Wrap hb_buffer_[s|g]et_cluster_level (#42)

* Wrap hb_buffer_[s|g]et_cluster_level

* Use IntEnum class for cluster level

src/uharfbuzz/_harfbuzz.pyx

@@ -1,4 +1,5 @@
 #cython: language_level=3
+from enum import IntEnum
 from charfbuzz cimport *
 from libc.stdlib cimport free, malloc
 from libc.string cimport const_char
@@ -80,6 +81,13 @@ cdef class GlyphPosition:
         return self._hb_glyph_position.y_offset
 
 
+class BufferClusterLevel(IntEnum):
+    MONOTONE_GRAPHEMES = HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES
+    MONOTONE_CHARACTERS = HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS
+    CHARACTERS = HB_BUFFER_CLUSTER_LEVEL_CHARACTERS
+    DEFAULT = HB_BUFFER_CLUSTER_LEVEL_DEFAULT
+
+
 cdef class Buffer:
     cdef hb_buffer_t* _hb_buffer
     cdef object _message_callback
@@ -173,6 +181,16 @@ cdef class Buffer:
         hb_buffer_set_script(
             self._hb_buffer, hb_script_from_string(cstr, -1))
 
+    @property
+    def cluster_level(self) -> BufferClusterLevel:
+        level = hb_buffer_get_cluster_level(self._hb_buffer)
+        return BufferClusterLevel(level)
+
+    @cluster_level.setter
+    def cluster_level(self, value: BufferClusterLevel):
+        level = BufferClusterLevel(value)
+        hb_buffer_set_cluster_level(self._hb_buffer, level)
+
     def set_language_from_ot_tag(self, value: str):
         cdef bytes packed = value.encode()
         cdef char* cstr = packed

src/uharfbuzz/charfbuzz.pxd

@@ -83,6 +83,12 @@ cdef extern from "hb.h":
         hb_position_t y_offset
         hb_var_int_t var
 
+    ctypedef enum hb_buffer_cluster_level_t:
+        HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES
+        HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS
+        HB_BUFFER_CLUSTER_LEVEL_CHARACTERS
+        HB_BUFFER_CLUSTER_LEVEL_DEFAULT
+
     hb_buffer_t* hb_buffer_create()
     hb_bool_t hb_buffer_allocation_successful(hb_buffer_t* buffer)
     void hb_buffer_add_codepoints(
@@ -116,6 +122,9 @@ cdef extern from "hb.h":
     void hb_buffer_set_script(hb_buffer_t* buffer, hb_script_t script)
     hb_language_t hb_buffer_get_language(hb_buffer_t* buffer)
     void hb_buffer_set_language(hb_buffer_t* buffer, hb_language_t language)
+    void hb_buffer_set_cluster_level(hb_buffer_t *buffer,
+        hb_buffer_cluster_level_t cluster_level)
+    hb_buffer_cluster_level_t hb_buffer_get_cluster_level(hb_buffer_t *buffer)
     void hb_buffer_destroy(hb_buffer_t* buffer)
     ctypedef hb_bool_t (*hb_buffer_message_func_t) (
         hb_buffer_t *buffer,

tests/test_uharfbuzz.py

@@ -92,6 +92,36 @@ def test_guess_set_segment_properties(self):
         buf.set_language_from_ot_tag("BGR")
         assert buf.language == "bg"
 
+    def test_cluster_level(self):
+        buf = hb.Buffer()
+
+        assert buf.cluster_level == hb.BufferClusterLevel.DEFAULT
+
+        buf.cluster_level = hb.BufferClusterLevel.MONOTONE_CHARACTERS
+        assert buf.cluster_level == hb.BufferClusterLevel.MONOTONE_CHARACTERS
+
+        buf.cluster_level = hb.BufferClusterLevel.MONOTONE_GRAPHEMES
+        assert buf.cluster_level == hb.BufferClusterLevel.MONOTONE_GRAPHEMES
+
+        buf.cluster_level = hb.BufferClusterLevel.CHARACTERS
+        assert buf.cluster_level == hb.BufferClusterLevel.CHARACTERS
+
+        buf.cluster_level = hb.BufferClusterLevel.DEFAULT
+        assert buf.cluster_level == hb.BufferClusterLevel.DEFAULT
+
+    def test_cluster_level_int(self):
+        buf = hb.Buffer()
+
+        assert buf.cluster_level == 0
+
+        buf.cluster_level = 1
+        assert buf.cluster_level == 1
+
+        with pytest.raises(ValueError):
+            # 5 is not a valid BufferClusterLevel
+            buf.cluster_level = 5
+        assert buf.cluster_level == 1
+
 
 class TestShape:
     @pytest.mark.parametrize(