172 lines
3.1 KiB
Python
172 lines
3.1 KiB
Python
# Import lexer and parser from ply module
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import ply.lex as lex
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import ply.yacc as yacc
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# List of token types.
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tokens = (
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'NUMBER',
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'OPERATE',
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'SIZE',
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'KIND',
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'COLOR',
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'MATERIAL'
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)
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# Token types may be defined as regular expressions, e.g. r'Buy | Sell'
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def t_OPERATE(t):
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r'Buy | Sell'
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return t
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def t_MATERIAL(t):
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r'metal | plastic'
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if t.value == 'metal':
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t.value = 1
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elif t.value == 'plastic':
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t.value = 2
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return t
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def t_COLOR(t):
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r'(black | white | red | green | blue)'
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if t.value == 'black':
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t.value = 1
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elif t.value == 'white':
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t.value = 2
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elif t.value == 'red':
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t.value = 3
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elif t.value == 'green':
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t.value = 4
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elif t.value == 'blue':
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t.value = 5
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return t
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def t_SIZE(t):
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r'tiny | small | big | large'
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if t.value == 'tiny':
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t.value = 1
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elif t.value == 'small':
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t.value = 2
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elif t.value == 'big':
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t.value = 3
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elif t.value == 'large':
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t.value = 4
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return t
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def t_KIND(t):
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r'box(es)? | ring(s)?'
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if t.value[0] == 'b':
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t.value = 1
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else:
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t.value = 2
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return t
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def t_NUMBER(t):
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r'\d+'
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t.value = int(t.value)
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return t
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# Lexer error handling rule (Handle words out of vocabulary)
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def t_error(t):
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print("Illegal character '%s'" % t.value[0])
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t.lexer.skip(1)
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# Ignore white spaces
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t_ignore = ' \t'
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# Main parser rule (command)
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def p_command(p):
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'command : OPERATE NUMBER article'
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index = p[3]
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# Buy article
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if p[1] == 'Buy':
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tab[index] += p[2]
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print('OK. I am buying ' + str(p[2]) +
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' new articles indexed as ' + str(index) + '.')
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print('No of articles in shop: ' + str(tab[index]))
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# Sell article
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elif p[1] == 'Sell':
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if p[2] > tab[index]:
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print('I do not have as many articles as you want.')
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else:
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tab[index] -= p[2]
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print('OK. I am selling ' + str(p[2]) +
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' articles indexed as ' + str(index) + '.')
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print('No of articles in shop: ' + str(tab[index]))
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# Parser rule (attribute)
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def p_attribute_color(p):
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'attribute : COLOR'
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p[0] = p[1]
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# Parser rule (attribute)
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def p_attribute_material(p):
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'attribute : MATERIAL'
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p[0] = 10 * p[1]
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# Parser rule (attribute)
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def p_attribute_size(p):
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'attribute : SIZE'
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p[0] = 100 * p[1]
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# Parser rule (article - stop)
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def p_article_kind(p):
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'article : KIND'
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p[0] = 1000 * p[1]
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# Parser rule (article - recursion)
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def p_article_attribute(p):
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'article : attribute article'
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p[0] = p[1] + p[2]
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# Syntax error handling rule
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def p_error(p):
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print("Syntax error in input!")
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#######################################
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# Main program
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# Initialize table of articles (zero articles at the beginning)
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tab = []
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for index in range(3000):
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tab.append(0)
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# Build the lexer
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lexer = lex.lex()
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# Tokenize (short version)
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# for tok in lexer:
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# print(tok)
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# Build the parser
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parser = yacc.yacc()
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# Main loop
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while True:
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s = input('What can I do for you? \n')
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if s == 'Bye':
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break
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parser.parse(s)
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