From e6440123eeb234ccb02e419816623f34f927759a Mon Sep 17 00:00:00 2001
From: "Guillem L. Jara" <4lon3ly0@tutanota.com>
Date: Mon, 4 May 2026 18:46:24 +0200
Subject: [PATCH] Revert "parser, lexer: solve function call ambiguity"

This reverts commit 5213c1e6fba7428b6c4eb823a3537ede46492650.
---
 lexer/src/lib.rs  | 15 ++++++---------
 parser/src/lex.rs |  6 ++----
 parser/src/lib.rs | 28 +++++++++++++++-------------
 3 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/lexer/src/lib.rs b/lexer/src/lib.rs
index c5ae782..cc8de2d 100644
--- a/lexer/src/lib.rs
+++ b/lexer/src/lib.rs
@@ -126,12 +126,9 @@ pub enum Token<'a> {
     RlengthVariable,
     #[token("ENVIRON", accept_expression)]
     EnvironVariable,
-    #[regex("(?&identifier)", |lex| Identifier::without_namespace::<0>(lex))]
-    #[regex(r"(?&identifier)::(?&identifier)", |lex| Identifier::with_namespace::<0>(lex))]
+    #[regex("(?&identifier)", Identifier::without_namespace)]
+    #[regex(r"(?&identifier)::(?&identifier)", Identifier::with_namespace)]
     Identifier(Identifier<'a>),
-    #[regex(r"(?&identifier)\(", |lex| Identifier::without_namespace::<1>(lex))]
-    #[regex(r"(?&identifier)::(?&identifier)\(", |lex| Identifier::with_namespace::<1>(lex))]
-    FunctionCall(Identifier<'a>),
     #[token("+", accept_expression)]
     Plus,
     #[token("-", accept_expression)]
@@ -379,19 +376,19 @@ fn parse_float(lex: &mut Lexer<'_>) -> f64 {
 }
 
 impl<'a> Identifier<'a> {
-    fn without_namespace<const TRIM: usize>(lex: &mut Lexer<'a>) -> Self {
+    fn without_namespace(lex: &mut Lexer<'a>) -> Self {
         Self {
             namespace: None,
-            literal: parse_ident(lex, ..lex.slice().len() - TRIM),
+            literal: parse_ident(lex, ..),
         }
     }
 
-    fn with_namespace<const TRIM: usize>(lex: &mut Lexer<'a>) -> Self {
+    fn with_namespace(lex: &mut Lexer<'a>) -> Self {
         // SAFETY: The regex matching ensures it is present and well-formed.
         let separator = unsafe { memchr(b':', lex.slice()).unwrap_unchecked() };
         Self {
             namespace: Some(parse_ident(lex, ..separator)),
-            literal: parse_ident(lex, separator + 2..lex.slice().len() - TRIM),
+            literal: parse_ident(lex, separator + 2..),
         }
     }
 }
diff --git a/parser/src/lex.rs b/parser/src/lex.rs
index c7c991b..94eecda 100644
--- a/parser/src/lex.rs
+++ b/parser/src/lex.rs
@@ -190,10 +190,8 @@ impl TokenExt for Token<'_> {
     fn is_expr_start(&self) -> bool {
         self.is_atom()
             || self.is_prefix_op()
-            || matches!(
-                self,
-                Token::OpenParent | Token::FunctionCall(_) | Token::Getline
-            )
+            || self == &Token::OpenParent
+            || self == &Token::Getline
     }
     fn is_place(&self) -> bool {
         matches!(
diff --git a/parser/src/lib.rs b/parser/src/lib.rs
index 688e371..6c89920 100644
--- a/parser/src/lib.rs
+++ b/parser/src/lib.rs
@@ -465,17 +465,7 @@ impl<'a> Parser<'a> {
 
     #[tracing::instrument]
     fn parse_function(&mut self, lex: &mut Lexer<'a>) -> Result<()> {
-        let name = match lex.expect_next()? {
-            Token::FunctionCall(ident) => ident,
-            Token::Identifier(ident) => {
-                lex.expect(&Token::OpenParent, |span| {
-                    ParsingError::NoFunctionSignature(span, ident.literal.to_string())
-                })?;
-                ident
-            }
-            _ => return Err(ParsingError::ExpectedIdentifier(lex.span())),
-        }
-        .qualify(self.namespace);
+        let name = lex.expect_identifier()?.qualify(self.namespace);
         let args = self.parse_signature(lex, &name)?;
         lex.consume(&Token::Newline);
         let body = self.parse_body(lex)?;
@@ -491,6 +481,9 @@ impl<'a> Parser<'a> {
         name: &Identifier<'a>,
     ) -> Result<Vec<'a, Identifier<'a>>> {
         let mut args = Vec::new_in(self.arena);
+        lex.expect(&Token::OpenParent, |s| {
+            ParsingError::NoFunctionSignature(s, name.to_string())
+        })?;
 
         if lex.consume(&Token::ClosedParent) {
             return Ok(args);
@@ -574,7 +567,10 @@ impl<'a> Parser<'a> {
             }
         } else {
             let next = lex.expect_next()?;
-            if let Token::FunctionCall(name) = next {
+            if let Token::Identifier(name) = next
+                && lex.peek_is(&Token::OpenParent)
+            {
+                // TODO: use spans to check there is no space between ident, (.
                 self.parse_function_call(lex, name.qualify(self.namespace), lex.span())?
             } else {
                 Expr::leaf(self.parse_atom(lex, next)?)
@@ -695,6 +691,10 @@ impl<'a> Parser<'a> {
         name: Identifier<'a>,
         span: Span,
     ) -> Result<Expr<'a>> {
+        lex.expect(&Token::OpenParent, ParsingError::ExpectedOpeningParenthesis)?;
+        if lex.span().start != span.end {
+            return Err(ParsingError::FunctionCallSeparatedIdent(span));
+        }
         let expr = ExprNode::FunctionCall(
             name,
             self.parse_arguments(lex, |t| t == &Token::ClosedParent)?,
@@ -724,7 +724,9 @@ impl<'a> Parser<'a> {
     #[tracing::instrument]
     fn get_place(&self, lex: &mut Lexer<'a>, token: Token<'a>) -> Option<Variable<'a>> {
         match token {
-            Token::Identifier(a) => Some(a.qualify(self.namespace).into()),
+            Token::Identifier(a) if !lex.peek_is(&Token::OpenParent) => {
+                Some(a.qualify(self.namespace).into())
+            }
             Token::NrVariable => Some(Variable::Nr),
             Token::NfVariable => Some(Variable::Nf),
             Token::FsVariable => Some(Variable::Fs),