replace regex in ParseUtil

Device/IO/ParseUtil.cpp

@@ -18,10 +18,8 @@
 #include "Base/Util/StringUtil.h"
 #include "Device/Data/Datafield.h"
 #include <cmath> // ignoreDenormalized
-#include <functional>
 #include <iostream>
 #include <iterator>
-#include <regex>
 
 namespace {
 
@@ -64,13 +62,29 @@ Scale* Util::Parse::parseScale(std::istream& input_stream)
 {
     std::string line;
     std::getline(input_stream, line);
-    std::smatch matched;
-    std::regex_match(line, matched, std::regex("(\\w+)\\(\"(.*?)\",\\s*(.+?)\\)"));
-    if (matched.size() != 4)
-        throw std::runtime_error("Cannot read axis from input");
-    const std::string type = matched[1];
-    const std::string name = matched[2];
-    const std::string body = matched[3];
+
+    size_t j = line.find_first_of('(');
+    if (j == std::string::npos)
+        throw std::runtime_error("Scale constructor has no '('");
+    std::string type = line.substr(0, j);
+
+    line = line.substr(j + 1);
+    if (line.back() != ')')
+        throw std::runtime_error("Scale constructor call not ending with ')'");
+    line = line.substr(0, line.size() - 1);
+
+    if (line[0] != '"')
+        throw std::runtime_error("Scale constructor arg 1 does not start with \"");
+    j = 1 + line.substr(1).find_first_of('"');
+    if (j == std::string::npos)
+        throw std::runtime_error("Scale constructor arg 1 has no closing \"");
+    std::string name = line.substr(1, j - 1);
+
+    if (line[j + 1] != ',')
+        throw std::runtime_error("Scale constructor arg 1 not followed by comma");
+    std::string body = line.substr(j + 2);
+    body = Base::String::trimFront(body, " ");
+
     if (type == "EquiDivision" || type == "FixedBinAxis" /* for compatibility with pre-21 */) {
         std::vector<std::string> arr = Base::String::split(body, ",");
         int nbins;