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-rw-r--r--ext/ply/test/yacc_sr.py62
1 files changed, 62 insertions, 0 deletions
diff --git a/ext/ply/test/yacc_sr.py b/ext/ply/test/yacc_sr.py
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+++ b/ext/ply/test/yacc_sr.py
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+# -----------------------------------------------------------------------------
+# yacc_sr.py
+#
+# A grammar with shift-reduce conflicts
+# -----------------------------------------------------------------------------
+import sys
+sys.tracebacklimit = 0
+
+from calclex import tokens
+
+# Parsing rules
+
+# 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[3] == '/': t[0] = t[1] / t[3]
+
+def p_expression_uminus(t):
+ 'expression : MINUS expression'
+ 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
+
+import yacc
+yacc.yacc()
+
+
+
+