Generators for Emscripten

api_struct_info.json:
//* This generator is used to produce part of Emscripten's struct_info.json,
//* which is a list of struct fields that it uses to generate field offset
//* information for its own code generators.
//* https://github.com/emscripten-core/emscripten/blob/master/src/struct_info.json

library_webgpu_enum_tables.js:
//* This generator is used to produce the number-to-string mappings for
//* Emscripten's library_webgpu.js.
//* https://github.com/emscripten-core/emscripten/blob/master/src/library_webgpu.js

Change-Id: I4704509737cde4685a093eb484dd977e5a106d19
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/15240
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

generator/dawn_json_generator.py

@@ -51,6 +51,14 @@ class Name:
     def snake_case(self):
         return '_'.join(self.chunks)
 
+    def js_enum_case(self):
+        result = self.chunks[0].lower()
+        for chunk in self.chunks[1:]:
+            if not result[-1].isdigit():
+                result += '-'
+            result += chunk.lower()
+        return result
+
 def concat_names(*names):
     return ' '.join([name.canonical_case() for name in names])
 
@@ -60,12 +68,26 @@ class Type:
         self.dict_name = name
         self.name = Name(name, native=native)
         self.category = json_data['category']
+        self.javascript = self.json_data.get('javascript', True)
 
-EnumValue = namedtuple('EnumValue', ['name', 'value', 'valid'])
+EnumValue = namedtuple('EnumValue', ['name', 'value', 'valid', 'jsrepr'])
 class EnumType(Type):
     def __init__(self, name, json_data):
         Type.__init__(self, name, json_data)
-        self.values = [EnumValue(Name(m['name']), m['value'], m.get('valid', True)) for m in self.json_data['values']]
+
+        self.values = []
+        self.contiguousFromZero = True
+        lastValue = -1
+        for m in self.json_data['values']:
+            value = m['value']
+            if value != lastValue + 1:
+                self.contiguousFromZero = False
+            lastValue = value
+            self.values.append(EnumValue(
+                Name(m['name']),
+                value,
+                m.get('valid', True),
+                m.get('jsrepr', None)))
 
         # Assert that all values are unique in enums
         all_values = set()
@@ -377,6 +399,10 @@ def as_cppType(name):
     else:
         return name.CamelCase()
 
+def as_jsEnumValue(value):
+    if value.jsrepr: return value.jsrepr
+    return "'" + value.name.js_enum_case() + "'"
+
 def convert_cType_to_cppType(typ, annotation, arg, indent=0):
     if typ.category == 'native':
         return arg
@@ -522,6 +548,7 @@ class MultiGeneratorFromDawnJSON(Generator):
             'as_cType': as_cType,
             'as_cTypeDawn': as_cTypeDawn,
             'as_cppType': as_cppType,
+            'as_jsEnumValue': as_jsEnumValue,
             'convert_cType_to_cppType': convert_cType_to_cppType,
             'as_varName': as_varName,
             'decorate': decorate,
@@ -544,6 +571,10 @@ class MultiGeneratorFromDawnJSON(Generator):
         if 'dawncpp' in targets:
             renders.append(FileRender('webgpu_cpp.cpp', 'src/dawn/webgpu_cpp.cpp', [base_params, api_params]))
 
+        if 'emscripten_bits' in targets:
+            renders.append(FileRender('webgpu_struct_info.json', 'src/dawn/webgpu_struct_info.json', [base_params, api_params]))
+            renders.append(FileRender('library_webgpu_enum_tables.js', 'src/dawn/library_webgpu_enum_tables.js', [base_params, api_params]))
+
         if 'mock_webgpu' in targets:
             mock_params = [
                 base_params,