Parse JSON using Nibble.

1 files changed, 257 insertions, 0 deletions

diff --git a/chomp-macro/benches/json.rs b/chomp-macro/benches/json.rs
new file mode 100644
index 0000000..d6ab021
--- /dev/null
+++ b/chomp-macro/benches/json.rs
@@ -0,0 +1,257 @@
+use chomp_macro::nibble;
+use std::{collections::HashMap, convert::TryInto, mem, ops::RangeInclusive};
+
+enum Value {
+    True,
+    False,
+    Null,
+    Number(f64),
+    String(String),
+    Array(Vec<Value>),
+    Object(HashMap<String, Value>),
+}
+
+// Note: this is only an ASCII subset. Need to add character sets.
+nibble! {
+    let opt(x) = _ : None | x : Some;
+    let plus(x) = [rec](x . opt(rec));
+    let star(x) = [rec](opt(x . rec));
+    let sep(x, p) = [rec](x . opt(p . rec));
+
+    let ws_char = " " | "\t" | "\n" | "\r";
+    let ws = star(ws_char);
+    let digit_1_9 = "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
+    let digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9";
+
+    let unsigned_number = (("0" | digit_1_9 . star(digit)) : Int)
+        . (opt("." . plus(digit)) : Frac)
+        . (opt(("e" | "E") . opt("+" | "-") . plus(digit)) : Exp);
+    let number = unsigned_number : Positive | "-" . unsigned_number : Negative;
+
+    let hex =
+        "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" |
+        "a" | "b" | "c" | "d" | "e" | "f" |
+        "A" | "B" | "C" | "D" | "E" | "F" ;
+    let char =
+        (" " | "!"       | "#" | "$" | "%" | "&" | "'" |
+         "(" | ")" | "*" | "+" | "," | "-" | "." | "/" |
+         "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |
+         "8" | "9" | ":" | ";" | "<" | "=" | ">" | "?" |
+         "@" | "A" | "B" | "C" | "D" | "E" | "F" | "G" |
+         "H" | "I" | "J" | "K" | "L" | "M" | "N" | "O" |
+         "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" |
+         "X" | "Y" | "Z" | "["       | "]" | "^" | "_" |
+         "`" | "a" | "b" | "c" | "d" | "e" | "f" | "g" |
+         "h" | "i" | "j" | "k" | "l" | "m" | "n" | "o" |
+         "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" |
+         "x" | "y" | "z" | "{" | "|" | "}" | "~") : Literal |
+    "\\" . (
+        ("\"" | "\\" | "/" | "b" | "f" | "n" | "r" | "t") : Ascii |
+        "u" . hex . hex . hex . hex : Unicode
+    ) : Escape;
+
+    let string = "\"" . star(char) . "\"";
+
+    let member(value) = (string : Key) . ws . ":" . ws . (value : Value) . ws;
+    let object(value) = "{" . ws . opt(sep(member(value), "," . ws)) . "}";
+
+    let array(value) = "[" . ws . opt(sep(value . ws, "," . ws)) . "]";
+
+    let value = [value](
+        "true" : True |
+        "false" : False |
+        "null" : Null |
+        number : Number |
+        string : String |
+        object(value) : Object |
+        array(value) : Array
+    );
+
+    match [rec](ws_char . rec | value . ws);
+}
+
+impl From<Ast> for Value {
+    fn from(mut ast: Ast) -> Self {
+        loop {
+            match ast.0 {
+                Alt184::Branch1(cat) => ast = *cat.rec1,
+                Alt184::Branch2(cat) => return cat.value1.into(),
+            }
+        }
+    }
+}
+
+impl From<Value1> for Value {
+    fn from(value: Value1) -> Self {
+        match value.0 {
+            Alt182::True1(_) => Self::True,
+            Alt182::False1(_) => Self::False,
+            Alt182::Null1(_) => Self::Null,
+            Alt182::Number1(n) => Self::Number(n.into()),
+            Alt182::String1(s) => Self::String(s.into()),
+            Alt182::Object1(o) => Self::Object(o.into()),
+            Alt182::Array1(a) => Self::Array(a.into()),
+        }
+    }
+}
+
+impl From<Number1> for f64 {
+    fn from(number: Number1) -> Self {
+        number.to_string().parse().unwrap()
+    }
+}
+
+impl From<String1> for String {
+    fn from(string: String1) -> Self {
+        string.star1.into_iter().collect()
+    }
+}
+
+impl Iterator for Star2 {
+    type Item = char;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        fn next(star: &mut Star2) -> Option<Char1> {
+            match mem::replace(star, Star2(Opt9::None1(Epsilon))).0 {
+                Opt9::None1(_) => None,
+                Opt9::Some1(s) => {
+                    *star = *s.rec1;
+                    Some(s.char1)
+                }
+            }
+        }
+
+        fn decode(u: Unicode1) -> u16 {
+            let chars: [char; 4] = [u.hex1.into(), u.hex2.into(), u.hex3.into(), u.hex4.into()];
+            u16::from_str_radix(&chars.iter().collect::<String>(), 16).unwrap()
+        }
+
+        fn decode_pair(one: u16, other: u16) -> u32 {
+            // Ranges are confusingly backwards
+            const LOW_SURROGATE_RANGE: RangeInclusive<u16> = 0xDC00..=0xDFFF;
+            const HIGH_SURROGATE_RANGE: RangeInclusive<u16> = 0xD800..=0xDBFF;
+
+            let (low, high) = if LOW_SURROGATE_RANGE.contains(&one) {
+                assert!(HIGH_SURROGATE_RANGE.contains(&other));
+                (one, other)
+            } else {
+                assert!(LOW_SURROGATE_RANGE.contains(&other));
+                assert!(HIGH_SURROGATE_RANGE.contains(&one));
+                (other, one)
+            };
+
+            u32::from(high - 0xD800) * 0x400 + u32::from(low - 0xDC00) + 0x10000
+        }
+
+        const SURROGATE_PAIR_RANGE: RangeInclusive<u16> = 0xD800..=0xDFFF;
+
+        match next(self) {
+            None => None,
+            Some(Char1::Literal1(l)) => Some(l.into()),
+            Some(Char1::Escape1(e)) => match e.1 {
+                Alt148::Ascii1(Ascii1::Branch1(_)) => Some('\"'),
+                Alt148::Ascii1(Ascii1::Branch2(_)) => Some('\\'),
+                Alt148::Ascii1(Ascii1::Branch3(_)) => Some('/'),
+                Alt148::Ascii1(Ascii1::Branch4(_)) => Some('\x08'),
+                Alt148::Ascii1(Ascii1::Branch5(_)) => Some('\x0c'),
+                Alt148::Ascii1(Ascii1::Branch6(_)) => Some('\n'),
+                Alt148::Ascii1(Ascii1::Branch7(_)) => Some('\r'),
+                Alt148::Ascii1(Ascii1::Branch8(_)) => Some('\t'),
+                Alt148::Unicode1(u) => {
+                    let codepoint = decode(u);
+
+                    if SURROGATE_PAIR_RANGE.contains(&codepoint) {
+                        let other = if let Some(Char1::Escape1(e)) = next(self) {
+                            if let Alt148::Unicode1(u) = e.1 {
+                                decode(u)
+                            } else {
+                                panic!()
+                            }
+                        } else {
+                            panic!()
+                        };
+
+                        assert!(SURROGATE_PAIR_RANGE.contains(&other));
+
+                        Some(decode_pair(codepoint, other).try_into().unwrap())
+                    } else {
+                        Some(u32::from(codepoint).try_into().unwrap())
+                    }
+                }
+            },
+        }
+    }
+}
+
+impl From<Object1> for HashMap<String, Value> {
+    fn from(object: Object1) -> Self {
+        match object.opt1 {
+            Opt12::None1(_) => HashMap::new(),
+            Opt12::Sep1(s) => s
+                .into_iter()
+                .map(|m| (m.string1.into(), (*m.value1).into()))
+                .collect(),
+        }
+    }
+}
+
+impl IntoIterator for Sep1 {
+    type Item = Member1;
+
+    type IntoIter = Sep1Iter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Sep1Iter(Some(self))
+    }
+}
+
+pub struct Sep1Iter(Option<Sep1>);
+
+impl Iterator for Sep1Iter {
+    type Item = Member1;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let inner = self.0.take()?.0;
+        let res = inner.member1;
+        self.0 = match inner.opt1 {
+            Opt11::None1(_) => None,
+            Opt11::Some1(s) => Some(*s.rec1),
+        };
+        Some(res)
+    }
+}
+
+impl From<Array1> for Vec<Value> {
+    fn from(array: Array1) -> Self {
+        match array.opt1 {
+            Opt14::None1(_) => Vec::new(),
+            Opt14::Sep1(s) => s.into_iter().map(|x| (*x.value1).into()).collect(),
+        }
+    }
+}
+
+impl IntoIterator for Sep2 {
+    type Item = X1;
+
+    type IntoIter = Sep2Iter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Sep2Iter(Some(self))
+    }
+}
+
+pub struct Sep2Iter(Option<Sep2>);
+
+impl Iterator for Sep2Iter {
+    type Item = X1;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let inner = self.0.take()?.0;
+        let res = inner.x1;
+        self.0 = match inner.opt1 {
+            Opt13::None1(_) => None,
+            Opt13::Some1(s) => Some(*s.rec1),
+        };
+        Some(res)
+    }
+}