Repository: not-fl3/nanoserde (rust)

Issue:
TomlParser doesn't allow keys with `0-9` in them
According to the [TOML spec](https://toml.io/en/v1.0.0#keys), this should be a valid TOML file
```toml
[thing]
1234 = "value"
```
If I parse it with nanoserde's TOML parser,
```rs
nanoserde::TomlParser::parse("[thing]\n1234 = \"value\"");
```
you get an error
```
Toml error: Unexpected token U64(1234) , line:2 col:1
```
Critically, a key with *any* `[0-9]` characters in it causes an error; `MyThing1 = "value"` leads to `Toml error: Unexpected token U64(1) , line:2 col:1`.

Pull request description:
Rework TOML token parsing
This PR closes #81 and also allows a number of other valid identifiers to be parsed by reworking the logic for parsing TOML tokens from characters.

For example, all of the identifiers in the following document are valid according to the TOML spec (ABNF [here](https://github.com/toml-lang/toml/blob/main/toml.abnf)), but none are currently able to be parsed:

```toml
[foo.bar.baz]
1key = "myval"
-inf = 0
2024-04-30 = 100
½ = 0.5
```
(although even github markdown highlighting doesn't get that last one)



Patch:
diff --git a/src/toml.rs b/src/toml.rs
index 29bab86..bfe4843 100644
--- a/src/toml.rs
+++ b/src/toml.rs
@@ -10,6 +10,42 @@ use hashbrown::HashMap;
 #[cfg(not(feature = "no_std"))]
 use std::collections::HashMap;
 
+/// Pattern matching any valid unquoted key character as u32.
+/// ABNF line: https://github.com/toml-lang/toml/blob/2431aa308a7bc97eeb50673748606e23a6e0f201/toml.abnf#L55
+macro_rules! ident_chars {
+    () => {
+        '\u{41}'..='\u{5A}'
+        | '\u{61}'..='\u{7A}'
+        | '\u{30}'..='\u{39}'
+        | '\u{2D}'
+        | '\u{5F}'
+        | '\u{B2}'
+        | '\u{B3}'
+        | '\u{B9}'
+        | '\u{BC}'..='\u{BE}'
+        | '\u{C0}'..='\u{D6}'
+        | '\u{D8}'..='\u{F6}'
+        | '\u{F8}'..='\u{37D}'
+        | '\u{37F}'..='\u{1FFF}'
+        | '\u{200C}'..='\u{200D}'
+        | '\u{203F}'..='\u{2040}'
+        | '\u{2070}'..='\u{218F}'
+        | '\u{2460}'..='\u{24FF}'
+        | '\u{2C00}'..='\u{2FEF}'
+        | '\u{3001}'..='\u{D7FF}'
+        | '\u{F900}'..='\u{FDCF}'
+        | '\u{FDF0}'..='\u{FFFD}'
+        | '\u{10000}'..='\u{EFFFF}'
+    }
+}
+
+/// Pattern matching a character that can terminate a valid ident.
+macro_rules! ident_term_chars {
+    () => {
+        ' ' | '\t' | '\n' | '\0' | '=' | ']'
+    };
+}
+
 /// A parser for TOML string values.
 ///
 /// ```rust
@@ -34,6 +70,7 @@ pub enum TomlTok {
     I64(i64),
     F64(f64),
     Bool(bool),
+    // TODO add option to enforce + sign for conversion to ident
     Nan(bool),
     Inf(bool),
     Date(String),
@@ -41,10 +78,42 @@ pub enum TomlTok {
     BlockOpen,
     BlockClose,
     Comma,
-    Bof,
     Eof,
 }
 
+impl From<TomlTok> for String {
+    fn from(value: TomlTok) -> Self {
+        match value {
+            TomlTok::Ident(string) => string,
+            TomlTok::Str(string) => string,
+            TomlTok::U64(number) => number.to_string(),
+            TomlTok::I64(number) => number.to_string(),
+            TomlTok::F64(number) => number.to_string(),
+            TomlTok::Bool(boolean) => boolean.to_string(),
+            TomlTok::Nan(negative) => {
+                if negative {
+                    "-nan".to_string()
+                } else {
+                    "nan".to_string()
+                }
+            }
+            TomlTok::Inf(negative) => {
+                if negative {
+                    "-inf".to_string()
+                } else {
+                    "inf".to_string()
+                }
+            }
+            TomlTok::Date(string) => string,
+            TomlTok::Equals => '='.to_string(),
+            TomlTok::BlockOpen => '['.to_string(),
+            TomlTok::BlockClose => ']'.to_string(),
+            TomlTok::Comma => ','.to_string(),
+            TomlTok::Eof => '\0'.to_string(),
+        }
+    }
+}
+
 /// A TOML value.
 #[derive(Debug, PartialEq)]
 pub enum Toml {
@@ -236,6 +305,13 @@ impl TomlParser {
                         let tok = self.next_tok(i)?;
                         let key = match tok {
                             TomlTok::Ident(key) => key,
+                            TomlTok::U64(_)
+                            | TomlTok::I64(_)
+                            | TomlTok::F64(_)
+                            | TomlTok::Bool(_)
+                            | TomlTok::Nan(_)
+                            | TomlTok::Inf(_)
+                            | TomlTok::Date(_) => tok.into(),
                             _ => return Err(self.err_token(tok)),
                         };
                         let tok = self.next_tok(i)?;
@@ -251,9 +327,15 @@ impl TomlParser {
                     _ => return Err(self.err_token(tok)),
                 }
             }
-            TomlTok::Str(key) | TomlTok::Ident(key) => {
-                self.parse_key_value(local_scope, key, i, out.out())?
-            }
+            TomlTok::Str(_)
+            | TomlTok::Ident(_)
+            | TomlTok::U64(_)
+            | TomlTok::I64(_)
+            | TomlTok::F64(_)
+            | TomlTok::Bool(_)
+            | TomlTok::Nan(_)
+            | TomlTok::Inf(_)
+            | TomlTok::Date(_) => self.parse_key_value(local_scope, tok.into(), i, out.out())?,
             _ => return Err(self.err_token(tok)),
         }
         Ok(true)
@@ -350,6 +432,8 @@ impl TomlParser {
             if self.cur == '\0' {
                 return Ok(TomlTok::Eof);
             }
+
+            #[allow(unreachable_patterns)]
             match self.cur {
                 ',' => {
                     self.next(i);
@@ -367,132 +451,6 @@ impl TomlParser {
                     self.next(i);
                     return Ok(TomlTok::Equals);
                 }
-                '+' | '-' | '0'..='9' => {
-                    let mut num = String::new();
-                    let is_neg = if self.cur == '-' {
-                        num.push(self.cur);
-                        self.next(i);
-                        true
-                    } else {
-                        if self.cur == '+' {
-                            self.next(i);
-                        }
-                        false
-                    };
-                    if self.cur == 'n' {
-                        self.next(i);
-                        if self.cur == 'a' {
-                            self.next(i);
-                            if self.cur == 'n' {
-                                self.next(i);
-                                return Ok(TomlTok::Nan(is_neg));
-                            } else {
-                                return Err(self.err_parse("nan"));
-                            }
-                        } else {
-                            return Err(self.err_parse("nan"));
-                        }
-                    }
-                    if self.cur == 'i' {
-                        self.next(i);
-                        if self.cur == 'n' {
-                            self.next(i);
-                            if self.cur == 'f' {
-                                self.next(i);
-                                return Ok(TomlTok::Inf(is_neg));
-                            } else {
-                                return Err(self.err_parse("inf"));
-                            }
-                        } else {
-                            return Err(self.err_parse("nan"));
-                        }
-                    }
-                    while self.cur >= '0' && self.cur <= '9' || self.cur == '_' {
-                        if self.cur != '_' {
-                            num.push(self.cur);
-                        }
-                        self.next(i);
-                    }
-                    if self.cur == '.' {
-                        num.push(self.cur);
-                        self.next(i);
-                        while self.cur >= '0' && self.cur <= '9' || self.cur == '_' {
-                            if self.cur != '_' {
-                                num.push(self.cur);
-                            }
-                            self.next(i);
-                        }
-                        if let Ok(num) = num.parse() {
-                            return Ok(TomlTok::F64(num));
-                        } else {
-                            return Err(self.err_parse("number"));
-                        }
-                    } else if self.cur == '-' {
-                        // lets assume its a date. whatever. i don't feel like more parsing today
-                        num.push(self.cur);
-                        self.next(i);
-                        while self.cur >= '0' && self.cur <= '9'
-                            || self.cur == ':'
-                            || self.cur == '-'
-                            || self.cur == 'T'
-                        {
-                            num.push(self.cur);
-                            self.next(i);
-                        }
-                        return Ok(TomlTok::Date(num));
-                    } else {
-                        if is_neg {
-                            if let Ok(num) = num.parse() {
-                                return Ok(TomlTok::I64(num));
-                            } else {
-                                return Err(self.err_parse("number"));
-                            }
-                        }
-                        if let Ok(num) = num.parse() {
-                            return Ok(TomlTok::U64(num));
-                        } else {
-                            return Err(self.err_parse("number"));
-                        }
-                    }
-                }
-                'a'..='z' | 'A'..='Z' | '_' => {
-                    let mut ident = String::new();
-                    while self.cur >= 'a' && self.cur <= 'z'
-                        || self.cur >= 'A' && self.cur <= 'Z'
-                        || self.cur == '_'
-                        || self.cur == '-'
-                    {
-                        ident.push(self.cur);
-                        self.next(i);
-                    }
-                    if self.cur == '.' {
-                        while self.cur == '.' {
-                            self.next(i);
-                            while self.cur >= 'a' && self.cur <= 'z'
-                                || self.cur >= 'A' && self.cur <= 'Z'
-                                || self.cur == '_'
-                                || self.cur == '-'
-                            {
-                                ident.push(self.cur);
-                                self.next(i);
-                            }
-                        }
-                        return Ok(TomlTok::Ident(ident));
-                    }
-                    if ident == "true" {
-                        return Ok(TomlTok::Bool(true));
-                    }
-                    if ident == "false" {
-                        return Ok(TomlTok::Bool(false));
-                    }
-                    if ident == "inf" {
-                        return Ok(TomlTok::Inf(false));
-                    }
-                    if ident == "nan" {
-                        return Ok(TomlTok::Nan(false));
-                    }
-                    return Ok(TomlTok::Ident(ident));
-                }
                 '#' => {
                     while self.cur != '\n' && self.cur != '\0' {
                         self.next(i);
@@ -506,6 +464,7 @@ impl TomlParser {
                         self.next(i);
                     }
                 }
+                '+' | '-' | '0'..='9' => return self.parse_num(i),
                 '"' => {
                     let mut val = String::new();
                     self.next(i);
@@ -544,10 +503,131 @@ impl TomlParser {
                     self.next(i);
                     return Ok(TomlTok::Str(val));
                 }
-                _ => {
-                    return Err(self.err_parse("tokenizer"));
+                ident_chars!() => return self.parse_ident(i, String::new()),
+                _ => return Err(self.err_parse("tokenizer")),
+            }
+        }
+    }
+
+    /// Parse an ident or similar, starting with the current character.
+    fn parse_ident(&mut self, i: &mut Chars, mut start: String) -> Result<TomlTok, TomlErr> {
+        while matches!(self.cur, ident_chars!()) {
+            start.push(self.cur);
+            self.next(i);
+        }
+
+        if self.cur == '.' {
+            start.push(self.cur);
+            self.next(i);
+            return self.parse_ident(i, start); // recursion here could be a problem
+        }
+
+        if matches!(self.cur, ident_term_chars!()) {
+            return Ok(match start.as_ref() {
+                "true" => TomlTok::Bool(true),
+                "false" => TomlTok::Bool(false),
+                "inf" => TomlTok::Inf(false),
+                "nan" => TomlTok::Nan(false),
+                _ => TomlTok::Ident(start),
+            });
+        }
+
+        Err(self.err_parse("tokenizer"))
+    }
+
+    /// Parses a number (or an ident that starts with numbers), starting with the current character.
+    fn parse_num(&mut self, i: &mut Chars) -> Result<TomlTok, TomlErr> {
+        let mut num = String::new();
+
+        let mut negative = false;
+        if self.cur == '+' {
+            self.next(i)
+        } else if self.cur == '-' {
+            num.push(self.cur);
+            negative = true;
+            self.next(i);
+        }
+
+        if self.cur == 'n' {
+            num.push(self.cur);
+            self.next(i);
+            if self.cur == 'a' {
+                num.push(self.cur);
+                self.next(i);
+                if self.cur == 'n' {
+                    num.push(self.cur);
+                    self.next(i);
+                    if matches!(self.cur, ident_term_chars!()) {
+                        return Ok(TomlTok::Nan(negative));
+                    }
                 }
             }
+        } else if self.cur == 'i' {
+            num.push(self.cur);
+            self.next(i);
+            if self.cur == 'n' {
+                num.push(self.cur);
+                self.next(i);
+                if self.cur == 'f' {
+                    num.push(self.cur);
+                    self.next(i);
+                    if matches!(self.cur, ident_term_chars!()) {
+                        return Ok(TomlTok::Inf(negative));
+                    }
+                }
+            }
+        }
+
+        while matches!(self.cur, '0'..='9' | '_') {
+            if self.cur != '_' {
+                num.push(self.cur);
+            }
+            self.next(i);
+        }
+
+        if self.cur == '.' {
+            num.push(self.cur);
+            self.next(i);
+            while matches!(self.cur, '0'..='9' | '_') {
+                if self.cur != '_' {
+                    num.push(self.cur);
+                }
+                self.next(i);
+            }
+            if let Ok(num) = num.parse() {
+                return Ok(TomlTok::F64(num));
+            } else {
+                return Err(self.err_parse("number"));
+            }
+        } else if self.cur == '-' {
+            // lets assume its a date. whatever. i don't feel like more parsing today
+            num.push(self.cur);
+            self.next(i);
+            while matches!(self.cur, '0'..='9' | ':' | '-' | 'T') {
+                num.push(self.cur);
+                self.next(i);
+            }
+            return Ok(TomlTok::Date(num));
+            // TODO rework this
         }
+
+        if matches!(self.cur, ident_chars!()) {
+            return self.parse_ident(i, num);
+        }
+
+        match negative {
+            true => {
+                if let Ok(num) = num.parse() {
+                    return Ok(TomlTok::I64(num));
+                }
+            }
+            false => {
+                if let Ok(num) = num.parse() {
+                    return Ok(TomlTok::U64(num));
+                }
+            }
+        }
+
+        Err(self.err_parse("tokenizer"))
     }
 }


Test patch:
diff --git a/tests/toml.rs b/tests/toml.rs
index c89d919..4b1c821 100644
--- a/tests/toml.rs
+++ b/tests/toml.rs
@@ -1,3 +1,8 @@
+#[cfg(feature = "no_std")]
+use hashbrown::HashMap;
+#[cfg(not(feature = "no_std"))]
+use std::collections::HashMap;
+
 use nanoserde::Toml;
 use nanoserde::TomlParser;
 
@@ -84,3 +89,27 @@ fn assert_specific_toml_types() {
         ]
     );
 }
+
+#[test]
+fn toml_key_chars() {
+    let toml_str = r#"
+        [foo.bar.baz]
+        123abc456def = "myval"
+        -inf = 0
+        2024-04-30 = 100
+        ½ = 0.5
+    "#;
+
+    assert_eq!(
+        TomlParser::parse(toml_str).unwrap(),
+        HashMap::from([
+            (
+                "foo.bar.baz.123abc456def".to_string(),
+                Toml::Str("myval".to_string())
+            ),
+            ("foo.bar.baz.-inf".to_string(), Toml::Num(0.0)),
+            ("foo.bar.baz.2024-04-30".to_string(), Toml::Num(100.0)),
+            ("foo.bar.baz.½".to_string(), Toml::Num(0.5))
+        ])
+    );
+}