feat(trixy-lang_parser): Add support for doc comments

Parsing right now works by simply comparing the input string:
```
"/" -> <comment_tokenizer> -> "/" -> <normal_comment>
                          |-> "//" -> <doc_comment>
```

A better method to do this though would be to turn "//" and "///" into
keywords and simply leave the parsing to the parser module not the
tokenizer.

trixy/trixy-lang_parser/docs/grammar.ebnf

@@ -6,15 +6,27 @@
 #  - Block comments (`/* */`).
 # *)
 
-CommandSpec = { Function | Namespace | Enumeration | Structure } ;
+CommandSpec = {Function | Namespace | Enumeration | Structure } ;
-Function = "fn" Identifier "(" [NamedType {"," NamedType }] ")" [ "->" Type ] ";" ;
+
-Namespace = "nasp" Identifier "{" {Function | Namespace | Enumeration | Structure} "}" ;
+Function = {DocComment} "fn" Identifier "(" [NamedType {"," NamedType }] ")" [ "->" Type ] ";" ;
-Structure = "struct" Identifier "{"  [NamedType {"," NamedType } [","]] "}" ";";
+Namespace = {DocComment} "nasp" Identifier "{" {Function | Namespace | Enumeration | Structure} "}" ;
-Enumeration = "enum" Identifier "{"  [Identifier {"," Identifier} [","]] "}" ";";
+Structure = {DocComment} "struct" Identifier "{"  [DocNamedType {"," DocNamedType } [","]] "}" ";";
-Identifier = (CHARACTER | "_") { NUMBER | CHARACTER | "_" } ;
+Enumeration = {DocComment} "enum" Identifier "{"  [DocIdentifier {"," DocIdentifier} [","]] "}" ";";
-NamedType = Identifier ":" Type;
+
 Type = Identifier ["<" Type {"," Type} ">"];
 
+Identifier = (CHARACTER | "_") { NUMBER | CHARACTER | "_" } ;
+DocIdentifier = {DocComment} (CHARACTER | "_") { NUMBER | CHARACTER | "_" } ;
+
+NamedType = Identifier ":" Type;
+DocNamedType = {DocComment} Identifier ":" Type;
+
+
+DocComment = "///" {ANYTHING} LineEnding;
+
+Comment = "//" [ NOT ("/" {ANYTHING} LineEnding) | "//"] {ANYTHING} LineEnding;
+LineEnding = "\\n" | "\\r" | "\\r\\n";
+
 # (*
 #  vim: ft=ebnf
 # *)

trixy/trixy-lang_parser/example/comments.tri

@@ -0,0 +1,12 @@
+fn print(message: String);
+
+/// First doc comment
+// Some more text
+nasp trinitrix {
+    /// Second doc comment
+    fn hi(name: String) -> String;
+}
+
+
+// That's a flat out lie, but it results in a rather nice syntax highlight compared to nothing:
+// vim: syntax=rust

trixy/trixy-lang_parser/example/failing_comments.tri

@@ -0,0 +1,13 @@
+fn print(message: CommandTransferValue);
+
+/// Some doc comment
+// Some more text
+nasp trinitrix {
+    fn hi(name: String) -> String;
+}
+
+/// Trailing doc comment (I will fail)
+
+
+// That's a flat out lie, but it results in a rather nice syntax highlight compared to nothing:
+// vim: syntax=rust

trixy/trixy-lang_parser/generate_docs

@@ -2,8 +2,8 @@
 
 
 
-ebnf2pdf "./docs/grammar.ebnf"
+ebnf2pdf make "./docs/grammar.ebnf"
-mv out.pdf ./docs/grammar.pdf
+mv grammar.ebnf.pdf ./docs/grammar.pdf
 
 
 # vim: ft=sh

trixy/trixy-lang_parser/src/command_spec/checked.rs

@@ -4,6 +4,8 @@ use std::fmt::Display;
 
 use crate::lexing::TokenKind;
 
+use super::unchecked;
+
 /// These are the "primitive" types used in trixy, you can use any of them to create new structures
 pub const BASE_TYPES: [ConstIdentifier; 8] = [
     Identifier::from("Integer"),
@@ -24,6 +26,7 @@ pub struct Namespace {
     pub structures: Vec<Structure>,
     pub enumerations: Vec<Enumeration>,
     pub namespaces: Vec<Namespace>,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -48,13 +51,15 @@ impl From<Namespace> for CommandSpec {
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Structure {
     pub identifier: Identifier,
-    pub contents: Vec<NamedType>,
+    pub contents: Vec<DocNamedType>,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Enumeration {
     pub identifier: Identifier,
-    pub states: Vec<Identifier>,
+    pub states: Vec<DocIdentifier>,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -62,6 +67,7 @@ pub struct Function {
     pub identifier: Identifier,
     pub inputs: Vec<NamedType>,
     pub output: Option<Type>,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -76,6 +82,13 @@ pub struct NamedType {
     pub r#type: Type,
 }
 
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct DocNamedType {
+    pub name: Identifier,
+    pub r#type: Type,
+    pub attributes: Vec<Attribute>,
+}
+
 impl From<TokenKind> for Identifier {
     fn from(value: TokenKind) -> Self {
         match value {
@@ -92,6 +105,19 @@ impl From<TokenKind> for Identifier {
     }
 }
 
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub enum Attribute {
+    #[allow(non_camel_case_types)]
+    doc(String),
+}
+impl From<unchecked::Attribute> for Attribute {
+    fn from(value: unchecked::Attribute) -> Self {
+        match value {
+            unchecked::Attribute::doc { content: name, .. } => Self::doc(name),
+        }
+    }
+}
+
 /// An Identifier
 /// These include
 ///     - Variable names
@@ -103,6 +129,12 @@ pub struct Identifier {
     pub name: String,
 }
 
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub struct DocIdentifier {
+    pub name: String,
+    pub attributes: Vec<Attribute>,
+}
+
 /// A const version of [Identifier]
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct ConstIdentifier {

trixy/trixy-lang_parser/src/command_spec/unchecked.rs

@@ -4,7 +4,7 @@
 
 use std::fmt::{Display, Write};
 
-use crate::lexing::Token;
+use crate::lexing::{Token, TokenSpan};
 
 #[derive(Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
 pub struct CommandSpec {
@@ -22,6 +22,7 @@ impl From<CommandSpec> for Namespace {
             structures: value.structures,
             enumerations: value.enumerations,
             namespaces: value.namespaces,
+            attributes: vec![],
         }
     }
 }
@@ -34,6 +35,8 @@ pub struct Namespace {
     pub structures: Vec<Structure>,
     pub enumerations: Vec<Enumeration>,
     pub namespaces: Vec<Namespace>,
+
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
@@ -44,23 +47,45 @@ pub enum Declaration {
     Namespace(Namespace),
 }
 
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub enum Attribute {
+    #[allow(non_camel_case_types)]
+    doc{content: String, span: TokenSpan},
+}
+
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
 pub struct Function {
     pub identifier: Token, // Will later become an Identifier
     pub inputs: Vec<NamedType>,
     pub output: Option<Type>,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
 pub struct Structure {
     pub identifier: Token, // Will later become an Identifier
-    pub contents: Vec<NamedType>,
+    pub contents: Vec<DocNamedType>,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
 pub struct Enumeration {
     pub identifier: Token,     // Will later become an Identifier
-    pub states: Vec<Token>, // Will later become an Identifier
+    pub states: Vec<DocToken>, // Will later become an Identifier
+    pub attributes: Vec<Attribute>,
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub struct DocToken {
+    pub token: Token,
+    pub attributes: Vec<Attribute>,
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
+pub struct DocNamedType {
+    pub name: Token, // Will later become an Identifier
+    pub r#type: Type,
+    pub attributes: Vec<Attribute>,
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]

trixy/trixy-lang_parser/src/error.rs

@@ -55,7 +55,7 @@ impl ErrorContext {
         };
 
         let line_above;
-        if line_number == 0 {
+        if line_number == 1 {
             // We only have one line, so no line above
             line_above = "".to_owned();
         } else {

trixy/trixy-lang_parser/src/lexing/error.rs

@@ -13,10 +13,12 @@ pub enum LexingError {
     UnknownCharacter(char),
     #[error("The Arrow token must be of the form: ->")]
     ExpectedArrow,
+    #[error("The Comment token must start with two slashes")]
+    ExpectedComment,
 }
 
 impl AdditionalHelp for LexingError {
-    fn additional_help(& self) -> String {
+    fn additional_help(&self) -> String {
         let out = match self {
                 LexingError::NoMatchesTaken => "This token does not produce a possible match".to_owned(),
                 LexingError::UnexpectedEOF => "This eof was completely unexpected".to_owned(),
@@ -24,6 +26,7 @@ impl AdditionalHelp for LexingError {
                 LexingError::UnknownCharacter(char) => {
                     format!("This char: `{char}`; is not a valid token")
                 },
+            LexingError::ExpectedComment => "The '/' started comment parsing, but I could not find a matching '/'".to_owned(),
             };
         out
     }

trixy/trixy-lang_parser/src/lexing/mod.rs

@@ -28,6 +28,18 @@ impl TokenStream {
             tokens.push(tok);
         }
 
+        // filter out comments
+        let tokens = tokens
+            .into_iter()
+            .filter(|token| {
+                if let TokenKind::Comment(_) = token.kind {
+                    false
+                } else {
+                    true
+                }
+            })
+            .collect();
+
         Ok(Self {
             tokens,
             original_file: src.to_owned(),
@@ -40,8 +52,8 @@ impl TokenStream {
     }
 
     /// Get a reference to the uppermost token, without modifying the token list
-    pub fn peek(&self) -> &Token {
+    pub fn peek(&self) -> Option<&Token> {
-        self.tokens.last().expect("This should not be emtpy")
+        self.tokens.last()
     }
 
     /// Remove to the uppermost token
@@ -80,6 +92,15 @@ pub struct TokenSpan {
     pub end: usize,
 }
 
+impl TokenSpan {
+    pub fn from_range(start: TokenSpan, end: TokenSpan) -> Self {
+        Self {
+            start: start.start,
+            end: end.end,
+        }
+    }
+}
+
 /// A Token
 #[derive(Debug, Default, PartialEq, PartialOrd, Ord, Eq, Clone)]
 pub struct Token {
@@ -123,6 +144,10 @@ pub enum TokenKind {
     ParenClose,
     SquareOpen,
     SquareClose,
+
+    DocComment(String),
+    Comment(String),
+
     /// This is not a real TokenKind, but only used for error handling
     #[default]
     Dummy,
@@ -135,6 +160,16 @@ impl TokenKind {
                 return true;
             }
         }
+        if let TokenKind::Comment(_) = self {
+            if let TokenKind::Comment(_) = other {
+                return true;
+            }
+        }
+        if let TokenKind::DocComment(_) = self {
+            if let TokenKind::DocComment(_) = other {
+                return true;
+            }
+        }
         self == other
     }
 }
@@ -161,6 +196,8 @@ impl Display for TokenKind {
             TokenKind::Dummy => f.write_str("DUMMY"),
             TokenKind::SquareOpen => f.write_str("SQUAREOPEN"),
             TokenKind::SquareClose => f.write_str("SQUARECLOSE"),
+            TokenKind::DocComment(text) => write!(f, "DOCCOMMENT({})", text),
+            TokenKind::Comment(text) => write!(f, "COMMENT({})", text),
         }
     }
 }
@@ -234,10 +271,13 @@ macro_rules! token {
     [struct] => { $crate::lexing::TokenKind::Keyword($crate::lexing::Keyword::r#struct) };
     [enum] => { $crate::lexing::TokenKind::Keyword($crate::lexing::Keyword::r#enum) };
 
-    // This is only works for checking for a identifier
+    // This is only works for checking for a identifier or comment
     // see the `same_kind` method on TokenKind
     [Ident] => { $crate::lexing::TokenKind::Identifier("".to_owned()) };
     [Identifier] => { $crate::lexing::TokenKind::Identifier("".to_owned()) };
+    [DocComment] => { $crate::lexing::TokenKind::DocComment("".to_owned()) };
+    [DocCommentMatch] => { $crate::lexing::TokenKind::DocComment(_doc_comment) };
+    [Comment] => { $crate::lexing::TokenKind::Comment("".to_owned()) };
 }
 
 #[cfg(test)]

trixy/trixy-lang_parser/src/lexing/tokenizer.rs

@@ -62,7 +62,9 @@ impl<'a> Tokenizer<'a> {
             ',' => (TokenKind::Comma, 1),
             '<' => (TokenKind::SquareOpen, 1),
             '>' => (TokenKind::SquareClose, 1),
+
             '-' => tokenize_arrow(self.remaining_text)?,
+            '/' => tokenize_comment(self.remaining_text)?,
 
             // can't use a OR (`|`) here, as the guard takes precedence
             c if c.is_alphabetic() => tokenize_ident(self.remaining_text)?,
@@ -74,17 +76,17 @@ impl<'a> Tokenizer<'a> {
         Ok((tok, length))
     }
 
-    /// Skip past any whitespace characters or comments.
     fn skip_ignored_tokens(&mut self) {
         loop {
             let ws = self.skip_whitespace();
-            let comments = self.skip_comments();
+            let comments = self.skip_block_comment();
-
             if ws + comments == 0 {
                 return;
             }
         }
     }
+
+    /// Skip past any whitespace characters
     fn skip_whitespace(&mut self) -> usize {
         let mut remaining = self.remaining_text;
 
@@ -102,21 +104,21 @@ impl<'a> Tokenizer<'a> {
         self.chomp(skip);
         skip
     }
+    fn skip_block_comment(&mut self) -> usize {
+        let pairs = [("/*", "*/")];
 
-    fn skip_comments(&mut self) -> usize {
+        let src = self.remaining_text;
-        let remaining = self.remaining_text;
-        let pairs = [("//", "\n"), ("/*", "*/")];
 
-        let mut skip = 0;
         for &(pattern, matcher) in &pairs {
-            if remaining.starts_with(pattern) {
+            if src.starts_with(pattern) {
-                let leftovers = skip_until(remaining, matcher);
+                let leftovers = skip_until(src, matcher);
-                skip = remaining.len() - leftovers.len();
+                let skip = src.len() - leftovers.len();
-                break;
-            }
-        }
                 self.chomp(skip);
-        skip
+                return skip;
+            }
+        }
+
+        0
     }
 
     fn chomp(&mut self, chars_to_chomp: usize) {
@@ -125,6 +127,36 @@ impl<'a> Tokenizer<'a> {
     }
 }
 
+fn tokenize_comment(text: &str) -> Result<(TokenKind, usize), LexingError> {
+    // every token starts with two slashes
+    let slashes: &str = &text[..2];
+    if slashes != "//" {
+        Err(LexingError::ExpectedComment)
+    } else {
+        let text: &str = &text[2..];
+        if let Some('/') = text.chars().next() {
+            let text = &text[1..];
+            let (doc_comment, chars_read) = take_while(text, |ch| ch != '\n' && ch != '\r')?;
+
+            // trim whitespace
+            let doc_comment = doc_comment.trim_start();
+            let doc_comment = doc_comment.trim_end();
+
+            return Ok((
+                TokenKind::DocComment(doc_comment.to_owned()),
+                chars_read + 3,
+            ));
+        }
+        let (comment, chars_read) = take_while(text, |ch| ch != '\n' && ch != '\r')?;
+
+        // trim whitespace
+        let comment = comment.trim_start();
+        let comment = comment.trim_end();
+
+        return Ok((TokenKind::Comment(comment.to_owned()), chars_read + 2));
+    }
+}
+
 fn tokenize_ident(text: &str) -> Result<(TokenKind, usize), LexingError> {
     let (got, chars_read) = take_while(text, |ch| ch == '_' || ch.is_alphanumeric())?;
 

trixy/trixy-lang_parser/src/parsing/checked/mod.rs

@@ -3,14 +3,14 @@ use std::mem;
 use crate::{
     command_spec::{
         checked::{
-            CommandSpec, Enumeration, Function, Identifier, NamedType, Namespace, Structure, Type,
+            CommandSpec, DocIdentifier, DocNamedType, Enumeration, Function, Identifier, NamedType,
-            BASE_TYPES,
+            Namespace, Structure, Type, BASE_TYPES,
         },
         unchecked::{
-            CommandSpec as UncheckedCommandSpec, Enumeration as UncheckedEnumeration,
+            CommandSpec as UncheckedCommandSpec, DocNamedType as UncheckedDocNamedType,
-            Function as UncheckedFunction, NamedType as UncheckedNamedType,
+            Enumeration as UncheckedEnumeration, Function as UncheckedFunction,
-            Namespace as UncheckedNamespace, Structure as UncheckedStructure,
+            NamedType as UncheckedNamedType, Namespace as UncheckedNamespace,
-            Type as UncheckedType,
+            Structure as UncheckedStructure, Type as UncheckedType,
         },
     },
     error::ErrorContext,
@@ -66,6 +66,12 @@ impl UncheckedCommandSpec {
     }
 }
 
+macro_rules! pass_attrs_along {
+    ($name:ident) => {
+        $name.attributes.into_iter().map(|a| a.into()).collect()
+    };
+}
+
 impl Parser {
     fn parse(mut self) -> Result<CommandSpec, SpannedParsingError> {
         let namespace: UncheckedNamespace =
@@ -129,6 +135,7 @@ impl Parser {
             structures,
             enumerations,
             namespaces,
+            attributes: pass_attrs_along!(namespace),
         })
     }
 
@@ -151,6 +158,7 @@ impl Parser {
             identifier,
             inputs,
             output,
+            attributes: pass_attrs_along!(function),
         })
     }
 
@@ -164,10 +172,20 @@ impl Parser {
 
         let mut states = vec![];
         for mut state in enumeration.states {
-            states.push(mem::take(&mut state.kind).into())
+            states.push({
+                let ident: Identifier = mem::take(&mut state.token.kind).into();
+                DocIdentifier {
+                    name: ident.name,
+                    attributes: pass_attrs_along!(state),
+                }
+            })
         }
 
-        Ok(Enumeration { identifier, states })
+        Ok(Enumeration {
+            identifier,
+            states,
+            attributes: pass_attrs_along!(enumeration),
+        })
     }
 
     fn process_structure(
@@ -179,12 +197,13 @@ impl Parser {
         let identifier: Identifier = mem::take(&mut structure.identifier.kind).into();
         let mut contents = vec![];
         for named_type in structure.contents {
-            contents.push(self.process_named_type(named_type)?);
+            contents.push(self.process_doc_named_type(named_type)?);
         }
 
         Ok(Structure {
             identifier,
             contents,
+            attributes: pass_attrs_along!(structure),
         })
     }
 
@@ -196,6 +215,18 @@ impl Parser {
         let r#type: Type = self.process_type(named_type.r#type)?;
         Ok(NamedType { name, r#type })
     }
+    fn process_doc_named_type(
+        &mut self,
+        mut doc_named_type: UncheckedDocNamedType,
+    ) -> Result<DocNamedType, ParsingError> {
+        let name: Identifier = mem::take(&mut doc_named_type.name.kind).into();
+        let r#type: Type = self.process_type(doc_named_type.r#type)?;
+        Ok(DocNamedType {
+            name,
+            r#type,
+            attributes: pass_attrs_along!(doc_named_type),
+        })
+    }
 
     fn process_type(&mut self, mut r#type: UncheckedType) -> Result<Type, ParsingError> {
         let identifier: Identifier = mem::take(&mut r#type.identifier.kind).into();

trixy/trixy-lang_parser/src/parsing/checked/test.rs

@@ -1,8 +1,11 @@
 use crate::command_spec::checked::{
-    CommandSpec, Enumeration, Function, Identifier, NamedType, Namespace, Structure, Type,
+    Attribute, CommandSpec, DocIdentifier, DocNamedType, Enumeration, Function, Identifier,
+    NamedType, Namespace, Structure, Type,
 };
 use crate::lexing::TokenStream;
 
+use pretty_assertions::assert_eq;
+
 #[test]
 fn test_full() {
     let input = "nasp trinitrix {
@@ -57,13 +60,14 @@ fn test_full() {
                     },
                 ],
                 output: None,
+                attributes: vec![],
             }],
             structures: vec![Structure {
                 identifier: Identifier {
                     name: "Callback".to_owned(),
                 },
                 contents: vec![
-                    NamedType {
+                    DocNamedType {
                         name: Identifier {
                             name: "func".to_owned(),
                         },
@@ -73,8 +77,9 @@ fn test_full() {
                             },
                             generic_args: vec![],
                         },
+                        attributes: vec![],
                     },
-                    NamedType {
+                    DocNamedType {
                         name: Identifier {
                             name: "timeout".to_owned(),
                         },
@@ -84,26 +89,33 @@ fn test_full() {
                             },
                             generic_args: vec![],
                         },
+                        attributes: vec![],
                     },
                 ],
+                attributes: vec![],
             }],
             enumerations: vec![Enumeration {
                 identifier: Identifier {
                     name: "CallbackPriority".to_owned(),
                 },
                 states: vec![
-                    Identifier {
+                    DocIdentifier {
                         name: "High".to_owned(),
+                        attributes: vec![],
                     },
-                    Identifier {
+                    DocIdentifier {
                         name: "Medium".to_owned(),
+                        attributes: vec![],
                     },
-                    Identifier {
+                    DocIdentifier {
                         name: "Low".to_owned(),
+                        attributes: vec![],
                     },
                 ],
+                attributes: vec![],
             }],
             namespaces: vec![],
+            attributes: vec![],
         }],
     };
     assert_eq!(output, expected);
@@ -132,3 +144,72 @@ fn execute_callback(callback: Name);
         _ => panic!("Wrong error in test!"),
     };
 }
+
+#[test]
+fn test_comments() {
+    let input = "fn print(message: String);
+
+/// First doc comment
+// Some more text
+nasp trinitrix {
+    /// Second doc comment
+    fn hi(name: String) -> String;
+}
+";
+    let output = TokenStream::lex(&input).unwrap().parse().unwrap();
+    let expected = CommandSpec {
+        structures: vec![],
+        enumerations: vec![],
+        functions: vec![Function {
+            identifier: Identifier {
+                name: "print".to_owned(),
+            },
+            inputs: vec![NamedType {
+                name: Identifier {
+                    name: "message".to_owned(),
+                },
+                r#type: Type {
+                    identifier: Identifier {
+                        name: "String".to_owned(),
+                    },
+                    generic_args: vec![],
+                },
+            }],
+            output: None,
+            attributes: vec![],
+        }],
+        namespaces: vec![Namespace {
+            name: Identifier {
+                name: "trinitrix".to_owned(),
+            },
+            functions: vec![Function {
+                identifier: Identifier {
+                    name: "hi".to_owned(),
+                },
+                inputs: vec![NamedType {
+                    name: Identifier {
+                        name: "name".to_owned(),
+                    },
+                    r#type: Type {
+                        identifier: Identifier {
+                            name: "String".to_owned(),
+                        },
+                        generic_args: vec![],
+                    },
+                }],
+                output: Some(Type {
+                    identifier: Identifier {
+                        name: "String".to_owned(),
+                    },
+                    generic_args: vec![],
+                }),
+                attributes: vec![Attribute::doc("Second doc comment".to_owned())],
+            }],
+            structures: vec![],
+            enumerations: vec![],
+            namespaces: vec![],
+            attributes: vec![Attribute::doc("First doc comment".to_owned())],
+        }],
+    };
+    assert_eq!(output, expected);
+}

trixy/trixy-lang_parser/src/parsing/unchecked/error.rs

@@ -2,37 +2,47 @@ use std::{error::Error, fmt::Display};
 use thiserror::Error;
 
 use crate::{
+    command_spec::unchecked::Attribute,
     error::{AdditionalHelp, ErrorContext, ErrorContextDisplay},
     lexing::{TokenKind, TokenSpan},
 };
 
 #[derive(Error, Debug, Clone)]
 pub enum ParsingError {
-    #[error("Expected '{expected}' but received '{actual}'")]
+    #[error("Expected '{expected}', but received: '{actual}'")]
     ExpectedDifferentToken {
         expected: TokenKind,
         actual: TokenKind,
         span: TokenSpan,
     },
 
+    #[error("Expected '{expected}', but the token stream stopped")]
+    UnexpectedEOF {
+        expected: TokenKind,
+        span: TokenSpan,
+    },
+
     #[error("Expected a Keyword to start a new declaration, but found: '{actual}'")]
     ExpectedKeyword { actual: TokenKind, span: TokenSpan },
+
+    #[error("DocComment does not have target")]
+    TrailingDocComment {
+        comments: Vec<Attribute>,
+        span: TokenSpan,
+    },
 }
 impl ParsingError {
     pub fn span(&self) -> &TokenSpan {
         match self {
             ParsingError::ExpectedDifferentToken { span, .. } => span,
             ParsingError::ExpectedKeyword { span, .. } => span,
+            ParsingError::TrailingDocComment { span, .. } => span,
+            ParsingError::UnexpectedEOF { span, .. } => span,
         }
     }
-}
 
-impl ParsingError {
     pub fn get_span(&self) -> TokenSpan {
-        match self {
+        *self.span()
-            ParsingError::ExpectedDifferentToken { span, .. } => *span,
-            ParsingError::ExpectedKeyword { span, .. } => *span,
-        }
     }
 }
 
@@ -50,6 +60,8 @@ impl AdditionalHelp for ParsingError {
             ParsingError::ExpectedKeyword { actual, .. } => format!(
             "I expected a keyword (that is something like 'fn' or 'nasp') but you put a '{}' there!",
             actual),
+            ParsingError::TrailingDocComment { .. } => "I expected some target (a function, namespace, enum, or something like this) which this doc comment annotates, but you put nothing there".to_owned(),
+            ParsingError::UnexpectedEOF { expected, .. } => format!("Put the expected token ('{expected}') here."),
         }
     }
 }

trixy/trixy-lang_parser/src/parsing/unchecked/mod.rs

@@ -1,9 +1,12 @@
+use std::mem;
+
 use crate::{
     command_spec::unchecked::{
-        CommandSpec, Declaration, Enumeration, Function, NamedType, Namespace, Structure, Type,
+        Attribute, CommandSpec, Declaration, DocNamedType, DocToken, Enumeration, Function,
+        NamedType, Namespace, Structure, Type,
     },
     error::ErrorContext,
-    lexing::{Token, TokenKind, TokenStream},
+    lexing::{Token, TokenKind, TokenSpan, TokenStream},
     token,
 };
 
@@ -22,12 +25,18 @@ impl TokenStream {
 
 pub(super) struct Parser {
     token_stream: TokenStream,
+    active_doc_comments: Vec<Attribute>,
+    last_span: TokenSpan,
 }
 
 impl Parser {
     fn new(mut token_stream: TokenStream) -> Self {
         token_stream.reverse();
-        Self { token_stream }
+        Self {
+            token_stream,
+            active_doc_comments: vec![],
+            last_span: TokenSpan::default(),
+        }
     }
 
     fn parse(&mut self) -> Result<CommandSpec, SpannedParsingError> {
@@ -52,15 +61,55 @@ impl Parser {
     }
 
     fn parse_next(&mut self) -> Result<Declaration, ParsingError> {
-        match self.peek().kind() {
+        // Use of [peek_raw] here is fine, as we know that the function is only called, when
+        // something should still be contained in the token stream
+        match self.peek_raw().kind() {
             token![nasp] => Ok(Declaration::Namespace(self.parse_namespace()?)),
             token![fn] => Ok(Declaration::Function(self.parse_function()?)),
             token![struct] => Ok(Declaration::Structure(self.parse_structure()?)),
             token![enum] => Ok(Declaration::Enumeration(self.parse_enumeration()?)),
+            token![DocCommentMatch] => {
+                while self.expect_peek(token![DocComment]) {
+                    let comment_to_push = {
+                        let doc_comment = self.expect(token![DocComment])?;
+                        let span = *doc_comment.span();
+                        let name = if let TokenKind::DocComment(content) = doc_comment.kind {
+                            content
+                        } else {
+                            unreachable!("The expect should have accounted for that case");
+                        };
+
+                        Attribute::doc {
+                            content: name,
+                            span,
+                        }
+                    };
+                    self.active_doc_comments.push(comment_to_push);
+                }
+
+                if self.token_stream.is_empty() {
+                    fn get_span(attr: Option<&Attribute>) -> TokenSpan {
+                        match attr.expect("Something should be here") {
+                            Attribute::doc { span, .. } => *span,
+                        }
+                    }
+
+                    let span = TokenSpan::from_range(
+                        get_span(self.active_doc_comments.first()),
+                        get_span(self.active_doc_comments.last()),
+                    );
+                    Err(ParsingError::TrailingDocComment {
+                        comments: mem::take(&mut self.active_doc_comments),
+                        span,
+                    })
+                } else {
+                    self.parse_next()
+                }
+            }
             _ => {
                 let err = ParsingError::ExpectedKeyword {
-                    span: *self.peek().span(),
+                    span: *self.peek_raw().span(),
-                    actual: self.peek().kind().clone(),
+                    actual: self.peek_raw().kind().clone(),
                 };
 
                 return Err(err);
@@ -88,11 +137,34 @@ impl Parser {
         })
     }
 
+    fn parse_doc_comments(&mut self) -> Result<Vec<Attribute>, ParsingError> {
+        let mut attrs = mem::take(&mut self.active_doc_comments);
+
+        while self.expect_peek(token![DocComment]) {
+            attrs.push({
+                let doc_comment = self.expect(token![DocComment])?;
+                let span = *doc_comment.span();
+                let name = if let TokenKind::DocComment(content) = doc_comment.kind {
+                    content
+                } else {
+                    unreachable!("The expect should have accounted for that case");
+                };
+                Attribute::doc {
+                    content: name,
+                    span,
+                }
+            });
+        }
+        Ok(attrs)
+    }
+
     fn parse_namespace(&mut self) -> Result<Namespace, ParsingError> {
+        let attributes = self.parse_doc_comments()?;
         self.expect(token![nasp])?;
 
         let mut namespace = Namespace::default();
         namespace.name = self.expect(token![Ident])?;
+        namespace.attributes = attributes;
 
         self.expect(token![BraceOpen])?;
 
@@ -113,40 +185,54 @@ impl Parser {
     }
 
     fn parse_enumeration(&mut self) -> Result<Enumeration, ParsingError> {
+        let attributes = self.parse_doc_comments()?;
         self.expect(token![enum])?;
         let identifier = self.expect(token![Ident])?;
         self.expect(token![BraceOpen])?;
 
         let mut states = vec![];
         if self.expect_peek(token![Ident]) {
-            states.push(self.expect(token![Ident])?);
+            let attributes = self.parse_doc_comments()?;
+            states.push(DocToken {
+                token: self.expect(token![Ident])?,
+                attributes,
+            });
         }
         while self.expect_peek(token![Comma]) {
             self.expect(token![Comma])?;
             if self.expect_peek(token![Ident]) {
-                states.push(self.expect(token![Ident])?);
+                let attributes = self.parse_doc_comments()?;
+                states.push(DocToken {
+                    token: self.expect(token![Ident])?,
+                    attributes,
+                });
             } else {
                 break;
             }
         }
         self.expect(token![BraceClose])?;
         self.expect(token![;])?;
-        Ok(Enumeration { identifier, states })
+        Ok(Enumeration {
+            identifier,
+            states,
+            attributes,
+        })
     }
 
     fn parse_structure(&mut self) -> Result<Structure, ParsingError> {
+        let attributes = self.parse_doc_comments()?;
         self.expect(token![struct])?;
         let name = self.expect(token![Ident])?;
         self.expect(token![BraceOpen])?;
 
         let mut contents = vec![];
         if self.expect_peek(token![Ident]) {
-            contents.push(self.parse_named_type()?);
+            contents.push(self.parse_doc_named_type()?);
         }
         while self.expect_peek(token![Comma]) {
             self.expect(token![Comma])?;
             if self.expect_peek(token![Ident]) {
-                contents.push(self.parse_named_type()?);
+                contents.push(self.parse_doc_named_type()?);
             } else {
                 break;
             }
@@ -157,6 +243,7 @@ impl Parser {
         Ok(Structure {
             identifier: name,
             contents,
+            attributes,
         })
     }
 
@@ -167,7 +254,20 @@ impl Parser {
         Ok(NamedType { name, r#type })
     }
 
+    fn parse_doc_named_type(&mut self) -> Result<DocNamedType, ParsingError> {
+        let attributes = self.parse_doc_comments()?;
+        let name = self.expect(token![Ident])?;
+        self.expect(token![Colon])?;
+        let r#type = self.parse_type()?;
+        Ok(DocNamedType {
+            name,
+            r#type,
+            attributes,
+        })
+    }
+
     fn parse_function(&mut self) -> Result<Function, ParsingError> {
+        let attributes = self.parse_doc_comments()?;
         self.expect(token![fn])?;
         let name = self.expect(token![Ident])?;
         self.expect(token![ParenOpen])?;
@@ -192,6 +292,7 @@ impl Parser {
             identifier: name,
             inputs,
             output: output_type,
+            attributes,
         })
     }
 
@@ -216,7 +317,14 @@ impl Parser {
     /// ```
     ///
     pub(super) fn expect(&mut self, token: TokenKind) -> Result<Token, ParsingError> {
-        let actual_token = self.peek();
+        let actual_token = if let Some(token) = self.peek() {
+            token
+        } else {
+            return Err(ParsingError::UnexpectedEOF {
+                expected: token,
+                span: self.last_span,
+            });
+        };
         if actual_token.kind().same_kind(&token) {
             Ok(self.pop())
         } else {
@@ -233,7 +341,10 @@ impl Parser {
     /// Check if the next token is of the specified TokenKind.
     /// Does not alter the token_stream
     fn expect_peek(&self, token: TokenKind) -> bool {
-        let actual_token = self.peek();
+        let actual_token = match self.peek() {
+            Some(ok) => ok,
+            None => return false,
+        };
         if actual_token.kind().same_kind(&token) {
             true
         } else {
@@ -242,12 +353,22 @@ impl Parser {
     }
 
     /// Looks at the next token without removing it
-    fn peek(&self) -> &Token {
+    fn peek(&self) -> Option<&Token> {
         self.token_stream.peek()
     }
 
+    /// Looks at the next token without removing it.
+    /// Unwraps the option returned from [peek], only use it, if you know that a token must exist
+    fn peek_raw(&self) -> &Token {
+        self.token_stream.peek().expect("The token should exist")
+    }
+
     /// Removes the next token
     fn pop(&mut self) -> Token {
+        self.last_span = *self
+            .peek()
+            .expect("Calling pop should mean, that a token was first peeked for")
+            .span();
         self.token_stream.pop()
     }
 }

trixy/trixy-lang_parser/src/parsing/unchecked/test.rs

@@ -20,8 +20,8 @@ nasp trinitrix { {}
     let parsed = TokenStream::lex(input).unwrap().parse_unchecked();
     let err = parsed.unwrap_err().source;
     match err {
-        ParsingError::ExpectedDifferentToken { .. } => panic!("Wrong error"),
         ParsingError::ExpectedKeyword { .. } => {}
+        _ => panic!("Wrong error"),
     }
 }
 
@@ -56,6 +56,7 @@ nasp trinitrix {
                 },
             }],
             output: None,
+            attributes: vec![],
         }],
         namespaces: vec![Namespace {
             name: Token {
@@ -87,10 +88,12 @@ nasp trinitrix {
                     },
                     generic_args: vec![],
                 }),
+                attributes: vec![],
             }],
             structures: vec![],
             enumerations: vec![],
             namespaces: vec![],
+            attributes: vec![],
         }],
     };