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// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { exit } from "./ops/os.ts";
import { core } from "./core.ts";
import { version } from "./version.ts";
import { stringifyArgs } from "./web/console.ts";
import { startRepl, readline } from "./ops/repl.ts";
import { close } from "./ops/resources.ts";
function replLog(...args: unknown[]): void {
core.print(stringifyArgs(args) + "\n");
}
function replError(...args: unknown[]): void {
core.print(stringifyArgs(args) + "\n", true);
}
// Error messages that allow users to continue input
// instead of throwing an error to REPL
// ref: https://github.com/v8/v8/blob/master/src/message-template.h
// TODO(kevinkassimo): this list might not be comprehensive
const recoverableErrorMessages = [
"Unexpected end of input", // { or [ or (
"Missing initializer in const declaration", // const a
"Missing catch or finally after try", // try {}
"missing ) after argument list", // console.log(1
"Unterminated template literal", // `template
// TODO(kevinkassimo): need a parser to handling errors such as:
// "Missing } in template expression" // `${ or `${ a 123 }`
];
function isRecoverableError(e: Error): boolean {
return recoverableErrorMessages.includes(e.message);
}
// Returns `true` if `close()` is called in REPL.
// We should quit the REPL when this function returns `true`.
function isCloseCalled(): boolean {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
return (globalThis as any).closed;
}
// eslint-disable-next-line @typescript-eslint/no-explicit-any
type Value = any;
let lastEvalResult: Value = undefined;
let lastThrownError: Value = undefined;
// Evaluate code.
// Returns true if code is consumed (no error/irrecoverable error).
// Returns false if error is recoverable
function evaluate(code: string): boolean {
// each evalContext is a separate function body, and we want strict mode to
// work, so we should ensure that the code starts with "use strict"
const [result, errInfo] = core.evalContext(`"use strict";\n\n${code}`);
if (!errInfo) {
// when a function is eval'ed with just "use strict" sometimes the result
// is "use strict" which should be discarded
lastEvalResult =
typeof result === "string" && result === "use strict"
? undefined
: result;
if (!isCloseCalled()) {
replLog(lastEvalResult);
}
} else if (errInfo.isCompileError && isRecoverableError(errInfo.thrown)) {
// Recoverable compiler error
return false; // don't consume code.
} else {
lastThrownError = errInfo.thrown;
if (errInfo.isNativeError) {
const formattedError = core.formatError(errInfo.thrown as Error);
replError(formattedError);
} else {
replError("Thrown:", errInfo.thrown);
}
}
return true;
}
// @internal
export async function replLoop(): Promise<void> {
const { console } = globalThis;
const historyFile = "deno_history.txt";
const rid = startRepl(historyFile);
const quitRepl = (exitCode: number): void => {
// Special handling in case user calls deno.close(3).
try {
close(rid); // close signals Drop on REPL and saves history.
} catch {}
exit(exitCode);
};
// Configure globalThis._ to give the last evaluation result.
Object.defineProperty(globalThis, "_", {
configurable: true,
get: (): Value => lastEvalResult,
set: (value: Value): Value => {
Object.defineProperty(globalThis, "_", {
value: value,
writable: true,
enumerable: true,
configurable: true,
});
console.log("Last evaluation result is no longer saved to _.");
},
});
// Configure globalThis._error to give the last thrown error.
Object.defineProperty(globalThis, "_error", {
configurable: true,
get: (): Value => lastThrownError,
set: (value: Value): Value => {
Object.defineProperty(globalThis, "_error", {
value: value,
writable: true,
enumerable: true,
configurable: true,
});
console.log("Last thrown error is no longer saved to _error.");
},
});
replLog(`Deno ${version.deno}`);
replLog("exit using ctrl+d or close()");
while (true) {
if (isCloseCalled()) {
quitRepl(0);
}
let code = "";
// Top level read
try {
code = await readline(rid, "> ");
if (code.trim() === "") {
continue;
}
} catch (err) {
if (err.message === "EOF") {
quitRepl(0);
} else {
// If interrupted, don't print error.
if (err.message !== "Interrupted") {
// e.g. this happens when we have deno.close(3).
// We want to display the problem.
const formattedError = core.formatError(err);
replError(formattedError);
}
// Quit REPL anyways.
quitRepl(1);
}
}
// Start continued read
while (!evaluate(code)) {
code += "\n";
try {
code += await readline(rid, " ");
} catch (err) {
// If interrupted on continued read,
// abort this read instead of quitting.
if (err.message === "Interrupted") {
break;
} else if (err.message === "EOF") {
quitRepl(0);
} else {
// e.g. this happens when we have deno.close(3).
// We want to display the problem.
const formattedError = core.formatError(err);
replError(formattedError);
quitRepl(1);
}
}
}
}
}
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