Add set and lookup glyph collection to C API

harfrust_capi/README.md

@@ -118,8 +118,8 @@ HarfRust is a shaping library, so anything outside shaping is absent:
 
 - Drawing and painting callbacks (`hb_draw_funcs_t`, `hb_paint_funcs_t`).
 - Subsetting.
-- Other layout table introspection (`hb_ot_layout_*`), and the `hb_set` /
-  `hb_map` containers it reports through.
+- Layout queries beyond the available GSUB/GPOS presence, lookup count, and
+  glyph collection functions; and the `hb_map` container.
 - Custom Unicode callbacks (`hb_unicode_funcs_t`); HarfRust's own Unicode data
   is always used.
 - `hb_buffer_diff`, buffer message callbacks, and `hb_font_get_glyph_name`.

harfrust_capi/include/hr-hb.h

@@ -211,6 +211,10 @@
 #define hb_ot_layout_get_baseline_with_fallback          hr_ot_layout_get_baseline_with_fallback
 #define hb_ot_layout_get_baseline_with_fallback2         hr_ot_layout_get_baseline_with_fallback2
 #define hb_ot_layout_get_horizontal_baseline_tag_for_script hr_ot_layout_get_horizontal_baseline_tag_for_script
+#define hb_ot_layout_has_positioning                     hr_ot_layout_has_positioning
+#define hb_ot_layout_has_substitution                    hr_ot_layout_has_substitution
+#define hb_ot_layout_lookup_collect_glyphs               hr_ot_layout_lookup_collect_glyphs
+#define hb_ot_layout_table_get_lookup_count              hr_ot_layout_table_get_lookup_count
 #define hb_ot_math_constant_t                            hr_ot_math_constant_t
 #define hb_ot_math_get_constant                          hr_ot_math_get_constant
 #define hb_ot_math_get_glyph_assembly                    hr_ot_math_get_glyph_assembly
@@ -238,6 +242,17 @@
 #define hb_segment_properties_hash                       hr_segment_properties_hash
 #define hb_segment_properties_overlay                    hr_segment_properties_overlay
 #define hb_segment_properties_t                          hr_segment_properties_t
+#define hb_set_add                                       hr_set_add
+#define hb_set_clear                                     hr_set_clear
+#define hb_set_create                                    hr_set_create
+#define hb_set_destroy                                   hr_set_destroy
+#define hb_set_get_empty                                 hr_set_get_empty
+#define hb_set_get_user_data                             hr_set_get_user_data
+#define hb_set_has                                       hr_set_has
+#define hb_set_is_empty                                  hr_set_is_empty
+#define hb_set_reference                                 hr_set_reference
+#define hb_set_set_user_data                             hr_set_set_user_data
+#define hb_set_t                                         hr_set_t
 #define hb_shape                                         hr_shape
 #define hb_shape_full                                    hr_shape_full
 #define hb_shape_list_shapers                            hr_shape_list_shapers

harfrust_capi/include/hr.h

@@ -87,6 +87,8 @@ typedef struct hr_font_t hr_font_t;
  */
 typedef struct hr_language_impl_t hr_language_impl_t;
 
+typedef struct hr_set_t hr_set_t;
+
 /**
  * A reusable plan for shaping text with given properties.
  */
@@ -3486,6 +3488,45 @@ void hr_font_funcs_set_glyph_extents_func(struct hr_font_funcs_t *ffuncs,
                                           void *user_data,
                                           hr_destroy_func_t destroy);
 
+/**
+ * Returns whether the face has a readable GSUB table.
+ *
+ * # Safety
+ * `face` must be `NULL` or live.
+ */
+hr_bool_t hr_ot_layout_has_substitution(struct hr_face_t *face);
+
+/**
+ * Returns whether the face has a readable GPOS table.
+ *
+ * # Safety
+ * `face` must be `NULL` or live.
+ */
+hr_bool_t hr_ot_layout_has_positioning(struct hr_face_t *face);
+
+/**
+ * Returns the number of lookups in GSUB or GPOS.
+ *
+ * # Safety
+ * `face` must be `NULL` or live.
+ */
+unsigned int hr_ot_layout_table_get_lookup_count(struct hr_face_t *face, hr_tag_t table_tag);
+
+/**
+ * Collects glyphs touched by one GSUB or GPOS lookup into the supplied sets.
+ * Forms not yet enumerated conservatively include every OpenType glyph ID.
+ *
+ * # Safety
+ * `face` and each non-`NULL` set must be live. Output sets may be the same.
+ */
+void hr_ot_layout_lookup_collect_glyphs(struct hr_face_t *face,
+                                        hr_tag_t table_tag,
+                                        unsigned int lookup_index,
+                                        struct hr_set_t *glyphs_before,
+                                        struct hr_set_t *glyphs_input,
+                                        struct hr_set_t *glyphs_after,
+                                        struct hr_set_t *glyphs_output);
+
 /**
  * Returns the dominant horizontal baseline for a Unicode script.
  */
@@ -3638,6 +3679,62 @@ unsigned int hr_ot_math_get_glyph_assembly(struct hr_font_t *font,
                                            struct hr_ot_math_glyph_part_t *parts,
                                            hr_position_t *italics_correction);
 
+struct hr_set_t *hr_set_create(void);
+
+struct hr_set_t *hr_set_get_empty(void);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live.
+ */
+struct hr_set_t *hr_set_reference(struct hr_set_t *set);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live, and the caller must own its reference.
+ */
+void hr_set_destroy(struct hr_set_t *set);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live, and `key` must outlive it.
+ */
+hr_bool_t hr_set_set_user_data(struct hr_set_t *set,
+                               const struct hr_user_data_key_t *key,
+                               void *data,
+                               hr_destroy_func_t destroy,
+                               hr_bool_t replace);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live.
+ */
+void *hr_set_get_user_data(struct hr_set_t *set, const struct hr_user_data_key_t *key);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live.
+ */
+void hr_set_clear(struct hr_set_t *set);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live.
+ */
+void hr_set_add(struct hr_set_t *set, hr_codepoint_t value);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live.
+ */
+hr_bool_t hr_set_has(const struct hr_set_t *set, hr_codepoint_t value);
+
+/**
+ * # Safety
+ * `set` must be `NULL` or live.
+ */
+hr_bool_t hr_set_is_empty(const struct hr_set_t *set);
+
 /**
  * Shapes a buffer with a font, applying the given features.
  *

harfrust_capi/src/lib.rs

@@ -10,9 +10,9 @@ as HarfBuzz itself without collisions.
 # Scope
 
 This covers shaping: blobs, faces, fonts, buffers and `hr_shape`, plus OpenType
-`BASE` baseline and `MATH` queries. It has no drawing or painting callbacks, no
-subsetting, no other layout table introspection and no `hb_set` / `hb_map`
-containers, because HarfRust does not provide them.
+`BASE` baseline and `MATH` queries. It also provides the layout lookup queries
+and sets used to inspect glyph participation. Drawing and painting callbacks,
+subsetting, and maps are outside this API.
 
 # Object lifetime
 
@@ -38,6 +38,7 @@ pub mod object;
 pub mod ot_layout;
 pub mod ot_math;
 mod plan;
+pub mod set;
 pub mod shape;
 pub mod shape_plan;
 
@@ -50,6 +51,7 @@ pub use font_funcs::*;
 pub use object::{hr_destroy_func_t, hr_user_data_key_t};
 pub use ot_layout::*;
 pub use ot_math::*;
+pub use set::*;
 pub use shape::*;
 pub use shape_plan::*;