jsonparser.py

from __future__ import print_function
from ply import lex, yacc

tokens = (
    "LBRACE", "RBRACE", "LBRACKET", "RBRACKET", "COLON",
    "STRING", "INT", "FLOAT", "COMMA", "NULL", "TRUE", "FALSE",
    "WHITESPACE"
)

t_LBRACE = r"\{"
t_RBRACE = r"\}"
t_LBRACKET = r"\["
t_RBRACKET = r"\]"
t_COLON = r":"
t_INT = r"[0-9]+(\.[0-9]+)?"
t_FLOAT = r"([0-9]+\.[0-9]*)|([0-9]*\.[0-9]+)"
t_COMMA = r","
t_NULL = r"null"
t_TRUE = r"true"
t_FALSE = r"false"

def t_ignore_WHITESPACE(t):
    r"[ \t\r\n]+"
    t.lexer.lineno += t.value.count("\n")

def t_STRING(t):
    r'\"([^\\"]|\\(.|\n))*\"'
    t.lexer.lineno += t.value.count("\n")
    return t

def t_error(t):
    print("Lexer error:", t.value)

lexer = lex.lex()

precedence = (
)

def p_object(p):
    "object : LBRACE kvpairs RBRACE"
    p[0] = p[2]

def p_kvpairs(p):
    """kvpairs : kvpair
               | kvpairs COMMA kvpair"""
    if len(p) == 4:
        p[1].update(p[3])
    p[0] = p[1]

def p_kvpair(p):
    "kvpair : string COLON value"
    p[0] = {p[1]: p[3]}

def p_value(p):
    """value : string
             | number
             | object
             | array
             | bool
             | null"""
    p[0] = p[1]

def p_string(p):
    "string : STRING"
    p[0] = p[1][1:-1]

def p_number(p):
    """number : int
              | float"""
    p[0] = p[1]

def p_int(p):
    "int : INT"
    p[0] = int(p[1])

def p_float(p):
    "float : FLOAT"
    p[0] = float(p[1])

def p_array(p):
    "array : LBRACKET values RBRACKET"
    p[0] = p[2]

def p_values(p):
    """values : value
              | values COMMA value"""
    if len(p) == 4:
        p[0] = p[1] + [p[3]]
    else:
        p[0] = [p[1]]

def p_bool(p):
    """bool : TRUE
            | FALSE"""
    p[0] = p[1] == "true"

def p_null(p):
    "null : NULL"
    p[0] = None

def p_error(p):
    print("Syntax error '{0.value}' in line {0.lineno}".format(p))

parser = yacc.yacc()

def parse(s):
    return parser.parse(s, lexer=lexer)

if __name__ == "__main__":
    import sys
    assert(len(sys.argv) > 1)
    with open(sys.argv[1]) as f:
        data = parse(f.read())
    print(data)