diff options
Diffstat (limited to 'example/newclasscalc/calc.py')
| -rwxr-xr-x | example/newclasscalc/calc.py | 73 |
1 files changed, 40 insertions, 33 deletions
diff --git a/example/newclasscalc/calc.py b/example/newclasscalc/calc.py index a12e498..43c9506 100755 --- a/example/newclasscalc/calc.py +++ b/example/newclasscalc/calc.py @@ -12,7 +12,7 @@ # ----------------------------------------------------------------------------- import sys -sys.path.insert(0,"../..") +sys.path.insert(0, "../..") if sys.version_info[0] >= 3: raw_input = input @@ -21,6 +21,7 @@ import ply.lex as lex import ply.yacc as yacc import os + class Parser(object): """ Base class for a lexer/parser that has the rules defined as methods @@ -28,17 +29,17 @@ class Parser(object): tokens = () precedence = () - def __init__(self, **kw): self.debug = kw.get('debug', 0) - self.names = { } + self.names = {} try: - modname = os.path.split(os.path.splitext(__file__)[0])[1] + "_" + self.__class__.__name__ + modname = os.path.split(os.path.splitext(__file__)[0])[ + 1] + "_" + self.__class__.__name__ except: - modname = "parser"+"_"+self.__class__.__name__ + modname = "parser" + "_" + self.__class__.__name__ self.debugfile = modname + ".dbg" self.tabmodule = modname + "_" + "parsetab" - #print self.debugfile, self.tabmodule + # print self.debugfile, self.tabmodule # Build the lexer and parser lex.lex(module=self, debug=self.debug) @@ -53,29 +54,30 @@ class Parser(object): s = raw_input('calc > ') except EOFError: break - if not s: continue + if not s: + continue yacc.parse(s) - + class Calc(Parser): tokens = ( - 'NAME','NUMBER', - 'PLUS','MINUS','EXP', 'TIMES','DIVIDE','EQUALS', - 'LPAREN','RPAREN', - ) + 'NAME', 'NUMBER', + 'PLUS', 'MINUS', 'EXP', 'TIMES', 'DIVIDE', 'EQUALS', + 'LPAREN', 'RPAREN', + ) # Tokens - t_PLUS = r'\+' - t_MINUS = r'-' - t_EXP = r'\*\*' - t_TIMES = r'\*' - t_DIVIDE = r'/' - t_EQUALS = r'=' - t_LPAREN = r'\(' - t_RPAREN = r'\)' - t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*' + t_PLUS = r'\+' + t_MINUS = r'-' + t_EXP = r'\*\*' + t_TIMES = r'\*' + t_DIVIDE = r'/' + t_EQUALS = r'=' + t_LPAREN = r'\(' + t_RPAREN = r'\)' + t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*' def t_NUMBER(self, t): r'\d+' @@ -84,7 +86,7 @@ class Calc(Parser): except ValueError: print("Integer value too large %s" % t.value) t.value = 0 - #print "parsed number %s" % repr(t.value) + # print "parsed number %s" % repr(t.value) return t t_ignore = " \t" @@ -92,7 +94,7 @@ class Calc(Parser): def t_newline(self, t): r'\n+' t.lexer.lineno += t.value.count("\n") - + def t_error(self, t): print("Illegal character '%s'" % t.value[0]) t.lexer.skip(1) @@ -100,11 +102,11 @@ class Calc(Parser): # Parsing rules precedence = ( - ('left','PLUS','MINUS'), - ('left','TIMES','DIVIDE'), + ('left', 'PLUS', 'MINUS'), + ('left', 'TIMES', 'DIVIDE'), ('left', 'EXP'), - ('right','UMINUS'), - ) + ('right', 'UMINUS'), + ) def p_statement_assign(self, p): 'statement : NAME EQUALS expression' @@ -122,12 +124,17 @@ class Calc(Parser): | expression DIVIDE expression | expression EXP expression """ - #print [repr(p[i]) for i in range(0,4)] - if p[2] == '+' : p[0] = p[1] + p[3] - elif p[2] == '-': p[0] = p[1] - p[3] - elif p[2] == '*': p[0] = p[1] * p[3] - elif p[2] == '/': p[0] = p[1] / p[3] - elif p[2] == '**': p[0] = p[1] ** p[3] + # print [repr(p[i]) for i in range(0,4)] + if p[2] == '+': + p[0] = p[1] + p[3] + elif p[2] == '-': + p[0] = p[1] - p[3] + elif p[2] == '*': + p[0] = p[1] * p[3] + elif p[2] == '/': + p[0] = p[1] / p[3] + elif p[2] == '**': + p[0] = p[1] ** p[3] def p_expression_uminus(self, p): 'expression : MINUS expression %prec UMINUS' |