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AyfriAyfri
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feat: Add Parser, Cursor and Tokens.
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4 files changed

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4 files changed

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‎src/Cursor.ts‎

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export class Cursor {
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public index = -1;
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public constructor(public input: string) {}
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public get hasNext() {
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return this.index < this.input.length - 1;
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}
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public get hasPrevious() {
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return this.index > 0;
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}
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public consumeRemaining() {
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let result = '';
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while (this.hasNext) result += this.next();
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return result;
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}
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public consumeWhile(predicate: (char: string) => boolean) {
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let result: string | undefined = undefined;
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while (this.hasNext && predicate(this.peekNext()!)) result = (result ?? '') + this.next();
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return result;
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}
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public skipWhitespace() {
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if (this.peekNext() !== ' ') return false;
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while (this.peekNext() === ' ') this.next();
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return true;
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}
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public next() {
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if (this.hasNext) {
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this.index++;
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return this.input[this.index];
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}
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}
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public previous() {
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if (this.hasPrevious) {
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this.index--;
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return this.input[this.index];
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}
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}
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public peek() {
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return this.input[this.index];
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}
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public peekNext() {
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return this.hasNext ? this.input[this.index + 1] : undefined;
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}
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public peekPrevious() {
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return this.hasPrevious ? this.input[this.index - 1] : undefined;
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}
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}

‎src/Parser.ts‎

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import {Cursor} from './Cursor';
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import {NamedArgumentToken, PositionalArgumentToken} from './Tokens';
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export class Parser {
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public cursor = new Cursor(this.input);
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public constructor(public input: string) {}
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public get hasNext() {
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return this.cursor.hasNext;
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}
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public parseNamed() {
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const tokens: NamedArgumentToken[] = [];
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let buffer = '';
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let outputBuffer = '';
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let isQuoted = false;
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let isFlag = false;
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let isFlagValue = false;
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let flagName = '';
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let isKeyword = false;
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let keywordName = '';
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while (this.cursor.hasNext) {
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const char = this.cursor.next();
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const canBeQuoted = !isQuoted && (!(isFlag && !isFlag) || isKeyword);
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if (char === '"' && buffer.length === 0 && canBeQuoted) {
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isQuoted = true;
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continue;
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}
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if (char === '-' && this.cursor.peekNext() === '-' && buffer.length === 0 && !isFlag && !isKeyword) {
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this.cursor.next();
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isFlag = true;
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continue;
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}
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if (char === '=' && buffer.length > 0 && !isKeyword && !isFlag) {
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keywordName = buffer;
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buffer = '';
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isKeyword = true;
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continue;
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}
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if (char === '\\' && this.cursor.peekNext() === '"' && isQuoted) {
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buffer += '"';
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this.cursor.next();
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continue;
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}
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if (char === '"' && isQuoted) {
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if (isFlagValue) {
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tokens.push(new NamedArgumentToken(flagName, buffer));
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flagName = '';
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isFlag = false;
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isFlagValue = false;
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} else if (isKeyword) {
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tokens.push(new NamedArgumentToken(keywordName, buffer));
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keywordName = '';
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isKeyword = false;
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} else {
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outputBuffer += `\"${buffer}\"`;
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this.cursor.skipWhitespace();
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}
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buffer = '';
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isQuoted = false;
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continue;
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}
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if (char === ' ' && !isQuoted) {
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if (isFlag) {
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if (!isFlagValue) {
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flagName = buffer;
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isFlagValue = true;
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} else {
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tokens.push(new NamedArgumentToken(flagName, buffer));
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this.cursor.skipWhitespace();
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flagName = '';
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isFlag = false;
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isFlagValue = false;
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}
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} else if (isKeyword) {
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tokens.push(new NamedArgumentToken(keywordName, buffer));
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this.cursor.skipWhitespace();
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keywordName = '';
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isKeyword = false;
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} else {
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outputBuffer += `${buffer} `;
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}
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buffer = '';
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continue;
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}
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buffer += char;
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}
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if (buffer.length > 0 && isFlag)
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if (isFlagValue) tokens.push(new NamedArgumentToken(flagName, buffer));
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else if (isKeyword) tokens.push(new NamedArgumentToken(keywordName, buffer));
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else outputBuffer += buffer;
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this.cursor = new Cursor(outputBuffer.trim());
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return tokens;
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}
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public peekNext() {
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const currentIndex = this.cursor.index;
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const token = this.parseNext();
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this.cursor.index = currentIndex;
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return token;
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}
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public parseNext() {
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let token: PositionalArgumentToken | undefined;
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let buffer = '';
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let isQuoted = false;
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while (this.cursor.hasNext) {
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const char = this.cursor.next();
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if (char === '"' && buffer.length === 0 && !isQuoted) {
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isQuoted = true;
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continue;
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}
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if (char === '\\' && this.cursor.peekNext() === '"' && isQuoted) {
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buffer += '"';
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this.cursor.next();
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continue;
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}
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if (char === '"' && isQuoted) {
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token = new PositionalArgumentToken(buffer);
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this.cursor.skipWhitespace();
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buffer = '';
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break;
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}
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if (char === ' ' && !isQuoted) {
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token = new PositionalArgumentToken(buffer);
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this.cursor.skipWhitespace();
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buffer = '';
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break;
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}
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buffer += char;
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}
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if (buffer.length > 0) token = new PositionalArgumentToken(buffer);
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return token;
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}
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public consumeRemaining() {
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return this.cursor.consumeRemaining();
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}
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public consumeWhile(predicate: (char: string) => boolean) {
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const result = this.cursor.consumeWhile(predicate);
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if (result) this.cursor.skipWhitespace();
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return result;
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}
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public peekRemaining() {
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const currentIndex = this.cursor.index;
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const result = this.cursor.consumeRemaining();
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this.cursor.index = currentIndex;
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return result;
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}
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public peekWhile(predicate: (char: string) => boolean) {
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const currentIndex = this.cursor.index;
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const result = this.cursor.consumeWhile(predicate);
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this.cursor.index = currentIndex;
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return result;
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}
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}

‎src/Tokens.ts‎

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export interface Token<T> {
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readonly data: T;
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}
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export class PositionalArgumentToken implements Token<string> {
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public constructor(public data: string) {}
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}
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export class NamedArgumentToken implements Token<string> {
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public constructor(public name: string, public data: string) {}
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}

‎src/index.ts‎

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export * from './Cursor';
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export * from './Parser';
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export * from './Tokens'

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