ir: Support hiding enum variants.

Signed-off-by: Emilio Cobos Álvarez <[email protected]>

Author: emilio

libbindgen/src/chooser.rs

@@ -1,7 +1,7 @@
 //! A public API for more fine-grained customization of bindgen behavior.
 
 pub use ir::int::IntKind;
-pub use ir::enum_ty::EnumVariantValue;
+pub use ir::enum_ty::{EnumVariantValue, EnumVariantCustomBehavior};
 use std::fmt;
 
 /// A trait to allow configuring different kinds of types in different
@@ -16,10 +16,11 @@ pub trait TypeChooser: fmt::Debug {
     /// This function should return whether, given the a given enum variant
     /// name, and value, returns whether this enum variant will forcibly be a
     /// constant.
-    fn constify_enum_variant(&self,
+    fn enum_variant_behavior(&self,
                              _enum_name: Option<&str>,
                              _variant_name: &str,
-                             _variant_value: EnumVariantValue) -> bool {
-        false
+                             _variant_value: EnumVariantValue)
+                             -> Option<EnumVariantCustomBehavior> {
+        None
     }
 }

libbindgen/src/codegen/mod.rs

@@ -1677,6 +1677,10 @@ impl CodeGenerator for Enum {
             let variant = iter.next()
                 .unwrap_or_else(|| constified_variants.remove(0));
 
+            if variant.hidden() {
+                continue;
+            }
+
             if variant.force_constification() && iter.peek().is_some() {
                 constified_variants.push(variant);
                 continue;

libbindgen/src/ir/enum_ty.rs

@@ -7,6 +7,15 @@ use super::context::{BindgenContext, ItemId};
 use super::item::Item;
 use super::ty::TypeKind;
 
+/// An enum representing custom handling that can be given to a variant.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum EnumVariantCustomBehavior {
+    /// This variant will be constified, that is, forced to generate a constant.
+    Constify,
+    /// This variant will be hidden entirely from the resulting enum.
+    Hide,
+}
+
 /// A C/C++ enumeration.
 #[derive(Debug)]
 pub struct Enum {
@@ -80,16 +89,25 @@ impl Enum {
                 };
                 if let Some(val) = value {
                     let name = cursor.spelling();
-                    let should_constify = ctx.type_chooser()
-                        .map_or(false, |c| {
-                            c.constify_enum_variant(type_name, &name, val)
-                        }) ||
-                        Annotations::new(&cursor).map_or(false, |anno| {
-                            anno.constify_enum_variant()
+                    let custom_behavior = ctx.type_chooser()
+                        .and_then(|t| {
+                            t.enum_variant_behavior(type_name, &name, val)
+                        })
+                        .or_else(|| {
+                            Annotations::new(&cursor).and_then(|anno| {
+                                if anno.hide() {
+                                    Some(EnumVariantCustomBehavior::Hide)
+                                } else if anno.constify_enum_variant() {
+                                    Some(EnumVariantCustomBehavior::Constify)
+                                } else {
+                                    None
+                                }
+                            })
                         });
+
                     let comment = cursor.raw_comment();
                     variants.push(
-                        EnumVariant::new(name, comment, val, should_constify));
+                        EnumVariant::new(name, comment, val, custom_behavior));
                 }
             }
             CXChildVisit_Continue
@@ -110,10 +128,8 @@ pub struct EnumVariant {
     /// The integer value of the variant.
     val: EnumVariantValue,
 
-    /// Whether this value should explicitly be constified.
-    ///
-    /// This allows us to solve situations as described in #392.
-    force_constify: bool,
+    /// The custom behavior this variant may have, if any.
+    custom_behavior: Option<EnumVariantCustomBehavior>,
 }
 
 /// A constant value assigned to an enumeration variant.
@@ -131,13 +147,13 @@ impl EnumVariant {
     pub fn new(name: String,
                comment: Option<String>,
                val: EnumVariantValue,
-               force_constify: bool)
+               custom_behavior: Option<EnumVariantCustomBehavior>)
                -> Self {
         EnumVariant {
             name: name,
             comment: comment,
             val: val,
-            force_constify: force_constify,
+            custom_behavior: custom_behavior,
         }
     }
 
@@ -154,6 +170,14 @@ impl EnumVariant {
     /// Returns whether this variant should be enforced to be a constant by code
     /// generation.
     pub fn force_constification(&self) -> bool {
-        self.force_constify
+        self.custom_behavior
+            .map_or(false, |b| b == EnumVariantCustomBehavior::Constify)
+    }
+
+    /// Returns whether the current variant should be hidden completely from the
+    /// resulting rust enum.
+    pub fn hidden(&self) -> bool {
+        self.custom_behavior
+            .map_or(false, |b| b == EnumVariantCustomBehavior::Hide)
     }
 }

libbindgen/tests/expectations/tests/constify-enum.rs

@@ -9,8 +9,6 @@ pub const nsCSSPropertyID_eCSSProperty_COUNT_unexistingVariantValue:
     nsCSSPropertyID::eCSSProperty_COUNT_unexistingVariantValue;
 pub const nsCSSPropertyID_eCSSProperty_COUNT: nsCSSPropertyID =
     nsCSSPropertyID::eCSSPropertyAlias_aa;
-pub const nsCSSPropertyID_eCSSProperty_COUNT_DUMMY2: nsCSSPropertyID =
-    nsCSSPropertyID::eCSSProperty_b;
 #[repr(u32)]
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum nsCSSPropertyID {

libbindgen/tests/headers/constify-enum.h

@@ -4,7 +4,7 @@ enum nsCSSPropertyID {
   eCSSProperty_b,
 
   eCSSProperty_COUNT, /**< <div rustbindgen constant></div> */
-  eCSSProperty_COUNT_DUMMY2 = eCSSProperty_COUNT - 1, /**< <div rustbindgen constant></div> */
+  eCSSProperty_COUNT_DUMMY2 = eCSSProperty_COUNT - 1, /**< <div rustbindgen hide></div> */
 
   eCSSPropertyAlias_aa,
   eCSSPropertyAlias_bb,