readline: add getPrompt to get the current prompt

Since there is a setPrompt() there should be a getPrompt().
There are use-cases where it is needed to know what the
current prompt is. Adding a getPrompt() negates the need
to store the set prompt externally or read the internal
_prompt which would be bad practice.
Co-authored-by: Colin Ihrig <cjihrig@gmail.com>
PR-URL: #33675
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>

Author: mattiasrunge

doc/api/readline.md

@@ -283,6 +283,15 @@ added: v0.1.98
 The `rl.setPrompt()` method sets the prompt that will be written to `output`
 whenever `rl.prompt()` is called.
 
+### `rl.getPrompt()`
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {string} the current prompt string
+
+The `rl.getPrompt()` method returns the current prompt used by `rl.prompt()`.
+
 ### `rl.write(data[, key])`
 <!-- YAML
 added: v0.1.98

lib/internal/repl/utils.js

@@ -144,7 +144,7 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
 letescaped=null;
 
 functiongetPreviewPos(){
-constdisplayPos=repl._getDisplayPos(`${repl._prompt}${repl.line}`);
+constdisplayPos=repl._getDisplayPos(`${repl.getPrompt()}${repl.line}`);
 constcursorPos=repl.line.length!==repl.cursor ?
 repl.getCursorPos() :
 displayPos;
@@ -177,7 +177,7 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
 rows=pos.displayPos.rows-pos.cursorPos.rows;
 moveCursor(repl.output,0,rows);
 }
-consttotalLine=`${repl._prompt}${repl.line}${completionPreview}`;
+consttotalLine=`${repl.getPrompt()}${repl.line}${completionPreview}`;
 constnewPos=repl._getDisplayPos(totalLine);
 // Minimize work for the terminal. It is enough to clear the right part of
 // the current line in case the preview is visible on a single line.
@@ -263,7 +263,7 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
 }
 repl.output.write(result);
 cursorTo(repl.output,cursorPos.cols);
-consttotalLine=`${repl._prompt}${repl.line}${suffix}`;
+consttotalLine=`${repl.getPrompt()}${repl.line}${suffix}`;
 constnewPos=repl._getDisplayPos(totalLine);
 constrows=newPos.rows-cursorPos.rows-(newPos.cols===0 ? 1 : 0);
 moveCursor(repl.output,0,-rows);
@@ -611,7 +611,7 @@ function setupReverseSearch(repl) {
 letrows=0;
 if(lastMatch!==-1){
 constline=repl.history[lastMatch].slice(0,lastCursor);
-rows=repl._getDisplayPos(`${repl._prompt}${line}`).rows;
+rows=repl._getDisplayPos(`${repl.getPrompt()}${line}`).rows;
 cursorTo(repl.output,promptPos.cols);
 }elseif(isInReverseSearch&&repl.line!==''){
 rows=repl.getCursorPos().rows;
@@ -631,7 +631,7 @@ function setupReverseSearch(repl) {
 
 // To know exactly how many rows we have to move the cursor back we need the
 // cursor rows, the output rows and the input rows.
-constprompt=repl._prompt;
+constprompt=repl.getPrompt();
 constcursorLine=`${prompt}${outputLine.slice(0,cursor)}`;
 constcursorPos=repl._getDisplayPos(cursorLine);
 constoutputPos=repl._getDisplayPos(`${prompt}${outputLine}`);
@@ -682,7 +682,7 @@ function setupReverseSearch(repl) {
 if(!isInReverseSearch){
 if(key.ctrl&&checkAndSetDirectionKey(key.name)){
 historyIndex=repl.historyIndex;
-promptPos=repl._getDisplayPos(`${repl._prompt}`);
+promptPos=repl._getDisplayPos(`${repl.getPrompt()}`);
 print(repl.line,`${labels[dir]}_`);
 isInReverseSearch=true;
 }

lib/readline.js

@@ -291,6 +291,11 @@ Interface.prototype.setPrompt = function(prompt) {
 };
 
 
+Interface.prototype.getPrompt=function(){
+returnthis._prompt;
+};
+
+
 Interface.prototype._setRawMode=function(mode){
 constwasInRawMode=this.input.isRaw;
 

test/parallel/test-readline-interface.js

@@ -898,6 +898,16 @@ for (let i = 0; i < 12; i++) {
 });
 }
 
+// Calling the getPrompt method
+{
+constexpectedPrompts=['$ ','> '];
+const[rli]=getInterface({ terminal });
+for(constpromptofexpectedPrompts){
+rli.setPrompt(prompt);
+assert.strictEqual(rli.getPrompt(),prompt);
+}
+}
+
 {
 constexpected=terminal ?
 ['\u001b[1G','\u001b[0J','$ ','\u001b[3G'] :
@@ -920,7 +930,7 @@ for (let i = 0; i < 12; i++) {
 
 rl.prompt();
 
-assert.strictEqual(rl._prompt,'$ ');
+assert.strictEqual(rl.getPrompt(),'$ ');
 }
 
 {

test/parallel/test-repl-options.js

@@ -104,7 +104,7 @@ assert.throws(r3, {
 // 4, Verify that defaults are used when no arguments are provided
 constr4=repl.start();
 
-assert.strictEqual(r4._prompt,'> ');
+assert.strictEqual(r4.getPrompt(),'> ');
 assert.strictEqual(r4.input,process.stdin);
 assert.strictEqual(r4.output,process.stdout);
 assert.strictEqual(r4.terminal,!!r4.output.isTTY);