v545362.py

source = """
{
    "root1"
    {
        "item1"    "1"
        "item2"    "abc"
        
        "item3"
        {
            "cell"
            {
                "cell1"
                {
                    "cell1Name"    "99"
                }
                "cell2"
                {
                    "cell2Name"    "cdb"
                }    
            }
        }
        
        "item4"    "valueI"
    }

    "root2"
    {
        "item1"    "88"
        "item2"    "tg"
        
        "item3"
        {
            "cell"
            {
                "cell1"
                {
                    "cell1Name"    "99"
                }
                "cell2"
                {
                    "cell2Name"    "ujh"
                }
                
            }
        }
        
        "item4"    "valueb"
    }
}
"""

i = 0
LP=1
RP=2
def nextToken():
    global i
    while i < len(source) and source[i].isspace():
        i += 1
    if source[i] == '{':
        i += 1
        return LP
    if source[i] == '}':
        i += 1
        return RP
    if source[i] == '"':
        start = i
        i += 1
        while i < len(source) and source[i] != '"':
            i += 1
        if i < len(source):
            i += 1
            return source[start+1:i-1]
        else:
            raise Exception('expect "')
    raise Exception('expect {}"')

    


def parseValue():
    nt = nextToken()
    if nt == LP:
        return parseObject()
    if nt == RP:
        raise Exception('expect { or string')
    return nt

def parseObject():
    obj = {}
    while True:
        nt = nextToken()
        if nt == RP:
            return obj
        if nt == LP:
            raise Exception('expect string')
        k = nt
        v = parseValue()
        obj[k] = v
    return obj
    
print(parseValue())