From 619c2c652420729c830736e6dfd0b0f4fe0ad0be Mon Sep 17 00:00:00 2001
From: Marcell Vazquez-Chanlatte <mvc@linux.com>
Date: Fri, 8 Jul 2016 20:59:56 -0700
Subject: [PATCH] absorb coefficients into sympy expr

---
 stl.py        | 15 +++------------
 stl_parser.py |  8 ++------
 2 files changed, 5 insertions(+), 18 deletions(-)

diff --git a/stl.py b/stl.py
index 3537585..557a1aa 100644
--- a/stl.py
+++ b/stl.py
@@ -17,12 +17,9 @@ t_sym = Symbol('t', positive=True)
 
 class LinEq(namedtuple("LinEquality", ["terms", "op", "const"])):
     def __repr__(self):
-        n = len(self.terms)
-        rep = "{}"
-        if n > 1:
-            rep += " + {}"*(n - 1)
-        rep += " {op} {c}"
-        return rep.format(*self.terms, op=self.op, c=self.const)
+        rep = "{lhs} {op} {c}"
+        lhs = sum(t.id for t in self.terms)
+        return rep.format(lhs=lhs, op=self.op, c=self.const)
 
     def children(self):
         return []
@@ -34,12 +31,6 @@ class Var(namedtuple("Var", ["kind", "id", "time"])):
         return "{i}{t}".format(k=self.kind.name, i=self.id, t=time_str)
 
 
-class Term(namedtuple("Term", ["coeff", "var"])):
-    def __repr__(self):
-        coeff = str(self.coeff) + "*" if self.coeff != 1 else ""
-        return "{c}{v}".format(c=coeff, v=self.var)
-
-
 class Interval(namedtuple('I', ['lower', 'upper'])):
     def __repr__(self):
         return "[{},{}]".format(self.lower, self.upper)
diff --git a/stl_parser.py b/stl_parser.py
index 28fc5a0..e19ee55 100644
--- a/stl_parser.py
+++ b/stl_parser.py
@@ -2,16 +2,12 @@
 
 # TODO: consider using sympy to interpret stuff
 # TODO: break out into seperate library
-# TODO: allow matrix to be symbolically parsed in STL_GRAMMAR
 # TODO: allow multiplication to be distributive
 # TODO: support reference specific time points
 # TODO: add Implies and Iff syntactic sugar
 # TODO: add support for parsing Until
 # TODO: support variables on both sides of ineq
 # TODO: Allow -x = -1*x
-# TODO: change way of parsing dt
-# - Allow inside of time index
-# - Allow dt*x rather than dt*1*x
 
 from functools import partialmethod
 from collections import namedtuple
@@ -137,7 +133,7 @@ class STLVisitor(NodeVisitor):
     def visit_term(self, _, children):
         coeffs, var = children
         c = coeffs[0] if coeffs else 1
-        return stl.Term(c, var)
+        return lens(var).id*c
 
     def visit_coeff(self, _, children):
         dt, coeff, *_ = children
@@ -147,7 +143,7 @@ class STLVisitor(NodeVisitor):
     def visit_terms(self, _, children):
         if isinstance(children[0], list):
             term, _1, sgn ,_2, terms = children[0]
-            terms = lens(terms)[0].coeff * sgn
+            terms = lens(terms)[0].id * sgn
             return [term] + terms
         else:
             return children