feat: parse conditionals

CHANGELOG.md

@@ -19,6 +19,10 @@
 - Begin work on the code formatter
 - Remove all panic! and todo!
 
+## v0.1.2
+
+- [x] Parse conditionals
+
 
 ## v0.1.1
 

src/lexic/scanner/identifier.rs

@@ -7,6 +7,8 @@ fn str_is_keyword(s: &String) -> Option<TokenType> {
         "val" => Some(TokenType::VAL),
         "var" => Some(TokenType::VAR),
         "fun" => Some(TokenType::FUN),
+        "if" => Some(TokenType::IF),
+        "else" => Some(TokenType::ELSE),
         _ => None,
     }
 }

src/lexic/token.rs

@@ -24,6 +24,8 @@ pub enum TokenType {
     VAR,
     EOF,
     FUN,
+    IF,
+    ELSE,
 }
 
 #[derive(Serialize, Debug, Clone, PartialEq)]

src/semantic/checks/function_declaration.rs

@@ -49,6 +49,7 @@ impl SemanticCheck for FunctionDeclaration<'_> {
 
                     return Err(MistiError::Semantic(error));
                 }
+                BlockMember::Stmt(Statement::Conditional(_)) => unimplemented!("check conditional"),
                 BlockMember::Expr(e) => e.check_semantics(scope)?,
             }
         }

src/semantic/checks/top_level_declaration.rs

@@ -22,6 +22,7 @@ impl SemanticCheck for Statement<'_> {
         match self {
             Statement::Binding(b) => b.check_semantics(scope),
             Statement::FnDecl(f) => f.check_semantics(scope),
+            Statement::Conditional(_) => unimplemented!("check conditional"),
         }
     }
 }

src/syntax/ast/mod.rs

@@ -31,8 +31,24 @@ pub enum ModuleMembers<'a> {
 pub enum Statement<'a> {
     Binding(VariableBinding<'a>),
     FnDecl(FunctionDeclaration<'a>),
+    // TODO: Implement conditionals as expressions
+    Conditional(Conditional<'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>>
+}
+
+#[derive(Debug)]
+pub struct Condition<'a> {
+    pub condition: Expression<'a>,
+    pub body: Block<'a>,
+}
+
+
 #[derive(Debug)]
 pub struct FunctionDeclaration<'a> {
     pub identifier: &'a Token,

src/syntax/parsers/conditional.rs

@@ -0,0 +1,181 @@
+use crate::{
+    error_handling::SyntaxError,
+    lexic::token::{Token, TokenType},
+    syntax::{
+        ast::{Block, Condition, Conditional, Expression, Positionable},
+        parseable::{Parseable, ParsingError, ParsingResult},
+        utils::parse_token_type,
+    },
+};
+
+impl<'a> Parseable<'a> for Conditional<'a> {
+    type Item = Conditional<'a>;
+
+    fn try_parse(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<'a, Self::Item> {
+        // if keyword
+        let (if_token, next) = match parse_token_type(tokens, current_pos, TokenType::IF) {
+            Ok(tuple) => tuple,
+            _ => return Err(ParsingError::Unmatched),
+        };
+
+        // if condition
+        let (if_expression, next) = match Expression::try_parse(tokens, next) {
+            Ok(tuple) => tuple,
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
+            Err(ParsingError::Mismatch(wrong_token)) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    reason: String::from("Expected an expression after the if token"),
+                    error_start: wrong_token.position,
+                    error_end: wrong_token.get_end_position(),
+                }));
+            }
+            Err(ParsingError::Unmatched) => {
+                return Err(ParsingError::Err(SyntaxError {
+                    reason: String::from("Expected an expression after the if token"),
+                    error_start: if_token.position,
+                    error_end: if_token.get_end_position(),
+                }));
+            }
+        };
+
+        // if block
+        let (if_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 condition"),
+                    error_start: wrong_token.position,
+                    error_end: wrong_token.get_end_position(),
+                }));
+            }
+            Err(ParsingError::Unmatched) => {
+                let (error_start, error_end) = if_expression.get_position();
+                return Err(ParsingError::Err(SyntaxError {
+                    reason: String::from("Expected a block after the condition"),
+                    error_start,
+                    error_end,
+                }));
+            }
+        };
+
+        let mut else_if_members = Vec::<Condition>::new();
+        let mut current_pos = next;
+        let tokens_len = tokens.len();
+
+        // many else if
+        while current_pos < tokens_len {
+            // else token
+            let (_, next) = match parse_token_type(tokens, current_pos, TokenType::ELSE) {
+                Ok(tuple) => tuple,
+                _ => {
+                    break;
+                }
+            };
+
+            // if token
+            let (if_token, next) = match parse_token_type(tokens, next, TokenType::IF) {
+                Ok(tuple) => tuple,
+                // This might be a else {}, not a else if {}
+                _ => {
+                    break;
+                }
+            };
+
+            // condition
+            let (condition, next) = match Expression::try_parse(tokens, next) {
+                Ok(tuple) => tuple,
+                Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
+                Err(ParsingError::Mismatch(wrong_token)) => {
+                    return Err(ParsingError::Err(SyntaxError {
+                        reason: String::from("Expected an expression after the if token"),
+                        error_start: wrong_token.position,
+                        error_end: wrong_token.get_end_position(),
+                    }));
+                }
+                Err(ParsingError::Unmatched) => {
+                    return Err(ParsingError::Err(SyntaxError {
+                        reason: String::from("Expected an expression after the if token"),
+                        error_start: if_token.position,
+                        error_end: if_token.get_end_position(),
+                    }));
+                }
+            };
+
+            // 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 condition"),
+                        error_start: wrong_token.position,
+                        error_end: wrong_token.get_end_position(),
+                    }));
+                }
+                Err(ParsingError::Unmatched) => {
+                    let (error_start, error_end) = condition.get_position();
+                    return Err(ParsingError::Err(SyntaxError {
+                        reason: String::from("Expected a block after the condition"),
+                        error_start,
+                        error_end,
+                    }));
+                }
+            };
+
+            else_if_members.push(Condition {
+                condition,
+                body: block,
+            });
+
+            current_pos = next;
+        }
+
+        // else
+        let (else_block, next) = {
+            match parse_token_type(tokens, current_pos, TokenType::ELSE) {
+                Ok((else_token, next)) => {
+                    // 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 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",
+                                ),
+                                error_start: else_token.position,
+                                error_end: else_token.get_end_position(),
+                            }));
+                        }
+                    };
+
+                    (Some(block), next)
+                }
+                _ => (None, current_pos),
+            }
+        };
+
+        // return
+
+        let result = Conditional {
+            if_member: Condition {
+                condition: if_expression,
+                body: if_block,
+            },
+            else_if_members,
+            else_block,
+        };
+
+        Ok((result, next))
+    }
+}

src/syntax/parsers/mod.rs

@@ -4,3 +4,4 @@ pub mod expression;
 pub mod function_declaration;
 pub mod module;
 pub mod statement;
+pub mod conditional;

src/syntax/parsers/statement.rs

@@ -1,15 +1,15 @@
-use crate::syntax::{
-    ast::{var_binding::VariableBinding, FunctionDeclaration, Statement},
-    parseable::{Parseable, ParsingError},
+use crate::{
+    lexic::token::Token,
+    syntax::{
+        ast::{var_binding::VariableBinding, Conditional, FunctionDeclaration, Statement},
+        parseable::{Parseable, ParsingError, ParsingResult},
+    },
 };
 
 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> {
+    fn try_parse(tokens: &'a Vec<Token>, current_pos: usize) -> ParsingResult<'a, Self::Item> {
         // Try to parse a variable binding
         match VariableBinding::try_parse(tokens, current_pos) {
             Ok((prod, next)) => {
@@ -34,6 +34,13 @@ impl<'a> Parseable<'a> for Statement<'a> {
             _ => {}
         }
 
+        // Try to parse a conditional
+        match Conditional::try_parse(tokens, current_pos) {
+            Ok((prod, next)) => return Ok((Statement::Conditional(prod), next)),
+            Err(ParsingError::Err(e)) => return Err(ParsingError::Err(e)),
+            _ => {}
+        }
+
         // Here nothing was parsed.
         Err(ParsingError::Unmatched)
     }