diff --git a/cpp/src/strings/regex/regcomp.cpp b/cpp/src/strings/regex/regcomp.cpp
index 829230d0842..f99acc3448a 100644
--- a/cpp/src/strings/regex/regcomp.cpp
+++ b/cpp/src/strings/regex/regcomp.cpp
@@ -44,17 +44,17 @@ enum OperatorType {
   NOP          = 0302,  // No operation, internal use only
 };
 
-static reclass ccls_w(1);   // [a-z], [A-Z], [0-9], and '_'
-static reclass ccls_W(8);   // now ccls_w plus '\n'
-static reclass ccls_s(2);   // all spaces or ctrl characters
-static reclass ccls_S(16);  // not ccls_s
-static reclass ccls_d(4);   // digits [0-9]
-static reclass ccls_D(32);  // not ccls_d plus '\n'
+static reclass ccls_w(CCLASS_W);   // \w
+static reclass ccls_s(CCLASS_S);   // \s
+static reclass ccls_d(CCLASS_D);   // \d
+static reclass ccls_W(NCCLASS_W);  // \W
+static reclass ccls_S(NCCLASS_S);  // \S
+static reclass ccls_D(NCCLASS_D);  // \D
 
 // Tables for analyzing quantifiers
 const std::array<int, 6> valid_preceding_inst_types{{CHAR, CCLASS, NCCLASS, ANY, ANYNL, RBRA}};
 const std::array<char, 5> quantifiers{{'*', '?', '+', '{', '|'}};
-// Valid regex characters that can be escaping to be used as literals
+// Valid regex characters that can be escaped and used as literals
 const std::array<char, 33> escapable_chars{
   {'.', '-', '+',  '*', '\\', '?', '^', '$', '|', '{', '}', '(', ')', '[', ']', '<', '>',
    '"', '~', '\'', '`', '_',  '@', '=', ';', ':', '!', '#', '%', '&', ',', '/', ' '}};
diff --git a/cpp/src/strings/regex/regcomp.h b/cpp/src/strings/regex/regcomp.h
index 798b43830b4..162a2090268 100644
--- a/cpp/src/strings/regex/regcomp.h
+++ b/cpp/src/strings/regex/regcomp.h
@@ -41,9 +41,9 @@ enum InstType {
   BOL     = 0303,  // Beginning of line, ^
   EOL     = 0304,  // End of line, $
   CCLASS  = 0305,  // Character class, []
-  NCCLASS = 0306,  // Negated character class, []
-  BOW     = 0307,  // Boundary of word, /b
-  NBOW    = 0310,  // Not boundary of word, /b
+  NCCLASS = 0306,  // Negated character class, [^ ]
+  BOW     = 0307,  // Boundary of word, \b
+  NBOW    = 0310,  // Not boundary of word, \B
   END     = 0377   // Terminate: match found
 };
 
@@ -57,6 +57,13 @@ struct reclass {
   reclass(int m) : builtins(m) {}
 };
 
+constexpr int32_t CCLASS_W{1 << 0};   // [a-z], [A-Z], [0-9], and '_'
+constexpr int32_t CCLASS_S{1 << 1};   // all spaces or ctrl characters
+constexpr int32_t CCLASS_D{1 << 2};   // digits [0-9]
+constexpr int32_t NCCLASS_W{1 << 3};  // not CCLASS_W or '\n'
+constexpr int32_t NCCLASS_S{1 << 4};  // not CCLASS_S
+constexpr int32_t NCCLASS_D{1 << 5};  // not CCLASS_D or '\n'
+
 /**
  * @brief Structure of an encoded regex instruction
  */
@@ -76,12 +83,11 @@ struct reinst {
 };
 
 /**
- * @brief Regex program handles parsing a pattern in to individual set
+ * @brief Regex program handles parsing a pattern into a vector
  * of chained instructions.
  */
 class reprog {
  public:
-  reprog()              = default;
   reprog(const reprog&) = default;
   reprog(reprog&&)      = default;
   ~reprog()             = default;
@@ -89,8 +95,12 @@ class reprog {
   reprog& operator=(reprog&&) = default;
 
   /**
-   * @brief Parses the given regex pattern and compiles
-   * into a list of chained instructions.
+   * @brief Parses the given regex pattern and produces an instance
+   * of this object
+   *
+   * @param pattern Regex pattern encoded as UTF-8
+   * @param flags For interpretting certain `pattern` characters
+   * @return Instance of reprog
    */
   static reprog create_from(std::string_view pattern, regex_flags const flags);
 
@@ -122,12 +132,13 @@ class reprog {
 #endif
 
  private:
-  std::vector<reinst> _insts;
-  std::vector<reclass> _classes;
-  int32_t _startinst_id;
+  std::vector<reinst> _insts;           // instructions
+  std::vector<reclass> _classes;        // data for CCLASS instructions
+  int32_t _startinst_id{};              // id of first instruction
   std::vector<int32_t> _startinst_ids;  // short-cut to speed-up ORs
   int32_t _num_capturing_groups{};
 
+  reprog() = default;
   void check_for_errors(int32_t id, int32_t next_id);
 };
 
diff --git a/cpp/src/strings/regex/regex.inl b/cpp/src/strings/regex/regex.inl
index bae6fb275f6..8e2194f2094 100644
--- a/cpp/src/strings/regex/regex.inl
+++ b/cpp/src/strings/regex/regex.inl
@@ -148,17 +148,17 @@ __device__ __forceinline__ bool reclass_device::is_match(char32_t const ch,
   uint32_t codept = utf8_to_codepoint(ch);
   if (codept > 0x00FFFF) return false;
   int8_t fl = codepoint_flags[codept];
-  if ((builtins & 1) && ((ch == '_') || IS_ALPHANUM(fl)))  // \w
+  if ((builtins & CCLASS_W) && ((ch == '_') || IS_ALPHANUM(fl)))  // \w
     return true;
-  if ((builtins & 2) && IS_SPACE(fl))  // \s
+  if ((builtins & CCLASS_S) && IS_SPACE(fl))  // \s
     return true;
-  if ((builtins & 4) && IS_DIGIT(fl))  // \d
+  if ((builtins & CCLASS_D) && IS_DIGIT(fl))  // \d
     return true;
-  if ((builtins & 8) && ((ch != '\n') && (ch != '_') && !IS_ALPHANUM(fl)))  // \W
+  if ((builtins & NCCLASS_W) && ((ch != '\n') && (ch != '_') && !IS_ALPHANUM(fl)))  // \W
     return true;
-  if ((builtins & 16) && !IS_SPACE(fl))  // \S
+  if ((builtins & NCCLASS_S) && !IS_SPACE(fl))  // \S
     return true;
-  if ((builtins & 32) && ((ch != '\n') && !IS_DIGIT(fl)))  // \D
+  if ((builtins & NCCLASS_D) && ((ch != '\n') && !IS_DIGIT(fl)))  // \D
     return true;
   //
   return false;