custom_json_parser.js

function parse_pre_block(id) {
    let pre_block = document.getElementById(id)
    if (pre_block == null || pre_block.childElementCount === 0) {
        return null;
    }
    let children = pre_block.childNodes
    let res = ""
    for (const child of children) {
        if (child.nodeType === 3) { // text node
            res += child.data.replace(/\\\*.*(?=\*\\)\*\\/g, "")
        }
    }
    res = res.replace(/\/\*.*?(?=\*\/)\*\//g, "")
    let final = ""
    let removeSpaces = true;
    for (const char of res) {
        if (char === '"') {
            removeSpaces = !removeSpaces
        }
        if (removeSpaces) {
            if(char !== " "){
                final += char
            }
        }else{
            final += char
        }
    }
    return parse_block(final,0)[0];
}


// block:= '{' text ':' '{' (decl|block) (',' (decl|block))* '}' '}'

// text:= '"' .*? '"'
// decl:= text ':'
// ( '[' text (',' text )* ']'
// | text
// | block )
// whitespace:=[ \r\n\t]* '/*' [ \r\n\t.(?=*/)]* '*/'

// final grammar, remove all whitespace (except in text before)
// block= '{' decl (',' decl)* ','? '}'
// decl= (text ':' ( text | array | block )) | block
// array= '[' text (',' text)* ','? ']'
// text='"' .*? '"'
function parse_block(string, index) {
    if (string[index] !== '{') {
        console.log("Error on outer block, missing first bracket")
        console.log(string.slice(index, index + 10))
        return null;
    }
    index++
    let acc = []
    while (true){
        let delc_r
        delc_r = parse_decl(string, index);
        if (delc_r === null) {
            console.log("Error on decl")
            console.log(string.slice(index, index + 10))
            return null;
        }
        let decl = delc_r[0];
        acc.push(decl)
        console.log(decl)
        index = delc_r[1];

        if (string[index]===','){
            index++;
            if (string[index]==='}'){ // this is to accomodate for a trailing comma
                break
            }
            continue
        }
        break
    }


    if (string[index] !== '}') {
        console.log("Error on outer block, missing last bracket")
        console.log(string.slice(index - 10, index))
        return null;
    }
    index++;
    return [acc, index]
}

function parse_decl(string, index) {
    if (string[index]==='{'){ //standalone block
        console.log("DEBUG: Standalone block")
        let res=parse_block(string,index);
        if (res==null){
            console.log("error on parsing block")
            return null;
        }
        return [res[0],res[1]];
    }
    console.log("DEBUG: Declaration: (decl|array|block) >")
    let text_r = parse_text(string, index)
    if (text_r === null) {
        console.log("Error on text in decl")
        console.log(string.slice(index, index + 10))
        return null;
    }
    let text = text_r[0];
    index = text_r[1];
    if (string[index] !== ':') {
        console.log("Error on outer block, missing colon")
        console.log(string.slice(index, index + 10))
        return null;
    }
    index++;
    if (string[index] === '[') {
        console.log("DEBUG: array")
        index++;
        let acc = []
        while (true){
            let text_r = parse_text(string, index);
            if (text_r === null) {
                console.log("Error on text")
                console.log(string.slice(index, index + 10))
                return null;
            }
            let text_array = text_r[0];
            acc.push(text_array)
            index = text_r[1];
            if (string[index]===','){
                index++;
                if (string[index]==='}'){ //this is to accomodate for trailing comma
                    break
                }
                continue
            }
            break
        }
        if (string[index]!==']'){
            console.log("Wrongfully terminated array");
            return null;
        }
        index++;
        return [[text, acc], index]
    } else if (string[index] === '{') {
        console.log("DEBUG: block")
        let res=parse_block(string,index);
        if (res == null) {
            console.log("Error on parsing block")
            console.log(string.slice(index, index + 10))
            return null;
        }
        return [[text, res[0]], res[1]]
    }else{
        console.log("DEBUG: champ")
        let text_r = parse_text(string, index);
        if (text_r == null) {
            console.log("Error on parsing text")
            console.log(string.slice(index, index + 10))
            return null;
        }
        return [[text,text_r[0]],text_r[1]]
    }
}

function parse_text(string, index) {
    if (string[index] !== '"') {
        console.log("Error on parsing text")
        console.log(string.slice(index, index + 10))
        return null;
    }
    index++
    let acc = ''
    while (index < string.length) {
        if (string[index] === '"') {
            return [acc, index + 1]
        }
        acc += string[index]
        index++;
    }
    return null;
}