[ui/base;css] adding string template expression replacement

base/strings/string_util.cc

Index: base/strings/string_util.cc
diff --git a/base/strings/string_util.cc b/base/strings/string_util.cc
index e3dcd8542fabcc263cf26f23014669097e9c3ba0..be08f18a541957db1e45570deda14756422e5e8e 100644
--- a/base/strings/string_util.cc
+++ b/base/strings/string_util.cc
@@ -16,6 +16,7 @@
 #include <wctype.h>
 
 #include <algorithm>
+#include <map>
 #include <vector>
 
 #include "base/basictypes.h"
@@ -860,11 +861,55 @@ string16 JoinString(const std::vector<string16>& parts,
   return JoinStringT(parts, separator);
 }
 
-template<class FormatStringType, class OutStringType>
-OutStringType DoReplaceStringPlaceholders(const FormatStringType& format_string,
-    const std::vector<OutStringType>& subst, std::vector<size_t>* offsets) {
-  size_t substitutions = subst.size();
+template <class FormatStringType, class OutStringType>
+OutStringType DoReplaceStringPlaceholders(
+    const FormatStringType& format_string,
+    const std::map<std::string, OutStringType>& subst) {
+  OutStringType formatted;
+  const size_t kValueLengthGuess = 16;
+  formatted.reserve(format_string.length() + subst.size() * kValueLengthGuess);
+  for (typename FormatStringType::const_iterator i = format_string.begin();
+       i != format_string.end(); ++i) {
+    if (*i == '$') {
+      if (i + 1 != format_string.end()) {
+        ++i;
+        if (*i == '{') {
+          std::string index;
+          ++i;
+          while (i != format_string.end() && *i != '}') {
+            index.push_back(*i);
+            ++i;
+          }
+          const auto& replacement = subst.find(index);
+          if (replacement != subst.end())
+            formatted.append(replacement->second);
+        } else if (*i == '$') {
+          while (i != format_string.end() && *i == '$') {
+            formatted.push_back('$');
+            ++i;
+          }
+          --i;
+        }
+      }
+    } else {
+      formatted.push_back(*i);
+    }
+  }
+  return formatted;
+}
 
+std::string ReplaceStringPlaceholders(
+    const std::string& format_string,
+    const std::map<std::string, std::string>& subst) {
+  return DoReplaceStringPlaceholders(format_string, subst);
+}
+
+template <class FormatStringType, class OutStringType>
+OutStringType DoReplaceStringPlaceholders(
+    const FormatStringType& format_string,
+    const std::vector<OutStringType>& subst,
+    std::vector<size_t>* offsets) {
+  size_t substitutions = subst.size();
   size_t sub_length = 0;
   for (typename std::vector<OutStringType>::const_iterator iter = subst.begin();
        iter != subst.end(); ++iter) {