From c70689ee2e09dbeccbef9948cc3b60e02493a549 Mon Sep 17 00:00:00 2001
From: Stanislav <vissi@vissi.su>
Date: Fri, 16 Oct 2026 02:51:03 +0400
Subject: [PATCH] Mark EmptySmallCircle, EmptySet and eight other shapes as
 letter-like

WMA documents EmptyCircle, EmptyDiamond, EmptyDownTriangle,
EmptyRectangle, EmptySet, EmptySmallCircle, EmptySmallSquare,
EmptySquare, EmptyUpTriangle and FilledDiamond as "Letter-like form"
(e.g. EmptySmallCircle: "Not the same as the infix operator
\[SmallCircle]"). Here they were neither letter-like nor operators, so
the tokeniser rejected them: Infix[t, \[EmptySmallCircle]] was a syntax
error.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 mathics_scanner/data/named-characters.yml | 20 ++++++++++----------
 test/test_tokeniser.py                    | 22 ++++++++++++++++++++++
 2 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/mathics_scanner/data/named-characters.yml b/mathics_scanner/data/named-characters.yml
index 689ce0b..3f09662 100644
--- a/mathics_scanner/data/named-characters.yml
+++ b/mathics_scanner/data/named-characters.yml
@@ -3532,7 +3532,7 @@ Ellipsis:
 EmptyCircle:
   esc-alias: eci
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25CB"
   unicode-equivalent-name: WHITE CIRCLE
   unicode-reference: https://www.compart.com/en/unicode/U+25CB
@@ -3542,7 +3542,7 @@ EmptyCircle:
 
 EmptyDiamond:
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25C7"
   unicode-equivalent-name: WHITE DIAMOND
   unicode-reference: https://www.compart.com/en/unicode/U+25C7
@@ -3552,7 +3552,7 @@ EmptyDiamond:
 
 EmptyDownTriangle:
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25BD"
   unicode-equivalent-name: WHITE DOWN-POINTING TRIANGLE
   unicode-reference: https://www.compart.com/en/unicode/U+25BD
@@ -3562,7 +3562,7 @@ EmptyDownTriangle:
 
 EmptyRectangle:
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25AF"
   unicode-equivalent-name: WHITE VERTICAL RECTANGLE
   unicode-reference: https://www.compart.com/en/unicode/U+25AF
@@ -3574,7 +3574,7 @@ EmptySet:
   amslatex: '\varnothing'
   esc-alias: es
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u2205"
   unicode-equivalent-name: EMPTY SET
   unicode-reference: https://www.compart.com/en/unicode/U+2205
@@ -3585,7 +3585,7 @@ EmptySet:
 EmptySmallCircle:
   esc-alias: esci
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25E6"
   unicode-equivalent-name: WHITE BULLET
   unicode-reference: https://www.compart.com/en/unicode/U+25E6
@@ -3596,7 +3596,7 @@ EmptySmallCircle:
 EmptySmallSquare:
   esc-alias: essq
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25FB"
   unicode-equivalent-name: WHITE MEDIUM SQUARE
   unicode-reference: https://www.compart.com/en/unicode/U+25FB
@@ -3607,7 +3607,7 @@ EmptySmallSquare:
 EmptySquare:
   esc-alias: esq
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25A1"
   unicode-equivalent-name: WHITE SQUARE
   unicode-reference: https://www.compart.com/en/unicode/U+25A1
@@ -3617,7 +3617,7 @@ EmptySquare:
 
 EmptyUpTriangle:
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25B3"
   unicode-equivalent-name: WHITE UP-POINTING TRIANGLE
   unicode-reference: https://www.compart.com/en/unicode/U+25B3
@@ -3841,7 +3841,7 @@ FilledCircle:
 
 FilledDiamond:
   has-unicode-inverse: false
-  is-letter-like: false
+  is-letter-like: true
   unicode-equivalent: "\u25C6"
   unicode-equivalent-name: BLACK DIAMOND
   unicode-reference: https://www.compart.com/en/unicode/U+25C6
diff --git a/test/test_tokeniser.py b/test/test_tokeniser.py
index d9264ad..b895878 100644
--- a/test/test_tokeniser.py
+++ b/test/test_tokeniser.py
@@ -191,6 +191,28 @@ def test_backslash_named_character():
     incomplete_error("\\")
 
 
+@pytest.mark.parametrize(
+    "name",
+    [
+        "EmptyCircle",
+        "EmptyDiamond",
+        "EmptyDownTriangle",
+        "EmptyRectangle",
+        "EmptySet",
+        "EmptySmallCircle",
+        "EmptySmallSquare",
+        "EmptySquare",
+        "EmptyUpTriangle",
+        "FilledDiamond",
+    ],
+)
+def test_letterlike_geometric_shapes(name):
+    r"""WMA documents these as "Letter-like form", so they can stand alone
+    as a symbol, e.g. Infix[t, \[EmptySmallCircle]]."""
+    assert tags(rf"\[{name}]") == ["Symbol"]
+    assert tags(rf"f[x, \[{name}]]") == tags("f[x, y]")
+
+
 def test_boxes():
     assert tokens("\\(1\\)") == [
         Token("LeftRowBox", "\\(", 0),