node: make builtin libs available for --eval

Make the builtin libraries available for the `--eval` and
`--print` CLI options, using the same mechanism that the
REPL uses.
This renders workarounds like `node -e 'require("fs").doStuff()'`
unnecessary.
As part of this, the list of builtin modules and the code for
adding the corresponding properties to the target context is moved
to `internal/module.js`, and the previously missing `repl` entry
is added.
PR-URL: #6207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: addaleax

doc/api/cli.markdown

@@ -36,7 +36,8 @@ The output of this option is less detailed than this document.
 
 ### `-e`, `--eval "script"`
 
-Evaluate the following argument as JavaScript.
+Evaluate the following argument as JavaScript. The modules which are
+predefined in the REPL can also be used in `script`.
 
 
 ### `-p`, `--print "script"`

lib/internal/bootstrap_node.js

@@ -94,6 +94,9 @@
 // User passed '-e' or '--eval' arguments to Node without '-i' or
 // '--interactive'
 preloadModules();
+
+constinternalModule=NativeModule.require('internal/module');
+internalModule.addBuiltinLibsToObject(global);
 evalScript('[eval]');
 }elseif(process.argv[1]){
 // make process.argv[1] into a full path

lib/internal/module.js

@@ -1,6 +1,10 @@
 'use strict';
 
-exports=module.exports={ makeRequireFunction, stripBOM };
+exports=module.exports={
+ makeRequireFunction,
+ stripBOM,
+ addBuiltinLibsToObject
+};
 
 exports.requireDepth=0;
 
@@ -44,3 +48,32 @@ function stripBOM(content) {
 }
 returncontent;
 }
+
+exports.builtinLibs=['assert','buffer','child_process','cluster',
+'crypto','dgram','dns','domain','events','fs','http','https','net',
+'os','path','punycode','querystring','readline','repl','stream',
+'string_decoder','tls','tty','url','util','v8','vm','zlib'];
+
+functionaddBuiltinLibsToObject(object){
+// Make built-in modules available directly (loaded lazily).
+exports.builtinLibs.forEach((name)=>{
+Object.defineProperty(object,name,{
+get: ()=>{
+constlib=require(name);
+// This implicitly invokes the setter, so that this getter is only
+// invoked at most once and does not overwrite anything.
+object[name]=lib;
+returnlib;
+},
+// Allow the creation of other globals with this name.
+set: (val)=>{
+// Deleting the property before re-assigning it disables the
+// getter/setter mechanism.
+deleteobject[name];
+object[name]=val;
+},
+configurable: true,
+enumerable: false
+});
+});
+}

lib/repl.js

@@ -64,10 +64,7 @@ function hasOwnProperty(obj, prop) {
 // This is the default "writer" value if none is passed in the REPL options.
 exports.writer=util.inspect;
 
-exports._builtinLibs=['assert','buffer','child_process','cluster',
-'crypto','dgram','dns','domain','events','fs','http','https','net',
-'os','path','punycode','querystring','readline','stream',
-'string_decoder','tls','tty','url','util','v8','vm','zlib'];
+exports._builtinLibs=internalModule.builtinLibs;
 
 
 constBLOCK_SCOPED_ERROR='Block-scoped declarations (let, const, function, '+
@@ -559,23 +556,7 @@ REPLServer.prototype.createContext = function() {
 this.lines=[];
 this.lines.level=[];
 
-// make built-in modules available directly
-// (loaded lazily)
-exports._builtinLibs.forEach(function(name){
-Object.defineProperty(context,name,{
-get: function(){
-varlib=require(name);
-context._=context[name]=lib;
-returnlib;
-},
-// allow the creation of other globals with this name
-set: function(val){
-deletecontext[name];
-context[name]=val;
-},
-configurable: true
-});
-});
+internalModule.addBuiltinLibsToObject(context);
 
 returncontext;
 };

test/parallel/test-cli-eval.js

@@ -53,6 +53,13 @@ child.exec(nodejs + ' --eval "require(\'' + filename + '\')"',
 assert.equal(status.code,42);
 });
 
+// Check that builtin modules are pre-defined.
+child.exec(nodejs+' --print "os.platform()"',
+function(status,stdout,stderr){
+assert.strictEqual(stderr,'');
+assert.strictEqual(stdout.trim(),require('os').platform());
+});
+
 // module path resolve bug, regression test
 child.exec(nodejs+' --eval "require(\'./test/parallel/test-cli-eval.js\')"',
 function(status,stdout,stderr){