feat: indentation for bypassing statement termination

CHANGELOG.md

@@ -9,6 +9,7 @@
     and a THP ast -> PHP ast process, so that the
     codegen section can focus only in codegen, not in
     translation of thp->php.
+- Ignore indentation where it doesn't matter
 - Parse __more__ binary operators
 - Store tokens for the semantic analysis phase, to have actual error reporting
 - Parse more complex bindings
@@ -31,6 +32,7 @@
 
 - [x] Begin work on a formal grammar
 - [x] Simplify/rewrite AST
+- [x] Properly parse expression indentation/dedentation
 - [x] Define the top level constructs
 - [ ] Include the original tokens in the AST
 - [ ] Finish the workflow for a hello world

src/syntax/parsers/expression/comparison.rs

@@ -3,6 +3,8 @@ use crate::{
     syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
+use super::utils::try_binary_op;
+
 /// Parses a factor expression.
 ///
 /// ```ebnf
@@ -14,44 +16,41 @@ pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
         _ => return Err(ParsingError::Unmatched),
     };
 
-    parse_many(tokens, next_pos, term)
+    parse_many(tokens, next_pos, term, 0)
 }
 
 fn parse_many<'a>(
     tokens: &'a Vec<Token>,
     pos: usize,
     prev_expr: Expression<'a>,
+    indentation_level: u32,
 ) -> ParsingResult<'a, Expression<'a>> {
     // comparison = term, ((">" | ">=" | "<" | "<="), term)*;
+    try_binary_op(
+        tokens,
+        pos,
+        prev_expr,
+        vec![">", ">=", "<", "<="],
+        indentation_level,
+        |tokens, next_pos, prev_expr, token, indent_count: u32| match super::term::try_parse(
+            tokens, next_pos,
+        ) {
+            Ok((expr, next_pos)) => {
+                let expr =
+                    Expression::BinaryOperator(Box::new(prev_expr), Box::new(expr), &token.value);
 
-    match tokens.get(pos) {
-        Some(token)
-            if token.value == "<"
-                || token.value == "<="
-                || token.value == ">"
-                || token.value == ">=" =>
-        {
-            match super::term::try_parse(tokens, pos + 1) {
-                Ok((expr, next_pos)) => {
-                    let expr = Expression::BinaryOperator(
-                        Box::new(prev_expr),
-                        Box::new(expr),
-                        &token.value,
-                    );
-
-                    parse_many(tokens, next_pos, expr)
-                }
-                _ => Err(ParsingError::Unmatched),
+                parse_many(tokens, next_pos, expr, indentation_level + indent_count)
             }
-        }
-        _ => Ok((prev_expr, pos)),
-    }
+            _ => return Err(ParsingError::Unmatched),
+        },
+    )
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::lexic::get_tokens;
+    use crate::lexic::token::TokenType;
 
     #[test]
     fn should_parse_comparison() {
@@ -88,4 +87,80 @@ mod tests {
             _ => panic!("Expected an Unmatched error"),
         }
     }
+
+    #[test]
+    fn should_parse_indented_1() {
+        let tokens = get_tokens(&String::from("a\n  >= b")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(tokens[5].token_type, TokenType::DEDENT);
+        assert_eq!(next, 6);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, ">=")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_2() {
+        let tokens = get_tokens(&String::from("a\n  <= b\n    <= c")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+        assert_eq!(next, 11);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "<=")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_3() {
+        let tokens = get_tokens(&String::from("a\n  <= b <= c")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(tokens[7].token_type, TokenType::DEDENT);
+        assert_eq!(next, 8);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "<=")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_4() {
+        let tokens = get_tokens(&String::from("a\n  <= b\n  <= c")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(next, 9);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "<=")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_5() {
+        let tokens = get_tokens(&String::from("a >=\n  b")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(next, 6);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, ">=")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
 }

src/syntax/parsers/expression/equality.rs

@@ -1,7 +1,10 @@
 use crate::{
-    handle_dedentation, handle_indentation, lexic::token::{Token, TokenType}, syntax::{ast::Expression, ParsingError, ParsingResult}
+    lexic::token::Token,
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
+use super::utils::try_binary_op;
+
 /// Parses a factor expression.
 ///
 /// ```ebnf
@@ -23,50 +26,30 @@ fn parse_many<'a>(
     indentation_level: u32,
 ) -> ParsingResult<'a, Expression<'a>> {
     // equality = comparison, (("==" | "!="), comparison )*;
+    try_binary_op(
+        tokens,
+        pos,
+        prev_expr,
+        vec!["==", "!="],
+        indentation_level,
+        |tokens, next_pos, prev_expr, token, indent_count: u32| match super::comparison::try_parse(
+            tokens, next_pos,
+        ) {
+            Ok((expr, next_pos)) => {
+                let expr =
+                    Expression::BinaryOperator(Box::new(prev_expr), Box::new(expr), &token.value);
 
-    let mut indent_count: u32 = 0;
-    let mut next_pos = pos;
-
-    // Handle possible indentation before binary operator
-    handle_indentation!(tokens, next_pos, indent_count, indentation_level);
-
-    let result = match tokens.get(next_pos) {
-        Some(token) if token.value == "==" || token.value == "!=" => {
-            next_pos += 1;
-            
-            // Handle possible indentation after binary operator
-            handle_indentation!(tokens, next_pos, indent_count, indentation_level);
-
-            match super::comparison::try_parse(tokens, next_pos) {
-                Ok((expr, next_pos)) => {
-                    let expr = Expression::BinaryOperator(
-                        Box::new(prev_expr),
-                        Box::new(expr),
-                        &token.value,
-                    );
-
-                    parse_many(tokens, next_pos, expr, indentation_level + indent_count)
-                }
-                _ => return Err(ParsingError::Unmatched),
+                parse_many(tokens, next_pos, expr, indentation_level + indent_count)
             }
-        }
-        _ => return Ok((prev_expr, pos)),
-    };
-   
-    let (new_expr, mut next_pos) = match result {
-        Ok((e, n)) => (e, n),
-        _ => return result,
-    };
-
-    handle_dedentation!(tokens, next_pos, indent_count);
-
-    Ok((new_expr, next_pos))
+            _ => return Err(ParsingError::Unmatched),
+        },
+    )
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::lexic::get_tokens;
+    use crate::lexic::{get_tokens, token::TokenType};
 
     #[test]
     fn should_parse_comparison() {

src/syntax/parsers/expression/factor.rs

@@ -1,5 +1,8 @@
 use crate::{
-    handle_dedentation, handle_indentation, lexic::token::{Token, TokenType}, syntax::{ast::Expression, ParsingError, ParsingResult}
+    lexic::token::Token,
+    syntax::{
+        ast::Expression, parsers::expression::utils::try_binary_op, ParsingError, ParsingResult,
+    },
 };
 
 /// Parses a factor expression.
@@ -23,20 +26,14 @@ fn parse_many<'a>(
     indentation_level: u32,
 ) -> ParsingResult<'a, Expression<'a>> {
     // (("/" | "*"), unary)*
-
-    let mut indent_count: u32 = 0;
-    let mut next_pos = pos;
-
-    // Handle possible indentation before binary operator
-    handle_indentation!(tokens, next_pos, indent_count, indentation_level);
-
-    let result = match tokens.get(next_pos) {
-        Some(token) if token.value == "/" || token.value == "*" => {
-            next_pos += 1;
-
-            // Handle possible indentation after binary operator
-            handle_indentation!(tokens, next_pos, indent_count, indentation_level);
-
+    try_binary_op(
+        tokens,
+        pos,
+        prev_expr,
+        vec!["/", "*"],
+        indentation_level,
+        |tokens, next_pos, prev_expr, token, indent_count: u32| {
+            // match next
             match super::unary::try_parse(tokens, next_pos) {
                 Ok((expr, next_pos)) => {
                     let expr = Expression::BinaryOperator(
@@ -49,24 +46,14 @@ fn parse_many<'a>(
                 }
                 _ => return Err(ParsingError::Unmatched),
             }
-        }
-        _ => return Ok((prev_expr, pos)),
-    };
-
-    let (new_expr, mut next_pos) = match result {
-        Ok((e, n)) => (e, n),
-        _ => return result,
-    };
-
-    handle_dedentation!(tokens, next_pos, indent_count);
-
-    Ok((new_expr, next_pos))
+        },
+    )
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::lexic::get_tokens;
+    use crate::lexic::{get_tokens, token::TokenType};
 
     #[test]
     fn should_parse_comparison() {

src/syntax/parsers/expression/term.rs

@@ -1,3 +1,4 @@
+use crate::syntax::parsers::expression::utils::try_binary_op;
 use crate::{
     lexic::token::Token,
     syntax::{ast::Expression, ParsingError, ParsingResult},
@@ -14,19 +15,26 @@ pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
         _ => return Err(ParsingError::Unmatched),
     };
 
-    parse_many(tokens, next_pos, factor)
+    parse_many(tokens, next_pos, factor, 0)
 }
 
 fn parse_many<'a>(
     tokens: &'a Vec<Token>,
     pos: usize,
     prev_expr: Expression<'a>,
+    indentation_level: u32,
 ) -> ParsingResult<'a, Expression<'a>> {
     // term = factor, (("-" | "+"), factor)*;
 
-    match tokens.get(pos) {
-        Some(token) if token.value == "+" || token.value == "-" => {
-            match super::factor::try_parse(tokens, pos + 1) {
+    try_binary_op(
+        tokens,
+        pos,
+        prev_expr,
+        vec!["+", "-"],
+        indentation_level,
+        |tokens, pos, prev_expr, token, indent_count: u32| {
+            // Parse the next factor
+            match super::factor::try_parse(tokens, pos) {
                 Ok((expr, next_pos)) => {
                     let expr = Expression::BinaryOperator(
                         Box::new(prev_expr),
@@ -34,19 +42,19 @@ fn parse_many<'a>(
                         &token.value,
                     );
 
-                    parse_many(tokens, next_pos, expr)
+                    parse_many(tokens, next_pos, expr, indentation_level + indent_count)
                 }
-                _ => Err(ParsingError::Unmatched),
+                _ => return Err(ParsingError::Unmatched),
             }
-        }
-        _ => Ok((prev_expr, pos)),
-    }
+        },
+    )
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::lexic::get_tokens;
+    use crate::lexic::token::TokenType;
 
     #[test]
     fn should_parse_comparison() {
@@ -83,4 +91,80 @@ mod tests {
             _ => panic!("Expected an Unmatched error"),
         }
     }
+
+    #[test]
+    fn should_parse_indented_1() {
+        let tokens = get_tokens(&String::from("a\n  + b")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(tokens[5].token_type, TokenType::DEDENT);
+        assert_eq!(next, 6);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "+")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_2() {
+        let tokens = get_tokens(&String::from("a\n  + b\n    + c")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+        assert_eq!(next, 11);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "+")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_3() {
+        let tokens = get_tokens(&String::from("a\n  + b + c")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(tokens[7].token_type, TokenType::DEDENT);
+        assert_eq!(next, 8);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "+")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_4() {
+        let tokens = get_tokens(&String::from("a\n  + b\n  + c")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(next, 9);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "+")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
+
+    #[test]
+    fn should_parse_indented_5() {
+        let tokens = get_tokens(&String::from("a +\n  b")).unwrap();
+        let (result, next) = try_parse(&tokens, 0).unwrap();
+
+        assert_eq!(next, 6);
+
+        match result {
+            Expression::BinaryOperator(_, _, op) => {
+                assert_eq!(op, "+")
+            }
+            _ => panic!("Expected a binary operator"),
+        }
+    }
 }

src/syntax/parsers/expression/utils.rs

@@ -1,43 +1,89 @@
-/// macro for handling indentation in expressions
-#[macro_export]
-macro_rules! handle_indentation {
-    ($tokens: ident, $next_pos: ident, $indent_count: ident, $indentation_level: ident) => {
-        match ($tokens.get($next_pos), $tokens.get($next_pos + 1)) {
-            // New indentation level
-            (Some(t1), Some(t2))
-                if t1.token_type == TokenType::NewLine && t2.token_type == TokenType::INDENT =>
-            {
-                // set indentation
-                $next_pos += 2;
-                $indent_count += 1;
-            }
-            // we are indented, ignore newlines
-            (Some(t), _) if t.token_type == TokenType::NewLine && $indentation_level > 0 => {
-                $next_pos += 1;
-            }
-            // let other handlers handle this
-            _ => {}
-        };
-    };
-}
+use crate::lexic::token::Token;
+use crate::lexic::token::TokenType::{NewLine, DEDENT, INDENT};
+use crate::syntax::ast::Expression;
+use crate::syntax::parseable::ParsingResult;
 
-/// macro for handling dedentation in expressions
-#[macro_export]
-macro_rules! handle_dedentation {
-    ($tokens: ident, $next_pos: ident, $indent_count: ident) => {
-        for _ in 0..$indent_count {
-            // Expect a DEDENT for each indentation matched
-            match $tokens.get($next_pos) {
-                // continue
-                Some(t) if t.token_type == TokenType::DEDENT => {}
-                // This should be unreachable, as the lexer always emits a DEDENT for each INDENT
-                _ => unreachable!(
-                    "Illegal parser state: Expected DEDENT (count: {})",
-                    $indent_count
-                ),
-            };
+/// Parses a binary operator, handles indentation and runs a function on it.
+///
+/// First, handles indentation before the binary operator. Then, tries to
+/// parse the binary operator. Then, handles indentation after the binary
+/// operator.
+///
+/// After this runs the function `fun`. Finishes by handling dedentation
+/// parsed in the previous phase.
+pub fn try_binary_op<'a, F>(
+    tokens: &'a Vec<Token>,
+    original_pos: usize,
+    prev_expr: Expression<'a>,
+    operators: Vec<&str>,
+    indentation_level: u32,
+    fun: F,
+) -> ParsingResult<'a, Expression<'a>>
+where
+    F: FnOnce(
+        &'a Vec<Token>,
+        usize,
+        Expression<'a>,
+        &'a Token,
+        u32,
+    ) -> ParsingResult<'a, Expression<'a>>,
+{
+    let mut indent_count = 0;
+    let pos = original_pos;
 
-            $next_pos += 1;
+    // handle possible opening indentation
+    let pos = match (tokens.get(pos), tokens.get(pos + 1)) {
+        // New indentation level
+        (Some(t1), Some(t2)) if t1.token_type == NewLine && t2.token_type == INDENT => {
+            indent_count += 1;
+            pos + 2
         }
+        // when indented, ignore newlines
+        (Some(t), _) if t.token_type == NewLine && indentation_level > 0 => pos + 1,
+        // let other handlers handle this
+        _ => pos,
     };
+
+    // try to parse any of the binary operators
+    let (matched_token, pos) = match tokens.get(pos) {
+        Some(token) if operators.contains(&token.value.as_str()) => (token, pos + 1),
+        // If not matched, return the existing expression
+        _ => return Ok((prev_expr, original_pos)),
+    };
+
+    // handle possible closing indentation
+    let pos = match (tokens.get(pos), tokens.get(pos + 1)) {
+        // New indentation level
+        (Some(t1), Some(t2)) if t1.token_type == NewLine && t2.token_type == INDENT => {
+            indent_count += 1;
+            pos + 2
+        }
+        // when indented, ignore newlines
+        (Some(t), _) if t.token_type == NewLine && indentation_level > 0 => pos + 1,
+        // let other handlers handle this
+        _ => pos,
+    };
+
+    // run the rest of the logic
+    let (new_expr, mut next_pos) = match fun(tokens, pos, prev_expr, matched_token, indent_count) {
+        Ok((e, n)) => (e, n),
+        x => return x,
+    };
+
+    // handle the possible dedentation before/after the operator
+    for _ in 0..indent_count {
+        // expect a DEDENT for each INDENT matched
+        match tokens.get(next_pos) {
+            // continue
+            Some(t) if t.token_type == DEDENT => {}
+            _ => unreachable!(
+                "Illegal parser state: Expected DEDENT (count: {})",
+                indent_count
+            ),
+        };
+
+        next_pos += 1;
+    }
+
+    Ok((new_expr, next_pos))
 }

src/syntax/utils.rs

@@ -4,8 +4,6 @@ use super::{ParsingError, ParsingResult};
 
 pub trait Tokenizer {
     fn get_significant<'a>(&'a self, index: usize) -> Option<(&'a Token, usize)>;
-
-    fn get_indented<'a>(&'a self, index: usize, indented: bool) -> (Option<&'a Token>, usize);
 }
 
 impl Tokenizer for Vec<Token> {
@@ -30,31 +28,6 @@ impl Tokenizer for Vec<Token> {
             }
         }
     }
-
-    fn get_indented<'a>(&'a self, index: usize, indented: bool) -> (Option<&'a Token>, usize) {
-        if !indented {
-            return (self.get(index), index + 1);
-        }
-
-        let mut current_pos = index;
-
-        // Ignore all whitespace and newlines
-        loop {
-            match self.get(current_pos) {
-                Some(token) => {
-                    if token.token_type == TokenType::INDENT
-                        || token.token_type == TokenType::DEDENT
-                        || token.token_type == TokenType::NewLine
-                    {
-                        current_pos += 1;
-                    } else {
-                        return (Some(token), current_pos);
-                    }
-                }
-                None => return (None, index + 1),
-            }
-        }
-    }
 }
 
 /// Expects the token at `pos` to be an operator of value `operator`. Doesn't ignore whitespace or newlines