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use crate::ast_types::Node;
use crate::token_types::Tokens;
pub fn parse<'a, T: Iterator<Item = Result<Box<Tokens>, String>>>(stream: T) -> Result<Box<Node>, String> {
let mut stream = stream.peekable();
let mut paren_level = 0;
let mut current_stack = vec!(Box::new(Node::ForumulaUnit(1, vec!())));
loop {
match stream.next() {
Some(Err(val)) => return Err(val),
Some(Ok(box Tokens::Number(val))) => {
let fu = current_stack.pop().unwrap();
if let box Node::ForumulaUnit(_,vec) = fu {
current_stack.push(Box::new(Node::ForumulaUnit(val, vec)));
} else {
return Err("Invalid parent".to_owned());
}
},
Some(Ok(box Tokens::Element(val))) => {
let mut fu = *current_stack.pop().unwrap();
if let Node::ForumulaUnit(_,ref mut vec) = fu {
if let Some(Ok(box Tokens::Number(count))) = stream.peek() {
vec.push(Node::Element(*count, val));
stream.next();
} else {
vec.push(Node::Element(1, val));
}
current_stack.push(Box::new(fu));
} else {
return Err("Invalid Parent".to_owned());
}
},
Some(Ok(box Tokens::Plus)) => {
let fu = *current_stack.pop().unwrap();
let mut maybe_reactants = current_stack.pop().map(|val| *val);
match maybe_reactants {
Some(Node::Reactants(ref mut vec)) => {
vec.push(fu);
current_stack.push(Box::new(maybe_reactants.unwrap()));
current_stack.push(Box::new(Node::ForumulaUnit(1, vec!())));
},
Some(Node::Products(ref mut vec)) => {
vec.push(fu);
current_stack.push(Box::new(maybe_reactants.unwrap()));
current_stack.push(Box::new(Node::ForumulaUnit(1, vec!())));
},
Some(_) => return Err("Invalid plus".to_owned()),
None => {
if let Node::ForumulaUnit(_,_) = fu {
current_stack.push(Box::new(Node::Reactants(vec!(fu))));
current_stack.push(Box::new(Node::ForumulaUnit(1, vec!())));
}
},
}
}
Some(Ok(box Tokens::Yields)) => {
let fu = *current_stack.pop().unwrap();
let mut maybe_reactants = current_stack.pop();
match maybe_reactants {
Some(box Node::Reactants(ref mut vec)) => {
vec.push(fu);
current_stack.push(maybe_reactants.unwrap());
current_stack.push(Box::new(Node::Products(vec!())));
current_stack.push(Box::new(Node::ForumulaUnit(1, vec!())));
},
Some(_) => return Err("Invalid yields location".to_owned()),
None => {
current_stack.push(Box::new(Node::Reactants(vec!(fu))));
current_stack.push(Box::new(Node::ForumulaUnit(1, vec!())));
},
}
}
Some(Ok(box Tokens::Paren(super::token_types::ParenType::OPEN))) => {
paren_level += 1;
current_stack.push(Box::new(Node::Group(1, vec!())));
},
Some(Ok(box Tokens::Paren(super::token_types::ParenType::CLOSE))) => {
if paren_level == 0 {
return Err("Invalid closing paren".to_owned());
};
paren_level -= 1;
let group = *current_stack.pop().unwrap();
let mut maybe_fu_or_group = current_stack.pop();
match maybe_fu_or_group {
Some(box Node::Group(_,ref mut vec)) => {
if let Some(Ok(box Tokens::Number(val))) = stream.peek() {
if let Node::Group(_,inner_vec) = group {
vec.push(Node::Group(*val, inner_vec));
}
}
current_stack.push(maybe_fu_or_group.unwrap());
},
Some(box Node::ForumulaUnit(_, ref mut vec)) => {
vec.push(group);
current_stack.push(maybe_fu_or_group.unwrap());
},
Some(_) => return Err("Invalid Parent".to_owned()),
None => return Err("Stack Underflow in group".to_owned()),
}
},
None => {
let fu = *current_stack.pop().unwrap();
let mut products_or_none = current_stack.pop();
match products_or_none {
Some(box Node::Products(ref mut vec)) => {
let reactants = current_stack.pop().unwrap();
vec.push(fu);
current_stack.push(Box::new(Node::Equation(reactants, products_or_none.unwrap())));
},
Some(_) => return Err("Stack had unexpected value".to_owned()),
None => {
current_stack.push(Box::new(fu));
},
}
break
},
}
}
Ok(current_stack.pop().unwrap())
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn can_parse_equation() {
let stream = vec!(
Box::new(Tokens::Number(2)),
Box::new(Tokens::Element("Fe".to_owned())),
Box::new(Tokens::Plus),
Box::new(Tokens::Element("Na".to_owned())),
Box::new(Tokens::Number(2)),
Box::new(Tokens::Element("F".to_owned())),
Box::new(Tokens::Number(3)),
Box::new(Tokens::Yields),
Box::new(Tokens::Number(2)),
Box::new(Tokens::Element("Fe".to_owned())),
Box::new(Tokens::Element("Na".to_owned())),
Box::new(Tokens::Plus),
Box::new(Tokens::Element("F".to_owned())),
Box::new(Tokens::Number(3)),
);
let exp = Node::Equation(
Box::new(Node::Reactants(vec!(
Node::ForumulaUnit(2, vec!(Node::Element(1, "Fe".to_owned()))),
Node::ForumulaUnit(1, vec!(Node::Element(2, "Na".to_owned()), Node::Element(3, "F".to_owned()))),
))),
Box::new(Node::Products(vec!(
Node::ForumulaUnit(2, vec!(
Node::Element(1, "Fe".to_owned()),
Node::Element(1, "Na".to_owned()),
)),
Node::ForumulaUnit(1, vec!(Node::Element(3, "F".to_owned())))
)))
);
let res = parse(
stream.into_iter()
.map(|box_tokens| Ok(box_tokens))
);
assert!(res.is_ok());
assert_eq!(exp, *res.unwrap());
}
#[test]
fn can_parse_formula_unit() {
let stream = vec!(
Box::new(Tokens::Number(2)),
Box::new(Tokens::Element("Fe".to_owned())),
Box::new(Tokens::Element("C".to_owned())),
Box::new(Tokens::Element("O".to_owned())),
Box::new(Tokens::Number(3)),
);
let exp = Node::ForumulaUnit(2, vec!(
Node::Element(1, "Fe".to_owned()),
Node::Element(1, "C".to_owned()),
Node::Element(3, "O".to_owned())
));
let res = parse(
stream.into_iter()
.map(|box_tokens| Ok(box_tokens))
);
assert!(res.is_ok());
assert_eq!(exp, *res.unwrap());
}
}
