Added Adnot parser, too
Getty Ritter
9 years ago
| 1 | use std::collections::HashMap; | |
| 2 | use std::iter::Peekable; | |
| 3 | use std::str::{Chars,FromStr}; | |
| 4 | ||
| 5 | #[derive(Clone,Debug,PartialEq)] | |
| 6 | pub enum Adnot { | |
| 7 | Sum(String, Vec<Adnot>), | |
| 8 | Prod(HashMap<String, Adnot>), | |
| 9 | List(Vec<Adnot>), | |
| 10 | Str(String), | |
| 11 | Sym(String), | |
| 12 | Num(i64), | |
| 13 | Dbl(f64), | |
| 14 | } | |
| 15 | ||
| 16 | #[derive(Debug)] | |
| 17 | pub struct AdnotError { | |
| 18 | message: String, | |
| 19 | } | |
| 20 | ||
| 21 | type Stream<'a> = Peekable<Chars<'a>>; | |
| 22 | ||
| 23 | fn fail<T>(s: &str) -> Result<T, AdnotError> { | |
| 24 | Err(AdnotError { message: s.to_string()}) | |
| 25 | } | |
| 26 | ||
| 27 | fn parse_val(s: &mut Stream) -> Result<Adnot, AdnotError> { | |
| 28 | if let Some(c) = s.next() { | |
| 29 | match c { | |
| 30 | '[' => parse_list(s), | |
| 31 | '(' => parse_sum(s), | |
| 32 | '{' => parse_prod(s), | |
| 33 | '"' => parse_string(s), | |
| 34 | _ if c.is_digit(10) || c == '-' => parse_num(c, s), | |
| 35 | _ if c.is_alphabetic() => | |
| 36 | Ok(Adnot::Sym(try!(parse_sym(c, s)))), | |
| 37 | _ => fail(&format!("Invalid character: {:?}", c)), | |
| 38 | } | |
| 39 | } else { | |
| 40 | fail("Unexpected end of input") | |
| 41 | } | |
| 42 | } | |
| 43 | ||
| 44 | fn parse_list(s: &mut Stream) -> Result<Adnot, AdnotError> { | |
| 45 | let mut vec = vec![]; | |
| 46 | loop { | |
| 47 | skip_space(s); | |
| 48 | if let Some(&']') = s.peek() { | |
| 49 | s.next(); | |
| 50 | return Ok(Adnot::List(vec)); | |
| 51 | } else { | |
| 52 | vec.push(try!(parse_val(s))); | |
| 53 | } | |
| 54 | } | |
| 55 | } | |
| 56 | ||
| 57 | fn parse_sum(s: &mut Stream) -> Result<Adnot, AdnotError> { | |
| 58 | let mut vec = vec![]; | |
| 59 | skip_space(s); | |
| 60 | let first = match s.next() { | |
| 61 | Some(c) if c.is_alphabetic() => c, | |
| 62 | Some(_) => { return fail("Expected a tagname character") } | |
| 63 | None => { return fail("Unexpected end of input") } | |
| 64 | }; | |
| 65 | let name = try!(parse_sym(first, s)); | |
| 66 | loop { | |
| 67 | skip_space(s); | |
| 68 | if let Some(&')') = s.peek() { | |
| 69 | s.next(); | |
| 70 | return Ok(Adnot::Sum(name, vec)); | |
| 71 | } else { | |
| 72 | vec.push(try!(parse_val(s))); | |
| 73 | } | |
| 74 | } | |
| 75 | } | |
| 76 | ||
| 77 | fn parse_prod(s: &mut Stream) -> Result<Adnot, AdnotError> { | |
| 78 | let mut map = HashMap::new(); | |
| 79 | loop { | |
| 80 | skip_space(s); | |
| 81 | if let Some(&'}') = s.peek() { | |
| 82 | s.next(); | |
| 83 | return Ok(Adnot::Prod(map)); | |
| 84 | } else { | |
| 85 | skip_space(s); | |
| 86 | let first = match s.next() { | |
| 87 | Some(c) if c.is_alphabetic() => c, | |
| 88 | Some(_) => { return fail("Expected a tagname character") } | |
| 89 | None => { return fail("Unexpected end of input") } | |
| 90 | }; | |
| 91 | let key = try!(parse_sym(first, s)); | |
| 92 | skip_space(s); | |
| 93 | let val = try!(parse_val(s)); | |
| 94 | map.insert(key, val); | |
| 95 | } | |
| 96 | } | |
| 97 | } | |
| 98 | ||
| 99 | fn parse_string(s: &mut Stream) -> Result<Adnot, AdnotError> { | |
| 100 | let mut chars = Vec::new(); | |
| 101 | while let Some(c) = s.next() { | |
| 102 | if c == '"' { | |
| 103 | break; | |
| 104 | } else if c == '\\' { | |
| 105 | match s.next() { | |
| 106 | Some('n') => chars.push('\n'), | |
| 107 | Some('r') => chars.push('\r'), | |
| 108 | Some('t') => chars.push('\t'), | |
| 109 | Some('\'') => chars.push('\''), | |
| 110 | Some('\"') => chars.push('\"'), | |
| 111 | Some('\\') => chars.push('\\'), | |
| 112 | _ => return fail("Invalid escape sequence"), | |
| 113 | } | |
| 114 | } else { | |
| 115 | chars.push(c); | |
| 116 | } | |
| 117 | }; | |
| 118 | Ok(Adnot::Str(chars.iter().cloned().collect())) | |
| 119 | } | |
| 120 | ||
| 121 | fn parse_num(c: char, s: &mut Stream) -> Result<Adnot, AdnotError> { | |
| 122 | let mut str = vec![c]; | |
| 123 | str.extend(s.take_while(|c| c.is_digit(10))); | |
| 124 | let string: String = str.iter().cloned().collect(); | |
| 125 | Ok(Adnot::Num(i64::from_str(&string).unwrap())) | |
| 126 | } | |
| 127 | ||
| 128 | fn parse_sym(c: char, s: &mut Stream) -> Result<String, AdnotError> { | |
| 129 | let mut chars = vec![c]; | |
| 130 | while let Some(&c) = s.peek() { | |
| 131 | if c.is_alphanumeric() || c == '_' { | |
| 132 | chars.push(s.next().unwrap()); | |
| 133 | } else { | |
| 134 | break; | |
| 135 | } | |
| 136 | }; | |
| 137 | Ok(chars.iter().cloned().collect()) | |
| 138 | } | |
| 139 | ||
| 140 | fn skip_space(s: &mut Stream) { | |
| 141 | while let Some(&c) = s.peek() { | |
| 142 | match c { | |
| 143 | '#' => { skip_comment(s); } | |
| 144 | _ if c.is_whitespace() => { s.next(); } | |
| 145 | _ => break, | |
| 146 | } | |
| 147 | } | |
| 148 | } | |
| 149 | ||
| 150 | fn skip_comment(s: &mut Stream) { | |
| 151 | s.next(); | |
| 152 | while let Some(&c) = s.peek() { | |
| 153 | if c == '\n' || c == '\r' { | |
| 154 | s.next(); | |
| 155 | return; | |
| 156 | } else { | |
| 157 | s.next(); | |
| 158 | } | |
| 159 | } | |
| 160 | } | |
| 161 | ||
| 162 | impl Adnot { | |
| 163 | pub fn parse(s: &str) -> Result<Adnot, AdnotError> { | |
| 164 | let mut stream = s.chars().peekable(); | |
| 165 | skip_space(&mut stream); | |
| 166 | parse_val(&mut stream) | |
| 167 | } | |
| 168 | } |