optimize CalcCapForJoin(StrVec)

sumatrapdfreader · May 24, 2024 · 5e57138 · 5e57138
1 parent 2f8d23c
commit 5e57138
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Showing 2 changed files with 10 additions and 6 deletions.
diff --git a/src/utils/StrVec.cpp b/src/utils/StrVec.cpp
@@ -72,12 +72,11 @@ int Split(StrVec& v, const char* s, const char* separator, bool collapse) {
 
 static int CalcCapForJoin(const StrVec& v, const char* joint) {
     // it's ok to over-estimate
-    int len = v.Size();
-    size_t jointLen = str::Len(joint);
-    int cap = len * (int)jointLen;
-    for (int i = 0; i < len; i++) {
-        char* s = v.At(i);
-        cap += (int)str::Len(s);
+    int cap = 0;
+    int jointLen = str::Leni(joint);
+    for (auto it = v.begin(); it != v.end(); it++) {
+        auto s = it.Span();
+        cap += s.Size() + 1 + jointLen;
     }
     return cap + 32; // +32 arbitrary buffer
 }
@@ -596,6 +595,10 @@ char* StrVec::iterator::operator*() const {
     return page->At(idxInPage);
 }
 
+StrSpan StrVec::iterator::Span() const {
+    return page->AtSpan(idxInPage);
+}
+
 static void Next(StrVec::iterator& it, int n) {
     // TODO: optimize for n > 1
     for (int i = 0; i < n; i++) {

diff --git a/src/utils/StrVec.h b/src/utils/StrVec.h
@@ -47,6 +47,7 @@ struct StrVec {
 
         iterator(const StrVec* v, int idx);
         char* operator*() const;
+        StrSpan Span() const;
         iterator& operator++();    // ++it
         iterator& operator++(int); // it++
         iterator& operator+(int);  // it += n