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#!/usr/bin/env python3
#
# Copyright © 2019 Keith Packard <keithp@keithp.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
#
import sys
lex_c = False
def getc():
global lex_c
if lex_c is not False:
c = lex_c
lex_c = False
else:
c = sys.stdin.read(1)
return c
def ungetc(c):
global lex_c
lex_c = c
lex_value = False
def lex():
global lex_value
while True:
c = getc()
if c == '':
return 'END'
if c == '{':
return "OC"
if c == '}':
return "CC"
if c == ',':
return "COMMA"
if c == ':':
return "COLON"
if c == '[':
return "OS"
if c == ']':
return "CS"
if c == '\n' or c == ' ' or c == '\t':
continue
if '0' <= c and c <= '9':
v = ord(c) - ord('0')
while True:
c = getc()
if '0' <= c and c <= '9':
v = v * 10 + ord(c) - ord('0')
else:
ungetc(c)
break;
lex_value = v
return "NUMBER"
if c == '"':
v = ''
while True:
c = getc()
if c == '"':
break
if c == '\\':
c = getc()
if c == 'b':
c = '\b'
elif c == 'f':
c = '\f'
elif c == 'n':
c = '\n'
elif c == 'r':
c = '\r'
elif c == 't':
c = '\t'
v += c
lex_value = v
return "STRING"
v = c
if 'a' <= c and c <= 'z':
while True:
c = getc()
if 'a' <= c and c <= 'z':
v = v + c
else:
ungetc(c)
break;
if v == 'true':
return "TRUE"
if v == 'false':
return "FALSE"
if v == 'null':
return "NULL"
print('Invalid token %s. Skipped' % v)
value_stack = ()
def head(s):
return s[0]
def rest(s):
return s[1:]
def push(v):
global value_stack
value_stack = (v,) + value_stack
def pop():
global value_stack
v = head(value_stack)
value_stack = rest(value_stack)
return v
#
# lines : line lines
# |
#
# expr : term PLUS expr
# | term MINUS expr
# | term
#
# expr : term expr-p
# expr-p: PLUS expr
# | MINUS expr
# |
from pyjson_gram import *
def is_non_terminal(item):
return item[0].islower()
def is_terminal(item):
return item[0].isupper()
def is_action(item):
return item[0] == '@'
def error(msg):
print(msg)
exit(1)
def test():
global lex_value
global value_stack
global parse_table
table = parse_table
stack = ('start',)
token = False
while True:
if stack:
top = head(stack)
stack = rest(stack)
else:
top = False
if top and is_action(top):
if top == "@VALUE":
print("%r\n" % pop())
break
elif top == "@OBJSTART":
push({})
elif top == "@OBJEND":
pass
elif top == "@NAME":
push(lex_value)
elif top == "@MEMBER":
value = pop()
name = pop()
obj = pop()
obj[name] = value
push(obj)
elif top == "@ARRSTART":
push([])
elif top == "@ARREND":
pass
elif top == "@ARRADD":
value = pop()
arr = pop()
arr.append(value)
push(arr)
elif top == "@STRING" or top == "@NUMBER":
push(lex_value)
elif top == "@TRUE":
push(True)
elif top == "@FALSE":
push(False)
elif top == "@NULL":
push(None)
continue
if not token:
token = lex()
if not top:
if token == 'END':
return
error("parse stack empty at %r" % token)
if is_terminal(top):
if top == token:
token = False
else:
error("parse error. got %r expected %r" % (token, top))
else:
key = (token, top)
if key not in table:
error("parse error at %r %r" % (token, top))
stack = table[key] + stack
test()
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