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refactor: Don't concatenate strings (#1045)
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@fb55
fb55 committed Dec 28, 2021
1 parent 11e48f6 commit fab8c4c
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Showing 4 changed files with 503 additions and 380 deletions.
4 changes: 2 additions & 2 deletions src/Parser.spec.ts
View file
Expand Up @@ -48,11 +48,11 @@ describe("API", () => {
p.resume();
expect(onText).toHaveBeenCalledTimes(1);
p.pause();
p.end("foo");
p.end("bar");
expect(onText).toHaveBeenCalledTimes(1);
p.resume();
expect(onText).toHaveBeenCalledTimes(2);
expect(onText).toHaveBeenLastCalledWith("foo");
expect(onText).toHaveBeenLastCalledWith("bar");
});

test("should back out of numeric entities (#125)", () => {
Expand Down
182 changes: 134 additions & 48 deletions src/Parser.ts
View file
@@ -1,4 +1,5 @@
import Tokenizer from "./Tokenizer";
import Tokenizer, { Callbacks, QuoteType } from "./Tokenizer";
import decodeCodePoint from "entities/lib/decode_codepoint";

const formTags = new Set([
"input",
Expand Down Expand Up @@ -195,7 +196,7 @@ export interface Handler {

const reNameEnd = /\s|\//;

export class Parser {
export class Parser implements Callbacks {
/** The start index of the last event. */
public startIndex = 0;
/** The end index of the last event. */
Expand All @@ -217,6 +218,13 @@ export class Parser {
private readonly lowerCaseAttributeNames: boolean;
private readonly tokenizer: Tokenizer;

private readonly buffers: string[] = [];
private bufferOffset = 0;
/** The index of the last written buffer. Used when resuming after a `pause()`. */
private writeIndex = 0;
/** Indicates whether the parser has finished running / `.end` has been called. */
private ended = false;

constructor(
cbs?: Partial<Handler> | null,
private readonly options: ParserOptions = {}
Expand All @@ -235,10 +243,18 @@ export class Parser {
// Tokenizer event handlers

/** @internal */
ontext(data: string): void {
const idx = this.tokenizer.getAbsoluteIndex();
this.endIndex = idx - 1;
ontext(start: number, endIndex: number): void {
const data = this.getSlice(start, endIndex);
this.endIndex = endIndex - 1;
this.cbs.ontext?.(data);
this.startIndex = endIndex;
}

/** @internal */
ontextentity(cp: number): void {
const idx = this.tokenizer.getIndex();
this.endIndex = idx - 1;
this.cbs.ontext?.(decodeCodePoint(cp));
this.startIndex = idx;
}

Expand All @@ -247,8 +263,10 @@ export class Parser {
}

/** @internal */
onopentagname(name: string): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
onopentagname(start: number, endIndex: number): void {
this.endIndex = endIndex;

let name = this.getSlice(start, endIndex);

if (this.lowerCaseTagNames) {
name = name.toLowerCase();
Expand Down Expand Up @@ -287,7 +305,6 @@ export class Parser {

private endOpenTag(isImplied: boolean) {
this.startIndex = this.openTagStart;
this.endIndex = this.tokenizer.getAbsoluteIndex();

if (this.attribs) {
this.cbs.onopentag?.(this.tagname, this.attribs, isImplied);
Expand All @@ -301,16 +318,19 @@ export class Parser {
}

/** @internal */
onopentagend(): void {
onopentagend(endIndex: number): void {
this.endIndex = endIndex;
this.endOpenTag(false);

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
this.startIndex = endIndex + 1;
}

/** @internal */
onclosetag(name: string): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
onclosetag(start: number, endIndex: number): void {
this.endIndex = endIndex;

let name = this.getSlice(start, endIndex);

if (this.lowerCaseTagNames) {
name = name.toLowerCase();
Expand Down Expand Up @@ -346,11 +366,12 @@ export class Parser {
}

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
this.startIndex = endIndex + 1;
}

/** @internal */
onselfclosingtag(): void {
onselfclosingtag(endIndex: number): void {
this.endIndex = endIndex;
if (
this.options.xmlMode ||
this.options.recognizeSelfClosing ||
Expand All @@ -359,10 +380,10 @@ export class Parser {
this.closeCurrentTag(false);

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
this.startIndex = endIndex + 1;
} else {
// Ignore the fact that the tag is self-closing.
this.onopentagend();
this.onopentagend(endIndex);
}
}

Expand All @@ -379,25 +400,39 @@ export class Parser {
}

/** @internal */
onattribname(name: string): void {
this.startIndex = this.tokenizer.getAbsoluteSectionStart();
onattribname(start: number, endIndex: number): void {
this.startIndex = start;
const name = this.getSlice(start, endIndex);

if (this.lowerCaseAttributeNames) {
name = name.toLowerCase();
}
this.attribname = name;
this.attribname = this.lowerCaseAttributeNames
? name.toLowerCase()
: name;
}

/** @internal */
onattribdata(value: string): void {
this.attribvalue += value;
onattribdata(start: number, endIndex: number): void {
this.attribvalue += this.getSlice(start, endIndex);
}

/** @internal */
onattribend(quote: string | undefined | null): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
onattribentity(cp: number): void {
this.attribvalue += decodeCodePoint(cp);
}

this.cbs.onattribute?.(this.attribname, this.attribvalue, quote);
/** @internal */
onattribend(quote: QuoteType, endIndex: number): void {
this.endIndex = endIndex;

const quoteVal =
quote === QuoteType.Double
? '"'
: quote === QuoteType.Single
? "'"
: quote === QuoteType.NoValue
? undefined
: null;

this.cbs.onattribute?.(this.attribname, this.attribvalue, quoteVal);
if (
this.attribs &&
!Object.prototype.hasOwnProperty.call(this.attribs, this.attribname)
Expand All @@ -420,45 +455,48 @@ export class Parser {
}

/** @internal */
ondeclaration(value: string): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
ondeclaration(start: number, endIndex: number): void {
this.endIndex = endIndex;
const value = this.getSlice(start, endIndex);

if (this.cbs.onprocessinginstruction) {
const name = this.getInstructionName(value);
this.cbs.onprocessinginstruction(`!${name}`, `!${value}`);
}

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
this.startIndex = endIndex + 1;
}

/** @internal */
onprocessinginstruction(value: string): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
onprocessinginstruction(start: number, endIndex: number): void {
this.endIndex = endIndex;
const value = this.getSlice(start, endIndex);

if (this.cbs.onprocessinginstruction) {
const name = this.getInstructionName(value);
this.cbs.onprocessinginstruction(`?${name}`, `?${value}`);
}

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
this.startIndex = endIndex + 1;
}

/** @internal */
oncomment(value: string): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
oncomment(start: number, endIndex: number, offset: number): void {
this.endIndex = endIndex;

this.cbs.oncomment?.(value);
this.cbs.oncomment?.(this.getSlice(start, endIndex - offset));
this.cbs.oncommentend?.();

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
this.startIndex = endIndex + 1;
}

/** @internal */
oncdata(value: string): void {
this.endIndex = this.tokenizer.getAbsoluteIndex();
oncdata(start: number, endIndex: number, offset: number): void {
this.endIndex = endIndex;
const value = this.getSlice(start, endIndex - offset);

if (this.options.xmlMode || this.options.recognizeCDATA) {
this.cbs.oncdatastart?.();
Expand All @@ -470,12 +508,7 @@ export class Parser {
}

// Set `startIndex` for next node
this.startIndex = this.endIndex + 1;
}

/** @internal */
onerror(err: Error): void {
this.cbs.onerror?.(err);
this.startIndex = endIndex + 1;
}

/** @internal */
Expand All @@ -501,10 +534,14 @@ export class Parser {
this.tagname = "";
this.attribname = "";
this.attribs = null;
this.stack = [];
this.stack.length = 0;
this.startIndex = 0;
this.endIndex = 0;
this.cbs.onparserinit?.(this);
this.buffers.length = 0;
this.bufferOffset = 0;
this.writeIndex = 0;
this.ended = false;
}

/**
Expand All @@ -518,13 +555,46 @@ export class Parser {
this.end(data);
}

private getSlice(start: number, end: number) {
while (start - this.bufferOffset >= this.buffers[0].length) {
this.shiftBuffer();
}

let str = this.buffers[0].slice(
start - this.bufferOffset,
end - this.bufferOffset
);

while (end - this.bufferOffset > this.buffers[0].length) {
this.shiftBuffer();
str += this.buffers[0].slice(0, end - this.bufferOffset);
}

return str;
}

private shiftBuffer(): void {
this.bufferOffset += this.buffers[0].length;
this.writeIndex--;
this.buffers.shift();
}

/**
* Parses a chunk of data and calls the corresponding callbacks.
*
* @param chunk Chunk to parse.
*/
public write(chunk: string): void {
this.tokenizer.write(chunk);
if (this.ended) {
this.cbs.onerror?.(new Error(".write() after done!"));
return;
}

this.buffers.push(chunk);
if (this.tokenizer.running) {
this.tokenizer.write(chunk);
this.writeIndex++;
}
}

/**
Expand All @@ -533,7 +603,14 @@ export class Parser {
* @param chunk Optional final chunk to parse.
*/
public end(chunk?: string): void {
this.tokenizer.end(chunk);
if (this.ended) {
this.cbs.onerror?.(Error(".end() after done!"));
return;
}

if (chunk) this.write(chunk);
this.ended = true;
this.tokenizer.end();
}

/**
Expand All @@ -548,6 +625,15 @@ export class Parser {
*/
public resume(): void {
this.tokenizer.resume();

while (
this.tokenizer.running &&
this.writeIndex < this.buffers.length
) {
this.tokenizer.write(this.buffers[this.writeIndex++]);
}

if (this.ended) this.tokenizer.end();
}

/**
Expand Down

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