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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193

use std::borrow::Cow;

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Position {
    LineNumberReference {
        start: usize,
        end: usize,
        line_number: usize,
    },
    LineNumber {
        content: Cow<'static, str>,
        line_number: usize,
    },
    Any {
        content: Cow<'static, str>,
    },
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum TriviaKind {
    Comment,
    Whitespace,
}

impl TriviaKind {
    pub fn at(self, start: usize, end: usize, line_number: usize) -> Trivia {
        Trivia {
            position: Position::LineNumberReference {
                start,
                end,
                line_number,
            },
            kind: self,
        }
    }

    pub fn with_content<IntoCowStr: Into<Cow<'static, str>>>(self, content: IntoCowStr) -> Trivia {
        Trivia {
            position: Position::Any {
                content: content.into(),
            },
            kind: self,
        }
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Trivia {
    position: Position,
    kind: TriviaKind,
}

impl Trivia {
    pub fn read<'a: 'b, 'b>(&'a self, code: &'b str) -> &'b str {
        match &self.position {
            Position::LineNumberReference { start, end, .. } => code
                .get(*start..*end)
                .expect("unable to extract code from position"),
            Position::LineNumber { content, .. } | Position::Any { content } => content,
        }
    }

    pub fn kind(&self) -> TriviaKind {
        self.kind.clone()
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Token {
    position: Position,
    leading_trivia: Vec<Trivia>,
    trailing_trivia: Vec<Trivia>,
}

impl Token {
    /// Creates a token where the position refers to the original code where
    /// the token was parsed with the line number where it starts.
    pub fn new_with_line(start: usize, end: usize, line_number: usize) -> Self {
        Self {
            position: Position::LineNumberReference {
                start,
                end,
                line_number,
            },
            leading_trivia: Vec::new(),
            trailing_trivia: Vec::new(),
        }
    }

    /// Creates a new token that is not contrained to any existing position.
    pub fn from_content<IntoCowStr: Into<Cow<'static, str>>>(content: IntoCowStr) -> Self {
        Self {
            position: Position::Any {
                content: content.into(),
            },
            leading_trivia: Vec::new(),
            trailing_trivia: Vec::new(),
        }
    }

    /// Creates a new token from a position.
    pub fn from_position(position: Position) -> Self {
        Self {
            position,
            leading_trivia: Vec::new(),
            trailing_trivia: Vec::new(),
        }
    }

    pub fn with_leading_trivia(mut self, trivia: Trivia) -> Self {
        self.leading_trivia.push(trivia);
        self
    }

    pub fn with_trailing_trivia(mut self, trivia: Trivia) -> Self {
        self.trailing_trivia.push(trivia);
        self
    }

    #[inline]
    pub fn push_leading_trivia(&mut self, trivia: Trivia) {
        self.leading_trivia.push(trivia);
    }

    #[inline]
    pub fn push_trailing_trivia(&mut self, trivia: Trivia) {
        self.trailing_trivia.push(trivia);
    }

    #[inline]
    pub fn iter_leading_trivia(&self) -> impl Iterator<Item = &Trivia> {
        self.leading_trivia.iter()
    }

    #[inline]
    pub fn iter_trailing_trivia(&self) -> impl Iterator<Item = &Trivia> {
        self.trailing_trivia.iter()
    }

    pub fn read<'a: 'b, 'b>(&'a self, code: &'b str) -> &'b str {
        match &self.position {
            Position::LineNumberReference { start, end, .. } => code
                .get(*start..*end)
                .expect("unable to extract code from position"),
            Position::LineNumber { content, .. } | Position::Any { content } => content,
        }
    }

    pub fn get_line_number(&self) -> Option<usize> {
        match &self.position {
            Position::LineNumber { line_number, .. }
            | Position::LineNumberReference { line_number, .. } => Some(*line_number),
            Position::Any { .. } => None,
        }
    }

    pub fn replace_with_content<IntoCowStr: Into<Cow<'static, str>>>(
        &mut self,
        content: IntoCowStr,
    ) {
        self.position = match &self.position {
            Position::LineNumber { line_number, .. }
            | Position::LineNumberReference { line_number, .. } => Position::LineNumber {
                line_number: *line_number,
                content: content.into(),
            },

            Position::Any { .. } => Position::Any {
                content: content.into(),
            },
        };
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn read_line_number_reference_token() {
        let code = "return true";
        let token = Token::new_with_line(7, 11, 1);

        assert_eq!("true", token.read(code));
    }

    #[test]
    fn read_any_position_token() {
        let token = Token::from_content("true");

        assert_eq!("true", token.read(""));
    }
}