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/* Copyright (C) 2019 Akshay Oppiliappan <[email protected]>
* Refer to LICENCE for more information.
* */
use lazy_static::lazy_static;
use std::collections::HashMap;
use crate::error::{CalcError, Math};
use crate::CONFIGURATION;
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct Operator {
token: char,
pub operation: fn(f64, f64) -> f64,
pub precedence: u8,
pub is_left_associative: bool,
}
impl Operator {
fn token_from_op(
token: char,
operation: fn(f64, f64) -> f64,
precedence: u8,
is_left_associative: bool,
) -> Token {
Token::Operator(Operator {
token,
operation,
precedence,
is_left_associative,
})
}
pub fn operate(self, x: f64, y: f64) -> Result<f64, CalcError> {
if self.token == '/' && y == 0. {
Err(CalcError::Math(Math::DivideByZero))
} else {
Ok((self.operation)(x, y))
}
}
}
#[derive(Debug, Clone, PartialEq)]
pub struct Function {
token: String,
relation: fn(f64) -> f64,
}
impl Function {
fn token_from_fn(token: String, relation: fn(f64) -> f64) -> Token {
Token::Function(Function { token, relation })
}
pub fn apply(self, arg: f64) -> Result<f64, CalcError> {
let result = (self.relation)(arg);
if !result.is_finite() {
Err(CalcError::Math(Math::OutOfBounds))
} else {
Ok(result)
}
}
}
#[derive(Debug, Clone, PartialEq)]
pub enum Token {
Operator(Operator),
Num(f64),
Function(Function),
LParen,
RParen,
}
lazy_static! {
pub static ref CONSTANTS: HashMap<&'static str, Token> = {
let mut m = HashMap::new();
m.insert("e", Token::Num(std::f64::consts::E));
m.insert("pi", Token::Num(std::f64::consts::PI));
m
};
pub static ref FUNCTIONS: HashMap<&'static str, Token> = {
let mut m = HashMap::new();
m.insert("sin", Function::token_from_fn("sin".into(), |x| is_radian_mode(x, CONFIGURATION.radian_mode).sin()));
m.insert("cos", Function::token_from_fn("cos".into(), |x| is_radian_mode(x, CONFIGURATION.radian_mode).cos()));
m.insert("tan", Function::token_from_fn("tan".into(), |x| is_radian_mode(x, CONFIGURATION.radian_mode).tan()));
m.insert("csc", Function::token_from_fn("csc".into(), |x| is_radian_mode(x, CONFIGURATION.radian_mode).sin().recip()));
m.insert("sec", Function::token_from_fn("sec".into(), |x| is_radian_mode(x, CONFIGURATION.radian_mode).cos().recip()));
m.insert("cot", Function::token_from_fn("cot".into(), |x| is_radian_mode(x, CONFIGURATION.radian_mode).tan().recip()));
m.insert("sinh", Function::token_from_fn("sinh".into(), |x| x.sinh()));
m.insert("cosh", Function::token_from_fn("cosh".into(), |x| x.cosh()));
m.insert("tanh", Function::token_from_fn("tanh".into(), |x| x.tanh()));
m.insert("ln", Function::token_from_fn("ln".into(), |x| x.ln()));
m.insert("log", Function::token_from_fn("log".into(), |x| x.log10()));
m.insert("sqrt", Function::token_from_fn("sqrt".into(), |x| x.sqrt()));
m.insert("ceil", Function::token_from_fn("ceil".into(), |x| x.ceil()));
m.insert("floor", Function::token_from_fn("floor".into(), |x| x.floor()));
m.insert("rad", Function::token_from_fn("rad".into(), |x| x.to_radians()));
m.insert("deg", Function::token_from_fn("deg".into(), |x| x.to_degrees()));
m.insert("abs", Function::token_from_fn("abs".into(), |x| x.abs()));
m.insert("asin", Function::token_from_fn("asin".into(), |x| x.asin()));
m.insert("acos", Function::token_from_fn("acos".into(), |x| x.acos()));
m.insert("atan", Function::token_from_fn("atan".into(), |x| x.atan()));
m.insert("acsc", Function::token_from_fn("acsc".into(), |x| (1./x).asin()));
m.insert("asec", Function::token_from_fn("asec".into(), |x| (1./x).acos()));
m.insert("acot", Function::token_from_fn("acot".into(), |x| (1./x).atan()));
m.insert("exp", Function::token_from_fn("exp".into(), |x| x.exp()));
m.insert("exp2", Function::token_from_fn("exp2".into(), |x| x.exp2()));
// single arg function s can be added here
m
};
pub static ref OPERATORS: HashMap<char, Token> = {
let mut m = HashMap::new();
m.insert('+', Operator::token_from_op('+', |x, y| x + y, 2, true));
m.insert('-', Operator::token_from_op('-', |x, y| x - y, 2, true));
m.insert('*', Operator::token_from_op('*', |x, y| x * y, 3, true));
m.insert('/', Operator::token_from_op('/', |x, y| x / y, 3, true));
m.insert('%', Operator::token_from_op('%', |x, y| x % y, 3, true));
m.insert('^', Operator::token_from_op('^', |x, y| x.powf(y) , 4, false));
m.insert('!', Operator::token_from_op('!', |x, _| factorial(x) , 4, true));
m
};
}
fn factorial(n: f64) -> f64 {
n.signum() * (1..=n.abs() as u64).fold(1, |p, n| p * n) as f64
}
pub fn lexer(input: &str, prev_ans: Option<f64>) -> Result<Vec<Token>, CalcError> {
let mut num_vec: String = String::new();
let mut char_vec: String = String::new();
let mut result: Vec<Token> = vec![];
let mut last_char_is_op = true;
let mut chars = input.chars().peekable();
while let Some(mut letter) = chars.next() {
match letter {
'0'..='9' | '.' => {
if !char_vec.is_empty() {
if FUNCTIONS.get(&char_vec[..]).is_some() {
char_vec.push(letter);
if !FUNCTIONS.get(&char_vec[..]).is_some() {
return Err(CalcError::Syntax(format!(
"Function '{}' expected parentheses",
&char_vec[..char_vec.chars().count()-1]
)));
}
} else {
return Err(CalcError::Syntax(format!(
"Unexpected character '{}'",
char_vec
)));
}
} else {
num_vec.push(letter);
last_char_is_op = false;
}
}
'_' => {
if prev_ans.is_none() {
return Err(CalcError::Syntax("No previous answer!".into()));
}
if !char_vec.is_empty() {
if FUNCTIONS.get(&char_vec[..]).is_some() {
return Err(CalcError::Syntax(format!(
"Function '{}' expected parentheses",
char_vec
)));
} else {
return Err(CalcError::Syntax(format!(
"Unexpected character '{}'",
char_vec
)));
}
}
let parse_num = num_vec.parse::<f64>().ok();
if let Some(x) = parse_num {
result.push(Token::Num(x));
result.push(OPERATORS.get(&'*').unwrap().clone());
num_vec.clear();
}
last_char_is_op = false;
result.push(Token::Num(prev_ans.unwrap()));
}
'a'..='z' | 'A'..='Z' => {
let parse_num = num_vec.parse::<f64>().ok();
if let Some(x) = parse_num {
result.push(Token::Num(x));
result.push(OPERATORS.get(&'*').unwrap().clone());
num_vec.clear();
}
char_vec.push(letter);
last_char_is_op = false;
}
'+' | '-' => {
let op_token = OPERATORS.get(&letter).unwrap().clone();
let parse_num = num_vec.parse::<f64>().ok();
if !last_char_is_op {
if let Some(x) = parse_num {
result.push(Token::Num(x));
num_vec.clear();
last_char_is_op = true;
} else if let Some(token) = CONSTANTS.get(&char_vec[..]) {
result.push(token.clone());
char_vec.clear();
last_char_is_op = true;
}
result.push(op_token);
} else if last_char_is_op {
result.push(Token::LParen);
result.push(Token::Num(
(letter.to_string() + "1").parse::<f64>().unwrap(),
));
result.push(Token::RParen);
result.push(Operator::token_from_op('*', |x, y| x * y, 10, true));
}
}
'/' | '*' | '%' | '^' | '!' => {
drain_stack(&mut num_vec, &mut char_vec, &mut result);
if letter == '*' && chars.peek() == Some(&'*') {
// Accept `**` operator as meaning `^` (exponentation).
let _ = chars.next();
letter = '^';
}
let operator_token: Token = OPERATORS.get(&letter).unwrap().clone();
result.push(operator_token);
last_char_is_op = true;
if letter == '!' {
result.push(Token::Num(1.));
last_char_is_op = false;
}
}
'(' => {
if !char_vec.is_empty() {
if let Some(res) = FUNCTIONS.get(&char_vec[..]) {
result.push(res.clone());
} else {
return Err(CalcError::Syntax(format!(
"Unknown function '{}'",
char_vec
)));
}
char_vec.clear();
} else {
let parse_num = num_vec.parse::<f64>().ok();
if let Some(x) = parse_num {
result.push(Token::Num(x));
result.push(OPERATORS.get(&'*').unwrap().clone());
num_vec.clear();
}
}
if let Some(Token::RParen) = result.last() {
result.push(OPERATORS.get(&'*').unwrap().clone());
}
result.push(Token::LParen);
last_char_is_op = true;
}
')' => {
drain_stack(&mut num_vec, &mut char_vec, &mut result);
result.push(Token::RParen);
last_char_is_op = false;
}
' ' => {}
_ => return Err(CalcError::Syntax(format!("Unexpected token: '{}'", letter))),
}
}
// println!("{:?}", result);
drain_stack(&mut num_vec, &mut char_vec, &mut result);
Ok(result)
}
fn drain_stack(num_vec: &mut String, char_vec: &mut String, result: &mut Vec<Token>) {
let parse_num = num_vec.parse::<f64>().ok();
if let Some(x) = parse_num {
result.push(Token::Num(x));
num_vec.clear();
} else if let Some(token) = CONSTANTS.get(&char_vec[..]) {
result.push(token.clone());
char_vec.clear();
}
}
fn is_radian_mode(x: f64, is_radian: bool) -> f64 {
if is_radian {
x
} else {
x.to_radians()
}
}
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