refactor: module constructions

src/syntax/ast/mod.rs

@@ -18,7 +18,7 @@ pub struct ModuleAST<'a> {
 pub enum ModuleMembers<'a> {
     // TODO: In the future implement module import
     Stmt(Statement<'a>),
-    Expression(Expression<'a>),
+    Expr(Expression<'a>),
 }
 
 #[derive(Debug)]

src/syntax/mod.rs

@@ -4,6 +4,8 @@ mod binding;
 mod block;
 mod expression;
 mod functions;
+mod parseable;
+mod parsers;
 mod statement;
 mod utils;
 
@@ -13,21 +15,7 @@ use crate::lexic::token::{Token, TokenType};
 use ast::ModuleAST;
 
 use self::ast::ModuleMembers;
-
-pub type ParsingResult<'a, A> = Result<(A, usize), ParsingError<'a>>;
-
-#[derive(Debug)]
-pub enum ParsingError<'a> {
-    /// Some other token was found than the expected one
-    Mismatch(&'a Token),
-    /// The parsing didn't succeed, but it's not a fatal error
-    Unmatched,
-    /// The parsing failed past a point of no return.
-    ///
-    /// For example, when parsing a function declaration
-    /// the `fun` token is found, but then no identifier
-    Err(SyntaxError),
-}
+use self::parseable::{ParsingError, ParsingResult};
 
 /// Constructs the Misti AST from a vector of tokens
 pub fn build_ast<'a>(tokens: &'a Vec<Token>) -> Result<ModuleAST, MistiError> {
@@ -66,10 +54,11 @@ pub fn build_ast<'a>(tokens: &'a Vec<Token>) -> Result<ModuleAST, MistiError> {
 }
 
 fn next_construct<'a>(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<ModuleMembers> {
+    todo!();
     // Try to parse a function declaration
     match functions::function_declaration::try_parse(tokens, current_pos) {
         Ok((declaration, next_pos)) => {
-            return Ok((ModuleMembers::FunctionDeclaration(declaration), next_pos))
+            return Ok((ModuleMembers::Stmt(FnDecl(declaration), next_pos)))
         }
         Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
         _ => {}
@@ -84,7 +73,7 @@ fn next_construct<'a>(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResu
 
     // Try to parse an expression
     match expression::try_parse(tokens, current_pos) {
-        Ok((expression, next_pos)) => return Ok((ModuleMembers::Expression(expression), next_pos)),
+        Ok((expression, next_pos)) => return Ok((ModuleMembers::Expr(expression), next_pos)),
         Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
         _ => {}
     }

src/syntax/parseable.rs

@@ -0,0 +1,27 @@
+use crate::{error_handling::SyntaxError, lexic::token::Token};
+
+/// The result of a parsing operation.
+/// On success, it contains the item and the position of the next token
+/// On failure, it contains the error
+pub type ParsingResult<'a, A> = Result<(A, usize), ParsingError<'a>>;
+
+#[derive(Debug)]
+pub enum ParsingError<'a> {
+    /// The parsing didn't succeed, but it's not a fatal error
+    Unmatched,
+    /// Some other token was found than the expected one
+    Mismatch(&'a Token),
+    /// The parsing failed past a point of no return.
+    ///
+    /// For example, when parsing a function declaration
+    /// the `fun` token is found, but then no identifier
+    Err(SyntaxError),
+}
+
+/// Represents a type that can be parsed using Recursive Descent
+pub trait Parseable<'a> {
+    type Item;
+
+    /// Try to parse the current production.
+    fn try_parse(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<'a, Self::Item>;
+}

src/syntax/parsers/expression.rs

@@ -0,0 +1,15 @@
+use crate::{
+    lexic::token::Token,
+    syntax::{
+        ast::Expression,
+        parseable::{Parseable, ParsingResult},
+    },
+};
+
+impl<'a> Parseable<'a> for Expression<'a> {
+    type Item = Expression<'a>;
+
+    fn try_parse(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<'a, Self::Item> {
+        todo!()
+    }
+}

src/syntax/parsers/mod.rs

@@ -0,0 +1,3 @@
+pub mod expression;
+pub mod module;
+pub mod statement;

src/syntax/parsers/module.rs

@@ -0,0 +1,67 @@
+use crate::{
+    error_handling::SyntaxError,
+    lexic::token::Token,
+    syntax::{
+        ast::{Expression, ModuleAST, ModuleMembers, Statement},
+        parseable::{Parseable, ParsingError, ParsingResult},
+    },
+};
+
+impl<'a> Parseable<'a> for ModuleAST<'a> {
+    type Item = ModuleAST<'a>;
+
+    /// Parses a THP module/source file
+    ///
+    /// As this function parses the whole file, it ignores `current_pos` and
+    /// always starts from token 0.
+    ///
+    /// Its grammar is defined it the spec, at the webpage
+    fn try_parse(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<'a, Self::Item> {
+        let mut productions = Vec::<ModuleMembers>::new();
+        let tokens_len = tokens.len();
+        let mut current_pos = 0;
+
+        // Minus one because last token is EOF
+        // TODO: Does that EOF do anything?
+        while current_pos < tokens_len - 1 {
+            // Attempt to parse an statement
+            match Statement::try_parse(tokens, current_pos) {
+                Ok((prod, next_pos)) => {
+                    productions.push(ModuleMembers::Stmt(prod));
+                    current_pos = next_pos;
+                    continue;
+                }
+                Err(ParsingError::Err(error)) => {
+                    // TODO: Better error handling, write a better error message
+                    return Err(ParsingError::Err(error));
+                }
+                _ => {}
+            };
+
+            // Attempt to parse an expression
+            // If this fails the whole thing fails
+            match Expression::try_parse(tokens, current_pos) {
+                Ok((prod, next_pos)) => {
+                    productions.push(ModuleMembers::Expr(prod));
+                    current_pos = next_pos;
+                }
+                Err(ParsingError::Err(error)) => {
+                    // TODO: Better error handling, write a better error message
+                    return Err(ParsingError::Err(error));
+                }
+                _ => {}
+            }
+
+            // If we reached this point we didn't match any productions and fail
+            let t = tokens[current_pos];
+
+            return Err(ParsingError::Err(SyntaxError {
+                error_start: t.position,
+                error_end: t.get_end_position(),
+                reason: "Expected an statement or an expresion at the top level.".into(),
+            }));
+        }
+
+        Ok((ModuleAST { productions }, current_pos))
+    }
+}

src/syntax/parsers/statement.rs

@@ -0,0 +1,12 @@
+use crate::syntax::{ast::Statement, parseable::Parseable};
+
+impl<'a> Parseable<'a> for Statement<'a> {
+    type Item = Statement<'a>;
+
+    fn try_parse(
+        tokens: &'a Vec<crate::lexic::token::Token>,
+        current_pos: usize,
+    ) -> crate::syntax::parseable::ParsingResult<'a, Self::Item> {
+        todo!()
+    }
+}