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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 11:44:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-21 11:44:51 +0000 |
commit | 9e3c08db40b8916968b9f30096c7be3f00ce9647 (patch) | |
tree | a68f146d7fa01f0134297619fbe7e33db084e0aa /third_party/python/ply/example/newclasscalc/calc.py | |
parent | Initial commit. (diff) | |
download | thunderbird-upstream.tar.xz thunderbird-upstream.zip |
Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/python/ply/example/newclasscalc/calc.py')
-rwxr-xr-x | third_party/python/ply/example/newclasscalc/calc.py | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/third_party/python/ply/example/newclasscalc/calc.py b/third_party/python/ply/example/newclasscalc/calc.py new file mode 100755 index 0000000000..43c9506a8a --- /dev/null +++ b/third_party/python/ply/example/newclasscalc/calc.py @@ -0,0 +1,167 @@ +#!/usr/bin/env python + +# ----------------------------------------------------------------------------- +# calc.py +# +# A simple calculator with variables. This is from O'Reilly's +# "Lex and Yacc", p. 63. +# +# Class-based example contributed to PLY by David McNab. +# +# Modified to use new-style classes. Test case. +# ----------------------------------------------------------------------------- + +import sys +sys.path.insert(0, "../..") + +if sys.version_info[0] >= 3: + raw_input = input + +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 + """ + tokens = () + precedence = () + + def __init__(self, **kw): + self.debug = kw.get('debug', 0) + self.names = {} + try: + modname = os.path.split(os.path.splitext(__file__)[0])[ + 1] + "_" + self.__class__.__name__ + except: + modname = "parser" + "_" + self.__class__.__name__ + self.debugfile = modname + ".dbg" + self.tabmodule = modname + "_" + "parsetab" + # print self.debugfile, self.tabmodule + + # Build the lexer and parser + lex.lex(module=self, debug=self.debug) + yacc.yacc(module=self, + debug=self.debug, + debugfile=self.debugfile, + tabmodule=self.tabmodule) + + def run(self): + while 1: + try: + s = raw_input('calc > ') + except EOFError: + break + if not s: + continue + yacc.parse(s) + + +class Calc(Parser): + + tokens = ( + '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_]*' + + def t_NUMBER(self, t): + r'\d+' + try: + t.value = int(t.value) + except ValueError: + print("Integer value too large %s" % t.value) + t.value = 0 + # print "parsed number %s" % repr(t.value) + return t + + t_ignore = " \t" + + 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) + + # Parsing rules + + precedence = ( + ('left', 'PLUS', 'MINUS'), + ('left', 'TIMES', 'DIVIDE'), + ('left', 'EXP'), + ('right', 'UMINUS'), + ) + + def p_statement_assign(self, p): + 'statement : NAME EQUALS expression' + self.names[p[1]] = p[3] + + def p_statement_expr(self, p): + 'statement : expression' + print(p[1]) + + def p_expression_binop(self, p): + """ + expression : expression PLUS expression + | expression MINUS expression + | expression TIMES expression + | 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] + + def p_expression_uminus(self, p): + 'expression : MINUS expression %prec UMINUS' + p[0] = -p[2] + + def p_expression_group(self, p): + 'expression : LPAREN expression RPAREN' + p[0] = p[2] + + def p_expression_number(self, p): + 'expression : NUMBER' + p[0] = p[1] + + def p_expression_name(self, p): + 'expression : NAME' + try: + p[0] = self.names[p[1]] + except LookupError: + print("Undefined name '%s'" % p[1]) + p[0] = 0 + + def p_error(self, p): + if p: + print("Syntax error at '%s'" % p.value) + else: + print("Syntax error at EOF") + +if __name__ == '__main__': + calc = Calc() + calc.run() |