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xo-tokenizer: docs + error-handling improvement

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drop exceptions for return-value error object
This commit is contained in:
Roland Conybeare 2025-06-23 23:08:12 -05:00
commit 6fbfd065a2
30 changed files with 1086 additions and 162 deletions
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106
xo-tokenizer/include/xo/tokenizer/tokenizer_error.hpp
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@ -7,47 +7,95 @@
#include "tokentype.hpp"
#include "span.hpp"
#include <iomanip>
namespace xo {
namespace scm {
/** represent a lexing error, with context **/
/** @class tokenizer_error
* @brief represent a lexing error, with context
*
* @tparam CharT representation for single characters
**/
template <typename CharT>
class tokenizer_error {
public:
using span_type = span<const CharT>;
public:
/** @brief default ctor represent a not-an-error error object **/
/** @defgroup tokenizer-error-ctors **/
///@{
/** Default ctor represent a not-an-error sentinel object **/
tokenizer_error() = default;
tokenizer_error(char const * src_function,
char const* error_description,
span_type input_line, size_t error_pos)
/** Constructor to capture parsing error context
* @p tk_start current position on entry to scanner
* @p whitespace number of chars initial whitespace
* @p error_pos error location relative to token start
**/
tokenizer_error(const char * src_function,
const char * error_description,
span_type input_line,
size_t tk_start,
size_t whitespace,
size_t error_pos)
: src_function_{src_function},
error_description_{error_description},
input_line_{input_line},
tk_entry_{tk_start},
whitespace_{whitespace},
error_pos_{error_pos} {}
///@}
char const* src_function() const { return src_function_; }
char const* error_description() const { return error_description_; }
size_t error_pos() const { return error_pos_; }
/** @defgroup tokenizer-error-access-methods **/
///@{
const char * src_function() const { return src_function_; }
const char * error_description() const { return error_description_; }
const span_type& input_line() const { return input_line_; }
size_t tk_start() const { return tk_entry_; }
size_t whitespace() const { return whitespace_; }
size_t error_pos() const { return error_pos_; }
bool is_not_an_error() const { return error_description_ == nullptr; }
///@}
/** @defgroup tokenizer-error-general-methods **/
///@{
/** true, except for a sentinel error object **/
bool is_error() const { return error_description_ != nullptr; }
/** true except for object in sentinel state **/
bool is_not_an_error() const { return error_description_ == nullptr; }
/** Print representation to stream @p os. Intended for tokenizer diagnostics.
* For Schematika errors prefer @ref report
**/
void print(std::ostream & os) const;
/** Print human-oriented error report on @p os. **/
void report(std::ostream & os) const;
///@}
private:
/** @defgroup tokenizer-error-instance-vars **/
///@{
/** source location (in tokenizer) at which error identified **/
char const * src_function_ = nullptr;
/** static error description **/
char const * error_description_ = nullptr;
/** position (relative to line_.lo) of error **/
size_t error_pos_ = 0;
/** complete input line (to the extent available)
* containing error
/** complete current input line (to the extent captured)
* that contains error
**/
span_type input_line_ = span_type::make_null();
/** position (relative to line_.lo) of token start where error encountered **/
size_t tk_entry_ = 0;
/** number of characters of initial whitespace skipped before token start **/
size_t whitespace_ = 0;
/** position (relative to @ref tk_entry_) of error **/
size_t error_pos_ = 0;
///@}
}; /*error_token*/
template <typename CharT>
@ -56,11 +104,41 @@ namespace xo {
os << "<tokenizer-error"
<< xtag("src-function", src_function_)
<< xtag("message", error_description_)
<< xtag("error-pos", error_pos_)
<< xtag("input", input_line_)
<< xtag("whitespace", whitespace_)
<< xtag("tk-start", tk_entry_)
<< xtag("error-pos", error_pos_)
<< ">";
}
template <typename CharT>
void
tokenizer_error<CharT>::report(std::ostream & os) const {
using namespace std;
if (error_description_) {
const char * prefix = "input: ";
const size_t tk_indent = strlen(prefix) + tk_entry_ + whitespace_;
//const size_t msg_length = strlen(error_description_);
const size_t error_pos = 1 + tk_entry_ + whitespace_ + error_pos_;
os << "char: " << error_pos << endl;
os << prefix;
for (const char *p = input_line_.lo(), *e = input_line_.hi(); p < e; ++p)
os << *p;
os << endl;
os << std::setw(tk_indent) << " ";
for (size_t i = 0; i < error_pos_; ++i) {
os << '_';
}
os << '^' << endl;
os << error_description_ << endl;
}
}
template <typename CharT>
inline std::ostream &
operator<< (std::ostream & os,