CodeGen: Introduce const_ref_t in blink_type_info

const_ref_t provides a type similar to ref_t with its constantness.


Bug: 839389
Change-Id: I4d654a483401fba5885da2cf3214bbe9674a869d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1994549
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#730080}

third_party/blink/renderer/bindings/scripts/bind_gen/blink_v8_bridge.py

@@ -47,6 +47,7 @@ def blink_type_info(idl_type):
       member_t: The type of a member variable.  E.g. T => Member<T>
       ref_t: The type of a local variable that references to an already-existing
           value.  E.g. String => String&
+      const_ref_t: A const-qualified reference type.
       value_t: The type of a variable that behaves as a value.  E.g. String =>
           String
       is_nullable: True if the Blink implementation type can represent IDL null
@@ -59,6 +60,7 @@ def blink_type_info(idl_type):
                      typename,
                      member_fmt="{}",
                      ref_fmt="{}",
+                     const_ref_fmt="{}",
                      value_fmt="{}",
                      is_nullable=False):
             self.member_t = member_fmt.format(typename)
@@ -87,14 +89,19 @@ def blink_type_info(idl_type):
         }
         return TypeInfo(cxx_type[real_type.keyword_typename])
 
-    if real_type.is_string:
-        return TypeInfo("String", ref_fmt="{}&", is_nullable=True)
+    if real_type.is_string or real_type.is_enumeration:
+        return TypeInfo(
+            "String",
+            ref_fmt="{}&",
+            const_ref_fmt="const {}&",
+            is_nullable=True)
 
     if real_type.is_buffer_source_type:
         return TypeInfo(
             'DOM{}'.format(real_type.keyword_typename),
             member_fmt="Member<{}>",
             ref_fmt="{}*",
+            const_ref_fmt="const {}*",
             value_fmt="{}*",
             is_nullable=True)
 
@@ -102,7 +109,11 @@ def blink_type_info(idl_type):
         assert False, "Blink does not support/accept IDL symbol type."
 
     if real_type.is_any or real_type.is_object:
-        return TypeInfo("ScriptValue", ref_fmt="{}&", is_nullable=True)
+        return TypeInfo(
+            "ScriptValue",
+            ref_fmt="{}&",
+            const_ref_fmt="const {}&",
+            is_nullable=True)
 
     if real_type.is_void:
         assert False, "Blink does not support/accept IDL void type."
@@ -113,6 +124,7 @@ def blink_type_info(idl_type):
             blink_impl_type,
             member_fmt="Member<{}>",
             ref_fmt="{}*",
+            const_ref_fmt="const {}*",
             value_fmt="{}*",
             is_nullable=True)
 
@@ -120,7 +132,9 @@ def blink_type_info(idl_type):
             or real_type.is_variadic):
         element_type = blink_type_info(real_type.element_type)
         return TypeInfo(
-            "VectorOf<{}>".format(element_type.value_t), ref_fmt="{}&")
+            "VectorOf<{}>".format(element_type.value_t),
+            ref_fmt="{}&",
+            const_ref_fmt="const {}&")
 
     if real_type.is_record:
         key_type = blink_type_info(real_type.key_type)
@@ -128,10 +142,12 @@ def blink_type_info(idl_type):
         return TypeInfo(
             "VectorOfPairs<{}, {}>".format(key_type.value_t,
                                            value_type.value_t),
-            ref_fmt="{}&")
+            ref_fmt="{}&",
+            const_ref_fmt="const {}&")
 
     if real_type.is_promise:
-        return TypeInfo("ScriptPromise", ref_fmt="{}&")
+        return TypeInfo(
+            "ScriptPromise", ref_fmt="{}&", const_ref_fmt="const {}&")
 
     if real_type.is_union:
         def_obj = real_type.union_definition_object
@@ -139,6 +155,7 @@ def blink_type_info(idl_type):
         return TypeInfo(
             blink_impl_type,
             ref_fmt="{}&",
+            const_ref_fmt="const {}&",
             is_nullable=def_obj.does_include_nullable_type)
 
     if real_type.is_nullable:
@@ -146,7 +163,9 @@ def blink_type_info(idl_type):
         if inner_type.is_nullable:
             return inner_type
         return TypeInfo(
-            "base::Optional<{}>".format(inner_type.value_t), ref_fmt="{}&")
+            "base::Optional<{}>".format(inner_type.value_t),
+            ref_fmt="{}&",
+            const_ref_fmt="const {}&")
 
     assert False, "Unknown type: {}".format(idl_type.syntactic_form)