angular-cn/packages/compiler/test/output/ts_emitter_spec.ts

502 lines
24 KiB
TypeScript

/**
* @license
* Copyright Google Inc. All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
import {StaticSymbol} from '@angular/compiler/src/aot/static_symbol';
import * as o from '@angular/compiler/src/output/output_ast';
import {TypeScriptEmitter} from '@angular/compiler/src/output/ts_emitter';
import {ParseLocation, ParseSourceFile, ParseSourceSpan} from '@angular/compiler/src/parse_util';
import {newArray} from '@angular/compiler/src/util';
import {stripSourceMapAndNewLine} from './abstract_emitter_spec';
const someGenFilePath = 'somePackage/someGenFile';
const anotherModuleUrl = 'somePackage/someOtherPath';
const sameModuleIdentifier = new o.ExternalReference(null, 'someLocalId', null);
const externalModuleIdentifier = new o.ExternalReference(anotherModuleUrl, 'someExternalId', null);
{
// Not supported features of our OutputAst in TS:
// - real `const` like in Dart
// - final fields
describe('TypeScriptEmitter', () => {
let emitter: TypeScriptEmitter;
let someVar: o.ReadVarExpr;
beforeEach(() => {
emitter = new TypeScriptEmitter();
someVar = o.variable('someVar', null, null);
});
function emitStmt(stmt: o.Statement | o.Statement[], preamble?: string): string {
const stmts = Array.isArray(stmt) ? stmt : [stmt];
const source = emitter.emitStatements(someGenFilePath, stmts, preamble);
return stripSourceMapAndNewLine(source);
}
it('should declare variables', () => {
expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt())).toEqual(`var someVar:any = 1;`);
expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(null, [o.StmtModifier.Final])))
.toEqual(`const someVar:any = 1;`);
expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(null, [o.StmtModifier.Exported])))
.toEqual(`export var someVar:any = 1;`);
expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(o.INT_TYPE)))
.toEqual(`var someVar:number = 1;`);
expect(emitStmt(someVar.set(o.literal(1)).toDeclStmt(o.INFERRED_TYPE)))
.toEqual(`var someVar = 1;`);
});
describe('declare variables with ExternExpressions as values', () => {
it('should create no reexport if the identifier is in the same module', () => {
// identifier is in the same module -> no reexport
expect(emitStmt(someVar.set(o.importExpr(sameModuleIdentifier)).toDeclStmt(null, [
o.StmtModifier.Exported
]))).toEqual('export var someVar:any = someLocalId;');
});
it('should create no reexport if the variable is not exported', () => {
expect(emitStmt(someVar.set(o.importExpr(externalModuleIdentifier)).toDeclStmt())).toEqual([
`import * as i0 from 'somePackage/someOtherPath';`, `var someVar:any = i0.someExternalId;`
].join('\n'));
});
it('should create no reexport if the variable is typed', () => {
expect(emitStmt(someVar.set(o.importExpr(externalModuleIdentifier))
.toDeclStmt(o.DYNAMIC_TYPE, [o.StmtModifier.Exported])))
.toEqual([
`import * as i0 from 'somePackage/someOtherPath';`,
`export var someVar:any = i0.someExternalId;`
].join('\n'));
});
it('should create a reexport', () => {
expect(emitStmt(someVar.set(o.importExpr(externalModuleIdentifier))
.toDeclStmt(null, [o.StmtModifier.Exported])))
.toEqual([
`export {someExternalId as someVar} from 'somePackage/someOtherPath';`, ``
].join('\n'));
});
it('should create multiple reexports from the same file', () => {
const someVar2 = o.variable('someVar2');
const externalModuleIdentifier2 =
new o.ExternalReference(anotherModuleUrl, 'someExternalId2', null);
expect(emitStmt([
someVar.set(o.importExpr(externalModuleIdentifier))
.toDeclStmt(null, [o.StmtModifier.Exported]),
someVar2.set(o.importExpr(externalModuleIdentifier2))
.toDeclStmt(null, [o.StmtModifier.Exported])
]))
.toEqual([
`export {someExternalId as someVar,someExternalId2 as someVar2} from 'somePackage/someOtherPath';`,
``
].join('\n'));
});
});
it('should read and write variables', () => {
expect(emitStmt(someVar.toStmt())).toEqual(`someVar;`);
expect(emitStmt(someVar.set(o.literal(1)).toStmt())).toEqual(`someVar = 1;`);
expect(emitStmt(someVar.set(o.variable('someOtherVar').set(o.literal(1))).toStmt()))
.toEqual(`someVar = (someOtherVar = 1);`);
});
it('should read and write keys', () => {
expect(emitStmt(o.variable('someMap').key(o.variable('someKey')).toStmt()))
.toEqual(`someMap[someKey];`);
expect(emitStmt(o.variable('someMap').key(o.variable('someKey')).set(o.literal(1)).toStmt()))
.toEqual(`someMap[someKey] = 1;`);
});
it('should read and write properties', () => {
expect(emitStmt(o.variable('someObj').prop('someProp').toStmt()))
.toEqual(`someObj.someProp;`);
expect(emitStmt(o.variable('someObj').prop('someProp').set(o.literal(1)).toStmt()))
.toEqual(`someObj.someProp = 1;`);
});
it('should invoke functions and methods and constructors', () => {
expect(emitStmt(o.variable('someFn').callFn([o.literal(1)]).toStmt())).toEqual('someFn(1);');
expect(emitStmt(o.variable('someObj').callMethod('someMethod', [o.literal(1)]).toStmt()))
.toEqual('someObj.someMethod(1);');
expect(emitStmt(o.variable('SomeClass').instantiate([o.literal(1)]).toStmt()))
.toEqual('new SomeClass(1);');
});
it('should support builtin methods', () => {
expect(emitStmt(o.variable('arr1')
.callMethod(o.BuiltinMethod.ConcatArray, [o.variable('arr2')])
.toStmt()))
.toEqual('arr1.concat(arr2);');
expect(emitStmt(o.variable('observable')
.callMethod(o.BuiltinMethod.SubscribeObservable, [o.variable('listener')])
.toStmt()))
.toEqual('observable.subscribe(listener);');
expect(
emitStmt(
o.variable('fn').callMethod(o.BuiltinMethod.Bind, [o.variable('someObj')]).toStmt()))
.toEqual('fn.bind(someObj);');
});
it('should support literals', () => {
expect(emitStmt(o.literal(0).toStmt())).toEqual('0;');
expect(emitStmt(o.literal(true).toStmt())).toEqual('true;');
expect(emitStmt(o.literal('someStr').toStmt())).toEqual(`'someStr';`);
expect(emitStmt(o.literalArr([o.literal(1)]).toStmt())).toEqual(`[1];`);
expect(emitStmt(o.literalMap([
{key: 'someKey', value: o.literal(1), quoted: false},
{key: 'a', value: o.literal('a'), quoted: false},
{key: '*', value: o.literal('star'), quoted: true},
]).toStmt())
.replace(/\s+/gm, ''))
.toEqual(`{someKey:1,a:'a','*':'star'};`);
});
it('should break expressions into multiple lines if they are too long', () => {
const values: o.Expression[] = newArray(100);
values.fill(o.literal(1));
values.splice(50, 0, o.fn([], [new o.ReturnStatement(o.literal(1))]));
expect(emitStmt(o.variable('fn').callFn(values).toStmt())).toEqual([
'fn(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,',
' 1,1,1,1,1,1,1,1,1,1,():void => {', ' return 1;',
' },1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,',
' 1,1,1,1,1,1,1,1,1,1,1,1);'
].join('\n'));
});
it('should support blank literals', () => {
expect(emitStmt(o.literal(null).toStmt())).toEqual('(null as any);');
expect(emitStmt(o.literal(undefined).toStmt())).toEqual('(undefined as any);');
expect(emitStmt(o.variable('a', null).isBlank().toStmt())).toEqual('(a == null);');
});
it('should support external identifiers', () => {
expect(emitStmt(o.importExpr(sameModuleIdentifier).toStmt())).toEqual('someLocalId;');
expect(emitStmt(o.importExpr(externalModuleIdentifier).toStmt())).toEqual([
`import * as i0 from 'somePackage/someOtherPath';`, `i0.someExternalId;`
].join('\n'));
});
it('should support operators', () => {
const lhs = o.variable('lhs');
const rhs = o.variable('rhs');
expect(emitStmt(someVar.cast(o.INT_TYPE).toStmt())).toEqual('(<number>someVar);');
expect(emitStmt(o.not(someVar).toStmt())).toEqual('!someVar;');
expect(emitStmt(o.assertNotNull(someVar).toStmt())).toEqual('someVar!;');
expect(
emitStmt(someVar.conditional(o.variable('trueCase'), o.variable('falseCase')).toStmt()))
.toEqual('(someVar? trueCase: falseCase);');
expect(emitStmt(lhs.equals(rhs).toStmt())).toEqual('(lhs == rhs);');
expect(emitStmt(lhs.notEquals(rhs).toStmt())).toEqual('(lhs != rhs);');
expect(emitStmt(lhs.identical(rhs).toStmt())).toEqual('(lhs === rhs);');
expect(emitStmt(lhs.notIdentical(rhs).toStmt())).toEqual('(lhs !== rhs);');
expect(emitStmt(lhs.minus(rhs).toStmt())).toEqual('(lhs - rhs);');
expect(emitStmt(lhs.plus(rhs).toStmt())).toEqual('(lhs + rhs);');
expect(emitStmt(lhs.divide(rhs).toStmt())).toEqual('(lhs / rhs);');
expect(emitStmt(lhs.multiply(rhs).toStmt())).toEqual('(lhs * rhs);');
expect(emitStmt(lhs.modulo(rhs).toStmt())).toEqual('(lhs % rhs);');
expect(emitStmt(lhs.and(rhs).toStmt())).toEqual('(lhs && rhs);');
expect(emitStmt(lhs.or(rhs).toStmt())).toEqual('(lhs || rhs);');
expect(emitStmt(lhs.lower(rhs).toStmt())).toEqual('(lhs < rhs);');
expect(emitStmt(lhs.lowerEquals(rhs).toStmt())).toEqual('(lhs <= rhs);');
expect(emitStmt(lhs.bigger(rhs).toStmt())).toEqual('(lhs > rhs);');
expect(emitStmt(lhs.biggerEquals(rhs).toStmt())).toEqual('(lhs >= rhs);');
});
it('should support function expressions', () => {
expect(emitStmt(o.fn([], []).toStmt())).toEqual(['():void => {', '};'].join('\n'));
expect(emitStmt(o.fn([], [new o.ReturnStatement(o.literal(1))], o.INT_TYPE).toStmt()))
.toEqual(['():number => {', ' return 1;\n};'].join('\n'));
expect(emitStmt(o.fn([new o.FnParam('param1', o.INT_TYPE)], []).toStmt())).toEqual([
'(param1:number):void => {', '};'
].join('\n'));
});
it('should support function statements', () => {
expect(emitStmt(new o.DeclareFunctionStmt('someFn', [], [
]))).toEqual(['function someFn():void {', '}'].join('\n'));
expect(emitStmt(new o.DeclareFunctionStmt('someFn', [], [], null, [o.StmtModifier.Exported])))
.toEqual(['export function someFn():void {', '}'].join('\n'));
expect(emitStmt(new o.DeclareFunctionStmt(
'someFn', [], [new o.ReturnStatement(o.literal(1))], o.INT_TYPE)))
.toEqual(['function someFn():number {', ' return 1;', '}'].join('\n'));
expect(emitStmt(new o.DeclareFunctionStmt('someFn', [new o.FnParam('param1', o.INT_TYPE)], [
]))).toEqual(['function someFn(param1:number):void {', '}'].join('\n'));
});
it('should support comments', () => {
expect(emitStmt(new o.CommentStmt('a\nb'))).toEqual(['// a', '// b'].join('\n'));
});
it('should support if stmt', () => {
const trueCase = o.variable('trueCase').callFn([]).toStmt();
const falseCase = o.variable('falseCase').callFn([]).toStmt();
expect(emitStmt(new o.IfStmt(o.variable('cond'), [trueCase]))).toEqual([
'if (cond) { trueCase(); }'
].join('\n'));
expect(emitStmt(new o.IfStmt(o.variable('cond'), [trueCase], [falseCase]))).toEqual([
'if (cond) {', ' trueCase();', '} else {', ' falseCase();', '}'
].join('\n'));
});
it('should support localized strings', () => {
expect(emitStmt(new o.ExpressionStatement(o.localizedString(
{}, ['ab\\:c', 'd"e\'f'], ['ph1'],
[o.literal(7, o.NUMBER_TYPE).plus(o.literal(8, o.NUMBER_TYPE))]))))
.toEqual('$localize `ab\\\\:c${(7 + 8)}:ph1:d"e\'f`;');
});
it('should support try/catch', () => {
const bodyStmt = o.variable('body').callFn([]).toStmt();
const catchStmt =
o.variable('catchFn').callFn([o.CATCH_ERROR_VAR, o.CATCH_STACK_VAR]).toStmt();
expect(emitStmt(new o.TryCatchStmt([bodyStmt], [catchStmt]))).toEqual([
'try {', ' body();', '} catch (error) {', ' const stack:any = error.stack;',
' catchFn(error,stack);', '}'
].join('\n'));
});
it('should support support throwing',
() => { expect(emitStmt(new o.ThrowStmt(someVar))).toEqual('throw someVar;'); });
describe('classes', () => {
let callSomeMethod: o.Statement;
beforeEach(() => { callSomeMethod = o.THIS_EXPR.callMethod('someMethod', []).toStmt(); });
it('should support declaring classes', () => {
expect(emitStmt(new o.ClassStmt('SomeClass', null !, [], [], null !, [
]))).toEqual(['class SomeClass {', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt('SomeClass', null !, [], [], null !, [], [
o.StmtModifier.Exported
]))).toEqual(['export class SomeClass {', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt('SomeClass', o.variable('SomeSuperClass'), [], [], null !, [
]))).toEqual(['class SomeClass extends SomeSuperClass {', '}'].join('\n'));
});
it('should support declaring constructors', () => {
const superCall = o.SUPER_EXPR.callFn([o.variable('someParam')]).toStmt();
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [], new o.ClassMethod(null !, [], []), [])))
.toEqual(['class SomeClass {', ' constructor() {', ' }', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [],
new o.ClassMethod(null !, [new o.FnParam('someParam', o.INT_TYPE)], []), [])))
.toEqual(
['class SomeClass {', ' constructor(someParam:number) {', ' }', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [], new o.ClassMethod(null !, [], [superCall]), [])))
.toEqual([
'class SomeClass {', ' constructor() {', ' super(someParam);', ' }', '}'
].join('\n'));
expect(
emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [], new o.ClassMethod(null !, [], [callSomeMethod]), [])))
.toEqual([
'class SomeClass {', ' constructor() {', ' this.someMethod();', ' }', '}'
].join('\n'));
});
it('should support declaring fields', () => {
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [new o.ClassField('someField')], [], null !, [])))
.toEqual(['class SomeClass {', ' someField:any;', '}'].join('\n'));
expect(
emitStmt(new o.ClassStmt(
'SomeClass', null !, [new o.ClassField('someField', o.INT_TYPE)], [], null !, [])))
.toEqual(['class SomeClass {', ' someField:number;', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !,
[new o.ClassField('someField', o.INT_TYPE, [o.StmtModifier.Private])], [],
null !, [])))
.toEqual(['class SomeClass {', ' /*private*/ someField:number;', '}'].join('\n'));
});
it('should support declaring getters', () => {
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [new o.ClassGetter('someGetter', [])], null !, [])))
.toEqual(['class SomeClass {', ' get someGetter():any {', ' }', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [new o.ClassGetter('someGetter', [], o.INT_TYPE)],
null !, [])))
.toEqual(['class SomeClass {', ' get someGetter():number {', ' }', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [new o.ClassGetter('someGetter', [callSomeMethod])],
null !, [])))
.toEqual([
'class SomeClass {', ' get someGetter():any {', ' this.someMethod();', ' }', '}'
].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [],
[new o.ClassGetter('someGetter', [], null !, [o.StmtModifier.Private])], null !,
[])))
.toEqual(
['class SomeClass {', ' private get someGetter():any {', ' }', '}'].join('\n'));
});
it('should support methods', () => {
expect(emitStmt(new o.ClassStmt('SomeClass', null !, [], [], null !, [
new o.ClassMethod('someMethod', [], [])
]))).toEqual(['class SomeClass {', ' someMethod():void {', ' }', '}'].join('\n'));
expect(emitStmt(new o.ClassStmt('SomeClass', null !, [], [], null !, [
new o.ClassMethod('someMethod', [], [], o.INT_TYPE)
]))).toEqual(['class SomeClass {', ' someMethod():number {', ' }', '}'].join('\n'));
expect(
emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [], null !,
[new o.ClassMethod('someMethod', [new o.FnParam('someParam', o.INT_TYPE)], [])])))
.toEqual([
'class SomeClass {', ' someMethod(someParam:number):void {', ' }', '}'
].join('\n'));
expect(emitStmt(new o.ClassStmt(
'SomeClass', null !, [], [], null !,
[new o.ClassMethod('someMethod', [], [callSomeMethod])])))
.toEqual([
'class SomeClass {', ' someMethod():void {', ' this.someMethod();', ' }', '}'
].join('\n'));
});
});
it('should support builtin types', () => {
const writeVarExpr = o.variable('a').set(o.NULL_EXPR);
expect(emitStmt(writeVarExpr.toDeclStmt(o.DYNAMIC_TYPE)))
.toEqual('var a:any = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(o.BOOL_TYPE)))
.toEqual('var a:boolean = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(o.INT_TYPE)))
.toEqual('var a:number = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(o.NUMBER_TYPE)))
.toEqual('var a:number = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(o.STRING_TYPE)))
.toEqual('var a:string = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(o.FUNCTION_TYPE)))
.toEqual('var a:Function = (null as any);');
});
it('should support external types', () => {
const writeVarExpr = o.variable('a').set(o.NULL_EXPR);
expect(emitStmt(writeVarExpr.toDeclStmt(o.importType(sameModuleIdentifier))))
.toEqual('var a:someLocalId = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(o.importType(externalModuleIdentifier)))).toEqual([
`import * as i0 from 'somePackage/someOtherPath';`,
`var a:i0.someExternalId = (null as any);`
].join('\n'));
});
it('should support expression types', () => {
expect(
emitStmt(o.variable('a').set(o.NULL_EXPR).toDeclStmt(o.expressionType(o.variable('b')))))
.toEqual('var a:b = (null as any);');
});
it('should support expressions with type parameters', () => {
expect(emitStmt(o.variable('a')
.set(o.NULL_EXPR)
.toDeclStmt(o.importType(externalModuleIdentifier, [o.STRING_TYPE]))))
.toEqual([
`import * as i0 from 'somePackage/someOtherPath';`,
`var a:i0.someExternalId<string> = (null as any);`
].join('\n'));
});
it('should support combined types', () => {
const writeVarExpr = o.variable('a').set(o.NULL_EXPR);
expect(emitStmt(writeVarExpr.toDeclStmt(new o.ArrayType(null !))))
.toEqual('var a:any[] = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(new o.ArrayType(o.INT_TYPE))))
.toEqual('var a:number[] = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(new o.MapType(null))))
.toEqual('var a:{[key: string]:any} = (null as any);');
expect(emitStmt(writeVarExpr.toDeclStmt(new o.MapType(o.INT_TYPE))))
.toEqual('var a:{[key: string]:number} = (null as any);');
});
describe('comments', () => {
it('should support a preamble', () => {
expect(emitStmt(o.variable('a').toStmt(), '/* SomePreamble */')).toBe([
'/* SomePreamble */', 'a;'
].join('\n'));
});
it('should support singleline comments', () => {
expect(emitStmt(new o.CommentStmt('Simple comment'))).toBe('// Simple comment');
});
it('should support multiline comments', () => {
expect(emitStmt(new o.CommentStmt('Multiline comment', true)))
.toBe('/* Multiline comment */');
expect(emitStmt(new o.CommentStmt(`Multiline\ncomment`, true)))
.toBe(`/* Multiline\ncomment */`);
});
it('should support JSDoc comments', () => {
expect(emitStmt(new o.JSDocCommentStmt([{text: 'Intro comment'}])))
.toBe(`/**\n * Intro comment\n */`);
expect(emitStmt(new o.JSDocCommentStmt([
{tagName: o.JSDocTagName.Desc, text: 'description'}
]))).toBe(`/**\n * @desc description\n */`);
expect(emitStmt(new o.JSDocCommentStmt([
{text: 'Intro comment'},
{tagName: o.JSDocTagName.Desc, text: 'description'},
{tagName: o.JSDocTagName.Id, text: '{number} identifier 123'},
])))
.toBe(
`/**\n * Intro comment\n * @desc description\n * @id {number} identifier 123\n */`);
});
});
describe('emitter context', () => {
it('should be able to back to the generating span', () => {
const file = new ParseSourceFile('some content', 'a.ts');
const returnSpan = new ParseSourceSpan(
new ParseLocation(file, 100, 10, 10), new ParseLocation(file, 200, 20, 10));
const referenceSpan = new ParseSourceSpan(
new ParseLocation(file, 150, 15, 10), new ParseLocation(file, 175, 17, 10));
const statements = [new o.ClassStmt(
'SomeClass', null, [], [], new o.ClassMethod(null, [], []),
[new o.ClassMethod('someMethod', [new o.FnParam('a', o.INT_TYPE)], [
o.variable('someVar', o.INT_TYPE).set(o.literal(0)).toDeclStmt(),
new o.ReturnStatement(o.variable('someVar', null, referenceSpan), returnSpan)
])])];
const {sourceText, context} =
emitter.emitStatementsAndContext('a.ts', statements, '/* some preamble /*\n\n');
const spanOf = (text: string, after: number = 0) => {
const location = sourceText.indexOf(text, after);
const {line, col} = calculateLineCol(sourceText, location);
return context.spanOf(line, col);
};
const returnLoc = sourceText.indexOf('return');
expect(spanOf('return someVar')).toEqual(returnSpan, 'return span calculated incorrectly');
expect(spanOf(';', returnLoc)).toEqual(returnSpan, 'reference span calculated incorrectly');
expect(spanOf('someVar', returnLoc))
.toEqual(referenceSpan, 'return span calculated incorrectly');
});
});
});
}
function calculateLineCol(text: string, offset: number): {line: number, col: number} {
const lines = text.split('\n');
let line = 0;
for (let cur = 0; cur < text.length; line++) {
const next = cur + lines[line].length + 1;
if (next > offset) {
return {line, col: offset - cur};
}
cur = next;
}
return {line, col: 0};
}