normal syntax tree i guess

programs/aidl/Cargo.toml

@@ -6,4 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-logos = "0.13.0"
+logos = "0"
+thiserror = "1"

programs/aidl/assets/core.idl

@@ -11,8 +11,6 @@ Union Option<T>{
     Some<T>
 }
 
-
-
 Structure Version {
     major: Byte,
     minor: Byte,

programs/aidl/assets/vfs.idl

@@ -1,3 +1,4 @@
+// core provides lots of useful types like String and Byte
 Use core;
 
 Constant VERSION Version {
@@ -6,7 +7,7 @@ Constant VERSION Version{
     patch: 0,
 }
 
-Type Path = String;
+Alias Path = String;
 
 Structure File {
     name: String, 

programs/aidl/assets/why.idl

@@ -0,0 +1,3 @@
+Use core;
+
+Alias Thing = Byte;

programs/aidl/src/ast.rs

@@ -10,34 +10,67 @@ pub struct IDLModule {
     // why: only allow use before other items
     // parser will error if use is present in any other place
     pub uses: Vec<UseDecl>,
-    pub items: Vec<Item>
+    pub items: Vec<Item>,
 }
 
 #[derive(Debug)]
 pub enum Item {
     Interface(ItemInterface),
-    Type(ItemType)
+    Type(ItemAlias),
+    Constant(ItemConstant),
 }
 
 #[derive(Debug)]
 pub struct Function {
     pub name: String,
-
 }
 
 #[derive(Debug)]
 pub struct ItemInterface {
     pub name: String,
-    pub functions: Vec<Function>
+    pub functions: Vec<Function>,
 }
 
 #[derive(Debug)]
-pub struct ItemType {
+pub struct ItemAlias {
+    pub name: String,
+    pub referree: String,
+}
+
+#[derive(Debug)]
+pub struct ItemConstant {
     pub name: String,
-    pub referree: String
 }
 
 #[derive(Debug)]
 pub struct UseDecl {
-    pub module: String
+    pub module: String,
+}
+
+#[derive(Debug)]
+pub enum Expr {
+    Literal(Literal),
+}
+
+#[derive(Debug)]
+pub enum Literal {
+    String(String),
+    Number(NumberLiteral),
+}
+
+#[derive(Debug)]
+pub enum NumberLiteral {
+    Ptr(usize),
+
+    U8(u8),
+    I8(i8),
+
+    U16(u16),
+    I16(i16),
+
+    U32(u32),
+    I32(i32),
+
+    U64(u64),
+    I64(i64),
 }

programs/aidl/src/lexer.rs

@@ -1,4 +1,4 @@
-use std::ops::{Range, Add};
+use std::{ops::{Range, Add}, fmt::Display};
 
 use logos::Logos;
 
@@ -35,9 +35,6 @@ pub enum Token {
     #[token("=")]
     Equals,
 
-    //#[regex(r#"[A-z]+"#, |lex| lex.slice().parse().ok())]
-    //Literal(String),
-
     #[regex(r#"[A-z]+"#, |lex| Ident::lexer(lex.slice()).next().and_then(Result::ok))]
     Ident(Ident),
 
@@ -64,8 +61,8 @@ pub enum Ident {
     Constant,
     #[token("Structure")]
     Structure,
-    #[token("Type")]
-    Type,
+    #[token("Alias")]
+    Alias,
     #[token("Use")]
     Use,
     #[regex(r"[A-z]+", |lex| lex.slice().parse().ok())]
@@ -90,6 +87,11 @@ impl Span {
         Self(min(self.lower(), other.lower())..max(self.upper(), other.upper()))
     }
 }
+impl Display for Span {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}..{}", self.lower(), self.upper())
+    }
+}
 impl Add for Span {
     type Output = Self;
 
@@ -109,3 +111,9 @@ impl<T> Spanned<T> {
         Spanned(f(self.0), self.1)
     }
 }
+
+impl<T: Display> Display for Spanned<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} @ {}", self.0, self.1)
+    }
+}

programs/aidl/src/main.rs

@@ -1,18 +1,19 @@
 #![allow(non_snake_case)]
 
-use logos::Logos;
 use parser::Parser;
 
-use crate::lexer::Token;
 mod ast;
 mod lexer;
 mod parser;
 
-const VFS: &str = include_str!("../assets/vfs.idl");
+const TEST: &str = include_str!("../assets/why.idl");
 
 fn main() {
-    dbg!(Token::lexer(VFS).for_each(|a| println!("{:#?}", a)));
-    dbg!(Parser::new(VFS).parse());
+    let res = Parser::new(TEST).parse();
+    match res {
+        Ok(ast) => { dbg!(ast); }
+        Err(e) => println!("{}", e)
+    }
 }
 
 #[macro_export]

programs/aidl/src/parser.rs

@@ -1,53 +1,56 @@
-use logos::{Logos, SpannedIter};
+use logos::{Lexer, Logos, SpannedIter};
 
 use crate::{
-    ast::{IDLModule, Item, ItemInterface, ItemType, UseDecl},
-    lexer::{Span, Spanned, Token, Ident},
-};
-use std::{
-    iter::{Iterator, Peekable, Filter},
-    ops::Range,
+    ast::{IDLModule, Item, ItemAlias, ItemConstant, ItemInterface, UseDecl},
+    lexer::{Ident, Span, Spanned, Token},
 };
+use std::iter::{Filter, Iterator, Peekable};
 
-type Wtf<'a> = Peekable<
-        Filter<SpannedIter<'a, Token>, Box<dyn Fn(&(Result<Token, ()>, Range<usize>)) -> bool>>,
-    >;
+type Wtf<'a> = Peekable<Filter<&'a mut Lexer<'a, Token>, Box<dyn Fn(&Result<Token, ()>) -> bool>>>;
 
 struct TokenIterator<'a> {
-    spanned: Wtf<'a>,
+    lexer: Lexer<'a, Token>,
+    peeked: Option<Option<Token>>,
 }
 
-fn token_is_not_comment((ref a, ..): &(Result<Token, ()>, Range<usize>)) -> bool {
+fn token_is_not_comment(a: &Result<Token, ()>) -> bool {
     !matches!(a, Err(_) | Ok(Token::Comment(..)))
 }
 
 impl<'a> TokenIterator<'a> {
     pub fn new(src: &'a str) -> Self {
-        let spanned = Token::lexer(src)
-            .spanned()
-            .filter(
-                Box::new(token_is_not_comment) as Box<dyn Fn(&(Result<Token, ()>, Range<usize>)) -> bool>,
-            )
-            .peekable();
+        let lexer = Token::lexer(src);
 
-        Self { spanned }
+        Self {
+            lexer,
+            peeked: None,
         }
-    pub fn next(&mut self) -> Option<Spanned<Token>> {
-        let nxt = self
-            .spanned
-            .next()
-            .and_then(|(token, span)| Some(Spanned(token.ok()?, Span(span))));
+    }
+    pub fn next(&mut self) -> Result<Spanned<Token>, ParserError> {
+        let n = match self.peeked.take() {
+            Some(thing) => thing,
+            None => self.lexer.find(token_is_not_comment).and_then(Result::ok),
+        };
+        let nxt = n.map(|token| Spanned(token, Span(self.lexer.span())));
         println!("[NEXT] {:#?}", nxt);
-        nxt
+        nxt.ok_or(ParserError::UnexpectedEOF)
     }
 
-    pub fn peek(&mut self) -> Option<Spanned<&Token>> {
-        let peek = self
-            .spanned
-            .peek()
-            .and_then(|(token, span)| Some(Spanned(token.as_ref().ok()?, Span(span.clone()))));
+    fn _peek(&mut self) -> Option<&Token> {
+        self.peeked
+            .get_or_insert_with(|| self.lexer.find(token_is_not_comment).and_then(Result::ok))
+            .as_ref()
+    }
+
+    pub fn peek(&mut self) -> Result<Spanned<&Token>, ParserError> {
+        let span = Span(self.lexer.span());
+        let peek = self._peek().map(|token| Spanned(token, span));
         println!("[PEEK] {:#?}", peek);
-        peek
+        peek.ok_or(ParserError::UnexpectedEOF)
+    }
+
+    pub fn current(&self) -> Spanned<String> {
+        Spanned(self.lexer.slice().to_owned(), Span(self.lexer.span()))
     }
 }
 
@@ -62,32 +65,44 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn get_real(&mut self, matcher: impl Fn(&Token) -> bool) -> Option<Spanned<Token>> {
+    fn get_real(
+        &mut self,
+        matcher: impl Fn(&Token) -> bool,
+        expected: &'static str,
+    ) -> Result<Spanned<Token>, ParserError> {
         if matcher(self.tokens.peek()?.0) {
             self.tokens.next()
         } else {
-            None
+            Err(self.unexpected(expected))
         }
     }
 
-    fn semi(&mut self) -> Option<Span> {
-        Some(self.get_real(|token| matches!(token, Token::Semicolon))?.1)
+    fn unexpected(&self, expected: &'static str) -> ParserError {
+        ParserError::Unexpected(expected.to_owned(), self.tokens.current())
     }
 
-    fn ask_ident(&mut self) -> Option<Spanned<String>> {
-        Some(crate::unwrap_match!(
-            self.get_real(|token| matches!(token, Token::Ident(Ident::Other(_))))?,
+    fn semi(&mut self) -> Result<Span, ParserError> {
+        Ok(self
+            .get_real(|token| matches!(token, Token::Semicolon), "a semicolon")?
+            .1)
+    }
+
+    fn ask_ident(&mut self) -> Result<Spanned<String>, ParserError> {
+        Ok(crate::unwrap_match!(
+            self.get_real(|token| matches!(token, Token::Ident(Ident::Other(_))), "an identifier")?,
             Spanned(Token::Ident(Ident::Other(ident)), span) =>
             Spanned(ident, span)
         ))
     }
 
-    fn ask_interface(&mut self) -> Option<Spanned<ItemInterface>> {
-        let Spanned(_, kSp) =
-            self.get_real(|token| matches!(token, Token::Ident(Ident::Interface)))?;
+    fn _ask_interface(&mut self) -> Result<Spanned<ItemInterface>, ParserError> {
+        let Spanned(_, kSp) = self.get_real(
+            |token| matches!(token, Token::Ident(Ident::Interface)),
+            "`Interface`",
+        )?;
         let Spanned(ident, iSp) = self.ask_ident()?;
 
-        Some(Spanned::new(
+        Ok(Spanned::new(
             ItemInterface {
                 name: ident,
                 functions: vec![],
@@ -96,55 +111,98 @@ impl<'a> Parser<'a> {
         ))
     }
 
-    fn ask_typealias(&mut self) -> Option<Spanned<ItemType>> {
-        let Spanned(_, kSp) =
-            self.get_real(|token| matches!(token, Token::Ident(Ident::Type)))?;
+    fn ask_alias(&mut self) -> Result<Spanned<ItemAlias>, ParserError> {
+        let Spanned(_, kSp) = self.get_real(
+            |token| matches!(token, Token::Ident(Ident::Alias)),
+            "`Alias`",
+        )?;
         let Spanned(name, nSp) = self.ask_ident()?;
 
-        let Spanned(_, eqSp) = self.get_real(|token| matches!(token, Token::Equals))?;
+        let Spanned(_, eqSp) = self.get_real(|token| matches!(token, Token::Equals), "`=`")?;
         let Spanned(referree, rSp) = self.ask_ident()?;
 
-        Some(Spanned::new(
-            ItemType { name, referree },
+        Ok(Spanned::new(
+            ItemAlias { name, referree },
             [kSp, nSp, eqSp, rSp, self.semi()?],
         ))
     }
 
-    fn ask_item(&mut self) -> Option<Spanned<Item>> {
-        Some(match self.tokens.peek()?.0 {
-            Token::Ident(Ident::Other(_)) => None?,
+    fn ask_constant(&mut self) -> Result<Spanned<ItemConstant>, ParserError> {
+        Err(self.unexpected(""))
+    }
+
+    fn ask_item(&mut self) -> Result<Spanned<Item>, ParserError> {
+        Ok(match self.tokens.peek()?.0 {
+            Token::Ident(Ident::Other(_)) => {
+                Err(self.unexpected("a keyword, not just an identifier"))?
+            }
             Token::Ident(keyword) => match keyword {
-                Ident::Interface => self.ask_interface()?.map(Item::Interface),
-                Ident::Type => self.ask_typealias()?.map(Item::Type),
-                _ => None?,
+                //Ident::Interface => self.ask_interface()?.map(Item::Interface),
+                Ident::Alias => self.ask_alias()?.map(Item::Type),
+                Ident::Constant => self.ask_constant()?.map(Item::Constant),
+                _ => Err(self.unexpected("`Alias` or `Constant`"))?,
             },
-            _ => None?,
+            _ => Err(self.unexpected("a keyword"))?,
         })
     }
 
-    fn ask_use(&mut self) -> Option<Spanned<UseDecl>> {
-        let Spanned(_, kSp) =
-            self.get_real(|token| matches!(token, Token::Ident(Ident::Use)))?;
+    fn ask_use(&mut self) -> Result<Spanned<UseDecl>, ParserError> {
+        let Spanned(_, kSp) = {
+            match self.tokens.peek()? {
+                Spanned(Token::Ident(Ident::Use), _) => Ok(self.tokens.next()?),
+                _ => Err(ParserError::PleaseStopParsingUse),
+            }
+        }?;
         let Spanned(name, nSp) = self.ask_ident()?;
 
-        Some(Spanned::new(
+        Ok(Spanned::new(
             UseDecl { module: name },
             [kSp, nSp, self.semi()?],
         ))
     }
 
-    pub fn parse(mut self) -> IDLModule {
-        IDLModule {
-            uses: fill_while(|| self.ask_use()),
-            items: fill_while(|| self.ask_item()),
+    pub fn parse(mut self) -> Result<IDLModule, ParserError> {
+        Ok(IDLModule {
+            uses: {
+                let mut real = vec![];
+                loop {
+                    let r = self.ask_use();
+                    match r {
+                        Ok(Spanned(a, _)) => real.push(a),
+                        Err(ParserError::UnexpectedEOF) => return Err(ParserError::UnexpectedEOF),
+                        Err(ParserError::PleaseStopParsingUse) => break,
+                        Err(unexpected @ ParserError::Unexpected(..)) => return Err(unexpected),
                     }
                 }
+                Ok(real)
+            }?,
+            items: fill_while(|| self.ask_item())?,
+        })
+    }
 }
 
-fn fill_while<T>(mut f: impl FnMut() -> Option<Spanned<T>>) -> Vec<T> {
+fn fill_while<T>(
+    mut f: impl FnMut() -> Result<Spanned<T>, ParserError>,
+) -> Result<Vec<T>, ParserError> {
     let mut real = vec![];
-    while let Some(Spanned(t, _)) = f() {
-        real.push(t);
+    loop {
+        match f() {
+            Ok(Spanned(next, _)) => real.push(next),
+            Err(unexpected @ ParserError::Unexpected(..)) => return Err(unexpected),
+            Err(ParserError::UnexpectedEOF) => break,
+            Err(ParserError::PleaseStopParsingUse) => unreachable!(),
         }
-    real
+    }
+    Ok(real)
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum ParserError {
+    // expected, got
+    #[error("Unexpected `{_1}`, expected {_0}")]
+    Unexpected(String, Spanned<String>),
+    #[error("Unexpected end of file")]
+    UnexpectedEOF,
+    #[error("please stop.")]
+    PleaseStopParsingUse,
 }