feat(trixy-lang_parser): Add first parser pass

trixy/trixy-lang_parser/.gitignore

@@ -2,5 +2,5 @@
 /target
 /result
 
-# lua_macros is a library
+# This crate is a library
 Cargo.lock

trixy/trixy-lang_parser/README.md

@@ -0,0 +1,6 @@
+# trixy-lang_parser
+This crate contains a parser (and lexer) for the Trixy language.
+The corresponding grammar is in the grammar file [here](./docs/grammar.ebnf) encoded in [Extended Backus-Naur Form](https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form).
+
+## Docs
+Run `./generate_docs` to turn the grammar file into railroad diagrams.

trixy/trixy-lang_parser/docs/grammar.ebnf

@@ -0,0 +1,17 @@
+# (*
+# Trixy is fully whitespace independent, this means that you can
+# interleave whitespace in the definitions.
+#  The same applies to comments:
+#  - Line comments (`// \n`) and
+#  - Block comments (`/* */`).
+# *)
+
+CommandSpec = { Function | Namespace } ;
+Function = "fn" Identifier "(" {Identifier ":" Type} ")" [ "->" Type ] ";" ;
+Namespace = "nasp" Identifier "{" {Function | Namespace} "}" ;
+Type = "String" | "Integer" ; # (* This corresponds to the CommandTransferValue *)
+Identifier = CHARACTER { NUMBER | CHARACTER } ;
+
+# (*
+#  vim: ft=ebnf
+# *)

trixy/trixy-lang_parser/example/failing.tri

@@ -0,0 +1,9 @@
+fn print(message: CommandTransferValue);
+
+nasp trinitrix { {}
+    fn hi honner(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/full.tri

@@ -0,0 +1,126 @@
+/// Prints to the output, with a newline.
+// HACK(@soispha): The stdlib Lua `print()` function has stdout as output hardcoded,
+// redirecting stdout seems too much like a hack thus we are just redefining the print function
+// to output to a controlled output.  <2023-09-09>
+fn print(input: CommandTransferValue);
+
+nasp trinitrix {
+    /// Language specific functions, which mirror the `trinitrix.api` namespace.
+    /// That is, if you have to choose between a `std` and a `api` function choose the `std`
+    /// one as it will most likely be more high-level and easier to use (as it isn't abstracted
+    /// over multiple languages). Feel free to drop down to the lower level api, if you feel
+    /// like that more, it should be as stable and user-oriented as the `std` functions
+    nasp std {}
+
+    /// Debug only functions, these are effectively useless
+    nasp debug {
+        /// Greets the user
+        fn greet(input: String) -> String;
+
+        /// Returns a table of greeted users
+        fn greet_multiple() -> Table;
+    }
+
+    /// General API to change stuff in Trinitrix
+    nasp api {
+        /// Closes the application
+        fn exit();
+
+        /// Send a message to the current room
+        /// The send message is interpreted literally.
+        fn room_message_send(msg: String);
+
+        /// Open the help pages at the first occurrence of
+        /// the input string if it is Some, otherwise open
+        /// the help pages at the start
+        fn help(input: Option<String>);
+
+        // Register a function to be used with the Trinitrix API
+        // (This function is actually implemented in the std namespace)
+        /* fn register_function(function: RawFunction); */
+
+        /// Function that change the UI, or UI state
+        nasp ui {
+            /// Shows the command line
+            fn command_line_show();
+
+            /// Hides the command line
+            fn command_line_hide();
+
+            /// Go to the next plane
+            fn cycle_planes();
+            /// Go to the previous plane
+            fn cycle_planes_rev();
+
+            /// Sets the current app mode to Normal / navigation mode
+            fn set_mode_normal();
+            /// Sets the current app mode to Insert / editing mode
+            fn set_mode_insert();
+        }
+
+        /// Manipulate keymappings, the mode is specified as a String build up of all mode
+        /// the keymapping should be active in. The mapping works as follows:
+        ///     n => normal Mode
+        ///     c => command Mode
+        ///     i => insert Mode
+        ///
+        /// The key works in a similar matter, specifying the required keypresses to trigger the
+        /// callback. For example "aba" for require the user to press "a" then "b" then "a" again
+        /// to trigger the mapping. Special characters are encoded as follows:
+        ///     "<C-a>ba" => "Ctrl+a" then "b" then "a"
+        ///     "<S-a>" => "A" or "Shift+a"
+        ///     "A" => "A"
+        ///     "<M-a> " => "Alt+a" (<A-a>) or "Meta+a"(<M-a>) (most terminals can't really differentiate between these characters)
+        ///     "a<C-b><C-a>" => "a" then "Ctrl+b" then "Ctrl+a" (also works for Shift, Alt and Super)
+        ///     "<CSM-b>" => "Ctrl+Shift+Alt+b" (the ordering doesn't matter)
+        ///     "a " => "a" then a literal space (" ")
+        ///     "å🙂" => "å" then "🙂" (full Unicode support!)
+        ///     "<ESC>" => escape key
+        ///     "<F3>" => F3 key
+        ///     "<BACKSPACE>" => backspace key (and so forth)
+        ///     "<DASH>" => a literal "-"
+        ///     "<ANGULAR_BRACKET_OPEN>" or "<ABO>"  => a literal "<"
+        ///     "<ANGULAR_BRACKET_CLOSE>" or "<ABC>" => a literal ">"
+        ///
+        /// The callback MUST be registered first by calling
+        /// `trinitrix.api.register_function()` the returned value can than be used to
+        /// set the keymap.
+        nasp keymaps {
+            /// Add a new keymapping
+            fn add(mode: String, key: String, callback: Function);
+
+            /// Remove a keymapping
+            ///
+            /// Does nothing, if the keymapping doesn't exists
+            fn remove((/* mode: */ String, /* key: */ String));
+
+            /// List declared keymappings
+            fn get(mode: String);
+        }
+
+        /// Functions only used internally within Trinitrix
+        nasp raw {
+            /// Send an error to the default error output
+            fn raise_error(input: String);
+
+            /// Send output to the default output
+            /// This is mainly used to display the final
+            /// output of evaluated lua commands.
+            fn display_output(input: String);
+
+            /// Input a character without checking for possible keymaps
+            /// If the current state does not expect input, this character is ignored
+            /// The encoding is the same as in the `trinitrix.api.keymaps` commands
+            fn send_input_unprocessed(input: String);
+
+            /// This namespace is used to store some command specific data (like functions, as
+            /// ensuring memory locations stay allocated in garbage collected language is hard)
+            ///
+            /// Treat it as an implementation detail
+            nasp __private {}
+        }
+    }
+}
+
+// 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/multiple.tri

@@ -3,7 +3,9 @@ fn print(message: CommandTransferValue);
 nasp trinitrix {
     fn hi(name: String) -> String;
 }
-namespace commands { >-
+
+nasp trinitrix {
+    fn ho(name: String) -> String;
 }
 
 

trixy/trixy-lang_parser/generate_docs

@@ -0,0 +1,9 @@
+#!/usr/bin/env sh
+
+
+
+ebnf2pdf "./docs/grammar.ebnf"
+mv out.pdf ./docs/grammar.pdf
+
+
+# vim: ft=sh

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

@@ -0,0 +1,58 @@
+//! This module contains the already type checked types.
+//!
+//!
+
+use crate::lexing::{Keyword, TokenKind};
+pub enum PrimitiveTypes {
+    String,
+    /// Nothing
+    Void,
+}
+
+impl From<TokenKind> for Identifier {
+    fn from(value: TokenKind) -> Self {
+        match value {
+            TokenKind::Identifier(ident) => Identifier(ident),
+            TokenKind::Keyword(_)
+            | TokenKind::Colon
+            | TokenKind::Semicolon
+            | TokenKind::Comma
+            | TokenKind::Arrow
+            | TokenKind::BraceOpen
+            | TokenKind::BraceClose
+            | TokenKind::ParenOpen
+            | TokenKind::Dummy
+            | TokenKind::ParenClose => {
+                panic!("Tried to convert a non Identifier TokenKind to a Identefier. This is a bug")
+            }
+        }
+    }
+}
+
+/// An Identifier
+/// These include
+///     - Variable names
+///     - Function names
+///     - Namespace names
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Identifier(String);
+
+impl From<TokenKind> for Keyword {
+    fn from(value: TokenKind) -> Self {
+        match value {
+            TokenKind::Keyword(keyword) => keyword,
+            TokenKind::Identifier(_)
+            | TokenKind::Colon
+            | TokenKind::Semicolon
+            | TokenKind::Comma
+            | TokenKind::Arrow
+            | TokenKind::BraceOpen
+            | TokenKind::BraceClose
+            | TokenKind::ParenOpen
+            | TokenKind::Dummy
+            | TokenKind::ParenClose => {
+                panic!("Tried to convert a non Keyword TokenKind to a Keyword. This is a bug")
+            }
+        }
+    }
+}

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

@@ -1,36 +1,2 @@
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub struct CommandSpec {
-    pub(crate) declarations: Vec<Declaration>,
-}
-
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub(crate) struct Declaration {
-    pub(crate) namespace: Vec<Namespace>,
-    pub(crate) genus: Genus,
-}
-
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub(crate) struct Namespace {
-    pub(crate) name: String,
-}
-
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub(crate) enum Genus {
-    Function {
-        name: String,
-        inputs: Vec<NamedType>,
-        output: Type,
-    },
-}
-
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub(crate) struct NamedType {
-    pub(crate) name: String,
-    pub(crate) base: Type,
-}
-
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
-pub(crate) enum Type {
-    String,
-    Void,
-}
+pub mod checked;
+pub mod unchecked;

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

@@ -0,0 +1,48 @@
+//! This module contains the not type checked types.
+//! These are generated on the first pass of the parser, to be later converted into the checked
+//! ones.
+
+use crate::lexing::Token;
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct CommandSpec {
+    pub declarations: Vec<Declaration>,
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Declaration {
+    pub namespace: Vec<Token>, // Will later be turned into Namespace
+    pub genus: Genus,
+}
+
+impl Declaration {
+    pub fn new_function(function: Function, namespace: Vec<Token>) -> Self {
+        Declaration { namespace, genus: Genus::Function(function) }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Namespace {
+    pub name: Token, // Will later become an Identifier
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Genus {
+    /// Not actually a genus, but used in parsing to accommodate multiple errors
+    Dummy,
+    /// A function
+    Function(Function),
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Function {
+    pub identifier: Token, // Will later become an Identifier
+    pub inputs: Vec<FunctionInput>,
+    pub output: Option<Token>, // Will later become an Type
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct FunctionInput {
+    pub name: Token, // Will later become an Identifier
+    pub r#type: Token, // Will later become an Type
+}

trixy/trixy-lang_parser/src/error.rs

@@ -1,9 +1,191 @@
+use core::fmt;
+
 use thiserror::Error;
 
-use crate::lexing::error::SpannedLexingError;
+use crate::lexing::{error::SpannedLexingError, TokenSpan};
 
 #[derive(Error, Debug)]
 pub enum TrixyError {
     #[error(transparent)]
     Parsing(#[from] SpannedLexingError),
 }
+
+/// The context of an Error.
+#[derive(Debug)]
+pub struct ErrorContext {
+    /// The span of the error in the source file
+    pub span: TokenSpan,
+    /// The span of the error in the context line relative to the context line
+    pub contexted_span: TokenSpan,
+    /// The line above the error
+    pub line_above: String,
+    /// The line below the error
+    pub line_below: String,
+    /// The line in which the error occurred
+    pub line: String,
+    /// The line number of the main error line
+    pub line_number: usize,
+}
+
+impl ErrorContext {
+    pub fn from_span(span: TokenSpan, original_file: &str) -> Self {
+        let line_number = original_file
+            .chars()
+            .take(span.start)
+            .filter(|a| a == &'\n')
+            .count()
+            // This is here, as we are missing one newline with the method above
+            + 1;
+
+        let lines: Vec<_> = original_file.lines().collect();
+
+        let line = (*lines
+            .get(line_number - 1)
+            .expect("This should work, as have *at least* one (index = 0) line"))
+        .to_owned();
+
+        let contexted_span = {
+            let matched_line: Vec<_> = original_file.match_indices(&line).collect();
+            let (index, matched_line) = matched_line.get(0).expect("This first index should always match, as we took the line from the string in the first place");
+            debug_assert_eq!(matched_line, &&line);
+            TokenSpan {
+                start: span.start - index,
+                end: span.end - index,
+            }
+        };
+
+        let line_above;
+        if line_number == 0 {
+            // We only have one line, so no line above
+            line_above = "".to_owned();
+        } else {
+            line_above = (*lines
+                .get((line_number - 1) - 1)
+                .expect("We checked that this should work"))
+            .to_owned();
+        }
+
+        let line_below;
+        if lines.len() - 1 > line_number {
+            // We have a line after the current line
+            line_below = (*lines
+                .get((line_number + 1) - 1)
+                .expect("We checked that this should work"))
+            .to_owned();
+        } else {
+            line_below = "".to_owned();
+        }
+
+        Self {
+            span,
+            contexted_span,
+            line_above,
+            line_below,
+            line,
+            line_number,
+        }
+    }
+
+    pub fn from_index(start: usize, orginal_file: &str) -> Self {
+        let span = TokenSpan {
+            start,
+            end: start,
+        };
+        Self::from_span(span, orginal_file)
+    }
+
+    pub fn get_error_line(&self, source_error: &str) -> String {
+        // deconstruct the structure
+        let ErrorContext {
+            contexted_span,
+            line_number,
+            ..
+        } = self;
+
+        let mut output = String::new();
+        output.push_str("\x1b[92;1m");
+
+        // pad to accommodate the line number printing.
+        // 32 -> needs two spaces padding to print it
+        line_number.to_string().chars().for_each(|_| {
+            output.push(' ');
+        });
+
+        // pad to the beginning of the error
+        for _ in 0..contexted_span.start {
+            output.push(' ');
+        }
+
+        // push the error markers
+        for _ in contexted_span.start..contexted_span.end {
+            output.push('^');
+        }
+
+        // // pad until end of line
+        // for _ in contexted_span.end..(line.len() - 1) {
+        //     output.push('-');
+        // }
+        //
+        // additional space to avoid having to end with a '-'
+        output.push(' ');
+
+        output.push_str("help: ");
+
+        output.push_str(source_error);
+        output.push_str("\x1b[0m");
+        output
+    }
+}
+
+pub trait AdditionalHelp {
+    fn additional_help(&self) -> String;
+}
+
+pub trait ErrorContextDisplay: fmt::Display {
+    type Error;
+
+    fn error_fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
+    where
+        <Self as ErrorContextDisplay>::Error: std::fmt::Display + AdditionalHelp,
+    {
+        let error_line = self
+            .context()
+            .get_error_line(&self.source().additional_help());
+
+        writeln!(f, "\x1b[31;1merror: \x1b[37;1m{}\x1b[0m", self.source())?;
+
+        if !self.line_above().is_empty() {
+            writeln!(
+                f,
+                "\x1b[32;1m{} |\x1b[0m     {}",
+                self.line_number() - 1,
+                self.line_above()
+            )?;
+        }
+        writeln!(
+            f,
+            "\x1b[36;1m{} |\x1b[0m     {}",
+            self.line_number(),
+            self.line()
+        )?;
+        writeln!(f, "       {}", error_line)?;
+        if !self.line_below().is_empty() {
+            writeln!(
+                f,
+                "\x1b[32;1m{} |\x1b[0m     {}",
+                self.line_number() + 1,
+                self.line_below()
+            )
+        } else {
+            write!(f, "")
+        }
+    }
+
+    // getters
+    fn context(&self) -> &ErrorContext;
+    fn source(&self) -> &Self::Error;
+    fn line_number(&self) -> usize;
+    fn line_above(&self) -> &str;
+    fn line_below(&self) -> &str;
+    fn line(&self) -> &str;
+}

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

@@ -1,6 +1,8 @@
 use std::{error::Error, fmt::Display};
 use thiserror::Error;
 
+use crate::error::{AdditionalHelp, ErrorContext, ErrorContextDisplay};
+
 #[derive(Error, Debug)]
 pub enum LexingError {
     #[error("No matches were found")]
@@ -13,88 +15,61 @@ pub enum LexingError {
     ExpectedArrow,
 }
 
+impl AdditionalHelp for LexingError {
+    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(),
+                LexingError::ExpectedArrow => "The `-` token is interpretet as a started arrow (`->`), but we could not find the arrow tip (`>`)".to_owned(),
+                LexingError::UnknownCharacter(char) => {
+                    format!("This char: `{char}`; is not a valid token")
+                },
+            };
+        out
+    }
+}
+
 #[derive(Debug)]
-pub enum SpannedLexingError {
-    Error {
-        source: LexingError,
-        /// The starting char index of the error in the source file
-        start: usize,
-        /// The starting char index of the error in the context line
-        contexted_start: usize,
-        /// The line above the error
-        line_above: String,
-        /// The line below the error
-        line_below: String,
-        /// The line in which the error occurred
-        line: String,
-        /// The line number of the main error line
-        line_number: usize,
-    },
+pub struct SpannedLexingError {
+    pub source: LexingError,
+    pub context: ErrorContext,
 }
 
 impl Error for SpannedLexingError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
-        let Self::Error { source, .. } = self;
-        Some(source)
+        Some(&self.source)
     }
 }
 
+impl ErrorContextDisplay for SpannedLexingError {
+    type Error = LexingError;
+
+    fn context(&self) -> &crate::error::ErrorContext {
+        &self.context
+    }
+
+    fn line_number(&self) -> usize {
+        self.context.line_number
+    }
+
+    fn line_above(&self) -> &str {
+        &self.context.line_above
+    }
+
+    fn line_below(&self) -> &str {
+        &self.context.line_below
+    }
+
+    fn line(&self) -> &str {
+        &self.context.line
+    }
+
+    fn source(&self) -> &<SpannedLexingError as ErrorContextDisplay>::Error {
+        &self.source
+    }
+}
 impl Display for SpannedLexingError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let Self::Error {
-            source,
-            line_above,
-            line_below,
-            line,
-            line_number,
-            contexted_start,
-            ..
-        } = self;
-        let error_line = {
-            let mut output = String::new();
-            output.push_str("\x1b[92;1m");
-            for _ in 0..(*contexted_start) {
-                output.push(' ');
-            }
-            line_number.to_string().chars().for_each(|_| {
-                output.push(' ');
-            });
-            output.push('^');
-            for _ in *contexted_start..(line.len() - 1) {
-                output.push('-');
-            }
-            output.push(' ');
-            let appandig_str = match source {
-                LexingError::NoMatchesTaken => "This token does not produce a possible match".to_owned(),
-                LexingError::UnexpectedEOF => "This eof was completely unexpected".to_owned(),
-                LexingError::UnknownCharacter(char) => format!("This char: `{char}`; is not a valid token"),
-                LexingError::ExpectedArrow => "The `-` token is interpretet as a started arrow (`->`), but we could not find the arrow tip (`>`)".to_owned(),
-            };
-            output.push_str(&appandig_str);
-            output.push_str("\x1b[0m");
-            output
-        };
-
-        writeln!(f, "\x1b[31;1merror: \x1b[37;1m{}\x1b[0m", source)?;
-        if !line_above.is_empty() {
-            writeln!(
-                f,
-                "\x1b[32;1m{} |\x1b[0m     {}",
-                line_number - 1,
-                line_above
-            )?;
-        }
-        writeln!(f, "\x1b[36;1m{} |\x1b[0m     {}", line_number, line)?;
-        writeln!(f, "       {}", error_line)?;
-        if !line_below.is_empty() {
-            writeln!(
-                f,
-                "\x1b[32;1m{} |\x1b[0m     {}",
-                line_number + 1,
-                line_below
-            )
-        } else {
-            write!(f, "")
-        }
+        self.error_fmt(f)
     }
 }

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

@@ -1,3 +1,5 @@
+use std::fmt::Display;
+
 use self::{error::SpannedLexingError, tokenizer::Tokenizer};
 
 pub mod error;
@@ -8,7 +10,7 @@ mod test;
 
 #[derive(Debug, PartialEq, PartialOrd, Ord, Eq)]
 pub struct TokenStream {
-    original_file: String,
+    pub original_file: String,
     tokens: Vec<Token>,
 }
 
@@ -31,34 +33,83 @@ impl TokenStream {
             original_file: src.to_owned(),
         })
     }
+
+    /// Get a token by index
+    pub fn get(&self, index: usize) -> Option<&Token> {
+        self.tokens.get(index)
+    }
+
+    /// Get a reference to the uppermost token, without modifying the token list
+    pub fn peek(&self) -> &Token {
+        self.tokens.last().expect("This should not be emtpy")
+    }
+
+    /// Remove to the uppermost token
+    pub fn pop(&mut self) -> Token {
+        self.tokens.pop().expect("This should not be emtpy")
+    }
+
+    /// Reverses the underlying tokes vector
+    /// This is facilitates using the pop and peek methods to parse the tokens from the beginning,
+    /// not the end
+    pub fn reverse(&mut self) {
+        self.tokens.reverse()
+    }
+
+    /// Check if the TokenStream is empty.
+    pub fn is_empty(&self) -> bool {
+        self.tokens.is_empty()
+    }
 }
 
 /// A token span is recorded in chars starting from the beginning of the file:
 /// A token span like this, for example:
-/// ```no_run
+/// ```dont_run
+///# use trixy_lang_parser::lexing::TokenSpan;
 /// TokenSpan {
 ///     start: 20,
 ///     end: 23,
 /// }
 /// ```
 /// signals, that the token starts at the 20th char in the source file and ends on the 23rd.
-#[derive(Debug, PartialEq, PartialOrd, Ord, Eq)]
+#[derive(Debug, PartialEq, PartialOrd, Ord, Eq, Clone, Copy)]
 pub struct TokenSpan {
-    start: usize,
     /// The start of the token span
-    end: usize,
+    pub start: usize,
+    /// The end of the token span
+    pub end: usize,
 }
 
 /// A Token
-#[derive(Debug, PartialEq, PartialOrd, Ord, Eq)]
+#[derive(Debug, PartialEq, PartialOrd, Ord, Eq, Clone)]
 pub struct Token {
     /// The token's original location in the source file
-    span: TokenSpan,
-    kind: TokenKind,
+    pub span: TokenSpan,
+    pub kind: TokenKind,
+}
+
+impl Token {
+    /// Return the TokenKind of a token
+    pub fn kind(&self) -> &TokenKind {
+        &self.kind
+    }
+
+    /// Return the TokenSpan of a token
+    pub fn span(&self) -> &TokenSpan {
+        &self.span
+    }
+
+    /// Get a dummy token, this is intended for error handling
+    pub fn get_dummy() -> Token {
+        Self {
+            span: TokenSpan { start: 0, end: 0 },
+            kind: TokenKind::Dummy,
+        }
+    }
 }
 
 /// Possibly kinds of tokens
-#[derive(Debug, PartialEq, PartialOrd, Ord, Eq)]
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
 pub enum TokenKind {
     Keyword(Keyword),
     Identifier(String),
@@ -68,12 +119,49 @@ pub enum TokenKind {
     Arrow,
     BraceOpen,
     BraceClose,
-    ParenthesisOpen,
-    ParenthesisClose,
+    ParenOpen,
+    ParenClose,
+    /// This is not a real TokenKind, but only used for error handling
+    Dummy,
+}
+
+impl TokenKind {
+    pub fn same_kind(&self, other: &TokenKind) -> bool {
+        if let TokenKind::Identifier(_) = self {
+            if let TokenKind::Identifier(_) = other {
+                return true;
+            }
+        }
+        self == other
+    }
+}
+
+impl Display for TokenKind {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            TokenKind::Keyword(word) => write!(f, "KEYWORD({})", word),
+            TokenKind::Identifier(ident) => {
+                if ident == "" {
+                    write!(f, "IDENTIFIER")
+                } else {
+                    write!(f, "IDENTIFIER({})", ident)
+                }
+            }
+            TokenKind::Colon => f.write_str("COLON"),
+            TokenKind::Semicolon => f.write_str("SEMICOLON"),
+            TokenKind::Comma => f.write_str("COMMA"),
+            TokenKind::Arrow => f.write_str("ARROW"),
+            TokenKind::BraceOpen => f.write_str("BRACEOPEN"),
+            TokenKind::BraceClose => f.write_str("BRACECLOSE"),
+            TokenKind::ParenOpen => f.write_str("PARENOPEN"),
+            TokenKind::ParenClose => f.write_str("PARENCLOSE"),
+            TokenKind::Dummy => f.write_str("DUMMY"),
+        }
+    }
 }
 
 /// Keywords used in the language
-#[derive(Debug, PartialEq, PartialOrd, Ord, Eq)]
+#[derive(Debug, PartialEq, PartialOrd, Ord, Eq, Clone, Copy)]
 pub enum Keyword {
     /// Start a namespace declaration
     #[allow(non_camel_case_types)]
@@ -82,3 +170,85 @@ pub enum Keyword {
     #[allow(non_camel_case_types)]
     r#fn,
 }
+
+impl Display for Keyword {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Keyword::nasp => f.write_str("nasp"),
+            Keyword::r#fn => f.write_str("fn"),
+        }
+    }
+}
+
+/// Shorthand macro for generating a token from *anything* which can be
+/// converted into a `TokenKind`, or any of the `TokenKind` variants.
+///
+/// # Examples
+///
+/// ```
+/// use trixy_lang_parser::token;
+/// # fn main() {
+/// token![nasp];
+/// token![;];
+/// token![Arrow];
+/// # }
+/// ```
+#[macro_export]
+macro_rules! token {
+    [Semicolon] => { $crate::lexing::TokenKind::Semicolon };
+    [;] => { $crate::lexing::TokenKind::Semicolon };
+    [Colon]    => { $crate::lexing::TokenKind::Colon };
+    [:]    => { $crate::lexing::TokenKind::Colon };
+    [Comma]    => { $crate::lexing::TokenKind::Comma };
+    [,]    => { $crate::lexing::TokenKind::Comma };
+    [Arrow]    => { $crate::lexing::TokenKind::Arrow };
+    [->] => { $crate::lexing::TokenKind::Arrow };
+    [BraceOpen]    => { $crate::lexing::TokenKind::BraceOpen };
+    // [{]    => { $crate::lexing::TokenKind::BraceOpen };
+    [BraceClose]    => { $crate::lexing::TokenKind::BraceClose };
+    // [}]    => { $crate::lexing::TokenKind::BraceClose };
+    [ParenOpen]    => { $crate::lexing::TokenKind::ParenOpen };
+    // [(]    => { $crate::lexing::TokenKind::ParenthesisOpen };
+    [ParenClose]    => { $crate::lexing::TokenKind::ParenClose };
+    // [)]    => { $crate::lexing::TokenKind::ParenthesisClose };
+
+    [nasp] => { $crate::lexing::TokenKind::Keyword($crate::lexing::Keyword::nasp) };
+    [fn] => { $crate::lexing::TokenKind::Keyword($crate::lexing::Keyword::r#fn) };
+
+    // This is only works for checking for a identifier
+    // see the `same_kind` method on TokenKind
+    [Ident] => { $crate::lexing::TokenKind::Identifier("".to_owned()) };
+    [Identifier] => { $crate::lexing::TokenKind::Identifier("".to_owned()) };
+}
+
+#[cfg(test)]
+mod tests {
+    use super::TokenKind;
+    use crate::token;
+
+    macro_rules! token_macro_test {
+        ($name:ident, $from:tt, => $to:expr) => {
+            #[test]
+            fn $name() {
+                let got: TokenKind = token![$from];
+                let should_be = $to;
+
+                assert_eq!(got, should_be);
+            }
+        };
+        ($name:ident, $from:tt, => $to:expr) => {
+            #[test]
+            fn $name() {
+                let got: TokenKind = token![$from];
+                let should_be = $to;
+
+                assert_eq!(got, should_be);
+            }
+        };
+    }
+
+    token_macro_test!(tok_expands_to_arrow, ->, => TokenKind::Arrow);
+    token_macro_test!(tok_expands_to_semicolon, Semicolon, => TokenKind::Semicolon);
+    token_macro_test!(tok_expands_to_nasp, nasp, => TokenKind::Keyword(crate::lexing::Keyword::nasp));
+    token_macro_test!(tok_expands_to_fn, fn, => TokenKind::Keyword(crate::lexing::Keyword::r#fn));
+}

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

@@ -36,7 +36,7 @@ nasp commands {
             },
             Token {
                 span: TokenSpan { start: 30, end: 31 },
-                kind: TokenKind::ParenthesisOpen,
+                kind: TokenKind::ParenOpen,
             },
             Token {
                 span: TokenSpan { start: 31, end: 36 },
@@ -52,7 +52,7 @@ nasp commands {
             },
             Token {
                 span: TokenSpan { start: 44, end: 45 },
-                kind: TokenKind::ParenthesisClose,
+                kind: TokenKind::ParenClose,
             },
             Token {
                 span: TokenSpan { start: 46, end: 48 },

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

@@ -1,6 +1,9 @@
 // This code is heavily inspired by: https://michael-f-bryan.github.io/static-analyser-in-rust/book/lex.html
 
-use crate::lexing::{Keyword, TokenSpan};
+use crate::{
+    error::ErrorContext,
+    lexing::{Keyword, TokenSpan},
+};
 
 use super::{
     error::{LexingError, SpannedLexingError},
@@ -29,61 +32,11 @@ impl<'a> Tokenizer<'a> {
             let start = self.current_index;
 
             let (token_kind, index) = self.get_next_tokenkind().map_err(|e| {
-                let (line_above, line, line_below, contexted_start, line_number) = {
-                    let line_number = self
-                        .original_text
-                        .chars()
-                        .take(start)
-                        .filter(|a| a == &'\n')
-                        .count();
-                    let lines: Vec<_> = self.original_text.lines().collect();
+                let context = ErrorContext::from_index(start, self.original_text);
 
-                    let line = (*lines
-                        .get(line_number)
-                        .expect("This should work, as have *at least* one (index = 0) line"))
-                    .to_owned();
-
-                    let contexted_start = {
-                        let matched_line: Vec<_> = self.original_text.match_indices(&line).collect();
-                        let (index, matched_line) = matched_line.get(0).expect("This first index should always match, as we took the line from the string in the first place");
-                        debug_assert_eq!(matched_line, &&line);
-                        start - index
-                    };
-
-                    let line_above;
-                    if line_number == 0 {
-                        // We only have one line, so no line above
-                        line_above = "".to_owned();
-                    } else {
-                        line_above = (*lines
-                            .get(line_number - 1)
-                            .expect("We checked that this should work"))
-                        .to_owned();
-                    }
-
-                    let line_below;
-                    if lines.len() - 1 > line_number {
-                        // We have a line after the current line
-                        line_below = (*lines
-                            .get(line_number + 1)
-                            .expect("We checked that this should work"))
-                        .to_owned();
-                    } else {
-                        line_below = "".to_owned();
-                    }
-
-                    (line_above, line, line_below, contexted_start, line_number)
-                };
-                SpannedLexingError::Error {
-                    source: e,
-                    start,
-                    contexted_start,
-                    line_above,
-                    line_below,
-                    line_number,
-                    line,
-                }
+                SpannedLexingError { source: e, context }
             })?;
+
             self.chomp(index); // end - start
             let end = self.current_index;
             Ok(Some(Token {
@@ -100,8 +53,8 @@ impl<'a> Tokenizer<'a> {
         };
 
         let (tok, length) = match next {
-            '(' => (TokenKind::ParenthesisOpen, 1),
-            ')' => (TokenKind::ParenthesisClose, 1),
+            '(' => (TokenKind::ParenOpen, 1),
+            ')' => (TokenKind::ParenClose, 1),
             '{' => (TokenKind::BraceOpen, 1),
             '}' => (TokenKind::BraceClose, 1),
             ':' => (TokenKind::Colon, 1),

trixy/trixy-lang_parser/src/lib.rs

@@ -2,11 +2,12 @@ use error::TrixyError;
 
 use crate::lexing::TokenStream;
 
-use self::command_spec::CommandSpec;
+use self::command_spec::unchecked::CommandSpec;
 
 mod command_spec;
 pub mod error;
 pub mod lexing;
+pub mod parsing;
 
 pub fn parse_trixy_lang(input: &str) -> Result<CommandSpec, TrixyError> {
     let input_tokens = TokenStream::lex(input)?;
@@ -14,45 +15,45 @@ pub fn parse_trixy_lang(input: &str) -> Result<CommandSpec, TrixyError> {
     todo!()
 }
 
-#[cfg(test)]
-mod test {
-    use crate::{
-        command_spec::{CommandSpec, Declaration, Genus, NamedType, Namespace, Type},
-        parse_trixy_lang,
-    };
-
-    #[test]
-    fn test_function_with_namespace() {
-        let expected = parse_trixy_lang(
-            "
-                nasp commands {
-                    fn say_something(name_to_greet: String, what_to_say: String) -> String;
-                }
-            ",
-        )
-        .unwrap();
-        let correct: CommandSpec = {
-            let declarations = vec![Declaration {
-                namespace: vec![Namespace {
-                    name: "commands".to_owned(),
-                }],
-                genus: Genus::Function {
-                    name: "say_something".to_owned(),
-                    inputs: vec![
-                        NamedType {
-                            name: "name_to_greet".to_owned(),
-                            base: Type::String,
-                        },
-                        NamedType {
-                            name: "what_to_say".to_owned(),
-                            base: Type::String,
-                        },
-                    ],
-                    output: Type::String,
-                },
-            }];
-            CommandSpec { declarations }
-        };
-        assert_eq!(expected, correct);
-    }
-}
+// #[cfg(test)]
+// mod test {
+//     use crate::{
+//         command_spec::unchecked::{CommandSpec, Declaration, Genus, Namespace},
+//         parse_trixy_lang,
+//     };
+//
+//     #[test]
+//     fn test_function_with_namespace() {
+//         let expected = parse_trixy_lang(
+//             "
+//                 nasp commands {
+//                     fn say_something(name_to_greet: String, what_to_say: String) -> String;
+//                 }
+//             ",
+//         )
+//         .unwrap();
+//         let correct: CommandSpec = {
+//             let declarations = vec![Declaration {
+//                 namespace: vec![Namespace {
+//                     name: "commands".to_owned(),
+//                 }],
+//                 genus: Genus::Function {
+//                     name: "say_something".to_owned(),
+//                     inputs: vec![
+//                         NamedType {
+//                             name: "name_to_greet".to_owned(),
+//                             base: Type::String,
+//                         },
+//                         NamedType {
+//                             name: "what_to_say".to_owned(),
+//                             base: Type::String,
+//                         },
+//                     ],
+//                     output: Type::String,
+//                 },
+//             }];
+//             CommandSpec { declarations }
+//         };
+//         assert_eq!(expected, correct);
+//     }
+// }

trixy/trixy-lang_parser/src/main.rs

@@ -23,6 +23,11 @@ pub enum Command {
         /// The file containing the trixy code to tokenize
         file: PathBuf,
     },
+    Parse {
+        #[clap(value_parser)]
+        /// The file containing the trixy code to parse
+        file: PathBuf,
+    },
 }
 
 pub fn main() {
@@ -34,12 +39,34 @@ pub fn main() {
             let input_tokens = match TokenStream::lex(&input) {
                 Ok(err) => err,
                 Err(ok) => {
-                    println!("{}", ok);
+                    eprintln!("{}", ok);
                     exit(1);
                 }
             };
 
             println!("{:#?}", input_tokens);
         }
+        Command::Parse { file } => {
+            let input = fs::read_to_string(file).unwrap();
+
+            let input_tokens = match TokenStream::lex(&input) {
+                Ok(ok) => ok,
+                Err(err) => {
+                    eprintln!("Error while tokenizing:");
+                    eprintln!("{}", err);
+                    exit(1);
+                }
+            };
+
+            let parsed = match input_tokens.parse_unchecked() {
+                Ok(ok) => ok,
+                Err(err) => {
+                    eprintln!("Error while doing the first (unchecked) parsing run:");
+                    eprintln!("{}", err);
+                    exit(1)
+                }
+            };
+            println!("{:#?}", parsed);
+        }
     }
 }

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

@@ -0,0 +1,93 @@
+use std::{error::Error, fmt::Display};
+use thiserror::Error;
+
+use crate::{
+    error::{AdditionalHelp, ErrorContext, ErrorContextDisplay},
+    lexing::{TokenKind, TokenSpan},
+};
+
+#[derive(Error, Debug)]
+pub enum ParsingError {
+    #[error("Expected '{expected}' but received '{actual}'")]
+    ExpectedDifferentToken {
+        expected: TokenKind,
+        actual: TokenKind,
+        span: TokenSpan,
+    },
+
+    #[error("Expected a Keyword to start a new declaration, but found: '{actual}'")]
+    ExpectedKeyword { actual: TokenKind, span: TokenSpan },
+}
+
+impl ParsingError {
+    pub fn get_span(&self) -> TokenSpan {
+        match self {
+            ParsingError::ExpectedDifferentToken { span, .. } => *span,
+            ParsingError::ExpectedKeyword { span, .. } => *span,
+        }
+    }
+}
+
+impl AdditionalHelp for ParsingError {
+    fn additional_help(&self) -> String {
+        match self {
+            ParsingError::ExpectedDifferentToken {
+                expected,
+                actual,
+                ..
+            } => format!(
+                "I expected a '{}' here, but you put a '{}' there!",
+                expected, actual
+            ),
+            ParsingError::ExpectedKeyword { actual, .. } => format!(
+            "I expected a keyword (that is something like 'fn' or 'nasp') but you put a '{}' there!",
+            actual),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct SpannedParsingError {
+    pub source: ParsingError,
+    pub context: ErrorContext,
+}
+
+impl Error for SpannedParsingError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        Some(&self.source)
+    }
+}
+
+impl Display for SpannedParsingError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.error_fmt(f)
+    }
+}
+
+impl ErrorContextDisplay for SpannedParsingError {
+    type Error = ParsingError;
+
+    fn context(&self) -> &crate::error::ErrorContext {
+        &self.context
+    }
+
+    fn line_number(&self) -> usize {
+        self.context.line_number
+    }
+
+    fn line_above(&self) -> &str {
+        &self.context.line_above
+    }
+
+    fn line_below(&self) -> &str {
+        &self.context.line_below
+    }
+
+    fn line(&self) -> &str {
+        &self.context.line
+    }
+
+    fn source(&self) -> &<SpannedParsingError as ErrorContextDisplay>::Error {
+        &self.source
+    }
+}

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

@@ -0,0 +1,4 @@
+mod error;
+mod unchecked;
+#[cfg(test)]
+mod test;

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

@@ -0,0 +1,88 @@
+use crate::{
+    command_spec::unchecked::{CommandSpec, Declaration, Function, FunctionInput, Genus},
+    lexing::{Token, TokenKind, TokenSpan, TokenStream},
+};
+
+use super::error::ParsingError;
+
+use pretty_assertions::assert_eq;
+
+#[test]
+fn test_failing() {
+    let input = "
+fn print(message: CommandTransferValue);
+
+nasp trinitrix { {}
+    fn hi honner(name: String) -> String; ;
+}
+
+";
+    let parsed = TokenStream::lex(input).unwrap().parse_unchecked();
+    let err = parsed.unwrap_err().source;
+    match err {
+        ParsingError::ExpectedDifferentToken { .. } => panic!("Wrong error"),
+        ParsingError::ExpectedKeyword { .. } => {}
+    }
+}
+
+#[test]
+fn test_full() {
+    let input = "fn print(message: CommandTransferValue);
+
+nasp trinitrix {
+    fn hi(name: String) -> String;
+}
+";
+    let parsed = TokenStream::lex(input).unwrap().parse_unchecked().unwrap();
+    let expected = CommandSpec {
+        declarations: vec![
+            Declaration {
+                namespace: vec![],
+                genus: Genus::Function(Function {
+                    identifier: Token {
+                        span: TokenSpan { start: 3, end: 8 },
+                        kind: TokenKind::Identifier("print".to_owned()),
+                    },
+                    inputs: vec![FunctionInput {
+                        name: Token {
+                            span: TokenSpan { start: 9, end: 16 },
+                            kind: TokenKind::Identifier("message".to_owned()),
+                        },
+                        r#type: Token {
+                            span: TokenSpan { start: 18, end: 38 },
+                            kind: TokenKind::Identifier("CommandTransferValue".to_owned()),
+                        },
+                    }],
+                    output: None,
+                }),
+            },
+            Declaration {
+                namespace: vec![Token {
+                    span: TokenSpan { start: 47, end: 56 },
+                    kind: TokenKind::Identifier("trinitrix".to_owned()),
+                }],
+                genus: Genus::Function(Function {
+                    identifier: Token {
+                        span: TokenSpan { start: 66, end: 68 },
+                        kind: TokenKind::Identifier("hi".to_owned()),
+                    },
+                    inputs: vec![FunctionInput {
+                        name: Token {
+                            span: TokenSpan { start: 69, end: 73 },
+                            kind: TokenKind::Identifier("name".to_owned()),
+                        },
+                        r#type: Token {
+                            span: TokenSpan { start: 75, end: 81 },
+                            kind: TokenKind::Identifier("String".to_owned()),
+                        },
+                    }],
+                    output: Some(Token {
+                        span: TokenSpan { start: 86, end: 92 },
+                        kind: TokenKind::Identifier("String".to_owned()),
+                    }),
+                }),
+            },
+        ],
+    };
+    assert_eq!(parsed, expected);
+}

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

@@ -0,0 +1,167 @@
+use crate::{
+    command_spec::unchecked::{CommandSpec, Declaration, Function, FunctionInput},
+    error::ErrorContext,
+    lexing::{Token, TokenKind, TokenStream},
+    token,
+};
+
+use super::error::{ParsingError, SpannedParsingError};
+
+impl TokenStream {
+    pub fn parse_unchecked(self) -> Result<CommandSpec, SpannedParsingError> {
+        let mut parser = Parser::new(self);
+        parser.parse()
+    }
+}
+
+pub(super) struct Parser {
+    token_stream: TokenStream,
+    current_namespaces: Vec<Token>, // This should in the second pass turn into Identifiers
+}
+
+impl Parser {
+    fn new(mut token_stream: TokenStream) -> Self {
+        token_stream.reverse();
+        Self {
+            token_stream,
+            current_namespaces: vec![],
+        }
+    }
+
+    fn parse(&mut self) -> Result<CommandSpec, SpannedParsingError> {
+        let mut declarations = vec![];
+        while !self.token_stream.is_empty() {
+            let mut next = self.parse_next().map_err(|err| {
+                let span = err.get_span();
+                SpannedParsingError {
+                    source: err,
+                    context: ErrorContext::from_span(span, &self.token_stream.original_file),
+                }
+            })?;
+
+            declarations.append(&mut next);
+        }
+
+        Ok(CommandSpec { declarations })
+    }
+
+    fn parse_next(&mut self) -> Result<Vec<Declaration>, ParsingError> {
+        match self.peek().kind() {
+            token![nasp] => Ok(self.parse_namespace()?),
+            token![fn] => Ok(vec![Declaration::new_function(
+                self.parse_function()?,
+                self.current_namespaces.clone(),
+            )]),
+            _ => {
+                let err = ParsingError::ExpectedKeyword {
+                    span: *self.peek().span(),
+                    actual: self.peek().kind().clone(),
+                };
+
+                return Err(err);
+            }
+        }
+    }
+
+    fn parse_namespace(&mut self) -> Result<Vec<Declaration>, ParsingError> {
+        self.expect(token![nasp])?;
+        let namespace_name = self.expect(token![Ident])?;
+        self.current_namespaces.push(namespace_name);
+        self.expect(token![BraceOpen])?;
+
+        let mut declarations = vec![];
+        while !self.expect_peek(token![BraceClose]) {
+            declarations.append(&mut self.parse_next()?);
+        }
+
+        self.expect(token![BraceClose])?;
+        self.current_namespaces.pop();
+        Ok(declarations)
+    }
+
+    fn parse_function(&mut self) -> Result<Function, ParsingError> {
+        self.expect(token![fn])?;
+        let name = self.expect(token![Ident])?;
+        self.expect(token![ParenOpen])?;
+        let mut inputs = vec![];
+
+        while self.expect_peek(token![Ident]) {
+            let input_name = self.expect(token![Ident])?;
+            self.expect(token![Colon])?;
+            let input_type = self.expect(token![Ident])?;
+            inputs.push(FunctionInput {
+                name: input_name,
+                r#type: input_type,
+            })
+        }
+
+        self.expect(token![ParenClose])?;
+        let mut output_type = None;
+        if self.expect_peek(token![->]) {
+            self.expect(token![->])?;
+            output_type = Some(self.expect(token![Ident])?);
+        }
+        self.expect(token![;])?;
+        Ok(Function {
+            identifier: name,
+            inputs,
+            output: output_type,
+        })
+    }
+
+    /// Expect a token in the next input position:
+    /// For example:
+    ///
+    /// ```dont_run
+    /// use trixy_lang_parser::{
+    ///     lexing::{Keyword, TokenKind, TokenStream},
+    ///     parsing::unchecked::Parser,
+    ///     token,
+    /// };
+    ///
+    /// # fn main() {
+    ///     let token_stream = TokenStream::lex("nasp {}").unwrap();
+    ///     let parser = Parser::new(token_stream);
+    ///     assert_eq!(parser.expect(token![nasp]).unwrap(), TokenKind::Keyword(Keyword::nasp));
+    ///     assert_eq!(parser.expect(token![BraceOpen]).unwrap(), TokenKind::BraceOpen);
+    ///     assert_eq!(parser.expect(token![BraceClose]).unwrap(), TokenKind::BraceClose);
+    ///     assert!(parser.expect(token![BraceClose]).is_err());
+    /// # }
+    /// ```
+    ///
+    pub(super) fn expect(&mut self, token: TokenKind) -> Result<Token, ParsingError> {
+        let actual_token = self.peek();
+        if actual_token.kind().same_kind(&token) {
+            Ok(self.pop())
+        } else {
+            let err = ParsingError::ExpectedDifferentToken {
+                expected: token,
+                actual: actual_token.kind().clone(),
+                span: *actual_token.span(),
+            };
+
+            Err(err)
+        }
+    }
+
+    /// 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();
+        if actual_token.kind().same_kind(&token) {
+            true
+        } else {
+            false
+        }
+    }
+
+    /// Looks at the next token without removing it
+    fn peek(&self) -> &Token {
+        self.token_stream.peek()
+    }
+
+    /// Removes the next token
+    fn pop(&mut self) -> Token {
+        self.token_stream.pop()
+    }
+}