lix/src/libutil/error.cc

#include "error.hh"

#include <iostream>
#include <optional>

namespace nix {

std::optional<string> ErrorInfo::programName = std::nullopt;

string showErrLine(ErrLine &errLine)
{
    if (errLine.columnRange.has_value()) 
    {
        return (format("(%1%:%2%)") % errLine.lineNumber % errLine.columnRange->start).str();
    }
    else
    {
        return (format("(%1%)") % errLine.lineNumber).str();
    };
}

void printCodeLines(string &prefix, NixCode &nixCode) 
{

  if (nixCode.errLine.has_value()) 
    {
        // previous line of code.
        if (nixCode.errLine->prevLineOfCode.has_value()) { 
            std::cout << format("%1% %|2$5d|| %3%")
                %    prefix
                % (nixCode.errLine->lineNumber - 1)
                % *nixCode.errLine->prevLineOfCode
                << std::endl;
        }

        // line of code containing the error.%2$+5d%
        std::cout << format("%1% %|2$5d|| %3%")
            %    prefix
            % (nixCode.errLine->lineNumber)
            % nixCode.errLine->errLineOfCode
            << std::endl;

      // error arrows for the column range.
        if (nixCode.errLine->columnRange.has_value()) 
        {
            int start = nixCode.errLine->columnRange->start;
            std::string spaces;
            for (int i = 0; i < start; ++i)
            {
                spaces.append(" ");
            }

            int len = nixCode.errLine->columnRange->len;
            std::string arrows;
            for (int i = 0; i < len; ++i)
            {
                arrows.append("^");
            }

          std::cout << format("%1%      |%2%" ANSI_RED "%3%" ANSI_NORMAL) % prefix % spaces % arrows << std::endl;
        }



        // next line of code.
        if (nixCode.errLine->nextLineOfCode.has_value()) { 
            std::cout << format("%1% %|2$5d|| %3%")
            %    prefix
            % (nixCode.errLine->lineNumber + 1)
            % *nixCode.errLine->nextLineOfCode
            << std::endl;
        }

    }

}

void printErrorInfo(ErrorInfo &einfo) 
{
    int errwidth = 80;
    string prefix = "    ";

    string levelString;
    switch (einfo.level) 
    {
        case ErrLevel::elError: 
            {
                levelString = ANSI_RED;
                levelString += "error:";
                levelString += ANSI_NORMAL;
                break;
            }
        case ErrLevel::elWarning: 
            {
                levelString = ANSI_YELLOW;
                levelString += "warning:";    
                levelString += ANSI_NORMAL;
                break;
            }
        default: 
            {
                levelString = (format("invalid error level: %1%") % einfo.level).str();    
                break;
            }
    }

    int ndl = prefix.length() + levelString.length() + 3 + einfo.name.length() + einfo.programName.value_or("").length();
    int dashwidth = ndl > (errwidth - 3) ? 3 : errwidth - ndl; 

    string dashes;
    for (int i = 0; i < dashwidth; ++i)
        dashes.append("-");

    // divider.
    std::cout << format("%1%%2%" ANSI_BLUE " %3% %4% %5% %6%" ANSI_NORMAL)
        % prefix
        % levelString
        % "---"
        % einfo.name
        % dashes
        % einfo.programName.value_or("")
        << std::endl;

    // filename.
    if (einfo.nixCode.has_value()) 
    {
        if (einfo.nixCode->nixFile.has_value()) 
        {
            string eline = einfo.nixCode->errLine.has_value()
                ? string(" ") + showErrLine(*einfo.nixCode->errLine)
                : "";

            std::cout << format("%1%in file: " ANSI_BLUE "%2%%3%" ANSI_NORMAL) 
                % prefix % *einfo.nixCode->nixFile % eline << std::endl;
            std::cout << prefix << std::endl;
        }
        else
        {
            std::cout << format("%1%from command line argument") % prefix << std::endl;
            std::cout << prefix << std::endl;
        }
    }

    // description
    std::cout << prefix << einfo.description << std::endl;
    std::cout << prefix << std::endl;

    // lines of code.
    if (einfo.nixCode.has_value())
    {
        printCodeLines(prefix, *einfo.nixCode);
        std::cout << prefix << std::endl;
    }

    // hint
    if (einfo.hint.has_value()) 
    {
        std::cout << prefix << *einfo.hint << std::endl;
        std::cout << prefix << std::endl;
    }
}

}