util/system: Add GetFixedPointArg helper

Author: luke-jr

src/common/args.cpp

@@ -503,6 +503,25 @@ int64_t SettingToInt(const common::SettingsValue& value, int64_t nDefault)
     return SettingToInt(value).value_or(nDefault);
 }
 
+std::optional<int64_t> ArgsManager::GetFixedPointArg(const std::string& arg, int decimals) const
+{
+    const common::SettingsValue value = GetSetting(arg);
+    return SettingToFixedPoint(value, decimals);
+}
+
+std::optional<int64_t> SettingToFixedPoint(const common::SettingsValue& value, int decimals)
+{
+    if (value.isNull()) return std::nullopt;
+    if (value.isFalse()) return 0;
+    if (value.isTrue()) return 1;
+    if (!value.isNum()) value.get_str();  // throws an exception if type is wrong
+    int64_t v;
+    if (!ParseFixedPoint(value.getValStr(), decimals, &v)) {
+        throw std::runtime_error(strprintf("Parse error ('%s')", value.getValStr()));
+    }
+    return v;
+}
+
 bool ArgsManager::GetBoolArg(const std::string& strArg, bool fDefault) const
 {
     return GetBoolArg(strArg).value_or(fDefault);

src/common/args.h

@@ -90,6 +90,8 @@ std::optional<std::string> SettingToString(const common::SettingsValue&);
 int64_t SettingToInt(const common::SettingsValue&, int64_t);
 std::optional<int64_t> SettingToInt(const common::SettingsValue&);
 
+std::optional<int64_t> SettingToFixedPoint(const common::SettingsValue&, int decimals);
+
 bool SettingToBool(const common::SettingsValue&, bool);
 std::optional<bool> SettingToBool(const common::SettingsValue&);
 
@@ -293,6 +295,15 @@ class ArgsManager
     int64_t GetIntArg(const std::string& strArg, int64_t nDefault) const;
     std::optional<int64_t> GetIntArg(const std::string& strArg) const;
 
+    /**
+     * Return fixed-point argument
+     *
+     * @param arg Argument to get (e.g. "-foo")
+     * @param decimals Number of fractional decimal digits to accept
+     * @return Command-line argument (0 if invalid number) multiplied by 10**decimals
+     */
+    std::optional<int64_t> GetFixedPointArg(const std::string& arg, int decimals) const;
+
     /**
      * Return boolean argument or default value
      *

test/lint/check-doc.py

@@ -15,7 +15,7 @@
 
 FOLDER_GREP = 'src'
 FOLDER_TEST = 'src/test/'
-REGEX_ARG = r'\b(?:GetArg|GetArgs|GetBoolArg|GetIntArg|GetPathArg|IsArgSet|get_net)\("(-[^"]+)"'
+REGEX_ARG = r'\b(?:GetArg|GetArgs|GetBoolArg|GetIntArg|GetFixedPointArg|GetPathArg|IsArgSet|get_net)\("(-[^"]+)"'
 REGEX_DOC = r'AddArg\("(-[^"=]+?)(?:=|")'
 CMD_ROOT_DIR = '$(git rev-parse --show-toplevel)/{}'.format(FOLDER_GREP)
 CMD_GREP_ARGS = r"git grep --perl-regexp '{}' -- {} ':(exclude){}'".format(REGEX_ARG, CMD_ROOT_DIR, FOLDER_TEST)