Implement compose table iterator

Added in libxkbcommon-1.6.0

Author: sde1000

tests/test_xkb.py

@@ -598,9 +598,25 @@ class TestCompose(TestCase):
     @classmethod
     def setUpClass(cls):
         ctx = xkb.Context()
-        ct = ctx.compose_table_new_from_buffer(
+        cls.ct = ctx.compose_table_new_from_buffer(
             sample_compose_bytes, "en_US.UTF-8")
-        cls.compose = ct.compose_state_new()
+        cls.compose = cls.ct.compose_state_new()
+
+    def test_compose_table_iterator(self):
+        # Our sample compose table has 5125 entries
+        self.assertEqual(len(list(self.ct)), 5125)
+
+        # Check that we can find the compose sequence DEAD_TILDE,
+        # DEAD_HORN, O and its results
+        seq = (self.XKB_KEYSYM_DEAD_TILDE, self.XKB_KEYSYM_DEAD_HORN,
+               self.XKB_KEYSYM_O)
+        for te in self.ct:
+            if te.sequence == seq:
+                self.assertEqual(te.keysym, self.XKB_KEYSYM_OHORNTILDE)
+                self.assertEqual(te.utf8, self.UTF8_OHORNTILDE)
+                break
+        else:
+            self.fail("Did not find test sequence in compose table")
 
     def test_compose_initial_status(self):
         self.compose.reset()

xkbcommon/ffi_build.py

@@ -1,7 +1,7 @@
 from cffi import FFI
 ffibuilder = FFI()
 
-# Currently implemented with reference to libxkbcommon-1.5.0
+# Currently implemented with reference to libxkbcommon-1.6.0
 
 ffibuilder.set_source("xkbcommon._ffi", """
 #include <stdarg.h>
@@ -443,6 +443,29 @@
 void
 xkb_compose_table_unref(struct xkb_compose_table *table);
 
+struct xkb_compose_table_entry;
+
+const xkb_keysym_t *
+xkb_compose_table_entry_sequence(struct xkb_compose_table_entry *entry,
+                                 size_t *sequence_length);
+
+xkb_keysym_t
+xkb_compose_table_entry_keysym(struct xkb_compose_table_entry *entry);
+
+const char *
+xkb_compose_table_entry_utf8(struct xkb_compose_table_entry *entry);
+
+struct xkb_compose_table_iterator;
+
+struct xkb_compose_table_iterator *
+xkb_compose_table_iterator_new(struct xkb_compose_table *table);
+
+void
+xkb_compose_table_iterator_free(struct xkb_compose_table_iterator *iter);
+
+struct xkb_compose_table_entry *
+xkb_compose_table_iterator_next(struct xkb_compose_table_iterator *iter);
+
 enum xkb_compose_state_flags {
     XKB_COMPOSE_STATE_NO_FLAGS = ...
 };

xkbcommon/xkb.py

@@ -1,6 +1,8 @@
 import enum
 import mmap
 import sys
+from dataclasses import dataclass
+from typing import Tuple
 
 from xkbcommon._ffi import ffi, lib
 
@@ -115,6 +117,11 @@ class XKBComposeTableCreationFailure(XKBError):
     pass
 
 
+class XKBComposeTableIteratorCreationFailure(XKBError):
+    """Unable to create a compose table iterator."""
+    pass
+
+
 class XKBComposeStateCreationFailure(XKBError):
     """Unable to create a compose state."""
     pass
@@ -1266,8 +1273,29 @@ def __init__(self, context, pointer, load_method):
         self._table = ffi.gc(
             pointer, _keepref(lib, lib.xkb_compose_table_unref))
 
-    # Methods to access and iterate over the compose table will be
-    # added for release 1.6
+    def __iter__(self):
+        local_lib = lib
+        iterator = local_lib.xkb_compose_table_iterator_new(self._table)
+        if not iterator:
+            raise XKBComposeTableIteratorCreationFailure()
+        # This allocates a single size_t
+        sequence_length_ptr = ffi.new("size_t *")
+        try:
+            while True:
+                entry = local_lib.xkb_compose_table_iterator_next(iterator)
+                if entry == ffi.NULL:
+                    return
+                sequence = local_lib.xkb_compose_table_entry_sequence(
+                    entry, sequence_length_ptr)
+                keysym = local_lib.xkb_compose_table_entry_keysym(entry)
+                utf8 = local_lib.xkb_compose_table_entry_utf8(entry)
+                yield ComposeTableEntry(
+                    sequence=tuple(sequence[0:sequence_length_ptr[0]]),
+                    keysym=keysym,
+                    string=ffi.string(utf8).decode('utf8'))
+        finally:
+            del sequence_length_ptr
+            local_lib.xkb_compose_table_iterator_free(iterator)
 
     def compose_state_new(self, flags=None):
         pointer = lib.xkb_compose_state_new(self._table, flags if flags else 0)
@@ -1277,6 +1305,29 @@ def compose_state_new(self, flags=None):
         return ComposeState(self, pointer)
 
 
+@dataclass
+class ComposeTableEntry:
+    """A Compose table entry
+
+    Enables access to the left-hand keysym sequence, right-hand result
+    keysym and right-hand result string of a compose table entry.
+
+    Do not instantiate this object directly. Instead, obtain a compose
+    table iterator by calling iter() on a ComposeTable; the iterator
+    will yield ComposeTableEntry instances
+    """
+    sequence: Tuple[int]
+    keysym: int
+    string: str
+
+    # Someone reading the libxkbcommon documentation may expect the
+    # right hand result string to be called "utf8". This is just an
+    # alias.
+    @property
+    def utf8(self):
+        return self.string
+
+
 class ComposeState:
     """A Compose state object.
 
@@ -1366,6 +1417,19 @@ def get_utf8(self):
         lib.xkb_compose_state_get_utf8(self._state, buffer, buffer_size)
         return ffi.string(buffer).decode("utf8")
 
+    # This is an alias for get_utf8() — the name is more logical but
+    # may be unexpected to somebody just reading the libxkbcommon
+    # documentation
+    def get_string(self):
+        """Get the result string for a compose sequence.
+
+        This function is only useful when the status is
+        ComposeStatus.XKB_COMPOSE_COMPOSED.
+
+        Returns string for composed sequence or empty string if not viable.
+        """
+        return self.get_utf8()
+
     def get_one_sym(self):
         """Get the result keysym for a composed sequence.