[Wisp-cvs] wisp/users/dig tran.py,1.24,1.25

[<di...@us...>]

Update of /cvsroot/wisp/wisp/users/dig
In directory sc8-pr-cvs1:/tmp/cvs-serv21595

Modified Files:
	tran.py 
Log Message:
wrote the Constant_Sum class

Index: tran.py
===================================================================
RCS file: /cvsroot/wisp/wisp/users/dig/tran.py,v
retrieving revision 1.24
retrieving revision 1.25
diff -u -d -r1.24 -r1.25
--- tran.py	16 Apr 2003 20:57:07 -0000	1.24
+++ tran.py	17 Apr 2003 11:16:09 -0000	1.25
@@ -49,6 +49,51 @@
 Semicolon = Unique_Token(';')
 Dollar = Unique_Stackable('$')
 
+class Constant_Sum (Stackable):
+    def __init__ (this, plus = (), minus = (), scalar = 0L):
+        this.scalar = long(scalar)
+        this.plus = []; this.minus = []
+        for item in plus:
+            if isinstance(item, Symbol_Literal) or item == Dollar:
+                this.plus.append(item)
+            else: raise 'bad addee', item
+        for item in minus:
+            if isinstance(item, Symbol_Literal) or item == Dollar:
+                try:
+                    i = this.plus.index(item)
+                    this.plus.pop(i)
+                except ValueError:
+                    this.minus.append(item)
+            else: raise 'bad subtractee', item
+        this.plus = tuple(this.plus); this.minus = tuple(this.minus)
+    def __add__ (this, that):
+        if isinstance(that, Symbol_Literal) or that == Dollar:
+            that = Constant_Sum(plus = [that])
+        return Constant_Sum(plus = this.plus + that.plus,
+                            minus = this.minus + that.minus,
+                            scalar = this.scalar + that.scalar)
+    def __sub__ (this, that):
+        if isinstance(that, Symbol_Literal) or that == Dollar:
+            that = Constant_Sum(plus = [that])
+        return Constant_Sum(plus = this.plus + that.minus,
+                            minus = this.minus + that.plus,
+                            scalar = this.scalar - that.scalar)
+    def __repr__ (this):
+        arg = []
+        if this.plus: arg.append('plus = ' + `this.plus`)
+        if this.minus: arg.append('minus = ' + `this.minus`)
+        if this.scalar: arg.append('scalar = ' + `this.scalar`)
+        return 'Constant_Sum(%s)' % ', '.join(arg)
+    def __str__ (this):
+        res = ''
+        for item in this.plus: res += ' + ' + str(item)
+        for item in this.minus: res += ' - ' + str(item)
+        if this.scalar > 0: res += ' + ' + str(this.scalar)
+        else: res += ' - ' + str(-this.scalar)
+        if res[0] == ' ': res = res[1:]
+        if res[:2] == '+ ': res = res[2:]
+        return '(' + res + ')'
+
 class Lexer (shlex):
     def __init__ (this, filename):
         shlex.__init__(this, instream = open(filename, 'r'), infile = filename)