[GitHub] [lucene-solr] cpoerschke commented on a change in pull request #1877: SOLR-13181: param macro expansion could throw

[GitBox <gi...@apache.org>]

cpoerschke commented on a change in pull request #1877:
URL: https://github.com/apache/lucene-solr/pull/1877#discussion_r489465208



##########
File path: solr/core/src/java/org/apache/solr/request/macro/MacroExpander.java
##########
@@ -136,11 +136,12 @@ private String _expand(String val) {
       }
       else if (idx < 0) {
         if (sb == null) return val;
-        sb.append(val.substring(start));
+        sb.append(val, start, val.length());
         return sb.toString();
       }
 
       // found unescaped "${"
+      int matchedStart = idx;

Review comment:
       ```suggestion
         final int matchedStart = idx;
   ```

##########
File path: solr/core/src/java/org/apache/solr/request/macro/MacroExpander.java
##########
@@ -154,14 +155,14 @@ else if (idx < 0) {
       }
 
       if (matchedStart > 0) {
-        sb.append(val.substring(start, matchedStart));
+        sb.append(val, start, matchedStart);
       }
 
       // update "start" to be at the end of ${...}
-      start = rbrace + 1;
+      idx = start = rbrace + 1;
 
-      // String inbetween = val.substring(idx, rbrace);
-      StrParser parser = new StrParser(val, idx, rbrace);
+      // String in-between = val.substring(idx, rbrace);

Review comment:
       How about removing rather than amending the `// String inbetween = val.substring(idx, rbrace);` commented out code line?

##########
File path: solr/core/src/java/org/apache/solr/request/macro/MacroExpander.java
##########
@@ -188,7 +189,7 @@ else if (failOnMissingParams) {
 
       } catch (SyntaxError syntaxError) {
         // append the part we would have skipped
-        sb.append( val.substring(matchedStart, start) );
+        sb.append(val, matchedStart, start);

Review comment:
       observation: `foo.append(bar.substring(x,y));` is also found in other places in the code base, not sure how it might work implementation wise but it would be lovely if tooling would flag up that there's a more efficient alternative

##########
File path: solr/core/src/java/org/apache/solr/request/macro/MacroExpander.java
##########
@@ -136,11 +136,12 @@ private String _expand(String val) {
       }
       else if (idx < 0) {
         if (sb == null) return val;
-        sb.append(val.substring(start));
+        sb.append(val, start, val.length());
         return sb.toString();
       }
 
       // found unescaped "${"
+      int matchedStart = idx;
       idx += macroStart.length();
 
       int rbrace = val.indexOf('}', idx);

Review comment:
       ```suggestion
         int rbrace = val.indexOf('}', matchedStart + macroStart.length());
   ```
   
   similar to line 165 below and then the `idx += macroStart.length();` assignment would not be needed since there would be no use of `idx` between that incrementing assigment and the `idx = start = rbrace + 1;` resetting assignment below.




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