Optimize substrings for performance (h/t @rodinaarssen)

toinehartman · toinehartman · commit fa8fe8b6cfa9 · 2025-08-29T13:15:14.000+02:00
diff --git a/src/org/rascalmpl/library/String.rsc b/src/org/rascalmpl/library/String.rsc
@@ -748,7 +748,7 @@ str(str) indentTabsAsSpaces(int tabSize) {
 * The number of substrings is quadratic in the size of the string; expensive to compute.
 }
 set[str] substrings(str input)
-    = {input[i..i+l] | int i <- [0..size(input)], int l <- [1..size(input)], i + l <= size(input)};
+    = {input[i..i+l] | int i <- [0..size(input)], int l <- [1..size(input)-i+1]} - input;
 
 @synopsis{If a string does not end with a newline character, append one. }
 str insertFinalNewline(str input, list[str] lineseps = newLineCharacters)

Original file line number	Diff line number	Diff line change
`@@ -748,7 +748,7 @@ str(str) indentTabsAsSpaces(int tabSize) {`
`748`	`748`	`* The number of substrings is quadratic in the size of the string; expensive to compute.`
`749`	`749`	`}`
`750`	`750`	`set[str] substrings(str input)`
`751`		`- = {input[i..i+l] \| int i <- [0..size(input)], int l <- [1..size(input)], i + l <= size(input)};`
	`751`	`+ = {input[i..i+l] \| int i <- [0..size(input)], int l <- [1..size(input)-i+1]} - input;`
`752`	`752`
`753`	`753`	`@synopsis{If a string does not end with a newline character, append one. }`
`754`	`754`	`str insertFinalNewline(str input, list[str] lineseps = newLineCharacters)`