how do I fix it?
On Feb 8, 12:58 pm, David Beazley <[email protected]> wrote:
> The calculator is printing the result of the parse. It's printing
> None because you're not propagating values.
>
> -Dave
>
> On Sun 08/02/09 7:50 AM , matio [email protected] sent:
>
>
>
> > what does that mean?
>
> > On Feb 8, 12:18 pm, David Beazley <[email protected]
> > om> wrote:> You're not propagating values correctly by
> > assigning to p[0].> For example, in the p_statement_expr()
> > rule.>
> > > -Dave
>
> > > On Sun 08/02/09 6:20 AM , matio ma...@hot
> > mail.co.uk sent:>
>
> > > > I've been using ply & have extended the
> > example slightly:>
> > > > [code]
> > > > <code>
> > > > import ply.lex as lex
>
> > > > reserved = {'print':'PRINT', 'quit' :
> > 'QUIT'}>
> > > > # List of token names. This is
> > always required> > tokens = [
> > > > 'NUMBER',
> > > > 'NAME',
> > > > 'PLUS',
> > > > 'MINUS',
> > > > 'TIMES',
> > > > 'DIVIDE',
> > > > 'LPAREN',
> > > > 'RPAREN',
> > > > 'EQUALS',
> > > > 'STRING',
> > > > ] + list(reserved.values())
>
> > > > # Regular expression rules for simple
> > tokens> > t_PLUS = r'\+'
> > > > t_MINUS = r'-'
> > > > t_TIMES = r'\*'
> > > > t_DIVIDE = r'/'
> > > > t_LPAREN = r'\('
> > > > t_RPAREN = r'\)'
> > > > t_EQUALS = r'='
>
> > > > def t_NAME(t):
> > > > r'[a-zA-Z_][a-zA-Z_0-9]*'
> > > > t.type = reserved.get(t.value,'NAME')
> > # Check for reserved> > words
> > > > return t
>
> > > > # A regular expression rule with some
> > action code> > def t_NUMBER(t):
> > > > r'\d+'
> > > > t.value = int(t.value)
> > > > return t
>
> > > > # Define a rule so we can track line
> > numbers> > def t_newline(t):
> > > > r'\n+'
> > > > t.lexer.lineno += len(t.value)
>
> > > > def t_STRING(t):
>
> > r'\"([^\\"]|(\\.))*\"'> > escaped = 0
> > > > str = t.value[1:-1]
> > > > new_str = ""
> > > > for i in range(0, len(str)):
> > > > c = str[i]
> > > > if escaped:
> > > > if c == "n":
> > > > c = "\n"
> > > > elif c == "t":
> > > > c = "\t"
> > > > new_str += c
> > > > escaped = 0
> > > > else:
> > > > if c == "\\":
> > > > escaped = 1
> > > > else:
> > > > new_str += c
> > > > t.value = new_str
> > > > return t
>
> > > > # A string containing ignored characters
> > (spaces and tabs)> > t_ignore = ' \t'
>
> > > > # Error handling rule
> > > > def t_error(t):
> > > > print "Illegal character '%s'" %
> > t.value[0]> > t.lexer.skip(1)
>
> > > > # Build the lexer
> > > > lexer = lex.lex()
> > > > [/code]
> > > > </code>
>
> > > > &
>
> > > > [code]
> > > > <code>
> > > > import ply.yacc as yacc
> > > > import sys
>
> > > > # Get the token map from the lexer.
> > This is required.> > from calclex import tokens
>
> > > > names = {}
> > > > def p_statement_assign(t):
> > > > 'statement : NAME EQUALS
> > expression'> > names[t[1]] = t[3]
>
> > > > def p_statement_expr(t):
> > > > 'statement : expression'
> > > > if t[1] != None:
> > > > print t[1]
> > > > else:
> > > > pass
>
> > > > def p_expression_name(t):
> > > > 'expression : NAME'
> > > > try:
> > > > t[0] = names[t[1]]
> > > > except LookupError:
> > > > print "Undefined name '%s'" %
> > t[1]> > t[0] = 0
>
> > > > def p_expression_plus(p):
> > > > 'expression : expression PLUS
> > term'> > p[0] = p[1] + p[3]
>
> > > > def p_expression_minus(p):
> > > > 'expression : expression MINUS
> > term'> > p[0] = p[1] - p[3]
>
> > > > def p_expression_term(p):
> > > > 'expression : term'
> > > > p[0] = p[1]
>
> > > > def p_term_times(p):
> > > > 'term : term TIMES factor'
> > > > p[0] = p[1] * p[3]
>
> > > > def p_term_div(p):
> > > > 'term : term DIVIDE factor'
> > > > p[0] = p[1] / p[3]
>
> > > > def p_term_factor(p):
> > > > 'term : factor'
> > > > p[0] = p[1]
>
> > > > def p_factor_num(p):
> > > > 'factor : NUMBER'
> > > > p[0] = p[1]
>
> > > > def p_factor_expr(p):
> > > > 'factor : LPAREN expression
> > RPAREN'> > p[0] = p[2]
>
> > > > def p_print(p):
> > > > '''expression : PRINT LPAREN STRING
> > RPAREN> > | PRINT LPAREN expression
> > RPAREN'''> > p[0] = p[3]
>
> > > > def p_quit(p):
> > > > 'expression : QUIT'
> > > > sys.exit()
>
> > > > # Error rule for syntax errors
> > > > def p_error(p):
> > > > print "Syntax error in
> > input!">
> > > > # Build the parser
> > > > parser = yacc.yacc()
>
> > > > if len(sys.argv) == 1:
> > > > while True:
> > > > try:
> > > > s = raw_input('calc > ')
> > > > except EOFError:
> > > > break
> > > > if not s: continue
> > > > result = parser.parse(s)
> > > > print result
>
> > > > elif sys.argv[1] ==
> > "-f":> > f = open(sys.argv[2],
> > "r")> > s = f.readlines()
> > > > for line in s:
> > > > result = parser.parse(line)
> > > > if result != None:
> > > > print "result != none"
> > > > print result
> > > > [/code]
> > > > </code>
> > > > When I run print("hello") it
> > says:> > hello
> > > > none
> > > > calc>
>
> > > > What's wrong?
> > > > I also posted it
> > > > athttp://ubuntuforums.org/showthread.php?p=6698006#post6698006&;
> > gt;>
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