initial eval() implementation

src/mapcss/Eval.py

@@ -0,0 +1,99 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#    This file is part of kothic, the realtime map renderer.
+
+#   kothic is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+
+#   kothic is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+
+#   You should have received a copy of the GNU General Public License
+#   along with kothic.  If not, see <http://www.gnu.org/licenses/>.
+
+NONE = ""
+
+class Eval():
+  def __init__(self, s='eval()'):
+    """
+    Parse expression and convert it into Python
+    """
+    s = s[5:-1].strip()
+    s
+    self.expr = compile (s, "MapCSS expression", "eval")
+
+  def compute(self, tags={}, props = {}, xscale = 1., zscale = 0.5 ):
+    """
+    Compute this eval()
+    """
+    for k,v in tags.iteritems():
+      try:
+        tag[k] = float(v)
+      except:
+        pass
+   # try:
+    return str(eval(self.expr, {}, {
+      "tags":lambda x: tags.get(x,""),
+      "prop":lambda x: props.get(x,""),
+      "num": m_num,
+      "metric": lambda x: m_metric(x, xscale),
+      "zmetric": lambda x: m_metric(x, zscale),
+      "str": str,
+      "any": m_any,
+        }))
+   # except:
+   #   return ""
+
+    
+  def __repr__(self):
+    return "eval(%s)"%repr(self.expr)
+
+def m_any(*x):
+  """
+  any() MapCSS feature
+  """
+  for t in x:
+    if t:
+      return t
+  else:
+    return ""
+
+def m_num(x):
+  """
+  num() MapCSS feature
+  """
+  try:
+    return float(str(x))
+  except ValueError:
+    return 0
+def m_metric(x, t):
+  """
+  metric() and zmetric() function.
+  """
+  x = str(x)
+  try:
+    return float(x)*float(t)
+  except:
+    "Heuristics."
+    # FIXME: add ft, m and friends
+    x = x.strip()
+    try:
+      if x[-1] == "m":
+        return float(x[0:-1])*float(t)
+    except:
+      return ""
+#def str(x):
+  #"""
+  #str() MapCSS feature
+  #"""
+  #return __builtins__.str(x)
+
+
+if __name__ == "__main__":
+  a = Eval("""eval( any(metric(tags("height")), metric ( tags("building:levels") ) * 3))""")
+  print repr(a)
+  print a.compute({"building:levels":"3m"})