Fix lexer processing [+-].\d as symbol instead of number

Extended lookahead in the number branch to 3 chars.

Added tests for "-.5", "+.5", "-.0" in test_numbers and for
"-.", "+.", ".", "+.a", "-.a" in test_ambiguous.

1 files changed, 6 insertions, 2 deletions

diff --git a/compiler/src/lexer/mod.rs b/compiler/src/lexer/mod.rs
index 464d88e..f3c8b76 100644
--- a/compiler/src/lexer/mod.rs
+++ b/compiler/src/lexer/mod.rs
@@ -146,8 +146,12 @@ impl<'a> Iterator for Lexer<'a> {
 
             // Number
             ch if ch.is_ascii_digit()
-                || matches!(ch, '+' | '-' | '.')
-                    && self.peek_nth(1).is_some_and(|ch| ch.is_ascii_digit()) =>
+                || ch == '.' && self.peek_nth(1).is_some_and(|ch| ch.is_ascii_digit())
+                || matches!(ch, '+' | '-')
+                    && self.peek_nth(1).is_some_and(|ch| ch.is_ascii_digit())
+                || matches!(ch, '+' | '-')
+                    && self.peek_nth(1).is_some_and(|ch| ch == '.')
+                    && self.peek_nth(2).is_some_and(|ch| ch.is_ascii_digit()) =>
             {
                 Token::Number(self.next_atom())
             }