"use strict";

function hex( ch ) {

    return ch.charCodeAt( 0 ).toString( 16 ).toUpperCase();

}

// JavaScript code generation helpers.
const js = {
    stringEscape( s ) {

        // ECMA-262, 5th ed., 7.8.4: All characters may appear literally in a string
        // literal except for the closing quote character, backslash, carriage
        // return, line separator, paragraph separator, and line feed. Any character
        // may appear in the form of an escape sequence.
        //
        // For portability, we also escape all control and non-ASCII characters.
        return s
            .replace( /\\/g, "\\\\" )   // backslash
            .replace( /"/g, "\\\"" )   // closing double quote
            .replace( /\0/g, "\\0" )    // null
            .replace( /\x08/g, "\\b" )    // backspace
            .replace( /\t/g, "\\t" )    // horizontal tab
            .replace( /\n/g, "\\n" )    // line feed
            .replace( /\v/g, "\\v" )    // vertical tab
            .replace( /\f/g, "\\f" )    // form feed
            .replace( /\r/g, "\\r" )    // carriage return
            .replace( /[\x00-\x0F]/g, ch => "\\x0" + hex( ch ) )
            .replace( /[\x10-\x1F\x7F-\xFF]/g, ch => "\\x" + hex( ch ) )
            .replace( /[\u0100-\u0FFF]/g, ch => "\\u0" + hex( ch ) )
            .replace( /[\u1000-\uFFFF]/g, ch => "\\u" + hex( ch ) );

    },

    regexpClassEscape( s ) {

        // Based on ECMA-262, 5th ed., 7.8.5 & 15.10.1.
        //
        // For portability, we also escape all control and non-ASCII characters.
        return s
            .replace( /\\/g, "\\\\" )   // backslash
            .replace( /\//g, "\\/" )    // closing slash
            .replace( /]/g, "\\]" )    // closing bracket
            .replace( /\^/g, "\\^" )    // caret
            .replace( /-/g, "\\-" )    // dash
            .replace( /\0/g, "\\0" )    // null
            .replace( /\x08/g, "\\b" )    // backspace
            .replace( /\t/g, "\\t" )    // horizontal tab
            .replace( /\n/g, "\\n" )    // line feed
            .replace( /\v/g, "\\v" )    // vertical tab
            .replace( /\f/g, "\\f" )    // form feed
            .replace( /\r/g, "\\r" )    // carriage return
            .replace( /[\x00-\x0F]/g, ch => "\\x0" + hex( ch ) )
            .replace( /[\x10-\x1F\x7F-\xFF]/g, ch => "\\x" + hex( ch ) )
            .replace( /[\u0100-\u0FFF]/g, ch => "\\u0" + hex( ch ) )
            .replace( /[\u1000-\uFFFF]/g, ch => "\\u" + hex( ch ) );

    }
};

module.exports = js;