diff ply-3.8/test/yacc_literal.py @ 7267:343ff337a19b

<ais523> ` tar -xf ply-3.8.tar.gz
author HackBot
date Wed, 23 Mar 2016 02:40:16 +0000
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ply-3.8/test/yacc_literal.py	Wed Mar 23 02:40:16 2016 +0000
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+# -----------------------------------------------------------------------------
+# yacc_literal.py
+#
+# Grammar with bad literal characters
+# -----------------------------------------------------------------------------
+import sys
+
+if ".." not in sys.path: sys.path.insert(0,"..")
+import ply.yacc as yacc
+
+from calclex import tokens
+
+# Parsing rules
+precedence = (
+    ('left','+','-'),
+    ('left','*','/'),
+    ('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 '+' expression
+                  | expression '-' expression
+                  | expression '*' expression
+                  | expression '/' expression
+                  | expression '**' 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_error(t):
+    print("Syntax error at '%s'" % t.value)
+
+yacc.yacc()
+
+
+
+