feat(change_detection): reimplement change detection
This commit is contained in:
vsavkin
259
modules/change_detection/src/dynamic_change_detector.js
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259
modules/change_detection/src/dynamic_change_detector.js
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import {isPresent, isBlank, BaseException, FunctionWrapper} from 'facade/lang';
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import {List, ListWrapper, MapWrapper, StringMapWrapper} from 'facade/collection';
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import {ContextWithVariableBindings} from './parser/context_with_variable_bindings';
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import {ArrayChanges} from './array_changes';
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import {KeyValueChanges} from './keyvalue_changes';
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import {
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ProtoRecord,
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RECORD_TYPE_SELF,
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RECORD_TYPE_PROPERTY,
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RECORD_TYPE_INVOKE_METHOD,
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RECORD_TYPE_CONST,
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RECORD_TYPE_INVOKE_CLOSURE,
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RECORD_TYPE_INVOKE_PURE_FUNCTION,
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RECORD_TYPE_INVOKE_FORMATTER,
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RECORD_TYPE_STRUCTURAL_CHECK,
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ProtoChangeDetector
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} from './proto_change_detector';
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import {ChangeDetector, ChangeRecord, ChangeDispatcher} from './interfaces';
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import {ExpressionChangedAfterItHasBeenChecked, ChangeDetectionError} from './exceptions';
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class SimpleChange {
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previousValue:any;
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currentValue:any;
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constructor(previousValue:any, currentValue:any) {
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this.previousValue = previousValue;
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this.currentValue = currentValue;
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}
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}
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export class DynamicChangeDetector extends ChangeDetector {
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dispatcher:any;
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formatters:Map;
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children:List;
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values:List;
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protos:List<ProtoRecord>;
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parent:ChangeDetector;
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constructor(dispatcher:any, formatters:Map, protoRecords:List<ProtoRecord>) {
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this.dispatcher = dispatcher;
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this.formatters = formatters;
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this.values = ListWrapper.createFixedSize(protoRecords.length + 1);
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this.protos = protoRecords;
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this.children = [];
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}
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addChild(cd:ChangeDetector) {
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ListWrapper.push(this.children, cd);
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cd.parent = this;
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}
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removeChild(cd:ChangeDetector) {
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ListWrapper.remove(this.children, cd);
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}
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remove() {
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this.parent.removeChild(this);
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}
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setContext(context:any) {
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this.values[0] = context;
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}
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detectChanges() {
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this._detectChanges(false);
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}
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checkNoChanges() {
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this._detectChanges(true);
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}
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_detectChanges(throwOnChange:boolean) {
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this._detectChangesInRecords(throwOnChange);
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this._detectChangesInChildren(throwOnChange);
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}
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_detectChangesInRecords(throwOnChange:boolean) {
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var protos:List<ProtoRecord> = this.protos;
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var updatedRecords = null;
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var currentGroup = null;
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for (var i = 0; i < protos.length; ++i) {
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var proto:ProtoRecord = protos[i];
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var change = this._check(proto);
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// only when the terminal record, which ends a binding, changes
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// we need to add it to a list of changed records
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if (isPresent(change) && proto.terminal) {
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if (throwOnChange) throw new ExpressionChangedAfterItHasBeenChecked(proto, change);
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currentGroup = proto.groupMemento;
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updatedRecords = this._addRecord(updatedRecords, proto, change);
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}
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if (isPresent(updatedRecords)) {
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var lastRecordOfCurrentGroup = protos.length == i + 1 ||
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currentGroup !== protos[i + 1].groupMemento;
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if (lastRecordOfCurrentGroup) {
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this.dispatcher.onRecordChange(currentGroup, updatedRecords);
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updatedRecords = null;
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}
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}
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}
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}
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_check(proto:ProtoRecord) {
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try {
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if (proto.mode == RECORD_TYPE_STRUCTURAL_CHECK) {
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return this._structuralCheck(proto);
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} else {
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return this._referenceCheck(proto);
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}
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} catch (e) {
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throw new ChangeDetectionError(proto, e);
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}
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}
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_referenceCheck(proto) {
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var prevValue = this._readSelf(proto);
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var currValue = this._calculateCurrValue(proto);
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if (! isSame(prevValue, currValue)) {
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this._writeSelf(proto, currValue);
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return new SimpleChange(prevValue, currValue);
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} else {
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return null;
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}
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}
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_calculateCurrValue(proto) {
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switch (proto.mode) {
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case RECORD_TYPE_SELF:
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throw new BaseException("Cannot evaluate self");
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case RECORD_TYPE_CONST:
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return proto.funcOrValue;
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case RECORD_TYPE_PROPERTY:
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var context = this._readContext(proto);
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while (context instanceof ContextWithVariableBindings) {
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if (context.hasBinding(proto.name)) {
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return context.get(proto.name);
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}
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context = context.parent;
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}
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var propertyGetter:Function = proto.funcOrValue;
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return propertyGetter(context);
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case RECORD_TYPE_INVOKE_METHOD:
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var methodInvoker:Function = proto.funcOrValue;
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return methodInvoker(this._readContext(proto), this._readArgs(proto));
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case RECORD_TYPE_INVOKE_CLOSURE:
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return FunctionWrapper.apply(this._readContext(proto), this._readArgs(proto));
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case RECORD_TYPE_INVOKE_PURE_FUNCTION:
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return FunctionWrapper.apply(proto.funcOrValue, this._readArgs(proto));
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case RECORD_TYPE_INVOKE_FORMATTER:
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var formatter = MapWrapper.get(this.formatters, proto.funcOrValue);
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return FunctionWrapper.apply(formatter, this._readArgs(proto));
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default:
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throw new BaseException(`Unknown operation ${proto.mode}`);
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}
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}
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_structuralCheck(proto) {
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var self = this._readSelf(proto);
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var context = this._readContext(proto);
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if (isBlank(self)) {
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if (ArrayChanges.supports(context)) {
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self = new ArrayChanges();
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} else if (KeyValueChanges.supports(context)) {
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self = new KeyValueChanges();
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}
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}
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if (ArrayChanges.supports(context)) {
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if (self.check(context)) {
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this._writeSelf(proto, self);
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return new SimpleChange(null, self); // TODO: don't wrap and return self instead
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}
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} else if (KeyValueChanges.supports(context)) {
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if (self.check(context)) {
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this._writeSelf(proto, self);
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return new SimpleChange(null, self); // TODO: don't wrap and return self instead
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}
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} else if (context == null) {
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this._writeSelf(proto, null);
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return new SimpleChange(null, null);
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} else {
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throw new BaseException(`Unsupported type (${context})`);
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}
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}
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_addRecord(updatedRecords:List, proto:ProtoRecord, change):List {
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// we can use a pool of change records not to create extra garbage
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var record = new ChangeRecord(proto.bindingMemento, change);
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if (isBlank(updatedRecords)) {
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updatedRecords = _singleElementList;
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updatedRecords[0] = record;
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} else if (updatedRecords === _singleElementList) {
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updatedRecords = [_singleElementList[0], record];
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} else {
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ListWrapper.push(updatedRecords, record);
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}
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return updatedRecords;
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}
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_detectChangesInChildren(throwOnChange:boolean) {
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var children = this.children;
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for(var i = 0; i < children.length; ++i) {
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children[i]._detectChanges(throwOnChange);
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}
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}
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_readContext(proto) {
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return this.values[proto.contextIndex];
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}
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_readSelf(proto) {
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return this.values[proto.record_type_selfIndex];
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}
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_writeSelf(proto, value) {
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this.values[proto.record_type_selfIndex] = value;
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}
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_readArgs(proto) {
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var res = ListWrapper.createFixedSize(proto.args.length);
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var args = proto.args;
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for (var i = 0; i < args.length; ++i) {
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res[i] = this.values[args[i]];
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}
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return res;
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}
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}
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var _singleElementList = [null];
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function isSame(a, b) {
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if (a === b) return true;
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if (a instanceof String && b instanceof String && a == b) return true;
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if ((a !== a) && (b !== b)) return true;
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return false;
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}
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