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#[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) -> f64 {
(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) -> f64 {
(self.relation)(arg)
}
}
#[derive(Debug, Clone, PartialEq)]
pub enum Token {
Operator(Operator),
Num(f64),
Function(Function),
LParen,
RParen
}
pub fn lexer(input: &str) -> Result<Vec<Token>, String> {
let mut num_vec: String = String::new();
let mut char_vec: String = String::new();
let mut result: Vec<Token> = vec![];
for letter in input.chars() {
match letter {
'0'...'9' | '.' => {
num_vec.push(letter);
},
'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(Operator::token_from_op('*', |x, y| x * y, 3, true));
num_vec.clear();
}
char_vec.push(letter);
},
'+' | '-' => {
let op_token = match letter {
'+' => Operator::token_from_op('+', |x, y| x + y, 2, true),
'-' => Operator::token_from_op('-', |x, y| x - y, 2, true),
_ => unreachable!()
};
let parse_num = num_vec.parse::<f64>().ok();
if let Some(x) = parse_num {
result.push(Token::Num(x));
num_vec.clear();
result.push(op_token);
} else {
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, 2, true));
}
},
'/' | '*' | '^' => {
drain_num_stack(&mut num_vec, &mut result);
let operator_token: Token = match letter {
'/' => Operator::token_from_op('/', |x, y| x / y, 3, true),
'*' => Operator::token_from_op('*', |x, y| x * y, 3, true),
'^' => Operator::token_from_op('^', |x, y| x.powf(y), 4, false),
_ => panic!("unexpected op whuuu"),
};
result.push(operator_token);
},
'(' => {
if char_vec.len() > 0 {
let funct = char_vec.clone();
match &funct[..] {
"sin" | "sine" => result.push(Function::token_from_fn("sin".into(), |x| x.to_radians().sin())),
"cos" | "cosine" => result.push(Function::token_from_fn("cos".into(), |x| x.to_radians().cos())),
"tan" | "tangent" => result.push(Function::token_from_fn("tan".into(), |x| x.to_radians().tan())),
"csc" | "cosec" => result.push(Function::token_from_fn("csc".into(), |x| 1f64 / x.to_radians().sin())),
"sec" | "secant" => result.push(Function::token_from_fn("sec".into(), |x| 1f64 / x.to_radians().cos())),
"cot" | "cotangent" => result.push(Function::token_from_fn("cot".into(), |x| 1f64 / x.to_radians().tan())),
"ln" => result.push(Function::token_from_fn("ln".into(), |x| x.ln())),
"log" => result.push(Function::token_from_fn("log".into(), |x| x.log10())),
"sqrt" => result.push(Function::token_from_fn("sqrt".into(), |x| x.sqrt())),
"floor" => result.push(Function::token_from_fn("floor".into(), |x| x.floor())),
"ceil" => result.push(Function::token_from_fn("ceil".into(), |x| x.ceil())),
_ => return Err(format!("Unexpected function {}", funct))
}
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(Operator::token_from_op('*', |x, y| x * y, 3, true));
num_vec.clear();
}
}
if let Some(x) = result.last() {
match x {
Token::RParen => {
result.push(Operator::token_from_op('*', |x, y| x * y, 3, true));
},
_ => {}
};
}
result.push(Token::LParen);
},
')' => {
drain_num_stack(&mut num_vec, &mut result);
result.push(Token::RParen);
}
' ' => {}
_ => {
return Err(format!("Unexpected character: {}", letter))
}
}
}
drain_num_stack(&mut num_vec, &mut result);
Ok(result)
}
fn drain_num_stack(num_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();
}
}
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