refactor(linter/plugins): reduce repeat code initializing tokensWithComments (#16017)

The same code was repeated in many places. Move it into a function.

Function is only called when `tokensWithComments` is not already initialized (cold path), so no function call cost in majority of cases. In Rust, the pattern of moving code which is rarely called into a separate function is usually positive for perf. Not sure whether JS engine works the same way, but it might well be that V8 makes inlining decisions in much the same way.

Author: overlookmotel

apps/oxlint/src-js/plugins/tokens.ts

@@ -167,6 +167,20 @@ function initTokens() {
   }));
 }
 
+/**
+ * Initialize `tokensWithComments`.
+ *
+ * Caller must ensure `tokens` and `comments` are initialized before calling this function.
+ */
+function initTokensWithComments() {
+  debugAssertIsNonNull(tokens);
+  debugAssertIsNonNull(comments);
+  // TODO: `tokens` and `comments` are already sorted, so there's a more efficient algorithm to merge them.
+  // That'd certainly be faster in Rust, but maybe here it's faster to leave it to JS engine to sort them?
+  // TODO: Replace `range[0]` with `start` once we have our own tokens which have `start` property.
+  tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
+}
+
 /**
  * Discard TS-ESLint tokens to free memory.
  */
@@ -228,12 +242,8 @@ export function getTokens(
   // Source array of tokens to search in
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      // TODO: `tokens` and `comments` are already sorted, so there's a more efficient algorithm to merge them.
-      // That'd certainly be faster in Rust, but maybe here it's faster to leave it to JS engine to sort them?
-      // TODO: Once we have our own tokens which have `start` and `end` properties, we can use them instead of `range`.
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -316,9 +326,8 @@ export function getFirstToken(node: Node, skipOptions?: SkipOptions | number | F
   // Source array of tokens
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -419,9 +428,8 @@ export function getFirstTokens(node: Node, countOptions?: CountOptions | number
 
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -536,9 +544,8 @@ export function getLastTokens(node: Node, countOptions?: CountOptions | number |
   // Source array of tokens to search in
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -644,9 +651,8 @@ export function getTokenBefore(
   // Source array of tokens to search in
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -757,9 +763,8 @@ export function getTokensBefore(
   // Source array of tokens to search in
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -850,9 +855,8 @@ export function getTokenAfter(
   // Source array of tokens to search in
   let nodeTokens: Token[] | null = null;
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;
@@ -958,9 +962,8 @@ export function getTokensAfter(
 
   let nodeTokens: Token[];
   if (includeComments) {
-    if (tokensWithComments === null) {
-      tokensWithComments = [...tokens, ...comments].sort((a, b) => a.range[0] - b.range[0]);
-    }
+    if (tokensWithComments === null) initTokensWithComments();
+    debugAssertIsNonNull(tokensWithComments);
     nodeTokens = tokensWithComments;
   } else {
     nodeTokens = tokens;