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use std::str;
#[derive(Debug)]
struct Token {
kind: String,
val: String,
}
fn main() {
let input: &str = "2y + 11(1 + 2 + 3) + 12 / 4";
let input = input.replace(" ", "");
println!("{}", input);
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() {
if letter.is_digit(10) {
num_vec.push(letter);
} else if letter == '.' {
num_vec.push(letter);
} else if letter.is_alphabetic() {
drain_buffer("Literal", &num_vec[..], &mut result);
char_vec.push(letter);
num_vec.clear();
} else if is_operator(letter) {
drain_buffer("Literal", &num_vec[..], &mut result);
num_vec.clear();
drain_buffer("Variable", &char_vec[..], &mut result);
char_vec.clear();
result.push(Token { kind: "Operator".into(), val: letter.to_string() });
} else if letter == '(' {
if char_vec.len() > 0 {
drain_buffer("Function", &char_vec[..], &mut result);
char_vec.clear();
} else if num_vec.len() > 0 {
drain_buffer("Literal", &num_vec[..], &mut result);
result.push( Token{kind: "Operator".into(), val: "*".to_string()} );
num_vec.clear();
}
result.push( Token{kind: "Left Paren".into(), val: letter.to_string()} );
} else if letter == ')' {
drain_buffer("Literal", &num_vec[..], &mut result);
num_vec.clear();
drain_buffer("Variable", &char_vec[..], &mut result);
char_vec.clear();
result.push(Token { kind: "Right Paren".into(), val: letter.to_string() });
} else if letter == ',' {
drain_buffer("Literal", &num_vec[..], &mut result);
num_vec.clear();
drain_buffer("Variable", &char_vec[..], &mut result);
char_vec.clear();
result.push(Token { kind: "Function Arg Separator".into(), val: letter.to_string() });
}
}
drain_buffer("Literal", &num_vec[..], &mut result);
num_vec.clear();
drain_buffer("Variable", &char_vec[..], &mut result);
char_vec.clear();
for token in &result {
println!("{} => {}", token.kind, token.val);
}
}
fn drain_buffer(k: &str, v: &str, result: &mut Vec<Token>) {
if v.len() > 0 {
let token = Token {
kind: k.into(),
val: v.chars().collect::<String>()
};
result.push(token);
}
}
fn is_operator(x: char) -> bool {
match x {
'+' | '-' | '/' | '*' | '^' => true,
_ => false
}
}
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