add hooks so generated code can pass in check item function

for clarity, separate out repeated field info construction

BUG=
[email protected]

Review URL: https://chromiumcodereview.appspot.com//1283113003.

lib/src/protobuf/builder_info.dart

@@ -24,6 +24,14 @@ class BuilderInfo {
       name, tagNumber, fieldType, defaultOrMaker, subBuilder, valueOf);
   }
 
+  void addRepeated(int tagNumber, String name, int fieldType,
+                   CheckFunc check,
+                   CreateBuilderFunc subBuilder,
+                   ValueOfFunc valueOf) {
+    fieldInfo[tagNumber] = byName[name] = new FieldInfo.repeated(
+        name, tagNumber, fieldType, check, subBuilder, valueOf);
+  }
+
   void a(int tagNumber, String name, int fieldType,
          [dynamic defaultOrMaker,
           CreateBuilderFunc subBuilder,
@@ -40,7 +48,7 @@ class BuilderInfo {
   }
 
   // Repeated message.
-  // TODO(antonm): change the order of CreateBuilderFunc and MakeDefaultFunc.
+  // TODO(skybrian): migrate to pp() and remove.
   void m(int tagNumber, String name,
          CreateBuilderFunc subBuilder, MakeDefaultFunc makeDefault) {
     add(tagNumber, name, FieldType._REPEATED_MESSAGE,
@@ -49,9 +57,16 @@ class BuilderInfo {
 
   // Repeated, not a message, group, or enum.
   void p(int tagNumber, String name, int fieldType) {
-    // The fieldType entirely determines the check function.
-    var makeDefault = () => new PbList.forFieldType(fieldType);
-    add(tagNumber, name, fieldType, makeDefault, null, null);
+    assert(!_isGroupOrMessage(fieldType) && !_isEnum(fieldType));
+    addRepeated(tagNumber, name, fieldType,
+        getCheckFunction(fieldType), null, null);
+  }
+
+  // Repeated message, group, or enum.
+  void pp(int tagNumber, String name, int fieldType, CheckFunc check,
+         [CreateBuilderFunc subBuilder, ValueOfFunc valueOf]) {
+    assert(_isGroupOrMessage(fieldType) || _isEnum(fieldType));
+    addRepeated(tagNumber, name, fieldType, check, subBuilder, valueOf);
   }
 
   bool containsTagNumber(int tagNumber) => fieldInfo.containsKey(tagNumber);

lib/src/protobuf/extension.dart

@@ -17,6 +17,12 @@ class Extension extends FieldInfo {
             ValueOfFunc valueOf]) :
      super(name, tagNumber, fieldType, defaultOrMaker, subBuilder, valueOf);
 
+  Extension.repeated(this.extendee, String name, int tagNumber, int fieldType,
+            CheckFunc check,
+            [CreateBuilderFunc subBuilder,
+            ValueOfFunc valueOf]) :
+  super.repeated(name, tagNumber, fieldType, check, subBuilder, valueOf);
+
   int get hashCode => extendee.hashCode * 31 + tagNumber;
 
   bool operator ==(other) {

lib/src/protobuf/field_error.dart

@@ -64,6 +64,13 @@ String _getFieldError(int fieldType, var value) {
   }
 }
 
+// entry points for generated code
+
+// generated checkItem for message, group, enum calls this
+void checkItemFailed(val, String className) {
+  throw new ArgumentError('Value ($val) is not an instance of ${className}');
+}
+
 /// Returns a function for validating items in a repeated field.
 ///
 /// For enum, group, and message fields, the check is only approximate,

lib/src/protobuf/field_info.dart

@@ -11,16 +11,47 @@ class FieldInfo {
   final String name;
   final int tagNumber;
   final int type;
+
+  // Constructs the default value of a field.
+  // TODO(skybrian): stop using this for repeated fields.
   final MakeDefaultFunc makeDefault;
+
+  // Creates an empty message or group when decoding a message.
+  // Not used for other types.
+  // see GeneratedMessage._getEmptyMessage
   final CreateBuilderFunc subBuilder;
+
+  // Looks up the enum value given its integer code.
+  // (Not used for other types.)
+  // see GeneratedMessage._getValueOfFunc
   final ValueOfFunc valueOf;
 
+  // Verifies an item being added to a repeated field
+  // (Not used for non-repeated fields.)
+  final CheckFunc check;
+
   FieldInfo(this.name, this.tagNumber, int type,
             [dynamic defaultOrMaker,
             this.subBuilder,
             this.valueOf])
       : this.type = type,
-        this.makeDefault = findMakeDefault(type, defaultOrMaker);
+        this.makeDefault = findMakeDefault(type, defaultOrMaker),
+        this.check = null {
+    assert(!_isGroupOrMessage(type) || subBuilder != null);
+    assert(!_isEnum(type) || valueOf != null);
+  }
+
+  FieldInfo.repeated(this.name, this.tagNumber, int type,
+                     CheckFunc check, this.subBuilder,
+                     [this.valueOf])
+    : this.type = type, this.check = check,
+      this.makeDefault = (() => new PbList(check: check)) {
+    assert(name != null);
+    assert(tagNumber != null);
+    assert(_isRepeated(type));
+    assert(check != null);
+    assert(!_isEnum(type) || valueOf != null);
+  }
 
   static MakeDefaultFunc findMakeDefault(int type, dynamic defaultOrMaker) {
     if (defaultOrMaker == null) return FieldType._defaultForType(type);

lib/src/protobuf/pb_list.dart

@@ -10,7 +10,9 @@ class PbList<E> extends Object with ListMixin<E> implements List<E> {
   final List<E> _wrappedList;
   final CheckFunc check;
 
-  PbList({this.check: _checkNotNull}) : _wrappedList = <E>[];
+  PbList({this.check: _checkNotNull}) : _wrappedList = <E>[] {
+    assert(check != null);
+  }
 
   PbList.from(List from)
       : _wrappedList = new List<E>.from(from),