feat: parse loops

CHANGELOG.md

@@ -23,6 +23,7 @@
 
 - [x] Parse conditionals
 - [x] Parse arrays
+- [x] Parse for loops
 
 
 ## v0.1.1

src/semantic/checks/block.rs

@@ -0,0 +1,17 @@
+use crate::{
+    error_handling::MistiError,
+    semantic::{impls::SemanticCheck, symbol_table::SymbolTable},
+    syntax::ast::BlockMember,
+};
+
+impl<'a> SemanticCheck for BlockMember<'a> {
+    // TODO: A block may contain a function declaration statement,
+    // but (afaik) those are not allowed inside conditionals/loops
+    // somehow detect those?
+    fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError> {
+        match self {
+            BlockMember::Stmt(s) => s.check_semantics(scope),
+            BlockMember::Expr(e) => e.check_semantics(scope),
+        }
+    }
+}

src/semantic/checks/function_declaration.rs

@@ -1,7 +1,7 @@
 use crate::{
     error_handling::{semantic_error::SemanticError, MistiError},
     semantic::{impls::SemanticCheck, symbol_table::SymbolTable, types::Type},
-    syntax::ast::{BlockMember, FunctionDeclaration, Statement},
+    syntax::ast::FunctionDeclaration,
 };
 
 impl SemanticCheck for FunctionDeclaration<'_> {
@@ -31,27 +31,7 @@ impl SemanticCheck for FunctionDeclaration<'_> {
         // TODO: Check the return type of the function body
         // This should be the last expression in the block
         for stmt in self.block.members.iter() {
-            match stmt {
-                BlockMember::Stmt(Statement::Binding(b)) => {
-                    if let Err(err) = b.check_semantics(&function_scope) {
-                        return Err(err);
-                    }
-                }
-                BlockMember::Stmt(Statement::FnDecl(f)) => {
-                    // TODO: (for now) a function cannot be declared inside another function.
-                    let error = SemanticError {
-                        error_start: f.identifier.position,
-                        error_end: f.identifier.get_end_position(),
-                        reason: format!(
-                            "A function cannot be defined inside another function."
-                        ),
-                    };
-
-                    return Err(MistiError::Semantic(error));
-                }
-                BlockMember::Stmt(Statement::Conditional(_)) => unimplemented!("check conditional"),
-                BlockMember::Expr(e) => e.check_semantics(scope)?,
-            }
+            stmt.check_semantics(&function_scope)?;
         }
 
         // TODO: Check that the return type of the function

src/semantic/checks/mod.rs

@@ -1,4 +1,5 @@
 pub mod binding;
+pub mod block;
 pub mod expression;
 pub mod function_declaration;
 pub mod top_level_declaration;

src/semantic/checks/top_level_declaration.rs

@@ -23,6 +23,7 @@ impl SemanticCheck for Statement<'_> {
             Statement::Binding(b) => b.check_semantics(scope),
             Statement::FnDecl(f) => f.check_semantics(scope),
             Statement::Conditional(_) => unimplemented!("check conditional"),
+            Statement::ForLoop(_) => unimplemented!("check for loop"),
         }
     }
 }

src/syntax/ast/loops.rs

@@ -0,0 +1,15 @@
+use crate::lexic::token::Token;
+
+use super::Block;
+
+#[derive(Debug)]
+pub struct ForLoop<'a> {
+    /// the start position of the
+    /// `for` keyword
+    pub loop_start: usize,
+    /// the position of the closing bracket
+    pub loop_end: usize,
+    pub key: Option<&'a Token>,
+    pub value: &'a Token,
+    pub body: Block<'a>,
+}

src/syntax/ast/mod.rs

@@ -1,9 +1,11 @@
 use crate::lexic::token::Token;
 
 use self::functions::FunctionCall;
+use loops::ForLoop;
 use var_binding::VariableBinding;
 
 pub mod functions;
+pub mod loops;
 pub mod var_binding;
 
 /// Trait that allows nodes to inform
@@ -33,13 +35,14 @@ pub enum Statement<'a> {
     FnDecl(FunctionDeclaration<'a>),
     // TODO: Implement conditionals as expressions
     Conditional(Conditional<'a>),
+    ForLoop(ForLoop<'a>),
 }
 
 #[derive(Debug)]
 pub struct Conditional<'a> {
     pub if_member: Condition<'a>,
     pub else_if_members: Vec<Condition<'a>>,
-    pub else_block: Option<Block<'a>>
+    pub else_block: Option<Block<'a>>,
 }
 
 #[derive(Debug)]
@@ -48,7 +51,6 @@ pub struct Condition<'a> {
     pub body: Block<'a>,
 }
 
-
 #[derive(Debug)]
 pub struct FunctionDeclaration<'a> {
     pub identifier: &'a Token,
@@ -59,9 +61,17 @@ pub struct FunctionDeclaration<'a> {
 
 #[derive(Debug)]
 pub struct Block<'a> {
+    pub start: usize,
+    pub end: usize,
     pub members: Vec<BlockMember<'a>>,
 }
 
+impl Positionable for Block<'_> {
+    fn get_position(&self) -> (usize, usize) {
+        (self.start, self.end)
+    }
+}
+
 /// Enum for productions available at the block level
 #[derive(Debug)]
 pub enum BlockMember<'a> {
@@ -125,9 +135,11 @@ impl Positionable for Expression<'_> {
                 let (_, end) = right_expr.get_position();
                 (start, end)
             }
-            Expression::Array(Array {start, end, exps: _}) => {
-                (*start, *end)
-            }
+            Expression::Array(Array {
+                start,
+                end,
+                exps: _,
+            }) => (*start, *end),
         }
     }
 }

src/syntax/parsers/block.rs

@@ -44,6 +44,7 @@ impl<'a> Parseable<'a> for Block<'a> {
                 Ok((prod, next_pos)) => {
                     members.push(BlockMember::Expr(prod));
                     current_pos = next_pos;
+                    continue;
                 }
                 Err(ParsingError::Err(error)) => {
                     // TODO: Better error handling, write a better error message
@@ -59,7 +60,7 @@ impl<'a> Parseable<'a> for Block<'a> {
         }
 
         // Parse closing brace
-        let (_closing_brace, next_pos) =
+        let (closing_brace, next_pos) =
             match parse_token_type(tokens, current_pos, TokenType::RightBrace) {
                 Ok((t, next)) => (t, next),
                 Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
@@ -82,7 +83,11 @@ impl<'a> Parseable<'a> for Block<'a> {
             };
         current_pos = next_pos;
 
-        let block = Block { members };
+        let block = Block {
+            members,
+            start: opening_brace.position,
+            end: closing_brace.position,
+        };
         Ok((block, current_pos))
     }
 }
@@ -152,24 +157,23 @@ mod tests {
         assert_eq!(block.members.len(), 1);
     }
 
-    /*
     #[test]
     fn test_parse_block_2() {
         let tokens = get_tokens(&String::from("{f()\ng()}")).unwrap();
-        let block = parse_block(&tokens, 0);
+        let block = Block::try_parse(&tokens, 0);
 
         let block = match block {
             ParsingResult::Ok((p, _)) => p,
             _ => panic!("Expected a block, got: {:?}", block),
         };
 
-        assert_eq!(block.statements.len(), 2);
+        assert_eq!(block.members.len(), 2);
     }
 
     #[test]
     fn test_parse_block_3() {
         let tokens = get_tokens(&String::from("{\n    f()\n}")).unwrap();
-        let block = parse_block(&tokens, 0);
+        let block = Block::try_parse(&tokens, 0);
 
         let block = match block {
             ParsingResult::Ok((p, _)) => p,
@@ -178,7 +182,6 @@ mod tests {
             }
         };
 
-        assert_eq!(block.statements.len(), 1);
+        assert_eq!(block.members.len(), 1);
     }
-    */
 }

src/syntax/parsers/conditional.rs

@@ -141,18 +141,14 @@ impl<'a> Parseable<'a> for Conditional<'a> {
                         Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
                         Err(ParsingError::Mismatch(wrong_token)) => {
                             return Err(ParsingError::Err(SyntaxError {
-                                reason: String::from(
-                                    "Expected a block after the else keyword",
-                                ),
+                                reason: String::from("Expected a block after the else keyword"),
                                 error_start: wrong_token.position,
                                 error_end: wrong_token.get_end_position(),
                             }));
                         }
                         Err(ParsingError::Unmatched) => {
                             return Err(ParsingError::Err(SyntaxError {
-                                reason: String::from(
-                                    "Expected a block after the else keyword",
-                                ),
+                                reason: String::from("Expected a block after the else keyword"),
                                 error_start: else_token.position,
                                 error_end: else_token.get_end_position(),
                             }));

src/syntax/parsers/expression/mod.rs

@@ -1,6 +1,7 @@
 use super::super::{ast::Expression, ParsingResult};
 use crate::{lexic::token::Token, syntax::parseable::Parseable};
 
+mod array;
 mod comparison;
 mod equality;
 mod factor;
@@ -9,7 +10,6 @@ mod primary;
 mod term;
 mod unary;
 mod utils;
-mod array;
 
 impl<'a> Parseable<'a> for Expression<'a> {
     type Item = Expression<'a>;

src/syntax/parsers/expression/primary.rs

@@ -1,7 +1,10 @@
 use crate::{
     lexic::token::{Token, TokenType},
     syntax::{
-        ast::{Array, Expression}, parseable::Parseable, utils::Tokenizer, ParsingError, ParsingResult,
+        ast::{Array, Expression},
+        parseable::Parseable,
+        utils::Tokenizer,
+        ParsingError, ParsingResult,
     },
 };
 
@@ -9,20 +12,18 @@ use crate::{
 ///
 /// ```ebnf
 /// primary = array
-///         | number 
-///         | string 
-///         | boolean 
-///         | identifier 
+///         | number
+///         | string
+///         | boolean
+///         | identifier
 ///         | ("(", expression, ")");
 /// ```
 pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     // array
     match Array::try_parse(tokens, pos) {
-        Ok((exp, next)) => {
-            return Ok((Expression::Array(exp), next))
-        },
+        Ok((exp, next)) => return Ok((Expression::Array(exp), next)),
         Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
-        Err(_) => {},
+        Err(_) => {}
     }
 
     match tokens.get_significant(pos) {

src/syntax/parsers/for_loop.rs

@@ -0,0 +1,152 @@
+use crate::{
+    error_handling::SyntaxError,
+    lexic::token::{Token, TokenType},
+    syntax::{
+        ast::{loops::ForLoop, Block, Expression, Positionable},
+        parseable::{Parseable, ParsingError, ParsingResult},
+        utils::parse_token_type,
+    },
+};
+
+impl<'a> Parseable<'a> for ForLoop<'a> {
+    type Item = ForLoop<'a>;
+
+    fn try_parse(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<'a, Self::Item> {
+        // for keyword
+        let (for_keyword, next) = match parse_token_type(tokens, current_pos, TokenType::FOR) {
+            Ok(tuple) => tuple,
+            _ => return Err(ParsingError::Unmatched),
+        };
+
+        // first identifier
+        let (first_id, next) = match parse_token_type(tokens, next, TokenType::Identifier) {
+            Ok(t) => t,
+            Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
+            Err(ParsingError::Mismatch(e)) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    error_start: e.position,
+                    error_end: e.get_end_position(),
+                    reason: format!(
+                        "Expected an identifier after the `for` keyword, found {}",
+                        e.value
+                    ),
+                }))
+            }
+            Err(ParsingError::Unmatched) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    error_start: for_keyword.position,
+                    error_end: for_keyword.get_end_position(),
+                    reason: format!("Expected an identifier after the `for` keyword"),
+                }))
+            }
+        };
+
+        // comma and possible second identifier
+        let (second_id, next) = 'block: {
+            // attempt to parse comma
+            let (comma, next) = match parse_token_type(tokens, next, TokenType::Comma) {
+                Ok(t) => t,
+                _ => break 'block (None, next),
+            };
+
+            // parse second id
+            // if this fails then its a syntax error, because a comma was already commited
+            match parse_token_type(&tokens, next, TokenType::Identifier) {
+                Ok((second_id, next)) => (Some(second_id), next),
+                Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
+                Err(ParsingError::Mismatch(t)) => {
+                    return Err(ParsingError::Err(SyntaxError {
+                        error_start: t.position,
+                        error_end: t.get_end_position(),
+                        reason: format!(
+                            "Expected an identifier after the comma, found `{}`",
+                            t.value
+                        ),
+                    }))
+                }
+                Err(ParsingError::Unmatched) => {
+                    return Err(ParsingError::Err(SyntaxError {
+                        error_start: comma.position,
+                        error_end: comma.get_end_position(),
+                        reason: format!("Expected an identifier after the comma"),
+                    }));
+                }
+            }
+        };
+
+        // in keyword
+        let (in_keyword, next) = match parse_token_type(tokens, next, TokenType::IN) {
+            Ok(tuple) => tuple,
+            Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
+            Err(ParsingError::Mismatch(t)) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    error_start: t.position,
+                    error_end: t.get_end_position(),
+                    reason: format!("Expected the `in` keyword, found `{}`", t.value),
+                }))
+            }
+            Err(ParsingError::Unmatched) => {
+                let previous_token = if second_id.is_none() {
+                    first_id
+                } else {
+                    second_id.unwrap()
+                };
+                return Err(ParsingError::Err(SyntaxError {
+                    error_start: previous_token.position,
+                    error_end: previous_token.get_end_position(),
+                    reason: format!("Expected the `in` keyword"),
+                }));
+            }
+        };
+
+        // expression
+        let (expr, next) = match Expression::try_parse(tokens, next) {
+            Ok(t) => t,
+            Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
+            Err(_) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    error_start: in_keyword.position,
+                    error_end: in_keyword.get_end_position(),
+                    reason: format!("Expected an expression after the `in` keyword"),
+                }))
+            }
+        };
+
+        // block
+        let (block, next) = match Block::try_parse(tokens, next) {
+            Ok(t) => t,
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
+            Err(ParsingError::Mismatch(wrong_token)) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    reason: String::from("Expected a block after the collection"),
+                    error_start: wrong_token.position,
+                    error_end: wrong_token.get_end_position(),
+                }));
+            }
+            Err(ParsingError::Unmatched) => {
+                let (error_start, error_end) = expr.get_position();
+                return Err(ParsingError::Err(SyntaxError {
+                    reason: String::from("Expected a block after the collection"),
+                    error_start,
+                    error_end,
+                }));
+            }
+        };
+
+        // return
+        let (key, value) = match second_id {
+            Some(id) => (Some(first_id), id),
+            None => (None, first_id),
+        };
+
+        let (_, loop_end) = block.get_position();
+        let for_loop = ForLoop {
+            loop_start: for_keyword.position,
+            loop_end,
+            key,
+            value,
+            body: block,
+        };
+        Ok((for_loop, next))
+    }
+}

src/syntax/parsers/mod.rs

@@ -1,7 +1,8 @@
 pub mod binding;
 pub mod block;
+pub mod conditional;
 pub mod expression;
+pub mod for_loop;
 pub mod function_declaration;
 pub mod module;
 pub mod statement;
-pub mod conditional;

src/syntax/parsers/statement.rs

@@ -1,7 +1,10 @@
 use crate::{
     lexic::token::Token,
     syntax::{
-        ast::{var_binding::VariableBinding, Conditional, FunctionDeclaration, Statement},
+        ast::{
+            loops::ForLoop, var_binding::VariableBinding, Conditional, FunctionDeclaration,
+            Statement,
+        },
         parseable::{Parseable, ParsingError, ParsingResult},
     },
 };
@@ -41,6 +44,13 @@ impl<'a> Parseable<'a> for Statement<'a> {
             _ => {}
         }
 
+        // Try to parse a for loop
+        match ForLoop::try_parse(tokens, current_pos) {
+            Ok((prod, next)) => return Ok((Statement::ForLoop(prod), next)),
+            Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
+            _ => {}
+        }
+
         // Here nothing was parsed.
         Err(ParsingError::Unmatched)
     }

src/syntax/utils.rs

@@ -85,10 +85,7 @@ pub fn parse_token_type(
 /// Ignores indentation, newlines and comments.
 ///
 /// Only returns: Ok or Unmatched.
-pub fn parse_terminator(
-    tokens: &Vec<Token>,
-    pos: usize,
-) -> ParsingResult<()> {
+pub fn parse_terminator(tokens: &Vec<Token>, pos: usize) -> ParsingResult<()> {
     let mut current_pos = pos;
 
     // Ignore all whitespace, newlines and semicolons