537 lines
16 KiB
JavaScript
537 lines
16 KiB
JavaScript
"use strict";
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import * as fs from "node:fs";
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import process from "node:process";
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function main() {
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const text = fs.readFileSync(process.argv[2]).toString();
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const ast = new Parser(text).parse();
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let lastValue = null;
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const evaluator = new Evaluator();
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for (const expr of ast) {
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const result = evaluator.eval(expr);
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if (result.type !== "value") {
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break;
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}
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lastValue = result.value;
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}
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if (lastValue !== null) {
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console.log(valueToJs(lastValue));
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}
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}
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class Evaluator {
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constructor() {
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this.syms = { parent: undefined, map: new Map(builtins) };
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}
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/**
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* @param {Expr} expr
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*/
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eval(expr) {
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if (expr.type === "list") {
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return this.evalList(expr, expr.line);
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} else if (expr.type === "int") {
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return { type: "value", value: { type: "int", value: expr.value } };
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} else if (expr.type === "string") {
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return {
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type: "value",
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value: { type: "string", value: expr.value },
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};
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} else if (expr.type === "ident") {
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const sym = this.findSym(expr.value);
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if (!sym) {
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throw new Error(
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`could not find symbol '${expr.value}' on line ${expr.line}`,
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);
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}
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return { type: "value", value: sym };
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} else {
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throw new Error(
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`unknown expr type '${expr.type}' on line ${expr.line}`,
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);
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}
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}
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evalToValue(expr) {
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const result = this.eval(expr);
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if (result.type !== "value") {
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throw new Error(`expected value on line ${expr.line}`);
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}
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return result.value;
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}
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evalList(expr) {
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const s = expr.values;
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const id = s[0]?.type === "ident" ? s[0].value : undefined;
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if (id === "fn") {
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const name = s[1].value;
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this.syms.map.set(name, {
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type: "fn",
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name,
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params: s[2].values.map((ident) => ident.value),
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body: s[3],
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syms: this.syms,
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});
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return { type: "value", value: { type: "null" } };
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} else if (id === "return") {
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return {
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type: "return",
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value: s[1] ? this.evalToValue(s[1]) : { type: "null" },
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};
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} else if (id === "let") {
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const value = this.evalToValue(s[2]);
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this.syms.map.set(s[1].value, value);
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return { type: "value", value: { type: "null" } };
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} else if (id === "if") {
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const cond = this.evalToValue(s[1]);
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if (cond.type !== "bool") {
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throw new Error(
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`expected bool on line ${expr.line}`,
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);
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}
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if (cond.value) {
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return this.eval(s[2]);
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} else if (s[3]) {
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return this.eval(s[3]);
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} else {
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return { type: "value", value: "null" };
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}
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} else if (id === "loop") {
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while (true) {
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const result = this.eval(s[1]);
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if (result.type === "break") {
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return { type: "value", value: result.value };
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} else if (result.type !== "value") {
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return result;
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}
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}
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} else if (id === "break") {
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return {
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type: "break",
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value: s[1] ? this.evalToValue(s[1]) : { type: "null" },
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};
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} else if (id === "do") {
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let lastValue = { type: "null" };
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for (const expr of s.slice(1)) {
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const result = this.eval(expr);
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if (result.type !== "value") {
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return result;
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}
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lastValue = result.value;
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}
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return { type: "value", value: lastValue };
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} else if (id === "call") {
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const args = s.slice(2).map((arg) => this.evalToValue(arg));
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const fnValue = this.evalToValue(s[1]);
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if (fnValue.type === "builtin") {
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return { type: "value", value: fnValue.fn(...args) };
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} else if (fnValue.type !== "fn") {
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throw new Error("cannot call non-function");
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}
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const callerSyms = this.syms;
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this.syms = {
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parent: fnValue.syms,
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map: new Map(),
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};
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if (fnValue.params.length !== args.length) {
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throw new Error(
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`incorrect amount of arguments on line ${line}`,
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);
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}
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for (let i = 0; i < fnValue.params.length; ++i) {
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this.syms.map.set(fnValue.params[i], args[i]);
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}
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let returnValue = { type: "null" };
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const result = this.eval(fnValue.body);
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if (result.type === "value" || result.type === "return") {
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returnValue = result.value;
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} else {
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throw new Error(`illegal ${result.type} across boundry`);
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}
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this.syms = callerSyms;
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return { type: "value", value: returnValue };
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} else if (id === "not") {
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const value = this.evalToValue(s[1]);
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return {
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type: "value",
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value: { type: "bool", value: !value.value },
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};
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} else if (id === "or") {
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const left = this.evalToValue(s[1]);
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if (left.value) {
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return { type: "value", value: left };
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} else {
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const right = this.evalToValue(s[2]);
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return { type: "value", value: right };
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}
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} else if (id === "and") {
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const left = this.evalToValue(s[1]);
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if (left.value) {
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const right = this.evalToValue(s[2]);
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return { type: "value", value: right };
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} else {
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return { type: "value", value: left };
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}
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} else if (id in artithmeticOps) {
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const left = this.evalToValue(s[1]);
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const right = this.evalToValue(s[2]);
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return {
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type: "value",
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value: {
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type: "int",
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value: artithmeticOps[id](left.value, right.value),
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},
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};
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} else if (id in comparisonOps) {
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const left = this.evalToValue(s[1]);
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const right = this.evalToValue(s[2]);
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return {
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type: "value",
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value: {
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type: "bool",
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value: comparisonOps[id](left.value, right.value),
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},
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};
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} else if (id in assignOps) {
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if (s[1].type === "ident") {
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const sym = this.findSym(s[1].value);
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if (!sym) {
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throw new Error(
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`could not find symbol '${expr.value}' on line ${expr.line}`,
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);
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}
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const right = this.evalToValue(s[2]);
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const newValue = assignOps[id](sym, right);
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sym.type = newValue.type;
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sym.value = newValue.value;
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} else {
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throw new Error(
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`cannot assign to expression on line ${expr.line}`,
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);
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}
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return { type: "value", value: { type: "null" } };
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} else {
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return {
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type: "value",
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value: {
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type: "list",
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values: s.map((expr) => this.evalToValue(expr)),
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},
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};
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}
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}
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findSym(ident, syms = this.syms) {
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if (syms.map.has(ident)) {
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return syms.map.get(ident);
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} else if (syms.parent) {
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return this.findSym(ident, syms.parent);
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} else {
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return undefined;
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}
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}
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}
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const artithmeticOps = {
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"+": (left, right) => right + left,
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"-": (left, right) => right - left,
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};
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const comparisonOps = {
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"==": (left, right) => left === right,
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"!=": (left, right) => left !== right,
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"<": (left, right) => left < right,
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">": (left, right) => left > right,
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"<=": (left, right) => left <= right,
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">=": (left, right) => left >= right,
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};
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const assignOps = {
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"=": (_, right) => right,
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"+=": (left, right) => ({ type: "int", value: left.value + right.value }),
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"-=": (left, right) => ({ type: "int", value: left.value - right.value }),
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};
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const builtinFns = {
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println(msg, ...args) {
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let text = valueToPrint(msg);
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for (const arg of args) {
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text = text.replace("%", valueToPrint(arg));
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}
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console.log(text);
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return { type: "null" };
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},
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read_text_file(path) {
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const text = fs.readFileSync(path.value).toString();
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return { type: "string", value: text };
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},
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push(list, value) {
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if (list.type === "string") {
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list.value += value.value;
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return list;
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}
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list.values.push(value);
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return list;
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},
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at(value, index) {
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if (value.type === "string") {
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return { type: "string", value: value.value[index.value] };
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}
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return value.values[index.value];
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},
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len(value) {
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if (value.type === "string") {
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return { type: "int", value: value.value.length };
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}
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return { type: "int", value: value.values.length };
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},
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};
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const consts = {
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"null": { type: "null" },
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"false": { type: "bool", value: false },
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"true": { type: "bool", value: true },
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};
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const builtins = [
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...Object.entries(builtinFns)
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.map(([key, fn]) => [key, { type: "builtin", fn }]),
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...Object.entries(consts),
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];
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function valueToPrint(value) {
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if (value.type === "null") {
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return "null";
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} else if (value.type === "bool") {
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return `${value.value}`;
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} else if (value.type === "int") {
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return `${value.value}`;
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} else if (value.type === "string") {
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return `${value.value}`;
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} else if (value.type === "list") {
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return `(${value.values.map((v) => valueToString(v)).join(" ")})`;
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} else {
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throw new Error(`unknown value type ${value.type}`);
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}
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}
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function valueToString(value) {
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if (value.type === "null") {
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return "null";
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} else if (value.type === "bool") {
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return `${value.value}`;
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} else if (value.type === "int") {
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return `${value.value}`;
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} else if (value.type === "string") {
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return `"${value.value}"`;
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} else if (value.type === "list") {
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return `(${value.values.map((v) => valueToString(v)).join(" ")})`;
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} else {
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throw new Error(`unknown value type ${value.type}`);
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}
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}
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function valueToJs(value) {
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if (value.type === "null") {
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return null;
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} else if (value.type === "bool") {
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return value.value;
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} else if (value.type === "int") {
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return value.value;
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} else if (value.type === "string") {
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return value.value;
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} else if (value.type === "list") {
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return value.values.map((v) => valueToJs(v));
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} else {
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throw new Error(`unknown value type ${value.type}`);
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}
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}
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/**
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* @param {Expr} expr
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* @returns {string}
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*/
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function exprToString(expr) {
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if (expr.type === "ident") {
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return expr.value;
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} else if (expr.type === "int") {
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return `${expr.value}`;
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} else if (expr.type === "string") {
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return `"${expr.value}"`;
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} else if (expr.type === "list") {
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return `(${expr.values.map((v) => exprToString(v)).join(" ")})`;
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} else {
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throw new Error(`unknown value type ${expr.type}`);
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}
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}
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/**
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* @typedef {{ type: string, line: number, value: any, values?: Expr } } Expr
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*/
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class Parser {
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constructor(text) {
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const stringExtractor = new StringExtractor(text);
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stringExtractor.extract();
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this.strings = stringExtractor.getStrings();
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this.text = stringExtractor.getOutputText();
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this.tokens = this.text
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.replace(/\/\/.*?$/mg, "")
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.replace(/([\(\)\n])/g, " $1 ")
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.split(/[ \t\r]/)
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.filter((tok) => tok !== "");
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this.idx = 0;
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this.line = 1;
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}
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/**
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* @returns {Expr[]}
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*/
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parse() {
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if (this.curr === "\n") {
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this.step();
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}
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const exprs = [];
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while (!this.done) {
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exprs.push(this.parseExpr());
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}
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return exprs;
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}
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parseExpr() {
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const line = this.line;
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if (this.eat("(")) {
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const values = [];
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while (!this.test(")")) {
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values.push(this.parseExpr());
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}
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if (!this.test(")")) {
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throw new Error(`expected ')'`);
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}
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this.step();
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return { type: "list", line, values };
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} else if (this.test(/STRING_\d+/)) {
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const id = Number(this.curr.match(/STRING_(\d+)/)[1]);
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this.step();
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return { type: "string", line, value: this.strings[id] };
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} else if (this.test(/0|(:?[1-9][0-9]*)/)) {
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const value = Number(this.curr);
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this.step();
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return { type: "int", line, value };
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} else if (this.test(/[a-zA-Z0-9\+\-\*/%&\|=\?\!<>'_]+/)) {
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const value = this.curr;
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this.step();
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return { type: "ident", line, value };
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} else {
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throw new Error(
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`expected expression, got ${this.curr} on line ${this.line}`,
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);
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}
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}
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eat(tok) {
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if (!this.test(tok)) {
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return false;
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}
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this.step();
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return true;
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}
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test(tok) {
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if (this.done) {
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return false;
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}
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if (typeof tok === "string") {
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return this.curr === tok;
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} else if (tok instanceof RegExp) {
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return new RegExp(`^${tok.source}$`)
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.test(this.curr);
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} else {
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throw new Error();
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}
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}
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step() {
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do {
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if (!this.done && this.curr === "\n") {
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this.line += 1;
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}
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this.idx += 1;
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} while (!this.done && this.curr === "\n");
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}
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get done() {
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return this.idx >= this.tokens.length;
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}
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get curr() {
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return this.tokens[this.idx];
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}
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}
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class StringExtractor {
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constructor(text) {
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this.text = text;
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this.idx = 0;
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this.outputText = "";
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this.strings = [];
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}
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extract() {
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while (this.idx < this.text.length) {
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if (this.text[this.idx] == '"') {
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this.extractString();
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} else {
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this.outputText += this.text[this.idx];
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this.idx += 1;
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}
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}
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}
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extractString() {
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this.idx += 1;
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let value = "";
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while (this.idx < this.text.length && this.text[this.idx] != '"') {
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if (this.text[this.idx] == "\\") {
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this.idx += 1;
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if (this.idx > this.text.length) {
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break;
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}
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const ch = this.text[this.idx];
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value += {
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"0": "\0",
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"t": "\t",
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"r": "\r",
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"n": "\n",
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}[ch] ?? ch;
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} else {
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value += this.text[this.idx];
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}
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this.idx += 1;
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}
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if (this.idx >= this.text.length || this.text[this.idx] != '"') {
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throw new Error("expected '\"'");
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}
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this.idx += 1;
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const id = this.strings.length;
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this.strings.push(value);
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this.outputText += `STRING_${id}`;
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}
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getStrings() {
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return this.strings;
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}
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getOutputText() {
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return this.outputText;
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}
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}
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main();
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