1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

use std::fmt;

use crate::{
    data::{
        expression::{
            self,
            Expression,
        },
        token::{
            self,
            Span,
            Token,
        },
    },
    pipeline::{
        self,
        tokenizer,
    },
};


pub struct Parser<Tokenizer> {
    tokenizer: Tokenizer,
}

impl<Tokenizer> Parser<Tokenizer> {
    pub fn new(tokenizer: Tokenizer) -> Self {
        Parser {
            tokenizer,
        }
    }
}

impl<Tokenizer> pipeline::Stage for Parser<Tokenizer>
    where Tokenizer: pipeline::Stage<Item=Token, Error=tokenizer::Error>
{
    type Item  = Expression;
    type Error = Error;

    fn next(&mut self) -> Result<Self::Item, Self::Error> {
        let token = self.tokenizer.next()?;

        let expr = match token.kind {
            token::Kind::ListOpen => {
                self.parse_list(token.span)?
            }
            token::Kind::ListClose => {
                return Err(Error::UnexpectedToken(token));
            }
            _ => {
                Expression::from_token(token)
            }
        };

        Ok(expr)
    }
}

impl<Tokenizer> Parser<Tokenizer>
    where Tokenizer: pipeline::Stage<Item=Token, Error=tokenizer::Error>
{
    fn parse_list(&mut self, mut list_span: Span) -> Result<Expression, Error> {
        let mut expressions = Vec::new();

        loop {
            let token = self.tokenizer.next()?;

            list_span = list_span.merge(&token.span);

            let expr = match token.kind {
                token::Kind::ListOpen => {
                    self.parse_list(token.span)?
                }
                token::Kind::ListClose => {
                    return Ok(
                        Expression {
                            kind: expression::Kind::List(expressions),
                            span: list_span,
                        }
                    );
                }
                _ => {
                    Expression::from_token(token)
                }
            };

            expressions.push(expr);
        }
    }
}


#[derive(Debug)]
pub enum Error {
    Tokenizer(tokenizer::Error),
    UnexpectedToken(Token),
    EndOfStream,
}

impl Error {
    pub fn spans<'r>(&'r self, spans: &mut Vec<&'r Span>) {
        match self {
            Error::UnexpectedToken(token) => spans.push(&token.span),

            Error::Tokenizer(_) => (),
            Error::EndOfStream  => (),
        }
    }
}

impl From<tokenizer::Error> for Error {
    fn from(from: tokenizer::Error) -> Self {
        match from {
            tokenizer::Error::EndOfStream => Error::EndOfStream,
            error                         => Error::Tokenizer(error),
        }
    }
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Error::Tokenizer(error) => {
                write!(f, "Tokenizer error:\n{:?}", error)?;
            }
            Error::UnexpectedToken(token) => {
                write!(f, "Unexpected token: `{}`", token.kind)?;
            }
            Error::EndOfStream => {
                panic!("Error variant should not be display: {:?}", self);
            }
        }

        Ok(())
    }
}