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author | David Beazley <dave@dabeaz.com> | 2006-11-21 15:09:46 +0000 |
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committer | David Beazley <dave@dabeaz.com> | 2006-11-21 15:09:46 +0000 |
commit | 80c8c2d0a6e63745ff099b33ad2848b6fb17285a (patch) | |
tree | 36d223fc55a5649dc85a4f8a3fa9d17cb130c6c3 /test/yacc_dup.py | |
download | ply-80c8c2d0a6e63745ff099b33ad2848b6fb17285a.tar.gz |
initial checkin
Diffstat (limited to 'test/yacc_dup.py')
-rw-r--r-- | test/yacc_dup.py | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/test/yacc_dup.py b/test/yacc_dup.py new file mode 100644 index 0000000..e0b683d --- /dev/null +++ b/test/yacc_dup.py @@ -0,0 +1,69 @@ +# ----------------------------------------------------------------------------- +# yacc_dup.py +# +# Duplicated rule name +# ----------------------------------------------------------------------------- +import sys +sys.tracebacklimit = 0 + +sys.path.insert(0,"..") +import ply.yacc as yacc + +from calclex import tokens + +# Parsing rules +precedence = ( + ('left','PLUS','MINUS'), + ('left','TIMES','DIVIDE'), + ('right','UMINUS'), + ) + +# dictionary of names +names = { } + +def p_statement(t): + 'statement : NAME EQUALS expression' + names[t[1]] = t[3] + +def p_statement(t): + 'statement : expression' + print t[1] + +def p_expression_binop(t): + '''expression : expression PLUS expression + | expression MINUS expression + | expression TIMES expression + | expression DIVIDE expression''' + if t[2] == '+' : t[0] = t[1] + t[3] + elif t[2] == '-': t[0] = t[1] - t[3] + elif t[2] == '*': t[0] = t[1] * t[3] + elif t[3] == '/': t[0] = t[1] / t[3] + +def p_expression_uminus(t): + 'expression : MINUS expression %prec UMINUS' + t[0] = -t[2] + +def p_expression_group(t): + 'expression : LPAREN expression RPAREN' + t[0] = t[2] + +def p_expression_number(t): + 'expression : NUMBER' + t[0] = t[1] + +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_error(t): + print "Syntax error at '%s'" % t.value + +yacc.yacc() + + + + |