add string utililities

common/util_string.hh

@@ -0,0 +1,73 @@
+#pragma once
+
+#include <algorithm>
+#include <optional>
+#include <span>
+#include <string>
+#include <string_view>
+#include <vector>
+
+
+namespace nf7::util {
+
+inline std::optional<std::string_view> IterateTerms(std::string_view str, char c, size_t& i) noexcept {
+  std::string_view ret;
+  while (ret.empty() && i < str.size()) {
+    auto j = str.find(c, i);
+    if (j == std::string::npos) j = str.size();
+
+    ret = str.substr(i, j-i);
+    i = j+1;
+  }
+  if (ret.empty()) return std::nullopt;
+  return ret;
+}
+
+inline void SplitAndAppend(std::vector<std::string>& dst, std::string_view src, char c = '\n') noexcept {
+  size_t itr = 0;
+  while (auto term = IterateTerms(src, c, itr)) {
+    dst.emplace_back(*term);
+  }
+}
+inline void JoinAndAppend(std::string& dst, std::span<const std::string> src, char c = '\n') noexcept {
+  for (auto& str : src) {
+    dst += str;
+    dst += c;
+  }
+}
+inline void Uniq(std::vector<std::string>& v) noexcept {
+  for (auto itr = v.begin(); itr < v.end();) {
+    if (v.end() != std::find(itr+1, v.end(), *itr)) {
+      itr = v.erase(itr);
+    } else {
+      ++itr;
+    }
+  }
+}
+
+inline std::optional<std::string_view> SplitAndValidate(
+    std::string_view v,
+    const std::function<bool(std::string_view)> validator, char c = '\n') noexcept {
+  size_t itr = 0;
+  while (auto term = IterateTerms(v, c, itr)) {
+    if (validator(*term)) {
+      return term;
+    }
+  }
+  return std::nullopt;
+}
+inline std::optional<std::string_view> SplitAndValidate(
+    std::string_view v,
+    const std::function<void(std::string_view)> validator, char c = '\n') noexcept {
+  size_t itr = 0;
+  while (auto term = IterateTerms(v, c, itr)) {
+    try {
+      validator(*term);
+    } catch (nf7::Exception&) {
+      return term;
+    }
+  }
+  return std::nullopt;
+}
+
+}  // namespace nf7::util