// This file is part of www.nand2tetris.org
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/12/String.jack

/**
 * Represents character strings. In addition for constructing and disposing
 * strings, the class features methods for getting and setting individual
 * characters of the string, for erasing the string's last character,
 * for appending a character to the string's end, and more typical
 * string-oriented operations.
 */
class String { 
    field Array str;
    field int length;
    static bool neg;

    /** constructs a new empty string with a maximum length of maxLength
     *  and initial length of 0. */
    constructor String new(int maxLength) {
        if (maxLength > 0){
            let str = Array.new(maxLength);
        }
        let length = 0;
        return this;
    }

    /** Disposes this string. */
    method void dispose() {
        if(length > 0){
            do str.dispose();
        }
        do Memory.deAlloc(this);
        return;
    }

    /** Returns the current length of this string. */
    method int length() {
        return length;
    }

    /** Returns the character at the j-th location of this string. */
    method char charAt(int j) {
        if(j > length){
            do Sys.error(7);
        }
        return str[j];          
    }

    /** Sets the character at the j-th location of this string to c. */
    method void setCharAt(int j, char c) {
        if(j > length){
            do Sys.error(7);
        }
        let str[j] = c;
        return;
    }

    /** Appends c to this string's end and returns this string. */
    method String appendChar(char c) {
        let str[length] = c;
        let length = length + 1;
        return this;
    }

    /** Erases the last character from this string. */
    method void eraseLastChar() {
        let str[length] = 0;
        let length = length - 1;
        return;
    }

    /** Returns the integer value of this string, 
     *  until a non-digit character is detected. */
    method int intValue() {
        var int d, sum, i;
        var bool f;
        while(i < length){
            let d = str[i]; // kak da go zavyrtq v realen int
            if ((d > 47) & (d < 58)){
                let sum = (sum * 10) + (d - 48);
            }
            else{
                if((i = 0) & (d = 45)){
                    let f = true;
                }
                else{
                    let i = length;
                }
            }
            let i = i + 1;
        }
        if (f){
            return -sum;
        }
        return sum;
    }

    /** Sets this string to hold a representation of the given value. */
    method void setInt(int val) {
        var int lastDigit, a, i;
        var char c;
        if(val < 0){
            let neg = true;
            let val = -val;
        }
        let a = val / 10;
        let lastDigit = val - (a * 10);
        let i = 48;
        while (i < 58){
            if (i = (48 + lastDigit)){
                let c = i;
                let i = 59;
            }
            let i = i + 1;
        }
        if (val < 10){
            let length = 0;
            if (neg){
                let neg = false;
                do this.appendChar("-");
            }
            do this.appendChar(c);
            return;
        }
        else{
            do this.setInt(a);
            do this.appendChar(c);
        }
        return;
    }

    /** Returns the new line character. */
    function char newLine() {
        return 128;
    }

    /** Returns the backspace character. */
    function char backSpace() {
        return 129;
    }

    /** Returns the double quote (") character. */
    function char doubleQuote() {
        return 34;
    }
}