add replace_char() method to SkString API (skbug.com/2651)

src/core/SkString.cpp

Index: src/core/SkString.cpp
diff --git a/src/core/SkString.cpp b/src/core/SkString.cpp
index ba1da4136893dffcbc5e1ac8252d9e3a4118a977..aeff325dca202a04d8e4b395092d960eef17aed9 100644
--- a/src/core/SkString.cpp
+++ b/src/core/SkString.cpp
@@ -555,6 +555,17 @@ void SkString::insertScalar(size_t offset, SkScalar value) {
     this->insert(offset, buffer, stop - buffer);
 }
 
+void SkString::replace_char(const char oldChar, const char newChar) {
+    if (this->isEmpty()) {
+        return;
+    }
+    for (size_t i = 0; i < this->size(); ++i) {
+        if (oldChar == this->operator[](i)) {

[epoger, 2014/06/11 11:01:33]

Instead of going through the [] operator, I suspect it would be more efficient
to do something like this:

size_t len = this->size();
if (len > 0) {
  char* writable = this->writable_str();
  for (size_t i = len - 1; i >= 0; --i) {
    if (oldChar == writable[i]) {
      writable[i] = newChar;
    }
  }
}

[rs.prinja, 2014/06/11 12:08:03]

Done, although since unsigned always compares as >= 0 I ran the loop from 0 to
len-1 instead.

+            fRec->data()[i] = newChar;
+        }
+    }
+}
+
 void SkString::printf(const char format[], ...) {
     char    buffer[kBufferSize];
     ARGS_TO_BUFFER(format, buffer, kBufferSize);