6 establish a complete exception handling framework

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "deps/Catch2"]
 	path = deps/Catch2
 	url = https://github.com/catchorg/Catch2.git
+[submodule "deps/fmt"]
+	path = deps/fmt
+	url = https://github.com/fmtlib/fmt

CMakeLists.txt

@@ -18,4 +18,5 @@ set(CMAKE_CXX_STANDARD_REQUIRED on)
 
 add_subdirectory(src)
 add_subdirectory(tests)
-add_subdirectory(deps/Catch2)
+add_subdirectory(deps/Catch2)
+add_subdirectory(deps/fmt)

src/CMakeLists.txt

@@ -3,3 +3,5 @@ file(GLOB sources "*.cpp")
 add_library(myxml ${sources})
 
 target_include_directories(myxml PUBLIC ".")
+
+target_link_libraries(myxml fmt::fmt)

src/error.cpp

@@ -0,0 +1,45 @@
+#include "error.hpp"
+
+namespace myxml
+{
+    ParseError::ParseError(std::string message)
+        : message(message)
+    {
+    }
+
+    const char *ParseError::what() const noexcept
+    {
+        this->fullMessage = this->prefix() + this->message;
+        return this->fullMessage.c_str();
+    }
+
+    const char *SyntaxError::prefix() const
+    {
+        return "Syntax Error: ";
+    }
+
+    SyntaxError::SyntaxError(std::string message)
+        : ParseError(message)
+    {
+    }
+
+    const char *SemanticError::prefix() const
+    {
+        return "Sematic Error: ";
+    }
+
+    SemanticError::SemanticError(std::string message)
+        : ParseError(message)
+    {
+    }
+
+    const char *UnexpectedEndOfInput::prefix() const
+    {
+        return "Unexpected End of Input: ";
+    }
+
+    UnexpectedEndOfInput::UnexpectedEndOfInput()
+        : ParseError("End of input")
+    {
+    }
+}

src/error.hpp

@@ -0,0 +1,60 @@
+#pragma once
+#include <stdexcept>
+
+namespace myxml
+{
+    class ParseError : public std::exception
+    {
+    private:
+        virtual const char *prefix() const = 0;
+
+    protected:
+        std::string message;
+        // store message after being concated with prefix
+        mutable std::string fullMessage;
+
+    public:
+        ParseError(std::string message);
+
+        virtual const char *what() const noexcept override;
+    };
+
+    /**
+     * The input data do not conform to the expected grammar rule. Including:
+     *  1. Missing or mismatch symbols. For example, missing a '>' in the end of a tag.
+     *  2. Unexpected token. Encounter a token that is not expected in the context. For example: extra semicolon.
+     *  ...
+     */
+    class SyntaxError : public ParseError
+    {
+    private:
+        virtual const char *prefix() const;
+
+    public:
+        SyntaxError(std::string);
+    };
+
+    /**
+     *
+     */
+    class SemanticError : public ParseError
+    {
+    private:
+        virtual const char *prefix() const;
+
+    public:
+        SemanticError(std::string);
+    };
+
+    /**
+     * e.g. EOF
+     */
+    class UnexpectedEndOfInput : public ParseError
+    {
+    private:
+        virtual const char *prefix() const;
+
+    public:
+        UnexpectedEndOfInput();
+    };
+}