fix: limit the number of terms, closes #312

docusaurus-search-local/src/client/utils/smartQueries.ts

@@ -81,17 +81,6 @@ export function smartQueries(
     refinedTerms = terms.slice();
   }
 
-  const MAX_TERMS = 10;
-  if (refinedTerms.length > MAX_TERMS) {
-    // Sort terms by length in ascending order.,
-    // And keep the top 10 terms.
-    refinedTerms.sort((a, b) => a.length - b.length);
-    refinedTerms.splice(MAX_TERMS, refinedTerms.length - MAX_TERMS);
-
-    terms.sort((a, b) => a.length - b.length);
-    terms.splice(MAX_TERMS, terms.length - MAX_TERMS);
-  }
-
   // Also try to add extra terms which miss one of the searched tokens,
   // when the term contains 3 or more tokens,
   // to improve the search precision.

docusaurus-search-local/src/client/utils/smartTerms.ts

@@ -1,6 +1,9 @@
 import { SmartTerm } from "../../shared/interfaces";
 import { cutZhWords } from "./cutZhWords";
 
+const MAX_TERMS = 12;
+const HALF_MAX_TERMS = MAX_TERMS / 2;
+
 /**
  * Get all possible terms for a list of tokens consists of words mixed in Chinese and non-Chinese,
  * by a Chinese words dictionary.
@@ -14,19 +17,53 @@ export function smartTerms(
   tokens: string[],
   zhDictionary: string[]
 ): SmartTerm[] {
-  const tokenTerms = tokens.map((token) => {
-    if (/\p{Unified_Ideograph}/u.test(token)) {
-      return cutZhWords(token, zhDictionary);
+  const tokenTerms = tokens
+    .map((token) => {
+      if (/\p{Unified_Ideograph}/u.test(token)) {
+        return cutZhWords(token, zhDictionary);
+      } else {
+        return [{ value: token }];
+      }
+    })
+    .slice(0, MAX_TERMS);
+
+  const tokenTermsThatAreMultiple = tokenTerms.filter(
+    (tokenTerm) => tokenTerm.length > 1
+  );
+
+  let termsProduct = 1;
+  let overflowed = false;
+
+  for (const tokenTerm of tokenTermsThatAreMultiple) {
+    if (overflowed) {
+      tokenTerm.splice(1, tokenTerm.length - 1);
     } else {
-      return [{ value: token }];
+      if (tokenTerm.length > HALF_MAX_TERMS) {
+        tokenTerm.splice(HALF_MAX_TERMS, tokenTerm.length - HALF_MAX_TERMS);
+      }
+      const product = termsProduct * tokenTerm.length;
+      if (product >= MAX_TERMS) {
+        if (product > MAX_TERMS) {
+          const max = Math.floor(MAX_TERMS / termsProduct);
+          tokenTerm.splice(max, tokenTerm.length - max);
+          termsProduct = max * termsProduct;
+        } else {
+          termsProduct = product;
+        }
+        if (termsProduct > HALF_MAX_TERMS) {
+          overflowed = true;
+        }
+      } else {
+        termsProduct = product;
+      }
     }
-  });
+  }
 
   // Get all possible combinations of terms.
   const terms: SmartTerm[] = [];
   function combine(index: number, carry: SmartTerm): void {
-    if (index === tokenTerms.length) {
-      terms.push(carry);
+    if (index === tokenTerms.length || carry.length >= MAX_TERMS) {
+      terms.push(carry.slice(0, MAX_TERMS));
       return;
     }
     for (const term of tokenTerms[index]) {