | {expr} - expr not unary & is closing
LParen | // {-expr} - is unary
// RParen | (expr) - expr not unary & is closing
LSquare | // [-expr] - is unary
// RSquare | [expr] - expr not unary & is closing
Plus |
UnaryPlus |
Minus |
UnaryMinus |
Multiply |
Divide |
Colon |
Comma |
Period |
Equals |
LessThan |
GreaterThan |
Bang |
LessThanEqual |
GreaterThanEqual |
EqualTo |
NotEqualTo |
Pipe |
Or |
Ampersand |
And |
Return => true,
_ => false,
}
}
#[allow(dead_code)]
pub fn is_bin_op(&self) -> bool {
use self::Token::*;
match *self {
RCurly |
RParen |
RSquare |
Plus |
Minus |
Multiply |
Divide |
Comma |
// Period | <- does period count?
Equals |
LessThan |
GreaterThan |
LessThanEqual |
GreaterThanEqual |
EqualTo |
NotEqualTo |
Pipe |
Or |
Ampersand |
And => true,
_ => false,
}
}
#[allow(dead_code)]
pub fn is_un_op(&self) -> bool {
use self::Token::*;
match *self {
UnaryPlus |
UnaryMinus |
Equals |
Bang |
Return => true,
_ => false,
}
}
}
pub struct TokenIterator<'a> {
last: Token,
char_stream: Peekable<Chars<'a>>,
}
@ -262,12 +350,8 @@ impl<'a> TokenIterator<'a> {
let out: String = result.iter().cloned().collect();
Ok(out)
}
}
impl<'a> Iterator for TokenIterator<'a> {
type Item = Token;
fn next(&mut self) -> Option<Self::Item> {
fn inner_next(&mut self) -> Option<Token> {
while let Some(c) = self.char_stream.next() {
match c {
'0'...'9' => {
@ -350,8 +434,14 @@ impl<'a> Iterator for TokenIterator<'a> {
')' => return Some(Token::RParen),
'[' => return Some(Token::LSquare),
']' => return Some(Token::RSquare),
'+' => return Some(Token::Plus),
'-' => return Some(Token::Minus),
'+' => {
if self.last.is_next_unary() { return Some(Token::UnaryPlus) }
else { return Some(Token::Plus) }
}
'-' => {
if self.last.is_next_unary() { return Some(Token::UnaryMinus) }
else { return Some(Token::Minus) }
}
'*' => return Some(Token::Multiply),
'/' => {
match self.char_stream.peek() {
@ -450,8 +540,21 @@ impl<'a> Iterator for TokenIterator<'a> {
}
}
impl<'a> Iterator for TokenIterator<'a> {
type Item = Token;
// TODO - perhaps this could be optimized to only keep track of last for operators?
fn next(&mut self) -> Option<Self::Item> {
self.last = match self.inner_next() {
Some(c) => c,
None => return None,
};
Some(self.last.clone())
}
}
pub fn lex(input: &str) -> TokenIterator {
TokenIterator { char_stream: input.chars().peekable() }
TokenIterator { last: Token::LexErr(LexError::Nothing), char_stream: input.chars().peekable() }
}
fn get_precedence(token: &Token) -> i32 {
@ -599,6 +702,20 @@ fn parse_primary<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, Pa
}
}
fn parse_unary<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
let tok = match input.peek() {
Some(tok) => tok.clone(),
None => return Err(ParseError::InputPastEndOfFile),
};
match tok {
Token::UnaryMinus => { input.next(); Ok(Expr::FnCall("-".to_string(), vec![parse_primary(input)?])) }
Token::UnaryPlus => { input.next(); parse_primary(input) }
Token::Bang => { input.next(); Ok(Expr::FnCall("!".to_string(), vec![parse_primary(input)?])) }
_ => parse_primary(input)
}
}
fn parse_binop<'a>(input: &mut Peekable<TokenIterator<'a>>,
prec: i32,
lhs: Expr)
@ -617,7 +734,7 @@ fn parse_binop<'a>(input: &mut Peekable<TokenIterator<'a>>,
}
if let Some(op_token) = input.next() {
let mut rhs = try!(parse_primary(input));
let mut rhs = try!(parse_unary(input));
let mut next_prec = -1;
@ -658,7 +775,7 @@ fn parse_binop<'a>(input: &mut Peekable<TokenIterator<'a>>,
}
fn parse_expr<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
let lhs = try!(parse_primary(input));
let lhs = try!(parse_unary(input));
parse_binop(input, 0, lhs)
}