Closes #7

.clang-format

@@ -0,0 +1,65 @@
+BasedOnStyle: LLVM
+AccessModifierOffset: -4
+AlignAfterOpenBracket: Align
+AlignConsecutiveAssignments: None
+AlignOperands: Align
+AllowAllArgumentsOnNextLine: false
+AllowAllConstructorInitializersOnNextLine: false
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortBlocksOnASingleLine: Always
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: Always
+AllowShortLambdasOnASingleLine: All
+AllowShortLoopsOnASingleLine: true
+AlwaysBreakAfterReturnType: None
+AlwaysBreakTemplateDeclarations: Yes
+BreakBeforeBraces: Custom
+BraceWrapping:
+  AfterCaseLabel: false
+  AfterClass: false
+  AfterControlStatement: Never
+  AfterEnum: false
+  AfterFunction: false
+  AfterNamespace: false
+  AfterUnion: false
+  BeforeCatch: false
+  BeforeElse: false
+  IndentBraces: false
+  SplitEmptyFunction: false
+  SplitEmptyRecord: true
+BreakBeforeBinaryOperators: None
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializers: BeforeColon
+BreakInheritanceList: BeforeColon
+ColumnLimit: 0
+CompactNamespaces: false
+ContinuationIndentWidth: 8
+IndentCaseLabels: true
+IndentPPDirectives: None
+IndentWidth: 4
+KeepEmptyLinesAtTheStartOfBlocks: true
+MaxEmptyLinesToKeep: 2
+NamespaceIndentation: All
+ObjCSpaceAfterProperty: false
+ObjCSpaceBeforeProtocolList: true
+PointerAlignment: Right
+ReflowComments: false
+SpaceAfterCStyleCast: true
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: false
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeParens: ControlStatements
+SpaceBeforeRangeBasedForLoopColon: false
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 0
+SpacesInAngles: false
+SpacesInCStyleCastParentheses: false
+SpacesInContainerLiterals: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+TabWidth: 4
+UseTab: Never

README.md

@@ -151,8 +151,11 @@ Files:
 
 - `dbc_parser.h`
 - `dbc_parser.cpp`
+- `dbc_statement_handler.h`
+- `dbc_statement_handler.cpp`
+- `typefactory.h`
 
-These parse the DBC file itself.
+The parser reads files and reports errors; registered statement handlers parse DBC constructs.
 
 ### Demo
 
@@ -414,6 +417,34 @@ Fields:
 
 ---
 
+### Raw value representation and precision
+
+`DecodedSignalValue::rawValue` is a C++17
+`std::variant<std::int64_t, std::uint64_t>`. For a valid signal, signed definitions
+produce the `int64_t` alternative and unsigned definitions produce the `uint64_t`
+alternative. Raw values remain exact across their full 64-bit ranges. Check
+`valid` before using the value; an invalid result's default value is not decoded data.
+
+Use `std::get` when the numeric type is known, or `std::visit` to handle both:
+
+```cpp
+std::visit([] (auto raw) { std::cout << raw; }, decodedSignal.rawValue);
+```
+
+This replaces the previous `int64_t` field: consumers that read or print
+`rawValue` directly must handle the variant.
+
+Physical conversion uses the active numeric type:
+`physicalValue = static_cast<double>(raw) * factor + offset`.
+`physicalValue` remains a `double` and is approximate for large integers.
+On usual IEEE 754 binary64 implementations, integers are exactly representable
+through 2^53; above that, some integers round to the same floating-point value.
+For example, unsigned `UINT64_MAX` remains exact in `rawValue`, but converts to
+approximately 18446744073709551616 in binary64 before scaling.
+Use `rawValue` whenever exact integer values are required.
+
+---
+
 ## `DecodedFrameValue`
 
 Represents one decoded frame result.
@@ -477,6 +508,35 @@ Parsed fields:
 
 ---
 
+### Frame validation and parse errors
+
+`BO_` definitions require a decimal CAN ID, a nonempty single-token frame name,
+a colon, a decimal payload length, and a transmitter token. Spaces or tabs may
+separate fields, and whitespace before the colon is accepted. Additional trailing
+fields are rejected.
+
+Numeric fields must contain decimal digits only; signs, hexadecimal notation,
+fractional values, suffixes, and overflow are rejected. CAN IDs may contain the
+29-bit identifier plus the optional DBC extended flag (bit 31). Bits 29 and 30
+are rejected rather than silently discarded. For compatibility, unflagged IDs
+above `0x7FF` are still treated as extended.
+
+The payload length must fit `uint8_t` (`0..255`). This is a storage-range check,
+not CAN or CAN FD protocol validation; no new 8-byte or 64-byte limit is imposed.
+
+Parsing stops at the first detected error. Exceptions raised while parsing a
+line are reported as `std::runtime_error` with the supplied file path and the
+one-based physical line number, including blank lines:
+
+```text
+example.dbc:3: Invalid CAN ID: invalid
+```
+
+This change validates frame definitions. Signal definitions are also validated as described below; comprehensive
+DBC grammar coverage is still planned. File-open errors contain the path but have no line number.
+
+---
+
 ## Signal definition
 
 Example:
@@ -501,6 +561,35 @@ Parsed fields:
 
 ---
 
+### Signal validation and parse errors
+
+`SG_` statements are matched completely. Signal names must be nonempty and
+contain no whitespace. Spaces and tabs are accepted between syntax elements;
+byte order and signedness remain adjacent (`@0+`, `@0-`, `@1+`, or `@1-`).
+A quoted unit (which may be empty) and a nonempty comma-separated receiver
+list are required. Unexpected trailing fields are rejected.
+
+Start bits must be unsigned decimal integers fitting `uint32_t`; lengths must
+be within `1..64` bits. Signs, fractional values, numeric suffixes, and overflow
+are rejected for these fields. Every signal bit must fit within the frame's
+declared payload length, using Intel increasing bit positions or Motorola
+sawtooth traversal. This uses the stored payload length without introducing
+an additional CAN or CAN FD payload limit.
+
+Factor, offset, minimum, and maximum accept signed decimal numbers, fractions,
+and scientific notation. The entire numeric token must be valid; hexadecimal
+numbers, NaN, infinity, conversion overflow, and conversion underflow are
+rejected. Minimum must not exceed maximum. Zero and negative factors are allowed.
+
+Multiplexing markers (`M`, `mN`, and combinations) are currently rejected rather
+than interpreted as part of a signal name. Multiplexing support and duplicate
+frame/signal detection remain separate work.
+
+Invalid signal definitions stop parsing with `path:line: description`, including
+when the signal exceeds the declared payload length.
+
+---
+
 ## Comments
 
 Frame comment example:
@@ -709,20 +798,47 @@ That is why `DecodeDatabase` is a separate layer.
 
 ---
 
-## Why No Abstract Factory Is Used
+## Statement Handler Factory
 
-At the current stage, abstract factory is intentionally avoided.
+`DbcParser` owns file reading, trimming, line numbers, and error reporting.
+Each `ParseFile()` call creates a fresh `DbcParseContext` and a
+`DbcStatementDispatcher`. The context contains the parsed database and current
+frame; handlers receive it by reference and retain no parsing state.
 
-The current design is already clean:
+The dispatcher uses `TypeFactory<std::string, DbcStatementHandler>` to create
+registered handlers once per parsing session, then reuses them for all matching
+lines:
 
-```text
-parser → parsed database → decode database
-                      ↘ tree builder → UI tree
+- `BO_` → `DbcFrameHandler`
+- `SG_` → `DbcSignalHandler`
+- `CM_` → `DbcCommentHandler`
+
+Grammar implementations live in `dbc_statement_handler.cpp`; their interface,
+context, and dispatcher live in `dbc_statement_handler.h`. `typefactory.h`
+provides the generic registry and object creation.
+
+To add a construct, implement a default-constructible handler deriving from
+`DbcStatementHandler` with:
+
+```cpp
+void Handle(const std::string &line, DbcParseContext &context) const override;
 ```
 
-Introducing factory layers now would increase complexity without solving an immediate problem.
+Register it in the dispatcher constructor:
 
-If later the project requires multiple output representations or multiple build strategies, that can be added then.
+```cpp
+RegisterType<DbcValueHandler>("VAL_"); // after implementing DbcValueHandler
+```
+
+Registration creates one handler; replacing a registration replaces that instance.
+Register during initialization before dispatching. A line is routed using its
+full first whitespace-delimited keyword, so `BO_TX_BU_` cannot match `BO_`.
+Unregistered keywords remain ignored. `SG_` accepts spaces and tabs after its keyword; `CM_` retains its existing
+policy requiring a literal space.
+
+This factory handles statements inside DBC files. A separate format-level
+factory can be introduced when another file format is implemented. The decoder
+and database builders remain independent of statement dispatch.
 
 ---
 
@@ -839,3 +955,10 @@ DBC parser → DbcDatabase → DecodeDatabase → DbcDecoder
 ```
 
 This gives FrameTap a much better foundation for real use, because both browsing and decoding are supported without forcing one representation to do the other's job.
+
+## Regression tests
+
+See [tests/README.md](tests/README.md) for compiler and qmake commands.
+Tests cover frame validation and error locations, Intel and Motorola extraction,
+signed and unsigned 64-bit boundaries,
+physical conversion, numeric output, and invalid signal payloads.

dbc.pro

@@ -7,6 +7,7 @@ SOURCES += \
         dbc_decode_builder.cpp \
         dbc_decoder.cpp \
         dbc_parser.cpp \
+        dbc_statement_handler.cpp \
         dbc_tree_builder.cpp \
         main.cpp \
         tree_node.cpp
@@ -16,6 +17,8 @@ HEADERS += \
   dbc_decode_builder.h \
   dbc_decoder.h \
   dbc_parser.h \
+  dbc_statement_handler.h \
+  typefactory.h \
   dbc_tree_builder.h \
   decode_database.h \
   frame_info.h \

dbc_decoder.cpp

@@ -55,10 +55,13 @@ DecodedFrameValue DbcDecoder::Decode (const DecodeDatabase &database,
         if (signal.valueType == ValueType::Signed)
             decoded.rawValue = SignExtend(unsignedValue, signal.length);
         else
-      decoded.rawValue = static_cast<std::int64_t> (unsignedValue);
+            decoded.rawValue = unsignedValue;
 
         decoded.physicalValue =
-      (static_cast<double> (decoded.rawValue) * signal.factor) + signal.offset;
+                std::visit([&signal](auto rawValue) {
+                    return (static_cast<double>(rawValue) * signal.factor) + signal.offset;
+                },
+                           decoded.rawValue);
         decoded.valid = true;
 
         result.signals.push_back(decoded);
@@ -111,47 +114,44 @@ bool DbcDecoder::ExtractMotorola (const std::vector<std::uint8_t> &data,
    * - startBit points to the most significant bit of the signal
    * - inside a byte, bit numbering goes 7..0
    * - crossing byte boundary moves to the next byte, bit 7
+   * Example: a signal starting at 7 follows 7..0, 15..8, 23..16.
    */
 
     value = 0U;
 
-  std::int32_t currentBit = static_cast<std::int32_t> (startBit);
+    std::size_t byteIndex = startBit / 8U;
+    std::uint32_t bitInByte = startBit % 8U;
 
     for (std::uint32_t bitIndex = 0U; bitIndex < length; ++bitIndex) {
-    if (currentBit < 0)
-      return false;
-
-    const std::uint32_t absoluteBit = static_cast<std::uint32_t> (currentBit);
-    const std::uint32_t byteIndex = absoluteBit / 8U;
-    const std::uint32_t bitFromMsb = absoluteBit % 8U;
-    const std::uint32_t bitInByte = 7U - bitFromMsb;
-
         if (byteIndex >= data.size())
             return false;
 
         value <<= 1U;
         value |= static_cast<std::uint64_t>((data[byteIndex] >> bitInByte) & 0x01U);
 
-    if ((absoluteBit % 8U) == 7U)
-      currentBit = static_cast<std::int32_t> ((byteIndex + 1U) * 8U);
-    else
-      --currentBit;
+        if (bitInByte == 0U) {
+            ++byteIndex;
+            bitInByte = 7U;
+        } else
+            --bitInByte;
     }
 
     return true;
 }
 
 std::int64_t DbcDecoder::SignExtend(std::uint64_t value, std::uint32_t bitLength) {
-  if ((bitLength == 0U) || (bitLength >= 64U))
-    return static_cast<std::int64_t> (value);
-
-  const std::uint64_t signMask = (static_cast<std::uint64_t> (1U) << (bitLength - 1U));
-  const std::uint64_t valueMask = (static_cast<std::uint64_t> (1U) << bitLength) - 1U;
+    if ((bitLength == 0U) || (bitLength > 64U))
+        return 0;
 
+    const std::uint64_t signMask = std::uint64_t(1U) << (bitLength - 1U);
+    const std::uint64_t valueMask = (bitLength == 64U)
+                                            ? ~std::uint64_t(0U)
+                                            : (std::uint64_t(1U) << bitLength) - 1U;
     value &= valueMask;
 
     if ((value & signMask) == 0U)
         return static_cast<std::int64_t>(value);
 
-  return static_cast<std::int64_t> (value | (~valueMask));
+    // The complemented magnitude fits int64_t, including for INT64_MIN.
+    return -1 - static_cast<std::int64_t>((~value) & valueMask);
 }

dbc_decoder.h

@@ -12,8 +12,9 @@
 #ifndef DBC_DECODER_H
 #define DBC_DECODER_H
 
-#include <vector>
 #include <cstdint>
+#include <variant>
+#include <vector>
 
 #include "decode_database.h"
 
@@ -26,9 +27,7 @@ struct RawCanFrame {
     std::vector<std::uint8_t> data; /**< Payload bytes. */
 
     RawCanFrame()
-    : canId (0U)
-    , isExtended (false)
-    , data() {
+        : canId(0U), isExtended(false), data() {
     }
 };
 
@@ -37,15 +36,12 @@ struct RawCanFrame {
  */
 struct DecodedSignalValue {
     const DecodeSignal *definition;                     /**< Signal definition. */
-  std::int64_t rawValue;          /**< Extracted raw integer value. */
+    std::variant<std::int64_t, std::uint64_t> rawValue; /**< Exact signed or unsigned raw value. */
     double physicalValue;                               /**< Converted physical value. */
     bool valid;                                         /**< true if decoding succeeded. */
 
     DecodedSignalValue()
-    : definition (nullptr)
-    , rawValue (0)
-    , physicalValue (0.0)
-    , valid (false) {
+        : definition(nullptr), rawValue(std::uint64_t(0U)), physicalValue(0.0), valid(false) {
     }
 };
 
@@ -58,9 +54,7 @@ struct DecodedFrameValue {
     bool valid;                              /**< true if frame was matched. */
 
     DecodedFrameValue()
-    : definition (nullptr)
-    , signals()
-    , valid (false) {
+        : definition(nullptr), signals(), valid(false) {
     }
 };
 

dbc_parser.cpp

@@ -10,11 +10,11 @@
  */
 
 #include "dbc_parser.h"
+#include "dbc_statement_handler.h"
 
-#include <fstream>
-#include <sstream>
-#include <stdexcept>
 #include <cctype>
+#include <fstream>
+#include <stdexcept>
 
 namespace {
     /**
@@ -35,7 +35,7 @@ namespace {
 
         return text.substr(begin, end - begin);
     }
-}
+}// namespace
 
 DbcDatabase DbcParser::ParseFile(const std::string &filePath) const {
     std::ifstream input(filePath.c_str());
@@ -43,314 +43,28 @@ DbcDatabase DbcParser::ParseFile (const std::string &filePath) const {
         throw std::runtime_error("Failed to open DBC file: " + filePath);
 
     DbcDatabase database;
-  FrameInfo *currentFrame = nullptr;
+    DbcParseContext context{database, nullptr};
+    const DbcStatementDispatcher dispatcher;
 
+    std::size_t lineNumber = 0U;
     std::string line;
     while (std::getline(input, line)) {
+        ++lineNumber;
         line = Trim(line);
         if (line.empty())
             continue;
 
-    if (IsFrameLine (line)) {
-      FrameInfo frame = ParseFrameLine (line);
-      database.frames.push_back (frame);
-      currentFrame = &database.frames.back();
-    } else if (IsSignalLine (line)) {
-      if (currentFrame == nullptr)
-        throw std::runtime_error ("Signal found before any frame definition.");
-
-      SignalInfo signal = ParseSignalLine (line);
-      currentFrame->signals.push_back (signal);
-    } else if (IsCommentLine (line))
-      ParseCommentLine (line, database);
+        try {
+            dispatcher.Dispatch(line, context);
+        } catch (const std::exception &error) {
+            throw std::runtime_error(filePath + ":" + std::to_string(lineNumber) +
+                                     ": " + error.what());
+        }
     }
 
     return database;
 }
 
-bool DbcParser::IsFrameLine (const std::string &line) {
-  return (line.size() >= 4U) && (line.compare (0U, 4U, "BO_ ") == 0);
-}
-
-bool DbcParser::IsSignalLine (const std::string &line) {
-  return (line.size() >= 4U) && (line.compare (0U, 4U, "SG_ ") == 0);
-}
-
-bool DbcParser::IsCommentLine (const std::string &line) {
-  return (line.size() >= 4U) && (line.compare (0U, 4U, "CM_ ") == 0);
-}
-
 std::string DbcParser::Trim(const std::string &text) {
     return TrimText(text);
 }
-
-std::vector<std::string> DbcParser::SplitReceivers (const std::string &text) {
-  std::vector<std::string> receivers;
-  std::string token;
-  std::istringstream stream (text);
-
-  while (std::getline (stream, token, ',')) {
-    token = TrimText (token);
-    if (!token.empty())
-      receivers.push_back (token);
-  }
-
-  return receivers;
-}
-
-void DbcParser::NormalizeCanId (std::uint32_t rawCanId,
-                                std::uint32_t &normalizedCanId,
-                                bool &isExtended) {
-  /*
-   * DBC commonly stores extended identifiers with bit 31 set.
-   * Example:
-   * raw id = 0x80000000 | actual_29_bit_id
-   */
-  if ((rawCanId & 0x80000000U) != 0U) {
-    isExtended = true;
-    normalizedCanId = (rawCanId & 0x1FFFFFFFU);
-  } else {
-    isExtended = (rawCanId > 0x7FFU);
-    normalizedCanId = rawCanId;
-  }
-}
-
-std::uint32_t DbcParser::TryExtractPgn (std::uint32_t canId, bool isExtended, bool &hasPgn) {
-  hasPgn = false;
-
-  if (!isExtended)
-    return 0U;
-
-  if ((canId & 0x1FFFFFFFU) != canId)
-    return 0U;
-
-  const std::uint32_t pf = (canId >> 16U) & 0xFFU;
-  const std::uint32_t ps = (canId >> 8U) & 0xFFU;
-  const std::uint32_t dp = (canId >> 24U) & 0x01U;
-
-  std::uint32_t pgn = 0U;
-
-  if (pf < 240U)
-    pgn = (dp << 16U) | (pf << 8U);
-  else
-    pgn = (dp << 16U) | (pf << 8U) | ps;
-
-  hasPgn = true;
-  return pgn;
-}
-
-FrameInfo DbcParser::ParseFrameLine (const std::string &line) {
-  /*
-   * Example:
-   * BO_ 256 EngineData: 8 EEC1
-   */
-
-  std::istringstream stream (line);
-  std::string token;
-  FrameInfo frame;
-  std::uint32_t rawCanId = 0U;
-
-  stream >> token;
-  if (token != "BO_")
-    throw std::runtime_error ("Invalid frame line: " + line);
-
-  stream >> rawCanId;
-  NormalizeCanId (rawCanId, frame.canId, frame.isExtended);
-
-  stream >> token;
-  if (token.empty())
-    throw std::runtime_error ("Missing frame name: " + line);
-
-  if (token[token.size() - 1U] == ':')
-    token.erase (token.size() - 1U, 1U);
-
-  frame.name = token;
-
-  {
-    unsigned int dlcValue = 0U;
-    stream >> dlcValue;
-    frame.dlc = static_cast<std::uint8_t> (dlcValue);
-  }
-
-  stream >> frame.transmitter;
-  frame.pgn = TryExtractPgn (frame.canId, frame.isExtended, frame.hasPgn);
-
-  return frame;
-}
-
-SignalInfo DbcParser::ParseSignalLine (const std::string &line) {
-  /*
-   * Example:
-   * SG_ EngineSpeed : 0|16@1+ (0.125,0) [0|8000] "rpm" ECU1,ECU2
-   */
-
-  SignalInfo signal;
-
-  std::string work = TrimText (line);
-  if (work.compare (0U, 4U, "SG_ ") != 0)
-    throw std::runtime_error ("Invalid signal line: " + line);
-
-  work.erase (0U, 4U);
-
-  const std::string::size_type colonPos = work.find (':');
-  if (colonPos == std::string::npos)
-    throw std::runtime_error ("Signal line missing ':' : " + line);
-
-  signal.name = TrimText (work.substr (0U, colonPos));
-  std::string rest = TrimText (work.substr (colonPos + 1U));
-
-  const std::string::size_type pipePos = rest.find ('|');
-  const std::string::size_type atPos = rest.find ('@');
-  const std::string::size_type signPos = rest.find_first_of ("+-", atPos);
-  const std::string::size_type factorBegin = rest.find ('(');
-  const std::string::size_type factorComma = rest.find (',', factorBegin);
-  const std::string::size_type factorEnd = rest.find (')', factorComma);
-  const std::string::size_type rangeBegin = rest.find ('[');
-  const std::string::size_type rangeSep = rest.find ('|', rangeBegin);
-  const std::string::size_type rangeEnd = rest.find (']', rangeSep);
-  const std::string::size_type unitBegin = rest.find ('"', rangeEnd);
-  const std::string::size_type unitEnd = rest.find ('"', unitBegin + 1U);
-
-  if ((pipePos == std::string::npos) ||
-      (atPos == std::string::npos) ||
-      (signPos == std::string::npos) ||
-      (factorBegin == std::string::npos) ||
-      (factorComma == std::string::npos) ||
-      (factorEnd == std::string::npos) ||
-      (rangeBegin == std::string::npos) ||
-      (rangeSep == std::string::npos) ||
-      (rangeEnd == std::string::npos) ||
-      (unitBegin == std::string::npos) ||
-      (unitEnd == std::string::npos))
-    throw std::runtime_error ("Unsupported signal syntax: " + line);
-
-  signal.startBit = static_cast<std::uint32_t> (
-                      std::stoul (TrimText (rest.substr (0U, pipePos)))
-                    );
-
-  signal.length = static_cast<std::uint32_t> (
-                    std::stoul (TrimText (rest.substr (pipePos + 1U, atPos - pipePos - 1U)))
-                  );
-
-  {
-    if ((atPos + 1U) >= rest.size())
-      throw std::runtime_error ("Invalid endianness in signal: " + line);
-
-    const char endianChar = rest[atPos + 1U];
-    signal.isLittleEndian = (endianChar == '1');
-  }
-
-  {
-    const char signChar = rest[signPos];
-    signal.isSigned = (signChar == '-');
-  }
-
-  signal.factor = std::stod (
-                    TrimText (rest.substr (factorBegin + 1U, factorComma - factorBegin - 1U))
-                  );
-
-  signal.offset = std::stod (
-                    TrimText (rest.substr (factorComma + 1U, factorEnd - factorComma - 1U))
-                  );
-
-  signal.minimum = std::stod (
-                     TrimText (rest.substr (rangeBegin + 1U, rangeSep - rangeBegin - 1U))
-                   );
-
-  signal.maximum = std::stod (
-                     TrimText (rest.substr (rangeSep + 1U, rangeEnd - rangeSep - 1U))
-                   );
-
-  signal.unit = rest.substr (unitBegin + 1U, unitEnd - unitBegin - 1U);
-
-  {
-    const std::string receiversText = TrimText (rest.substr (unitEnd + 1U));
-    signal.receivers = SplitReceivers (receiversText);
-  }
-
-  return signal;
-}
-
-void DbcParser::ParseCommentLine (const std::string &line, DbcDatabase &database) {
-  /*
-   * Examples:
-   * CM_ BO_ 256 "Frame comment";
-   * CM_ SG_ 256 EngineSpeed "Signal comment";
-   */
-
-  std::istringstream stream (line);
-  std::string token;
-  stream >> token;
-
-  if (token != "CM_")
-    return;
-
-  stream >> token;
-
-  if (token == "BO_") {
-    std::uint32_t rawCanId = 0U;
-    std::uint32_t canId = 0U;
-    bool isExtended = false;
-
-    stream >> rawCanId;
-    NormalizeCanId (rawCanId, canId, isExtended);
-
-    const std::string::size_type quoteBegin = line.find ('"');
-    const std::string::size_type quoteEnd = line.rfind ('"');
-
-    if ((quoteBegin == std::string::npos) ||
-        (quoteEnd == std::string::npos) ||
-        (quoteEnd <= quoteBegin))
-      return;
-
-    FrameInfo *frame = FindFrameById (database, canId, isExtended);
-    if (frame != nullptr)
-      frame->comment = line.substr (quoteBegin + 1U, quoteEnd - quoteBegin - 1U);
-  } else if (token == "SG_") {
-    std::uint32_t rawCanId = 0U;
-    std::uint32_t canId = 0U;
-    bool isExtended = false;
-    std::string signalName;
-
-    stream >> rawCanId;
-    stream >> signalName;
-
-    NormalizeCanId (rawCanId, canId, isExtended);
-
-    const std::string::size_type quoteBegin = line.find ('"');
-    const std::string::size_type quoteEnd = line.rfind ('"');
-
-    if ((quoteBegin == std::string::npos) ||
-        (quoteEnd == std::string::npos) ||
-        (quoteEnd <= quoteBegin))
-      return;
-
-    FrameInfo *frame = FindFrameById (database, canId, isExtended);
-    if (frame != nullptr) {
-      SignalInfo *signal = FindSignalByName (*frame, signalName);
-      if (signal != nullptr)
-        signal->comment = line.substr (quoteBegin + 1U, quoteEnd - quoteBegin - 1U);
-    }
-  }
-}
-
-FrameInfo *DbcParser::FindFrameById (DbcDatabase &database,
-                                     std::uint32_t canId,
-                                     bool isExtended) {
-  for (std::size_t index = 0U; index < database.frames.size(); ++index) {
-    if ((database.frames[index].canId == canId) &&
-        (database.frames[index].isExtended == isExtended))
-      return &database.frames[index];
-  }
-
-  return nullptr;
-}
-
-SignalInfo *DbcParser::FindSignalByName (FrameInfo &frame, const std::string &signalName) {
-  for (std::size_t index = 0U; index < frame.signals.size(); ++index) {
-    if (frame.signals[index].name == signalName)
-      return &frame.signals[index];
-  }
-
-  return nullptr;
-}

dbc_parser.h

@@ -13,8 +13,6 @@
 #define DBC_PARSER_H
 
 #include <string>
-#include <vector>
-#include <cstdint>
 
 #include "dbc_database.h"
 
@@ -39,31 +37,12 @@ class DbcParser {
      * @param filePath Path to input file.
      * @return Parsed database.
      * @throws std::runtime_error on file or parse errors.
+     * Line parse errors include the file path and one-based line number.
      */
     DbcDatabase ParseFile(const std::string &filePath) const;
 
 private:
-    static bool IsFrameLine (const std::string &line);
-    static bool IsSignalLine (const std::string &line);
-    static bool IsCommentLine (const std::string &line);
     static std::string Trim(const std::string &text);
-    static std::vector<std::string> SplitReceivers (const std::string &text);
-    static std::uint32_t TryExtractPgn (std::uint32_t canId, bool isExtended, bool &hasPgn);
-
-    static void NormalizeCanId (std::uint32_t rawCanId,
-                                std::uint32_t &normalizedCanId,
-                                bool &isExtended);
-
-    static FrameInfo ParseFrameLine (const std::string &line);
-    static SignalInfo ParseSignalLine (const std::string &line);
-
-    static void ParseCommentLine (const std::string &line, DbcDatabase &database);
-
-    static FrameInfo *FindFrameById (DbcDatabase &database,
-                                     std::uint32_t canId,
-                                     bool isExtended);
-
-    static SignalInfo *FindSignalByName (FrameInfo &frame, const std::string &signalName);
 };
 
 #endif /* DBC_PARSER_H */

dbc_statement_handler.cpp

@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: MIT
+#include "dbc_statement_handler.h"
+#include <cctype>
+#include <charconv>
+#include <cmath>
+#include <limits>
+#include <regex>
+#include <sstream>
+#include <stdexcept>
+
+namespace {
+    std::uint32_t ParseDecimal(const std::string &text,
+                               std::uint32_t maximum,
+                               const char *field) {
+        std::uint32_t value = 0U;
+        const auto parsed = std::from_chars(text.data(), text.data() + text.size(), value);
+        if (text.empty() || parsed.ec != std::errc() ||
+            parsed.ptr != text.data() + text.size() || value > maximum)
+            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
+        return value;
+    }
+
+    /**
+   * @brief Remove leading and trailing spaces.
+   * @param text Input text.
+   * @return Trimmed text.
+   */
+    std::string TrimText(const std::string &text) {
+        std::string::size_type begin = 0U;
+        while ((begin < text.size()) &&
+               std::isspace(static_cast<unsigned char>(text[begin])))
+            ++begin;
+
+        std::string::size_type end = text.size();
+        while ((end > begin) &&
+               std::isspace(static_cast<unsigned char>(text[end - 1U])))
+            --end;
+
+        return text.substr(begin, end - begin);
+    }
+    FrameInfo *FindFrameById(DbcDatabase &, std::uint32_t, bool);
+    SignalInfo *FindSignalByName(FrameInfo &, const std::string &);
+}// namespace
+
+namespace {
+    std::vector<std::string> SplitReceivers(const std::string &text) {
+        std::vector<std::string> receivers;
+        std::string token;
+        std::istringstream stream(text);
+
+        while (std::getline(stream, token, ',')) {
+            token = TrimText(token);
+            if (!token.empty())
+                receivers.push_back(token);
+        }
+
+        return receivers;
+    }
+
+    void NormalizeCanId(std::uint32_t rawCanId,
+                        std::uint32_t &normalizedCanId,
+                        bool &isExtended) {
+        /*
+   * DBC commonly stores extended identifiers with bit 31 set.
+   * Example:
+   * raw id = 0x80000000 | actual_29_bit_id
+   */
+        if ((rawCanId & 0x80000000U) != 0U) {
+            isExtended = true;
+            normalizedCanId = (rawCanId & 0x1FFFFFFFU);
+        } else {
+            isExtended = (rawCanId > 0x7FFU);
+            normalizedCanId = rawCanId;
+        }
+    }
+
+    std::uint32_t TryExtractPgn(std::uint32_t canId, bool isExtended, bool &hasPgn) {
+        hasPgn = false;
+
+        if (!isExtended)
+            return 0U;
+
+        if ((canId & 0x1FFFFFFFU) != canId)
+            return 0U;
+
+        const std::uint32_t pf = (canId >> 16U) & 0xFFU;
+        const std::uint32_t ps = (canId >> 8U) & 0xFFU;
+        const std::uint32_t dp = (canId >> 24U) & 0x01U;
+
+        std::uint32_t pgn = 0U;
+
+        if (pf < 240U)
+            pgn = (dp << 16U) | (pf << 8U);
+        else
+            pgn = (dp << 16U) | (pf << 8U) | ps;
+
+        hasPgn = true;
+        return pgn;
+    }
+
+}// namespace
+
+FrameInfo DbcFrameHandler::ParseFrameLine(const std::string &line) {
+    /*
+   * Example:
+   * BO_ 256 EngineData: 8 EEC1
+   */
+
+    std::istringstream stream(line);
+    std::string keyword;
+    std::string idText;
+    if (!(stream >> keyword >> idText) || keyword != "BO_")
+        throw std::runtime_error("Missing CAN ID in frame definition.");
+
+    const std::uint32_t rawCanId = ParseDecimal(
+            idText, std::numeric_limits<std::uint32_t>::max(), "CAN ID");
+    // Only bit 31 may accompany the actual 29-bit identifier.
+    if ((rawCanId & 0x60000000U) != 0U)
+        throw std::runtime_error("CAN ID exceeds the 29-bit identifier range.");
+
+    std::string nameText;
+    if (!std::getline(stream, nameText, ':') || stream.eof())
+        throw std::runtime_error("Missing ':' in frame definition.");
+    std::istringstream nameStream(nameText);
+    FrameInfo frame;
+    std::string extra;
+    if (!(nameStream >> frame.name) || (nameStream >> extra))
+        throw std::runtime_error("Missing or invalid frame name.");
+
+    std::string lengthText;
+    if (!(stream >> lengthText))
+        throw std::runtime_error("Missing payload length in frame definition.");
+    frame.dlc = static_cast<std::uint8_t>(ParseDecimal(
+            lengthText, std::numeric_limits<std::uint8_t>::max(), "payload length"));
+    if (!(stream >> frame.transmitter))
+        throw std::runtime_error("Missing transmitter in frame definition.");
+    if (stream >> extra)
+        throw std::runtime_error("Unexpected trailing field in frame definition: " + extra);
+
+    NormalizeCanId(rawCanId, frame.canId, frame.isExtended);
+    frame.pgn = TryExtractPgn(frame.canId, frame.isExtended, frame.hasPgn);
+
+    return frame;
+}
+
+SignalInfo DbcSignalHandler::ParseSignalLine(const std::string &line) {
+    // Match the complete statement before converting any numeric fields.
+    static const std::regex syntax(
+            R"dbc(^SG_[ \t]+([^:]+):[ \t]*([^| \t]+)[ \t]*\|[ \t]*([^@ \t]+)[ \t]*@[ \t]*([01])([+-])[ \t]*\([ \t]*([^, \t]+)[ \t]*,[ \t]*([^ )\t]+)[ \t]*\)[ \t]*\[[ \t]*([^| \t]+)[ \t]*\|[ \t]*([^\] \t]+)[ \t]*\][ \t]*"([^"\r\n]*)"[ \t]+([^ \t,]+(?:[ \t]*,[ \t]*[^ \t,]+)*)[ \t]*$)dbc");
+    std::smatch fields;
+    if (!std::regex_match(line, fields, syntax))
+        throw std::runtime_error("Malformed or unsupported SG_ signal definition.");
+
+    SignalInfo signal;
+    signal.name = TrimText(fields[1].str());
+    if (signal.name.empty() || signal.name.find_first_of(" \t\r\n") != std::string::npos)
+        throw std::runtime_error("Invalid signal name or unsupported multiplexing syntax.");
+
+    signal.startBit = ParseDecimal(fields[2].str(),
+                                   std::numeric_limits<std::uint32_t>::max(), "signal start bit");
+    signal.length = ParseDecimal(fields[3].str(), 64U, "signal length");
+    if (signal.length == 0U)
+        throw std::runtime_error("Signal length must be within 1..64 bits.");
+    signal.isLittleEndian = fields[4].str() == "1";
+    signal.isSigned = fields[5].str() == "-";
+
+    const auto parsePhysical = [](const std::string &text, const char *field) {
+        static const std::regex number(
+                R"(^[+-]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[eE][+-]?[0-9]+)?$)");
+        if (!std::regex_match(text, number))
+            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
+        std::size_t consumed = 0U;
+        double value;
+        try {
+            value = std::stod(text, &consumed);
+        } catch (const std::exception &) {
+            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
+        }
+        if (consumed != text.size() || !std::isfinite(value))
+            throw std::runtime_error(std::string("Invalid ") + field + ": " + text);
+        return value;
+    };
+    signal.factor = parsePhysical(fields[6].str(), "signal factor");
+    signal.offset = parsePhysical(fields[7].str(), "signal offset");
+    signal.minimum = parsePhysical(fields[8].str(), "signal minimum");
+    signal.maximum = parsePhysical(fields[9].str(), "signal maximum");
+    if (signal.minimum > signal.maximum)
+        throw std::runtime_error("Signal minimum exceeds maximum.");
+    signal.unit = fields[10].str();
+    signal.receivers = SplitReceivers(fields[11].str());
+    return signal;
+}
+
+void DbcCommentHandler::ParseCommentLine(const std::string &line, DbcDatabase &database) {
+    /*
+   * Examples:
+   * CM_ BO_ 256 "Frame comment";
+   * CM_ SG_ 256 EngineSpeed "Signal comment";
+   */
+
+    std::istringstream stream(line);
+    std::string token;
+    stream >> token;
+
+    if (token != "CM_")
+        return;
+
+    stream >> token;
+
+    if (token == "BO_") {
+        std::uint32_t rawCanId = 0U;
+        std::uint32_t canId = 0U;
+        bool isExtended = false;
+
+        stream >> rawCanId;
+        NormalizeCanId(rawCanId, canId, isExtended);
+
+        const std::string::size_type quoteBegin = line.find('"');
+        const std::string::size_type quoteEnd = line.rfind('"');
+
+        if ((quoteBegin == std::string::npos) ||
+            (quoteEnd == std::string::npos) ||
+            (quoteEnd <= quoteBegin))
+            return;
+
+        FrameInfo *frame = FindFrameById(database, canId, isExtended);
+        if (frame != nullptr)
+            frame->comment = line.substr(quoteBegin + 1U, quoteEnd - quoteBegin - 1U);
+    } else if (token == "SG_") {
+        std::uint32_t rawCanId = 0U;
+        std::uint32_t canId = 0U;
+        bool isExtended = false;
+        std::string signalName;
+
+        stream >> rawCanId;
+        stream >> signalName;
+
+        NormalizeCanId(rawCanId, canId, isExtended);
+
+        const std::string::size_type quoteBegin = line.find('"');
+        const std::string::size_type quoteEnd = line.rfind('"');
+
+        if ((quoteBegin == std::string::npos) ||
+            (quoteEnd == std::string::npos) ||
+            (quoteEnd <= quoteBegin))
+            return;
+
+        FrameInfo *frame = FindFrameById(database, canId, isExtended);
+        if (frame != nullptr) {
+            SignalInfo *signal = FindSignalByName(*frame, signalName);
+            if (signal != nullptr)
+                signal->comment = line.substr(quoteBegin + 1U, quoteEnd - quoteBegin - 1U);
+        }
+    }
+}
+
+namespace {
+    FrameInfo *FindFrameById(DbcDatabase &database,
+                             std::uint32_t canId,
+                             bool isExtended) {
+        for (std::size_t index = 0U; index < database.frames.size(); ++index) {
+            if ((database.frames[index].canId == canId) &&
+                (database.frames[index].isExtended == isExtended))
+                return &database.frames[index];
+        }
+
+        return nullptr;
+    }
+
+    SignalInfo *FindSignalByName(FrameInfo &frame, const std::string &signalName) {
+        for (std::size_t index = 0U; index < frame.signals.size(); ++index) {
+            if (frame.signals[index].name == signalName)
+                return &frame.signals[index];
+        }
+
+        return nullptr;
+    }
+}// namespace
+
+void DbcFrameHandler::Handle(const std::string &line, DbcParseContext &context) const {
+    context.database.frames.push_back(ParseFrameLine(line));
+    context.currentFrame = &context.database.frames.back();
+}
+
+void DbcSignalHandler::Handle(const std::string &line, DbcParseContext &context) const {
+    if (context.currentFrame == nullptr)
+        throw std::runtime_error("Signal found before any frame definition.");
+    SignalInfo signal = ParseSignalLine(line);
+    const std::uint64_t payloadBits = static_cast<std::uint64_t>(context.currentFrame->dlc) * 8U;
+    std::uint64_t bit = signal.startBit;
+    for (std::uint32_t index = 0U; index < signal.length; ++index) {
+        if (bit >= payloadBits)
+            throw std::runtime_error("Signal exceeds the frame payload length.");
+        if (signal.isLittleEndian)
+            ++bit;
+        else
+            bit = (bit % 8U == 0U) ? bit + 15U : bit - 1U;
+    }
+    context.currentFrame->signals.push_back(std::move(signal));
+}
+
+void DbcCommentHandler::Handle(const std::string &line, DbcParseContext &context) const {
+    if (line.compare(0U, 4U, "CM_ ") == 0)
+        ParseCommentLine(line, context.database);
+}
+
+DbcStatementDispatcher::DbcStatementDispatcher() {
+    RegisterType<DbcFrameHandler>("BO_");
+    RegisterType<DbcSignalHandler>("SG_");
+    RegisterType<DbcCommentHandler>("CM_");
+}
+
+bool DbcStatementDispatcher::Dispatch(const std::string &line,
+                                      DbcParseContext &context) const {
+    std::istringstream stream(line);
+    std::string keyword;
+    stream >> keyword;
+    const auto handler = m_handlers.find(keyword);
+    if (handler == m_handlers.end())
+        return false;
+    handler->second->Handle(line, context);
+    return true;
+}

dbc_statement_handler.h

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: MIT
+#ifndef DBC_STATEMENT_HANDLER_H
+#define DBC_STATEMENT_HANDLER_H
+
+#include "dbc_database.h"
+#include "typefactory.h"
+#include <string>
+#include <unordered_map>
+
+/** Mutable state belonging to one file parse. Handlers do not retain it. */
+struct DbcParseContext {
+    DbcDatabase &database;
+    FrameInfo *currentFrame = nullptr;
+};
+
+class DbcStatementHandler {
+public:
+    virtual ~DbcStatementHandler() = default;
+    virtual void Handle(const std::string &line, DbcParseContext &context) const = 0;
+};
+
+class DbcFrameHandler : public DbcStatementHandler {
+public:
+    void Handle(const std::string &line, DbcParseContext &context) const override;
+
+private:
+    static FrameInfo ParseFrameLine(const std::string &line);
+};
+
+class DbcSignalHandler : public DbcStatementHandler {
+public:
+    void Handle(const std::string &line, DbcParseContext &context) const override;
+
+private:
+    static SignalInfo ParseSignalLine(const std::string &line);
+};
+
+class DbcCommentHandler : public DbcStatementHandler {
+public:
+    void Handle(const std::string &line, DbcParseContext &context) const override;
+
+private:
+    static void ParseCommentLine(const std::string &line, DbcDatabase &database);
+};
+
+/** Exact-key dispatch to handlers created once per registration via TypeFactory. */
+class DbcStatementDispatcher {
+public:
+    DbcStatementDispatcher();
+
+    template<class Handler>
+    void RegisterType(const std::string &keyword) {
+        m_factory.registerType<Handler>(keyword);
+        m_handlers.insert_or_assign(keyword, m_factory.create(keyword));
+    }
+
+    /** Returns false for an unregistered keyword; input must be trimmed. */
+    bool Dispatch(const std::string &line, DbcParseContext &context) const;
+
+private:
+    TypeFactory<std::string, DbcStatementHandler> m_factory;
+    std::unordered_map<std::string, std::shared_ptr<DbcStatementHandler>> m_handlers;
+};
+
+#endif /* DBC_STATEMENT_HANDLER_H */

decode_database.h

@@ -12,10 +12,10 @@
 #ifndef DECODE_DATABASE_H
 #define DECODE_DATABASE_H
 
-#include <string>
-#include <vector>
-#include <unordered_map>
 #include <cstdint>
+#include <string>
+#include <unordered_map>
+#include <vector>
 
 /**
  * @brief Signal byte order used for runtime decoding.
@@ -51,18 +51,7 @@ struct DecodeSignal {
     std::string comment;                /**< Comment. */
 
     DecodeSignal()
-    : name()
-    , startBit (0U)
-    , length (0U)
-    , byteOrder (ByteOrder::Intel)
-    , valueType (ValueType::Unsigned)
-    , factor (1.0)
-    , offset (0.0)
-    , minimum (0.0)
-    , maximum (0.0)
-    , unit()
-    , receivers()
-    , comment() {
+        : name(), startBit(0U), length(0U), byteOrder(ByteOrder::Intel), valueType(ValueType::Unsigned), factor(1.0), offset(0.0), minimum(0.0), maximum(0.0), unit(), receivers(), comment() {
     }
 };
 
@@ -81,15 +70,7 @@ struct DecodeFrame {
     std::vector<DecodeSignal> signals; /**< Signal definitions. */
 
     DecodeFrame()
-    : name()
-    , canId (0U)
-    , isExtended (false)
-    , dlc (0U)
-    , pgn (0U)
-    , hasPgn (false)
-    , transmitter()
-    , comment()
-    , signals() {
+        : name(), canId(0U), isExtended(false), dlc(0U), pgn(0U), hasPgn(false), transmitter(), comment(), signals() {
     }
 };
 
@@ -101,13 +82,11 @@ struct FrameKey {
     bool isExtended;
 
     FrameKey()
-    : canId (0U)
-    , isExtended (false) {
+        : canId(0U), isExtended(false) {
     }
 
     FrameKey(std::uint32_t id, bool extended)
-    : canId (id)
-    , isExtended (extended) {
+        : canId(id), isExtended(extended) {
     }
 
     bool operator==(const FrameKey &other) const {

frame_info.h

@@ -12,9 +12,9 @@
 #ifndef FRAME_INFO_H
 #define FRAME_INFO_H
 
+#include <cstdint>
 #include <string>
 #include <vector>
-#include <cstdint>
 
 #include "signal_info.h"
 
@@ -33,15 +33,7 @@ struct FrameInfo {
     std::vector<SignalInfo> signals; /**< Signals contained in the frame. */
 
     FrameInfo()
-    : name()
-    , canId (0U)
-    , isExtended (false)
-    , pgn (0U)
-    , hasPgn (false)
-    , dlc (0U)
-    , transmitter()
-    , comment()
-    , signals() {
+        : name(), canId(0U), isExtended(false), pgn(0U), hasPgn(false), dlc(0U), transmitter(), comment(), signals() {
     }
 };
 

issue-sg-validation.md

@@ -0,0 +1,40 @@
+# Validate `SG_` signal definitions and report malformed or unsupported syntax
+
+## Description
+
+Following strict validation of `BO_` frame definitions, add equivalent validation for `SG_` signal definitions. Currently, some malformed statements are accepted silently, and unsupported syntax can produce incorrect decoding.
+
+Examples of current behavior:
+
+- `@2+` is interpreted as Motorola instead of being rejected.
+- Numeric fields containing suffixes, such as `0junk` or `1junk`, are partially parsed and accepted.
+- `SG_ Value m1 : ...` is treated as an ordinary signal named `Value m1`, without multiplexing conditions.
+- A statement containing a tab after `SG_` is silently skipped.
+
+## Scope
+
+- Validate statement structure and require a nonempty signal name without whitespace.
+- Accept spaces and tabs between syntax elements.
+- Parse numeric fields completely, rejecting overflow and trailing characters; preserve support for fractional values and scientific notation in physical parameters.
+- Accept only byte order `@0` or `@1` and signedness `+` or `-`.
+- Require signal lengths within `1..64` bits.
+- Validate that the signal fits within the frame's declared payload length, using the appropriate Intel or Motorola bit traversal.
+- Reject NaN and infinite values for factor, offset, minimum, and maximum; require `minimum <= maximum`.
+- Explicitly reject multiplexing markers `M`, `mN`, and their combinations until multiplexing is implemented.
+- Preserve the error format `path:line: description`.
+
+## Acceptance criteria
+
+- [ ] Existing valid signal definitions continue to parse successfully.
+- [ ] Malformed and unsupported definitions stop parsing with a clear error.
+- [ ] Regression tests cover the cases above, numeric boundaries, and Intel/Motorola payload boundaries.
+- [ ] Existing parser and decoder tests pass.
+- [ ] README documents the new validation rules and limitations.
+
+## Out of scope
+
+Duplicate detection, multiplexing support, and `VAL_` support remain separate tasks.
+
+## Suggested branch
+
+`codex/validate-sg-definitions`

main.cpp

@@ -9,16 +9,16 @@
  * See LICENSE file in the project root for full license text.
  */
 
-#include <iostream>
+#include <cstddef>
 #include <iomanip>
+#include <iostream>
 #include <memory>
 #include <vector>
-#include <cstddef>
 
-#include "dbc_parser.h"
-#include "dbc_tree_builder.h"
 #include "dbc_decode_builder.h"
 #include "dbc_decoder.h"
+#include "dbc_parser.h"
+#include "dbc_tree_builder.h"
 
 static void PrintTree(const TreeNode *node, int indent) {
     if (node == nullptr)
@@ -87,8 +87,9 @@ static void PrintDecodedFrame (const DecodedFrameValue &decoded) {
             continue;
 
         std::cout << "  " << signal.definition->name
-              << " raw=" << signal.rawValue
-              << " physical=" << signal.physicalValue
+                  << " raw=";
+        std::visit([](auto rawValue) { std::cout << rawValue; }, signal.rawValue);
+        std::cout << " physical=" << signal.physicalValue
                   << " " << signal.definition->unit
                   << "\n";
     }

signal_info.h

@@ -12,9 +12,9 @@
 #ifndef SIGNAL_INFO_H
 #define SIGNAL_INFO_H
 
+#include <cstdint>
 #include <string>
 #include <vector>
-#include <cstdint>
 
 /**
  * @brief Describes one signal inside a DBC frame.
@@ -34,18 +34,7 @@ struct SignalInfo {
     std::string comment;                /**< Optional signal comment. */
 
     SignalInfo()
-    : name()
-    , startBit (0U)
-    , length (0U)
-    , isLittleEndian (true)
-    , isSigned (false)
-    , factor (1.0)
-    , offset (0.0)
-    , minimum (0.0)
-    , maximum (0.0)
-    , unit()
-    , receivers()
-    , comment() {
+        : name(), startBit(0U), length(0U), isLittleEndian(true), isSigned(false), factor(1.0), offset(0.0), minimum(0.0), maximum(0.0), unit(), receivers(), comment() {
     }
 };
 

tests/README.md

@@ -0,0 +1,53 @@
+# Decoder regression tests
+
+Run from the repository root with a C++17 compiler:
+
+```sh
+g++ -std=c++17 -Wall -Wextra -Wpedantic -I. \
+  tests/dbc_decoder_test.cpp dbc_decoder.cpp -o /tmp/dbc_decoder_test
+/tmp/dbc_decoder_test
+```
+
+Alternatively, build the standalone qmake project out of source:
+
+```sh
+mkdir -p /tmp/dbc_decoder_test_build
+cd /tmp/dbc_decoder_test_build
+qmake /absolute/path/to/dbc/tests/dbc_decoder_test.pro
+make
+./dbc_decoder_test
+```
+
+The executable returns a nonzero exit code if any case fails. Checks remain
+active in release builds and do not depend on `assert` or an external test framework.
+
+Coverage includes Motorola bit numbering within and across bytes, unaligned
+signals, signed values, scaling, 64-bit extraction, signed/unsigned boundary values
+(including `INT64_MIN`, `INT64_MAX`, and `UINT64_MAX`), numeric output, invalid lengths, insufficient
+payloads, and Intel regression cases. Frame validity means the definition was
+found; insufficient payloads are checked through signal validity.
+
+## Parser regression tests
+
+Run from the repository root:
+
+```sh
+g++ -std=c++17 -Wall -Wextra -Wpedantic -Werror -I. \
+  tests/dbc_parser_test.cpp dbc_parser.cpp dbc_statement_handler.cpp -o /tmp/dbc_parser_test
+/tmp/dbc_parser_test
+```
+
+For qmake, use `tests/dbc_parser_test.pro` in a separate build directory,
+following the decoder instructions above, then run `./dbc_parser_test`.
+
+Parser tests cover standard and extended CAN IDs, whitespace, payload storage
+boundaries, missing fields, malformed and overflowing numbers, reserved ID bits,
+error paths and line numbers, and integration with signals and comments.
+Signal tests cover complete syntax and numeric validation, scientific notation,
+finite physical parameters and ordered ranges, spaces and tabs, receiver lists,
+unsupported multiplexing, and Intel/Motorola declared-payload boundaries.
+Temporary DBC fixtures are created in the system temporary directory and removed
+automatically.
+
+Dispatch tests also verify exact keyword matching, handler construction and reuse,
+unknown statements, and independent parsing sessions, including recovery after errors.

tests/dbc_decoder_test.cpp

@@ -0,0 +1,139 @@
+#include "dbc_decoder.h"
+
+#include <iostream>
+#include <limits>
+#include <sstream>
+
+struct DecodeCase {
+    const char *name;
+    ByteOrder byteOrder;
+    std::uint32_t startBit;
+    std::uint32_t length;
+    ValueType valueType;
+    std::vector<std::uint8_t> data;
+    bool valid;
+    std::int64_t rawValue;
+    double factor;
+    double offset;
+    double physicalValue;
+};
+
+int main() {
+    const DecodeCase cases[] = {
+            {"Motorola reproduction", ByteOrder::Motorola, 7U, 16U, ValueType::Unsigned, {0x12, 0x34}, true, 0x1234, 1.0, 0.0, 4660.0},
+            {"Motorola within byte", ByteOrder::Motorola, 5U, 4U, ValueType::Unsigned, {0xAC}, true, 11, 1.0, 0.0, 11.0},
+            {"Motorola unaligned crossing", ByteOrder::Motorola, 3U, 12U, ValueType::Unsigned, {0xAB, 0xCD}, true, 0xBCD, 1.0, 0.0, 3021.0},
+            {"Motorola starts at bit zero", ByteOrder::Motorola, 0U, 2U, ValueType::Unsigned, {0x01, 0x80}, true, 3, 1.0, 0.0, 3.0},
+            {"Motorola second byte", ByteOrder::Motorola, 15U, 16U, ValueType::Unsigned, {0xFF, 0x12, 0x34}, true, 0x1234, 1.0, 0.0, 4660.0},
+            {"Motorola signed scaled", ByteOrder::Motorola, 7U, 16U, ValueType::Signed, {0xFF, 0xFE}, true, -2, 0.5, 10.0, 9.0},
+            {"Motorola 64 bits", ByteOrder::Motorola, 7U, 64U, ValueType::Unsigned, {0, 0, 0, 0, 0, 0, 0x12, 0x34}, true, 0x1234, 1.0, 0.0, 4660.0},
+            {"Motorola 64 bits high bit", ByteOrder::Motorola, 7U, 64U, ValueType::Unsigned, {0x40, 0, 0, 0, 0, 0, 0, 0}, true, 0x4000000000000000LL, 1.0, 0.0, 4611686018427387904.0},
+            {"Motorola short payload", ByteOrder::Motorola, 7U, 16U, ValueType::Unsigned, {0x12}, false, 0, 1.0, 0.0, 0.0},
+            {"Motorola empty payload", ByteOrder::Motorola, 7U, 8U, ValueType::Unsigned, {}, false, 0, 1.0, 0.0, 0.0},
+            {"Motorola large start", ByteOrder::Motorola, std::numeric_limits<std::uint32_t>::max(), 8U, ValueType::Unsigned, {0xFF}, false, 0, 1.0, 0.0, 0.0},
+            {"Motorola zero length", ByteOrder::Motorola, 7U, 0U, ValueType::Unsigned, {0xFF}, false, 0, 1.0, 0.0, 0.0},
+            {"Motorola excessive length", ByteOrder::Motorola, 7U, 65U, ValueType::Unsigned,
+             std::vector<std::uint8_t>(9U, 0xFF), false, 0, 1.0, 0.0, 0.0},
+            {"Intel regression", ByteOrder::Intel, 0U, 16U, ValueType::Unsigned, {0x12, 0x34}, true, 0x3412, 1.0, 0.0, 13330.0},
+            {"Intel signed regression", ByteOrder::Intel, 0U, 16U, ValueType::Signed, {0xFE, 0xFF}, true, -2, 0.5, 10.0, 9.0},
+            {"Intel short payload", ByteOrder::Intel, 0U, 16U, ValueType::Unsigned, {0x12}, false, 0, 1.0, 0.0, 0.0}};
+
+    int failures = 0;
+    for (const DecodeCase &test: cases) {
+        DecodeSignal signal;
+        signal.name = test.name;
+        signal.byteOrder = test.byteOrder;
+        signal.startBit = test.startBit;
+        signal.length = test.length;
+        signal.valueType = test.valueType;
+        signal.factor = test.factor;
+        signal.offset = test.offset;
+
+        DecodeFrame definition;
+        definition.canId = 0x123U;
+        definition.dlc = static_cast<std::uint8_t>(test.data.size());
+        definition.signals.push_back(signal);
+        DecodeDatabase database;
+        database.frames.push_back(definition);
+        database.frameIndexByKey.emplace(FrameKey(definition.canId, false), 0U);
+
+        RawCanFrame frame;
+        frame.canId = definition.canId;
+        frame.data = test.data;
+        const DecodedFrameValue result = DbcDecoder().Decode(database, frame);
+        const bool passed = result.valid &&
+                            (result.definition == &database.frames[0]) &&
+                            (result.signals.size() == 1U) &&
+                            (result.signals[0].definition == &database.frames[0].signals[0]) &&
+                            (result.signals[0].valid == test.valid) &&
+                            (!test.valid || (((test.valueType == ValueType::Signed)
+                                                      ? (std::get_if<std::int64_t>(&result.signals[0].rawValue) &&
+                                                         std::get<std::int64_t>(result.signals[0].rawValue) == test.rawValue)
+                                                      : (std::get_if<std::uint64_t>(&result.signals[0].rawValue) &&
+                                                         std::get<std::uint64_t>(result.signals[0].rawValue) ==
+                                                                 static_cast<std::uint64_t>(test.rawValue))) &&
+                                             (result.signals[0].physicalValue == test.physicalValue)));
+        if (!passed) {
+            std::cerr << "FAIL: " << test.name << '\n';
+            ++failures;
+        }
+    }
+    std::size_t boundaryCases = 0U;
+    for (ByteOrder order: {ByteOrder::Intel, ByteOrder::Motorola}) {
+        for (ValueType type: {ValueType::Unsigned, ValueType::Signed}) {
+            for (std::uint64_t bits: {std::uint64_t(0U), std::uint64_t(0x7FFFFFFFFFFFFFFFULL),
+                                      std::uint64_t(0x8000000000000000ULL),
+                                      std::uint64_t(0x8000000000000001ULL),
+                                      std::uint64_t(0xFFFFFFFFFFFFFFFFULL)}) {
+                DecodeDatabase database;
+                DecodeFrame definition;
+                DecodeSignal signal;
+                signal.startBit = order == ByteOrder::Intel ? 0U : 7U;
+                signal.length = 64U;
+                signal.byteOrder = order;
+                signal.valueType = type;
+                signal.factor = 0.5;
+                signal.offset = 10.0;
+                definition.signals.push_back(signal);
+                database.frames.push_back(definition);
+                database.frameIndexByKey.emplace(FrameKey(0U, false), 0U);
+                RawCanFrame frame;
+                for (unsigned byte = 0U; byte < 8U; ++byte) {
+                    const unsigned shift = (order == ByteOrder::Intel ? byte : 7U - byte) * 8U;
+                    frame.data.push_back(static_cast<std::uint8_t>(bits >> shift));
+                }
+                const auto result = DbcDecoder().Decode(database, frame);
+                const std::int64_t signedExpected = bits <= 0x7FFFFFFFFFFFFFFFULL
+                                                            ? static_cast<std::int64_t>(bits)
+                                                            : std::numeric_limits<std::int64_t>::min() +
+                                                                      static_cast<std::int64_t>(bits - 0x8000000000000000ULL);
+                const auto &decoded = result.signals.at(0U);
+                const auto expected = type == ValueType::Unsigned
+                                              ? std::variant<std::int64_t, std::uint64_t>(bits)
+                                              : std::variant<std::int64_t, std::uint64_t>(signedExpected);
+                const double physical = (type == ValueType::Unsigned
+                                                 ? static_cast<double>(bits)
+                                                 : static_cast<double>(signedExpected)) *
+                                                0.5 +
+                                        10.0;
+                std::ostringstream actualText;
+                std::ostringstream expectedText;
+                std::visit([&actualText](auto raw) { actualText << raw; }, decoded.rawValue);
+                if (type == ValueType::Unsigned)
+                    expectedText << bits;
+                else
+                    expectedText << signedExpected;
+                if (!decoded.valid || decoded.rawValue != expected ||
+                    decoded.physicalValue != physical || actualText.str() != expectedText.str()) {
+                    std::cerr << "FAIL: 64-bit boundary " << bits << '\n';
+                    ++failures;
+                }
+                ++boundaryCases;
+            }
+        }
+    }
+    if (failures != 0)
+        return 1;
+    std::cout << "All " << sizeof(cases) / sizeof(cases[0]) + boundaryCases << " decoder cases passed.\n";
+    return 0;
+}

tests/dbc_decoder_test.pro

@@ -0,0 +1,7 @@
+TEMPLATE = app
+TARGET = dbc_decoder_test
+CONFIG += console c++17
+CONFIG -= app_bundle qt
+INCLUDEPATH += ..
+SOURCES += dbc_decoder_test.cpp ../dbc_decoder.cpp
+HEADERS += ../dbc_decoder.h ../decode_database.h

tests/dbc_parser_test.cpp

@@ -0,0 +1,253 @@
+#include "dbc_parser.h"
+#include "dbc_statement_handler.h"
+
+#include <chrono>
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <stdexcept>
+
+struct Fixture {
+    std::filesystem::path path = std::filesystem::temp_directory_path() /
+                                 ("dbc_parser_test_" + std::to_string(std::chrono::steady_clock::now().time_since_epoch().count()) + ".dbc");
+    ~Fixture() {
+        std::error_code error;
+        std::filesystem::remove(path, error);
+    }
+    void Write(const std::string &text) const {
+        std::ofstream output(path);
+        output << text;
+        if (!output)
+            throw std::runtime_error("Cannot write test fixture.");
+    }
+};
+
+class CountingHandler : public DbcStatementHandler {
+public:
+    inline static int instances = 0;
+    inline static int calls = 0;
+    CountingHandler() { ++instances; }
+    void Handle(const std::string &, DbcParseContext &context) const override {
+        ++calls;
+        context.database.frames.emplace_back();
+    }
+};
+
+int main() {
+    Fixture fixture;
+    int failures = 0;
+    std::size_t count = 0U;
+    const auto check = [&](bool passed, const std::string &name) {
+        ++count;
+        if (!passed) {
+            ++failures;
+            std::cerr << "FAIL: " << name << '\n';
+        }
+    };
+    struct ValidCase {
+        const char *line;
+        std::uint32_t id;
+        bool extended;
+        unsigned length;
+    };
+    const ValidCase valid[] = {
+            {"BO_ 0 Frame: 0 ECU", 0U, false, 0U},
+            {"BO_ 2047 Frame: 8 ECU", 2047U, false, 8U},
+            {"BO_ 2048 Frame: 64 ECU", 2048U, true, 64U},
+            {"BO_ 536870911 Frame: 255 ECU", 0x1FFFFFFFU, true, 255U},
+            {"BO_ 2147483649 Frame: 8 ECU", 1U, true, 8U},
+            {"BO_ 2684354559 Frame: 8 ECU", 0x1FFFFFFFU, true, 8U},
+            {"  BO_\t256\tFrame :\t8\tECU  \r", 256U, false, 8U}};
+    for (const auto &test: valid) {
+        fixture.Write(std::string(test.line) + '\n');
+        try {
+            const auto database = DbcParser().ParseFile(fixture.path.string());
+            check(database.frames.size() == 1U && database.frames[0].name == "Frame" &&
+                          database.frames[0].canId == test.id &&
+                          database.frames[0].isExtended == test.extended &&
+                          database.frames[0].dlc == test.length &&
+                          database.frames[0].transmitter == "ECU",
+                  test.line);
+        } catch (const std::exception &error) { check(false, error.what()); }
+    }
+    const char *invalid[] = {
+            "BO_ invalid", "BO_", "BO_ 1", "BO_ 1 : 8 ECU", "BO_ 1 Frame 8 ECU",
+            "BO_ 1 Frame:", "BO_ 1 Frame: 8", "BO_ 1 Frame: 8 ECU extra",
+            "BO_ 1 Two Names: 8 ECU", "BO_ -1 Frame: 8 ECU", "BO_ +1 Frame: 8 ECU",
+            "BO_ 1x Frame: 8 ECU", "BO_ 0x123 Frame: 8 ECU", "BO_ 1.5 Frame: 8 ECU",
+            "BO_ 4294967296 Frame: 8 ECU", "BO_ 999999999999999999999 Frame: 8 ECU",
+            "BO_ 536870912 Frame: 8 ECU", "BO_ 1073741824 Frame: 8 ECU",
+            "BO_ 2684354560 Frame: 8 ECU", "BO_ 4294967295 Frame: 8 ECU",
+            "BO_ 1 Frame: -1 ECU", "BO_ 1 Frame: +8 ECU", "BO_ 1 Frame: 8x ECU",
+            "BO_ 1 Frame: 8.5 ECU", "BO_ 1 Frame: 256 ECU",
+            "BO_ 1 Frame: 4294967296 ECU", "BO_\tinvalid"};
+    for (const auto *line: invalid) {
+        fixture.Write(std::string("VERSION \"test\"\n\n") + line + '\n');
+        try {
+            DbcParser().ParseFile(fixture.path.string());
+            check(false, line);
+        } catch (const std::runtime_error &error) {
+            const std::string prefix = fixture.path.string() + ":3: ";
+            check(std::string(error.what()).find(prefix) == 0U &&
+                          std::string(error.what()).size() > prefix.size(),
+                  line);
+        }
+    }
+    fixture.Write(
+            "BO_TX_BU_ 256 : ECU;\nBO_ 256 Frame: 8 ECU\n"
+            " SG_ Speed : 0|16@1+ (0.5,1) [0|100] \"rpm\" ECU\n"
+            "CM_ BO_ 256 \"Frame comment\";\nCM_ SG_ 256 Speed \"Signal comment\";\n"
+            "BO_ 257 Second: 8 ECU\n");
+    const auto database = DbcParser().ParseFile(fixture.path.string());
+    check(database.frames.size() == 2U && database.frames[0].signals.size() == 1U &&
+                  database.frames[0].comment == "Frame comment" &&
+                  database.frames[0].signals[0].comment == "Signal comment",
+          "Integration");
+    fixture.Write("\nSG_ Speed : invalid\n");
+    try {
+        DbcParser().ParseFile(fixture.path.string());
+        check(false, "Signal error location");
+    } catch (const std::runtime_error &error) {
+        check(std::string(error.what()).find(fixture.path.string() + ":2: ") == 0U,
+              "Signal error location");
+    }
+    const DbcParser signalParser;
+    const auto signalLine = [](const std::string &start, const std::string &length,
+                               const std::string &order, const std::string &factor,
+                               const std::string &offset, const std::string &minimum,
+                               const std::string &maximum) {
+        return "SG_ Value : " + start + "|" + length + "@" + order +
+               " (" + factor + "," + offset + ") [" + minimum + "|" + maximum + "] \"\" ECU";
+    };
+    const auto rejectSignal = [&](const std::string &line, unsigned payload = 8U) {
+        fixture.Write("BO_ 1 Frame: " + std::to_string(payload) + " ECU\n\n" + line + "\n");
+        try {
+            signalParser.ParseFile(fixture.path.string());
+            check(false, "Reject " + line);
+        } catch (const std::runtime_error &error) {
+            const std::string prefix = fixture.path.string() + ":3: ";
+            check(std::string(error.what()).find(prefix) == 0U &&
+                          std::string(error.what()).size() > prefix.size(),
+                  "Reject " + line);
+        }
+    };
+    const std::string ordinary = signalLine("0", "8", "1+", "1", "0", "0", "255");
+    for (const std::string value: {"-1", "+1", "0junk", "0x10", "1.5",
+                                   "4294967296", "999999999999999999999"}) {
+        rejectSignal(signalLine(value, "8", "1+", "1", "0", "0", "255"));
+        rejectSignal(signalLine("0", value, "1+", "1", "0", "0", "255"));
+    }
+    for (const std::string length: {"0", "65"})
+        rejectSignal(signalLine("0", length, "1+", "1", "0", "0", "255"));
+    for (const std::string order: {"2+", "9-", "1", "1x", "1++", "01+"})
+        rejectSignal(signalLine("0", "8", order, "1", "0", "0", "255"));
+    for (const std::string value: {"1junk", "nan", "NaN", "inf", "-inf", "1e999", "1e-999", "0x1p2", "", "1e", "1.2.3"}) {
+        rejectSignal(signalLine("0", "8", "1+", value, "0", "0", "255"));
+        rejectSignal(signalLine("0", "8", "1+", "1", value, "0", "255"));
+        rejectSignal(signalLine("0", "8", "1+", "1", "0", value, "255"));
+        rejectSignal(signalLine("0", "8", "1+", "1", "0", "0", value));
+    }
+    rejectSignal(signalLine("0", "8", "1+", "1", "0", "2", "1"));
+    for (const std::string name: {"", "Two Names", "Value M", "Value m1", "Value m1M"}) {
+        std::string line = ordinary;
+        line.replace(4U, 5U, name);
+        rejectSignal(line);
+    }
+    for (const std::string broken: {
+                 "SG_", "SG_ Value", "SG_ Value : 0|8@1+ (1,0) [0|255] ECU",
+                 "SG_ Value : 0|8@1+ (1,0) [0|255] \"\"",
+                 "SG_ Value : 0|8@1+ (1,0) [0|255] \"\" ECU,",
+                 "SG_ Value : 0|8@1+ (1,0) [0|255] \"\" ECU extra"})
+        rejectSignal(broken);
+    rejectSignal(signalLine("64", "1", "1+", "1", "0", "0", "1"));
+    rejectSignal(signalLine("63", "2", "1+", "1", "0", "0", "3"));
+    rejectSignal(signalLine("56", "2", "0+", "1", "0", "0", "3"));
+    rejectSignal(signalLine("4294967295", "64", "1+", "1", "0", "0", "1"));
+    rejectSignal(ordinary, 0U);
+    for (const char delimiter: {'|', '@', '(', ')', '[', ']', '"'}) {
+        std::string line = ordinary;
+        line.erase(line.find(delimiter), 1U);
+        rejectSignal(line);
+    }
+    fixture.Write("BO_ 1 Frame: 8 ECU\n" +
+                  signalLine("0", "8", "1+", "0", "0", "0", "0") + "\n" +
+                  signalLine("8", "8", "1-", "-1", "0", "-255", "0") + "\n");
+    const auto factors = signalParser.ParseFile(fixture.path.string());
+    check(factors.frames[0].signals.size() == 2U &&
+                  factors.frames[0].signals[0].factor == 0.0 &&
+                  factors.frames[0].signals[1].factor == -1.0,
+          "Zero and negative factors and equal range boundaries");
+
+    struct SignalCase {
+        const char *start;
+        const char *length;
+        const char *order;
+        unsigned payload;
+    };
+    const SignalCase validSignals[] = {
+            {"0", "1", "1+", 1U},
+            {"7", "1", "0-", 1U},
+            {"0", "64", "1+", 8U},
+            {"7", "64", "0-", 8U},
+            {"63", "1", "1+", 8U},
+            {"56", "1", "0+", 8U},
+            {"3", "12", "0+", 2U},
+            {"2039", "1", "1+", 255U}};
+    for (const auto &test: validSignals) {
+        fixture.Write("BO_ 1 Frame: " + std::to_string(test.payload) + " ECU\n" +
+                      signalLine(test.start, test.length, test.order, ".5e+1", "-2.5E-1", "-1.", "+2e2") + "\n");
+        try {
+            const auto parsed = signalParser.ParseFile(fixture.path.string());
+            const auto &signal = parsed.frames.at(0).signals.at(0);
+            check(signal.startBit == std::stoul(test.start) &&
+                          signal.length == std::stoul(test.length) &&
+                          signal.isLittleEndian == (test.order[0] == '1') &&
+                          signal.isSigned == (test.order[1] == '-') &&
+                          signal.factor == 5.0 && signal.offset == -0.25 &&
+                          signal.minimum == -1.0 && signal.maximum == 200.0,
+                  "Valid signal boundary and numeric metadata");
+        } catch (const std::exception &error) { check(false, error.what()); }
+    }
+    fixture.Write("BO_ 1 Frame: 8 ECU\n"
+                  "SG_\tValue\t:\t0 | 8 @1+ ( 1 , 0 ) [ 0 | 255 ] \"rpm\" ECU1,\tECU2\n");
+    try {
+        const auto parsed = signalParser.ParseFile(fixture.path.string());
+        const auto &signal = parsed.frames.at(0).signals.at(0);
+        check(signal.name == "Value" && signal.unit == "rpm" &&
+                      signal.receivers == std::vector<std::string>({"ECU1", "ECU2"}),
+              "Signal tabs, spaces, and receiver list");
+    } catch (const std::exception &error) { check(false, error.what()); }
+    DbcDatabase dispatchDatabase;
+    DbcParseContext context{dispatchDatabase, nullptr};
+    DbcStatementDispatcher dispatcher;
+    dispatcher.RegisterType<CountingHandler>("TEST_");
+    check(dispatcher.Dispatch("TEST_ first", context) &&
+                  dispatcher.Dispatch("TEST_ second", context) &&
+                  CountingHandler::instances == 1 && CountingHandler::calls == 2 &&
+                  dispatchDatabase.frames.size() == 2U,
+          "Factory dispatch and handler reuse");
+    check(!dispatcher.Dispatch("TEST_OTHER data", context) &&
+                  !dispatcher.Dispatch("BO_TX_BU_ 1 : ECU;", context) &&
+                  !dispatcher.Dispatch("VAL_ 1 Speed 0 \"Stopped\";", context) &&
+                  CountingHandler::calls == 2,
+          "Exact and unknown keyword dispatch");
+    const DbcParser parser;
+    fixture.Write("BO_ 1 First: 8 ECU\n");
+    check(parser.ParseFile(fixture.path.string()).frames.size() == 1U, "First parse");
+    fixture.Write("SG_ Speed : invalid\n");
+    try {
+        parser.ParseFile(fixture.path.string());
+        check(false, "Independent parse context");
+    } catch (const std::runtime_error &error) {
+        check(std::string(error.what()).find("Signal found before any frame") !=
+                      std::string::npos,
+              "Independent parse context");
+    }
+    fixture.Write("BO_ 2 Second: 8 ECU\n");
+    const auto recovered = parser.ParseFile(fixture.path.string());
+    check(recovered.frames.size() == 1U && recovered.frames[0].canId == 2U,
+          "Fresh parse after error");
+    if (failures != 0) return 1;
+    std::cout << "All " << count << " parser cases passed.\n";
+    return 0;
+}

tests/dbc_parser_test.pro

@@ -0,0 +1,7 @@
+TEMPLATE = app
+TARGET = dbc_parser_test
+CONFIG += console c++17
+CONFIG -= app_bundle qt
+INCLUDEPATH += ..
+SOURCES += dbc_parser_test.cpp ../dbc_parser.cpp ../dbc_statement_handler.cpp
+HEADERS += ../dbc_statement_handler.h ../typefactory.h ../dbc_parser.h ../dbc_database.h ../frame_info.h ../signal_info.h

tree_node.cpp

@@ -12,27 +12,15 @@
 #include "tree_node.h"
 
 TreeNode::TreeNode()
-  : m_type (NodeType::Root)
-  , m_name ("dbc")
-  , m_children()
-  , m_frame()
-  , m_signal() {
+    : m_type(NodeType::Root), m_name("dbc"), m_children(), m_frame(), m_signal() {
 }
 
 TreeNode::TreeNode(const FrameInfo &frame)
-  : m_type (NodeType::Frame)
-  , m_name (frame.name)
-  , m_children()
-  , m_frame (new FrameInfo (frame))
-  , m_signal() {
+    : m_type(NodeType::Frame), m_name(frame.name), m_children(), m_frame(new FrameInfo(frame)), m_signal() {
 }
 
 TreeNode::TreeNode(const SignalInfo &signal)
-  : m_type (NodeType::Signal)
-  , m_name (signal.name)
-  , m_children()
-  , m_frame()
-  , m_signal (new SignalInfo (signal)) {
+    : m_type(NodeType::Signal), m_name(signal.name), m_children(), m_frame(), m_signal(new SignalInfo(signal)) {
 }
 
 void TreeNode::AddChild(std::unique_ptr<TreeNode> child) {

tree_node.h

@@ -12,10 +12,10 @@
 #ifndef TREE_NODE_H
 #define TREE_NODE_H
 
+#include <cstddef>
+#include <memory>
 #include <string>
 #include <vector>
-#include <memory>
-#include <cstddef>
 
 #include "frame_info.h"
 #include "signal_info.h"

typefactory.h

@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2026 Dim Himro
+
+#ifndef TYPEFACTORY_H
+#define TYPEFACTORY_H
+
+#include <memory>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>// std::move
+
+/**
+ * @brief Registry-based factory for creating objects by runtime identifier.
+ *
+ * Allows registering derived types and instantiating them using a ClassId key.
+ *
+ * Notes:
+ * - Not thread-safe. Register types during initialization phase only.
+ * - Re-registering the same id overwrites the previous entry ("last wins").
+ * - ClassId must be hashable (std::hash<ClassId> specialization must exist).
+ *
+ * @tparam ClassId -Unique class identifier type (e.g. std::string, int, enum).
+ * @tparam BaseClass -Base type for all created objects.
+ * @tparam Arg - Constructor arguments forwarded to registered derived types (by value).
+ *
+ * Usage example:
+ * @code
+ * #include <string>
+ *
+ * struct Base {
+ *   virtual ~Base() = default;
+ *   virtual int get() = 0;
+ * };
+ *
+ * struct Derived1 : Base {
+ *   explicit Derived1(int start) : m_start(start) {}
+ *   int get() override { return m_start + 1; }
+ *   int m_start = 0;
+ * };
+ *
+ * struct Derived2 : Base {
+ *   explicit Derived2(int start) : m_start(start) {}
+ *   int get() override { return m_start + 2; }
+ *   int m_start = 0;
+ * };
+ *
+ * TypeFactory<std::string, Base, int> factory;
+ * factory.registerType<Derived1>("one");
+ * factory.registerType<Derived2>("two");
+ *
+ * auto a = factory.create("one", 10);
+ * auto b = factory.creator("two")(10); // advanced API: get creator function
+ *
+ * (void)a->get();
+ * (void)b->get();
+ * @endcode
+ */
+template<class ClassId, class BaseClass, class... Args>
+class TypeFactory {
+public:
+    using BasePtr = std::shared_ptr<BaseClass>;
+    using CreatorFn = BasePtr (*)(Args...);
+
+    TypeFactory() = default;
+
+    /**
+   * @brief Registers a Derived type under the given id.
+   *
+   * Requirements (checked at compile-time):
+   * - Derived must inherit from BaseClass
+   * - Derived must be constructible from Args...
+   *
+   * Re-registering the same id overwrites the previous entry ("last wins").
+   */
+    template<class Derived>
+    void registerType(const ClassId &id) {
+        static_assert(std::is_base_of_v<BaseClass, Derived>,
+                      "Derived must inherit from BaseClass");
+        static_assert(std::is_constructible_v<Derived, Args...>,
+                      "Derived must be constructible from Args...");
+
+        classes.insert_or_assign(id, &instantiate<Derived>);
+    }
+
+    /**
+   * @brief Returns creator function for the given id.
+   * @throws std::out_of_range when id is not registered.
+   */
+    [[nodiscard]] CreatorFn creator(const ClassId &id) const {
+        return classes.at(id);
+    }
+
+    /**
+   * @brief Creates an instance for the given id using provided arguments.
+   * @throws std::out_of_range when id is not registered.
+   */
+    [[nodiscard]] BasePtr create(const ClassId &id, Args... args) const {
+        return creator(id)(std::move(args)...);
+    }
+
+    /**
+   * @brief Checks whether an id is registered.
+   */
+    [[nodiscard]] bool contains(const ClassId &id) const {
+        return classes.find(id) != classes.end();
+    }
+
+protected:
+    // Protected by design: derived factories may extend/inspect the registry.
+    std::unordered_map<ClassId, CreatorFn> classes;
+
+private:
+    template<class Derived>
+    static BasePtr instantiate(Args... args) {
+        return std::make_shared<Derived>(std::move(args)...);
+    }
+};
+#endif// TYPEFACTORY_H