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| author | Polina Dudnik <pdudnik@gmail.com> | 2009-08-17 11:33:32 -0500 |
|---|---|---|
| committer | Polina Dudnik <pdudnik@gmail.com> | 2009-08-17 11:33:32 -0500 |
| commit | c438b2e431066d9324238e1c678ef68a3b721f33 (patch) | |
| tree | b79e72b3074441ce01d5c95207f96f71d16bed35 /ext/ply/test/yacc_unused_rule.py | |
| parent | 6654fe02daf6285cb43aa1c6e0e35f6c9c8786f1 (diff) | |
| parent | a43ae579dd3128a0ced2238532f26d99db197361 (diff) | |
| download | gem5-c438b2e431066d9324238e1c678ef68a3b721f33.tar.xz | |
Branch Merge
Diffstat (limited to 'ext/ply/test/yacc_unused_rule.py')
| -rw-r--r-- | ext/ply/test/yacc_unused_rule.py | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/ext/ply/test/yacc_unused_rule.py b/ext/ply/test/yacc_unused_rule.py new file mode 100644 index 000000000..4868ef863 --- /dev/null +++ b/ext/ply/test/yacc_unused_rule.py @@ -0,0 +1,72 @@ +# ----------------------------------------------------------------------------- +# yacc_unused_rule.py +# +# Grammar with an unused rule +# ----------------------------------------------------------------------------- +import sys + +if ".." not in sys.path: 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_assign(t): + 'statement : NAME EQUALS expression' + names[t[1]] = t[3] + +def p_statement_expr(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[2] == '/': 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_integer(t): + 'integer : NUMBER' + t[0] = t[1] + +def p_error(t): + print("Syntax error at '%s'" % t.value) + +yacc.yacc() + + + + |