How can I have two spaces before the broken lines in inputlisting?

Question

I am using the solution from How can I write line numbers inside boxed code. Its code with slightly changes:

\begin{filecontents*}{\jobname.sol}
    function hello_world(uint a, uint b, uint c, uint d, uint e, uint f) public returns bool {
            uint256 amount = 100
            return amount * 100
            return true;
        }
\end{filecontents*}
\documentclass[10pt,journal,compsoc]{IEEEtran}
\usepackage[english]{babel}
\usepackage{pgfplots}
\usepackage{booktabs}
\usepackage{listings}
\usepackage[many]{tcolorbox}
\tcbuselibrary{listings}
\ifCLASSOPTIONcompsoc
    \usepackage[nocompress]{cite}
\else
    \usepackage{cite}
\fi
\pgfplotsset{compat=1.18}
\hyphenation{op-tical net-works semi-conduc-tor}
\newtcbinputlisting{\inputlisting}[2][]{%
    listing file={#2},
    top=0pt,
    left=16pt,
    bottom=0pt,
    right=8pt,
    colback=verylightgray,
    colframe=black,
    listing only,
    breakable,
    sharp corners,
    boxrule=0.2pt,
    listing options={#1},
}
\lstdefinelanguage{Solidity}{
    keywords=[1]{% generic keywords including crypto operations
            anonymous, assembly, assert, balance, break, call, callcode, case,
            catch, class, constant, continue, constructor, contract, debugger,
            default, delegatecall, delete, do, else, emit, event, experimental,
            export, external, false, finally, for, function, gas, if, implements,
            import, in, indexed, instanceof, interface, internal, is, length,
            library, log0, log1, log2, log3, log4, memory, modifier, new, payable,
            pragma, private, protected, public, pure, push, require, return,
            returns, revert, selfdestruct, send, solidity, storage, struct,
            suicide, super, switch, then, this, throw, transfer, true, try,
            typeof, using, value, view, while, with, addmod, ecrecover, keccak256,
            mulmod, ripemd160, sha256, sha3
        },
    keywordstyle=[1]\color{blue}\bfseries,
    keywords=[2]{% types; money and time units
            address, bool, byte, bytes, bytes1, bytes2, bytes3, bytes4, bytes5,
            bytes6, bytes7, bytes8, bytes9, bytes10, bytes11, bytes12, bytes13,
            bytes14, bytes15, bytes16, bytes17, bytes18, bytes19, bytes20, bytes21,
            bytes22, bytes23, bytes24, bytes25, bytes26, bytes27, bytes28, bytes29,
            bytes30, bytes31, bytes32, enum, int, int8, int16, int24, int32, int40,
            int48, int56, int64, int72, int80, int88, int96, int104, int112, int120,
            int128, int136, int144, int152, int160, int168, int176, int184, int192,
            int200, int208, int216, int224, int232, int240, int248, int256, mapping,
            string, uint, uint8, uint16, uint24, uint32, uint40, uint48, uint56,
            uint64, uint72, uint80, uint88, uint96, uint104, uint112, uint120,
            uint128, uint136, uint144, uint152, uint160, uint168, uint176, uint184,
            uint192, uint200, uint208, uint216, uint224, uint232, uint240, uint248,
            uint256, var, void, ether, finney, szabo, wei, days, hours, minutes,
            seconds, weeks, years},
    keywordstyle=[2]\color{teal}\bfseries,
    keywords=[3]{% environment variables
            block, blockhash, coinbase, difficulty, gaslimit, number, timestamp,
            msg, data, gas, sender, sig, value, now, tx, gasprice, origin
        },
    keywordstyle=[3]\color{violet}\bfseries,
    identifierstyle=\color{black},
    sensitive=false,
    comment=[l]{//},
    morecomment=[s]{/}{/},
    commentstyle=\color{gray}\ttfamily,
    stringstyle=\color{red}\ttfamily,
    morestring=[b]',
    morestring=[b]"
}
\lstset{
    language=Solidity,
    extendedchars=true,
    basicstyle=\footnotesize\ttfamily,
    showstringspaces=false,
    showspaces=false,
    numbers=none,
    numberstyle=\footnotesize,
    numbersep=9pt,
    tabsize=1,
    breaklines=true,
    showtabs=false,
    captionpos=b
}
\begin{document}
\section{Introduction}
\inputlisting{\jobname.sol}
\end{document}

Seems like broken lines have four spaces.

Is it possible to have the linebreak tab size as two space? Please note that I have changed tabsize=1 to smaller values but it did not have any effect.

As an example, see where there are two spaces before uint d and bool {:

function hello_world(uint a, uint b, uint c, 
  uint d, uint e, uint f) public returns bool {
  uint256 amount = 100
  return amount * 100
  return true;
}

Related:

• How to make tabsize also affect lstinputlisting?

Answer 1

Use breakindent.

\documentclass[11pt]{article}
\usepackage{amsmath,amssymb}
\usepackage{listings}
\usepackage{lstautogobble}
\lstdefinestyle{mystyle}
{
    basicstyle=\ttfamily,
    frame=single,
    breaklines,
    basewidth=0.6em,
    breakindent=1.2em,
    breakatwhitespace
}
\begin{document}
\begin{lstlisting}[style=mystyle,autogobble]
    function hello_world(uint a, uint b, uint c, uint d, uint e, uint f) public returns bool {
        uint256 amount = 100
        return amount * 100
        return true;
    }
\end{lstlisting}
\begin{lstlisting}[style=mystyle,autogobble,postbreak=\hbox{$\hookrightarrow$\space}]
    function hello_world(uint a, uint b, uint c, uint d, uint e, uint f) public returns bool {
        uint256 amount = 100
        return amount * 100
        return true;
    }
\end{lstlisting}
\end{document}

I have set basewidth (which is the width of a character) explicitly so that breakindent can be set exactly to 2 characters wide. In case you wish to use, the second version prints a hook to distinguish a line break.

Output: