From: Eric S. Raymond <esr@thyrsus,com>
Date: Wed, 14 Jan 2004 04:23:36 +0000 (+0000)
Subject: All the MAD rules about expressions.
X-Git-Tag: 1.0~204
X-Git-Url: http://thyrsus.com/gitweb/?a=commitdiff_plain;h=b40873d69791da2be7aff0cb62169c8f857bc0f6;p=mad.git

All the MAD rules about expressions.
---

diff --git a/mad b/mad
index f32c76c..446b8c7 100755
--- a/mad
+++ b/mad
@@ -5,15 +5,25 @@ tokens = (
     'LPAREN','RPAREN',
     'PLUS','MINUS','TIMES','DIVIDE','EQUALS',
     'NOT', 'OR', 'AND', 'THEN', 'EQV',
+    'EQ', 'NE', 'LT', 'LE', 'GT', 'GE',
+    'ABS', 'EXP',
     )
 
 # Tokens
 
-t_NOT      = r'\.NOT\.'
+t_ABS     = r'\.ABS\.'
+t_EXP     = r'\.P\.'
+t_NOT     = r'\.NOT\.'
 t_OR      = r'\.OR\.'
 t_AND     = r'\.AND\.'
 t_THEN    = r'\.OR\.'
 t_EQV     = r'\.EQV\.'
+t_LT      = r'\.L\.'
+t_LE      = r'\.LE\.'
+t_GT      = r'\.G\.'
+t_GE      = r'\.GE\.'
+t_EQ      = r'\.E\.'
+t_NE      = r'.\NE\.'
 t_PLUS    = r'\+'
 t_MINUS   = r'-'
 t_TIMES   = r'\*'
@@ -47,9 +57,12 @@ precedence = (
     ('left','OR'),
     ('left','AND'),
     ('right','NOT'),
+    ('left', 'EQ', 'NE', 'LT', 'LE', 'GT', 'GE'),
     ('left','PLUS','MINUS'),
     ('left','TIMES','DIVIDE'),
     ('right','UMINUS'),
+    ('left','EXP'),
+    ('right', 'ABS', 'UPLUS')
     )
 
 def p_statement_assign(t):
@@ -73,7 +86,15 @@ def p_expression_binop2(t):
     '''expression : expression OR expression
                   | expression AND expression
                   | expression THEN expression
-                  | expression EQV expression'''
+                  | expression EQV expression
+                  | expression LT expression
+                  | expression LE expression
+                  | expression GT expression
+                  | expression GE expression
+                  | expression EQ expression
+                  | expression NE expression
+                  | expression EXP expression
+                  '''
     t[0] = (t[2][1:-1].lower(), t[1], t[3])
 
 def p_expression_not(t):
@@ -84,6 +105,14 @@ def p_expression_uminus(t):
     'expression : MINUS expression %prec UMINUS'
     t[0] = ('-', t[2])
 
+def p_expression_uplus(t):
+    'expression : PLUS expression %prec UPLUS'
+    t[0] = ('+', t[2])
+
+def p_expression_abs(t):
+    'expression : ABS expression %prec ABS'
+    t[0] = ('abs', t[2])
+
 def p_expression_group(t):
     'expression : LPAREN expression RPAREN'
     t[0] = t[2]
@@ -106,6 +135,8 @@ def p_error(t):
 import yacc
 yacc.yacc()
 
+import readline
+
 while 1:
     try:
         s = raw_input('calc > ')