Add validation for Pango Markup - Fixes #8

manimpango/cmanimpango.pxd

@@ -2,6 +2,7 @@ cdef extern from "glib.h":
     ctypedef void* gpointer
     ctypedef int gint
     ctypedef unsigned int guint
+    ctypedef unsigned int guint32
     ctypedef gint gboolean
     ctypedef unsigned short guint16
     void g_object_unref(gpointer object)
@@ -34,6 +35,17 @@ cdef extern from "cairo-svg.h":
         double	height_in_points
     )
 
+cdef extern from "pango/pango-attributes.h":
+    gboolean pango_parse_markup(
+       const char *markup_text,
+       int length,
+       void* accel_marker,
+       void* attr_list,
+       void* text,
+       void* accel_char,
+       void* error
+    )
+
 cdef extern from "pango/pangocairo.h":
     int PANGO_SCALE
     int pango_units_from_double(double d)

manimpango/cmanimpango.pyx

@@ -264,6 +264,11 @@ def text2svg(
     return file_name
 
 class MarkupUtils:
+    @staticmethod
+    def validate(text: str) -> bool:
+       text_bytes = text.encode("utf-8")
+       return pango_parse_markup(text_bytes, len(text_bytes), NULL, NULL, NULL, NULL, NULL)
+
     @staticmethod
     def text2svg(
         text: str,

tests/test_markup.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+def test_good_markup():
+    import manimpango  # noqa: F401
+
+    assert manimpango.MarkupUtils.validate(
+        "foo"
+    ), '"foo" should not fail validation'
+    assert manimpango.MarkupUtils.validate(
+        "<b>bar</b>"
+    ), '"<b>bar</b>" should not fail validation'
+
+
+def test_bad_markup():
+    import manimpango  # noqa: F401
+
+    assert not manimpango.MarkupUtils.validate(
+        "<b>foo"
+    ), '"<b>foo" should fail validation (unbalanced tags)'
+    assert not manimpango.MarkupUtils.validate(
+        "<xyz>foo</xyz>"
+    ), '"<xyz>foo</xyz>" should fail validation (invalid tag)'